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2017 | Buch

Converging Clinical and Engineering Research on Neurorehabilitation II

Proceedings of the 3rd International Conference on NeuroRehabilitation (ICNR2016), October 18-21, 2016, Segovia, Spain

herausgegeben von: Jaime Ibáñez, José González-Vargas, José María Azorín, Metin Akay, José Luis Pons

Verlag: Springer International Publishing

Buchreihe : Biosystems & Biorobotics

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Über dieses Buch

The book reports on advanced topics in the areas of neurorehabilitation research and practice. It focuses on new methods for interfacing the human nervous system with electronic and mechatronic systems to restore or compensate impaired neural functions. Importantly, the book merges different perspectives, such as the clinical, neurophysiological, and bioengineering ones, to promote, feed and encourage collaborations between clinicians, neuroscientists and engineers. Based on the 2016 International Conference on Neurorehabilitation (ICNR 2016) held on October 18-21, 2016, in Segovia, Spain, this book covers various aspects of neurorehabilitation research and practice, including new insights into biomechanics, brain physiology, neuroplasticity, and brain damages and diseases, as well as innovative methods and technologies for studying and/or recovering brain function, from data mining to interface technologies and neuroprosthetics. In this way, it offers a concise, yet comprehensive reference guide to neurosurgeons, rehabilitation physicians, neurologists, and bioengineers. Moreover, by highlighting current challenges in understanding brain diseases as well as in the available technologies and their implementation, the book is also expected to foster new collaborations between the different groups, thus stimulating new ideas and research directions.

Inhaltsverzeichnis

Frontmatter
Erratum to: Stance Sub-phases Gait Event Detection in Real-Time for Ramp Ascent and Descent
Hafiz F. Maqbool, Muhammad A. B. Husman, Mohammed I. Awad, Alireza Abouhossein, Nadeem Iqbal, Abbas A. Dehghani-Sanij

Characterization and Modulation of Neurophysiological Signals: New Approaches for Targeted Neuromodulation of the Motor Nervous System (I)

Frontmatter
Motor Outcomes of Repetitive Transcranial Magnetic Stimulation Are Dependent on the Specific Interneuron Circuit Targeted

Different aspects of motor behaviour may engage distinct interneuron circuits in the human motor cortex. If so, the behavioural effects of repetitive transcranial magnetic stimulation (rTMS) protocols may critically depend on the specific circuit stimulated. We used TMS of the hand area to activate two distinct synaptic inputs to corticospinal neurons by altering the direction of current induced in the brain: posterior-anterior (PA inputs) and anterior-posterior (AP inputs). We found AP inputs to be preferentially suppressed during motor preparation in a reaction time task. We also show that preconditioning PA, but not AP, inputs with via rTMS facilitates performance of a ballistic motor task. These results suggest that behavioural effects of rTMS may be most evident when relevant interneuron circuits are targeted.

Ricci Hannah, Martin Sommer, Sean Cavanagh, Steven Jerjian, John C. Rothwell
Novel Non-invasive Brain Stimulation Techniques to Modify Brain Networks After Stroke

Improving motor function after stroke is an in an important area of research in neurorehabilitation. Clinical trials using non-invasive brain stimulation (NIBS) to improve rehabilitation outcome after stroke showed modest effect sizes or even lack of efficacy [1–3]. One important reason for this limited therapeutic success may be too simplistic “one hat fits it all” strategies, e.g. aiming at increasing excitability in the ipsilesional primary motor cortex [4] that disregard high interindividual variability in responses to NIBS protocols, even in healthy subjects [5]. Several strategies that have been recently developed to improve therapeutic effect size of NIBS during stroke neurorehabilitation will be detailed in this presentation.

Ulf Ziemann
Effect of Feedback Type on the Effectiveness of a Novel Associative BCI Protocol Targeting the Tibialis Anterior Muscle

By continuous pairing of user intend (interpreted with a Brain-computer-interface—BCI system) and artificial reproduction of that movement BCIs for neuromodulation follow the principle of Hebbian association that underlies motor learning leading to neuroplasticity and associated functional changes. In the current study, movement-related cortical potentials (MRCPs) were detected using elecroencephalography (EEG) during repetitions of foot dorsiflexion. Detection triggered a either a robotic actuator or a functional electrical stimulator timed so that the resulting afferent volley arrived at the peak negative phase of the MRCP. The tibialis anterior motor evoked potentials increased significantly following both types of interventions (p = 0.006) and there was no difference between their effectiveness (p = 0.344). Results have implications for the design of BCIs intended for neuromodulation.

Natalie Mrachacz-Kersting
Static Magnetic Field Stimulation: An Ancient-Novel Member of the Non-invasive Brain Stimulation Techniques

The neurophysiological techniques that can induce plasticity or simply modulate cortical excitability or produce interference with normal brain activity and behavior are known as neuromodulation techniques. The interest in using neuromodulation techniques in neurorehabilitation has sharply increased in the last years. Recently we described that transcranial application of static magnetic field is able to interfere with brain activity.

Antonio Oliviero

Characterization and Modulation of Neurophysiological Signals: New Approaches for Targeted Neuromodulation of the Motor Nervous System (II)

Frontmatter
A Computational Framework for the Design of Spinal Neuroprostheses

Severe Spinal Cord Injury (SCI) alters the communication between supra-spinal centers and the sensorimotor networks coordinating limb movements, which are usually located below the injury. Epidural electrical stimulation of lumbar segments has shown the ability to enable descending motor control of the lower limbs in rodents and humans with severe paralysis. Using computational models and in vivo experiments in rodents, we found that EES facilitates motor control through the recruitment of muscle spindle feedback circuits. Stimulation protocols targeting these circuits allowed the selective modulation of synergistic muscle groups, both in rodents and non-human primates. This framework supports the design of stimulation strategies for humans.

Marco Capogrosso, Erwan Bezard, Jocelyne Bloch, Gregoire Courtine, Silvestro Micera
Operant Conditioning of the Tibialis Anterior Motor Evoked Potential to Transcranial Magnetic Stimulation

The activity of corticospinal pathways is important in movement control and its plasticity is essential for learning motor skills and re-learning them after spinal cord injury (SCI) and other CNS disorders. After SCI, corticospinal excitability and connectivity diminish, as SCI disturbs supraspinal connections. However, this can be reversed. Thus, if there is a way to enhance the function of corticospinal pathways, motor function recovery may be improved. The central hypothesis of this study is that operant conditioning of the corticospinal motor evoked potential can strengthen corticospinal connectivity and thereby improve motor function recovery in people after incomplete SCI.

Aiko K. Thompson, Rachel H. Cote, Christina R. Thompson
Cycling with Plantar Stimulation Increases Cutaneomuscular-Conditioned Spinal Excitability in Subjects with Incomplete Spinal Cord Injury

The aim of this study was to investigate the effects of a rehabilitation exercise for people with incomplete Spinal Cord Injury (iSCI), based on cycling and combined afferent electrical stimulation (ES-cycling), to normalize spinal activity in response to a plantar cutaneous stimulation. We studied Soleus H-reflex excitability following ipsilateral plantar electrical stimulation applied at 25–100 ms inter-stimulus intervals (ISI’s), on 13 non-injured subjects and 10 subjects with iSCI. Reflexes were tested before and after a 10 min session of ES-cycling to evaluate the effects of the exercise. Plantar-conditioned H-reflex modulation increased in the iSCI group after ES-cycling, compared to the limited modulation observed before the exercise. Conversely, the non-injured group presented pronounced modulation both before and after the exercise. We conclude that ES-cycling improved plantar-conditioned spinal neuronal excitability in subjects with iSCI. Results could be used in the design of more effective leg-cycling therapies, to promote central neuroplasticity and rehabilitation in lower limb muscle activity following iSCI.

Stefano Piazza, Diego Serrano-Muñoz, Julio Gómez-Soriano, Diego Torricelli, Gerardo Avila-Martin, Iriana Galan-Arriero, Jose Luis Pons, Julian Taylor
Identifying Spinal Lesion Site from Surface EMG Grid Recordings

Human spinal cord injuries (SCI) disrupt the pathways between the brain and spinal cord, resulting in substantial impairment and loss of function. We recorded surface electromyogram signals (sEMG) using grids of electrodes (8 × 8) applied on Biceps Brachii and Triceps Brachii muscles. We aimed to identify dysfunctional muscle activation in individuals with incomplete injuries of the cervical cord. We recorded sEMG and force from one SCI individual (Chronic, C5-C7, ASIA score D) and from a neurologically intact person during the generation of an isometric sinusoidal force trajectory (15s elbow flexion + 15s elbow extension). We found that the SCI subject was not able to follow the target force during elbow extension as precisely as in elbow flexion. Failure in tracking force was quantified using the root mean squared error between the target and generated forces. Our data suggest that C7 was the most affected spinal segment while the anatomical level had been diagnosed C5-C7. These data show the potential use of sEMG grid recording for localizing the motor lesion level within the spinal cord. Additional confirmatory studies are necessary to validate our results.

B. Afsharipour, M. Sandhu, G. Rasool, N. L. Suresh, W. Z. Rymer
New Tools for Old Problems: Magnetic Stimulation to Study (and Help) the Brain

Magnetic stimulation techniques, either repetitive TMS (rTMS) or Static Magnetic Fields, allow to modulate brain activity through the skull in a non invasive and painless way. When rTMS is used, low frequencies of stimulation (≤1 Hz) produce inhibitory changes in excitability whilst higher rates (above 5 Hz) appear to produce increasing excitability Pascual-Leone et al. (J. Clin. Neurophysiol. 15(4):333–343, 1998) [1]. By using two different experimental approaches (anaestethetized cat and monkey) to study the early visual system, we show here that rTMS applied at low and high frequency has opposing effects on the EEG. These effects can be detected locally but also in a wider spatial extent. Further, we report data supporting the suppressive nature of the static magnetic stimulation. It supports the idea that static magnets could be used for different purposes ranging from experimental studies to clinical applications.

Casto Rivadulla, Jordi Aguilá-Macías, Sandra Prieto-Soler, Juan Aguilar, Javier Cudeiro

Characterization and Modulation of Neurophysiological Signals: Operant Conditioning of Spinal Reflexes: From Basic Science to Functional Changes in Health and Disease

Frontmatter
Effects of H-Reflex Operant Conditioning in Humans

Operant conditioning of a spinal reflex can modify specific spinal cord pathways and can thereby affect behaviors that use these pathways. We have shown that down-conditioning the soleus H-reflex during standing can improve walking in people with chronic incomplete spinal cord injury (SCI); after successful conditioning people walked faster and more symmetrically with better locomotor EMG activity [1]. Based on this success, we are currently testing the hypothesis that locomotor reflex activity can be further improved toward a more normal pattern by reducing the soleus H-reflex size during the swing phase of the gait cycle, where the H-reflex is very small or absent in normal subjects but abnormally large in people with spasticity due to chronic SCI.

Aiko K. Thompson, Stephanie D. Pudlik, Christina R. Thompson
Operant Conditioning of the Human Soleus Short Latency Stretch Reflex and Implications for the Medium Latency Soleus Stretch Reflex

The human soleus stretch reflex is comprised of several components with different latencies typically termed the SLR, MLR and in some cases LLR component. The SLR is suggested to be mediated by Gr Ia afferent arising from activation of spindle afferents, the MLR is predominantly due to gr Ib and II feedback while LLR likely contains a cortical component. Here we report data on the changes in both the SLR and MLR following a well-established conditioning protocol. Participants attended 30 sessions where the initial six served as a baseline measure of reflex size and the following 24 sessions were devoted to training the participants to either increase or decrease the SLR component. Following successful up-conditioning of the SLR, the MLR remained unchanged. However the SLR and MLR both decreased with down-conditioning. This suggests that the MLR is not exclusively Gr Ib or II based but has some Ia afferent input.

Natalie Mrachacz-Kersting, Uwe G. Kersting

Characterization and Modulation of Neurophysiological Signals: Experimental Approaches to Restore Loss of Function

Frontmatter
Human Adult Oligodendrocyte Precursor Cell Biology: The Bottleneck for Effective Pro-remyelinating Therapies for Multiple Sclerosis

During pre- and postnatal development, mature oligodendrocytes derive from Oligodendrocyte Precursor Cells (OPCs).

Fernando de Castro
Modulation of Input-Output Balance by the Axon Initial Segment

Brain stimulation therapies involve activating or touching the brain directly with electricity, magnets, or implants to treat different brain traumas or disorders. However, most studies do not take in account the relation between these therapies and the corresponding morphological and molecular changes in neurons. These changes depend on the external stimulation frequency and intensity, and are different in each subset of neurons, meaning an absence of neuronal excitability control. In this sense, the Axon Initial Segment is place of action potential initiation. This axonal domain has the property of changing its density of voltage gated ion channels, its position and length in response to different levels of stimuli. In this presentation we will review the molecular mechanisms that control neuronal excitability at the Axon Initial Segment and the different types of AIS plasticity that may explain the success or failure of therapies involving electrical stimulation of neurons.

Juan José Garrido
Using LFP Generators to Detect Abnormal Activity in Multiple Networks: A Tool to Explore Diaschisis

Following focal brain insults, besides primary lesions others in remote sites undergo secondary damage, a phenomenon known as diaschisis. The mechanisms underlying secondary damage are not known. Presumably, the damage is transmitted through vascular or neural pathways, but current techniques are poorly sensitive to detect changes in activity of specific pathways. We proposed here the use of local field potential (LFP) generators obtained through spatial discrimination techniques applied to high-density intracerebral recordings. These allow the characterization of normal and abnormal ranges of activity in isolated synaptic pathways. As a test in anesthetized animals we used the generation of spreading depolarization (SD) waves, characteristic of the ischemic penumbra. We found that unilateral SDs in the hippocampus led to changes of activity in nearby populations, but also in specific remote locations in both hemispheres. These remote LFP generators displayed distinct temporal patterns, and their relative variance is modified in a complex manner. The initial findings indicate that irradiation of abnormal synaptic activity to several interlaced networks may promote secondary malfunctioning in distant brain regions through both hypo and hyperactivity.

Óscar Herreras, Daniel Torres, Tania Ortuño, Julia Makarova
The Brain’s Camera. Optimal Algorithms for Wiring the Eye to the Brain Shape How We See

The problem of sending information at long distances, without significant attenuation and at a low cost, is common to both artificial and natural environments. In the brain, a widespread strategy to solve the cost-efficiency trade off in long distance communication is the presence of convergent pathways, or bottlenecks. In the visual system, for example, to preserve resolution, information is acquired by a first layer with a large number of neurons (the photoreceptors in the retina) and then compressed into a much smaller number of units in the output layer (the retinal ganglion cells), to send that information to the brain at the lowest possible metabolic cost. Recently, we found experimental evidence for an optimal compression-decompression algorithm in the early visual pathway that reproduces the strategies used in digital image processing. Our results bear strong consequences for our current understanding of the development and function of the visual thalamus and cortex.

M. Molano-Mazón, A. J. Valiño-Perez, S. Sala, M. Martínez-García, J. Malo, F. T. Sommer, J. A. Hirsch, L. M. Martinez
How Do Interconnected Neuronal Networks Adjust to External Stimulation: Parametric Studies of DBS-FMRI

The use of intracranial electrical microstimulation for the treatment of neurologic and psychiatric disorders, as well as in neural prosthesis, has experienced an exponential growth in the last decade. Despite this spectacular expansion and the great promise of some applications, little is known about the precise neurobiological mechanisms underlying its actions, the rules governing activity propagation during stimulation and the probable roles obeyed by short and long-term plasticity processes in the synapses being activated. We combine deep brain electric microstimulation and functional magnetic resonance imaging (fMRI) to investigate local and brain-wide functional networks activated by different sets of stimulation parameters that produced distinct behavioral effects.

Javier Moya, Daniel Torres, David Moratal, Santiago Canals

Characterization and Modulation of Neurophysiological Signals: Sensory Restoration and Adaptive Neural Interfaces

Frontmatter
Monitoring Parkinson’s Disease Rehabilitation from Phonation Biomechanics

Neuromotor disease rehabilitation may benefit from certain phonation tasks as singing exercises. A protocol is being designed to combine certain rehabilitation tasks, consisting in respiratory and phonation, while carrying out simple singing drills. The objective evaluation of phonation before, during and after singing exercises is conducted from the estimation of biomechanical features of the glottal source. These features are compared using information theory and quadratic entropy principles. Results from Parkinson Disease patients under the rehabilitation programme are presented and discussed.

P. Gómez-Vilda, P. Lirio, D. Palacios-Alonso, V. Rodellar-Biarge, N. Polo
Influence of Interactions Between Virtual Channels in Cochlear Implants: Biological Stimulation Using Current Source Method

Cochlear implants are devices which are surgically inserted into the internal ear, partially restoring hearing to people with profound deafness. Alternatives to improve levels of auditory perception are to increase the number of channels or frequency bands, that would need to increase the number of electrodes or electrode pairs per channel. Monopolar Virtual Channel (MPVC) stimulation mode increases the number of channels without increasing the number of electrodes using current steering. With this stimulation mode what still happens is interaction between the virtual channels, so some people who have these implants have not reported a striking improvement. In the present work, parameters of this electrical stimulation mode are modeled and evaluated. The results suggested that the maximal stimulation current can be determined so that no electrical interaction will occur between adjacent channels. If the stimulation current is higher than the calculated value, electrical interactions will occur between adjacent channels.

Ernesto A. Martínez–Rams, Vicente Garcerán–Hernández, Mikel Val, Eduardo Fernandez, José Manuel Ferrández
Epileptic Photosensitivity: Towards Implementation of Preventative Measures

Photosensitive epilepsy (PSE) is the most common form of human reflex epilepsy, affecting up to 10 % of children with epilepsy. Moreover, between 4 and 9 % of the population carries this risk factor, and may be unaware of this risk until an unfortunate stimulus might discover it [1].

Jaime Parra
Neuroplasticity and Blindness: From Clinical Setting to Technology Research

Clinical applications such as artificial vision require extraordinary, diverse, lengthy and intimate collaborations among basic scientists, engineers and clinicians. The greater impediments to future progress in this field are not only the technical, engineering and surgical issues that remain to be solved, but also the development and implementation of strategies designed to interface with visually deprived brain specifically tailored for an individual patient’s own needs.

Arantxa Alfaro, Angela Bernabeu, Eduardo Fernández
Visual Prostheses—The Past and the Future

We have entered a new era for visual prostheses brought about by the clinical application of this medical technology. Following the success of cochlear implants we are now starting to see patients fitted with retinal prostheses. Here I discuss the history of visual prosthesis development, the obstacles that have been faced along the path to its clinical use, some of the barriers that remain before its full promise can be fulfilled and ongoing research, which seeks to break down these barriers. The development of a complex medical device like a visual prosthesis can be considered a case study for the development of invasive medical devices, particularly those that interface with the nervous system. So the lessons learned in developing such devices should have value for those interested in developing other complex medical technologies. Vision is the sense that is most valued by humans and it occupies a substantial fraction of our brains. It is little surprising therefore that restoration of vision for those who have lost this sense is particularly valued.

John B. Troy

Characterization and Modulation of Neurophysiological Signals: Investigating Neural Control Strategies of Movement with EMG Signals

Frontmatter
Introduction to EMG for the Study of Movement: From Bipolar to High-Density

Appropriate inter-electrode distance (IED) is needed to enable the reconstruction of detailed muscle activity and obtain correct map’s features of a High Density surface EMG (HDsEMG). The spatial frequency bandwidth of sEMG was estimated by placing a grid of 16 × 8 pin electrodes (IED = 5 mm) on biceps brachii (BB) and medial deltoid (MD) of a subject and sampling the signals at 2048 Hz. The zero padded 2D FFT (64 × 64 points) was performed for each instantaneous map without removing the offset of the map. Two arbitrary definitions of spatial bandwidth f max were tested: (1) f max ≤ 87.5 c/m that supports 90 % of total power, (2) f max ≤ 87.5 c/m such that the amplitudes of all spectral lines after it are <5 % of PSD max. We found that 90 % of the f max values for BB (MD) muscle lies between 25.0–87.5 (21.9–87.5) c/m and 18.8–46.9 c/m for definition 1 and 2 respectively.

S. D. H. Soedirdjo, B. Afsharipour, P. Cattarello, R. Merletti
A Novel Measure of Motor Unit Action Potential Variability in Nonstationary Surface Electromyograms

We introduce and validate a novel measure of motor unit action potential (MUAP) variability in surface electromyograms (EMG) that are recorded during dynamic muscle contractions. This measure is fully automatic, builds on the motor unit spike trains as estimated by previously introduced Convolution Kernel Compensation method and allows tracking of MUAP variability for each individual motor unit separately. Preliminary tests on synthetic surface EMG signals demonstrate its high accuracy and capability of identifying cyclostationary changes of MUAP shapes. This measure represents the first, but very important step towards motor unit identification in dynamic muscle contractions.

Vojko Glaser, Aleš Holobar
Neural Control of Muscles in Tremor Patients

Essential tremor and Parkinson’s disease cause abnormal oscillatory activity in a variety of brain structures that is transmitted to spinal motoneurons and generates tremor. Because the motoneuron pool integrates synaptic inputs from descending and spinal circuits, the decoding of its activity provides a view on all the neural pathways involved in tremor generation. We investigated tremor mechanisms by analyzing the behavior of populations of motoneurons within a single muscle, across antagonist muscle pairs, and in relation to cortical activity. We observed that tremor is caused by a common cortical input projected to all motoneurons. We also found that spinal reflex pathways contribute fundamentally to shaping tremor properties. We posit that although ET and PD tremor are centrally generated, tremor properties are strongly determined by the interaction between descending and afferent inputs to the motoneuron pool.

Juan A. Gallego, Jakob L. Dideriksen, Ales Holobar, Eduardo Rocon, José L. Pons, Dario Farina
Corticospinal Coherence During Frequency-Modulated Isometric Ankle Dorsiflexion

In this paper we analyze the role of corticomuscular transmission for the time-varying force control. Corticospinal coherence is assessed during frequency-modulated isometric ankle dorsiflexions. Our preliminary results show a significant coupling between EEG signals and motor unit spike trains at the target frequency, suggesting that low-frequency cortical oscillations may have an important functional role in force control.

A. Úbeda, A. Del Vecchio, M. Sartori, U. Ş. Yavuz, F. Negro, F. Felici, J. M. Azorín, D. Farina
Stretch Reflexes in Shoulder Muscles Are Described Best by Heteronymous Pathways

The shoulder is a highly mobile joint spanned by complex musculature. Careful coordination of muscles is required to maintain shoulder integrity and stability. The objective of this study was to determine the role of stretch reflexes in maintaining this coordination. Specifically, we quantified whether stretch reflexes elicited in muscles spanning the glenohumeral joint were best described by homonymous pathways linking each muscle to itself, or heteronymous pathways coordinating activity between muscles. We used a novel robotic manipulandum to perturb shoulder posture in three degrees of freedom as subjects exerted isometric torques. Electromyograms were used to measure the elicited stretch reflexes. Our results suggest that stretch reflexes are coordinated between muscles, and that this coordination is mediated at least in part through rapid, spinal networks.

M. Hongchul Sohn, Emma M. Baillargeon, David B. Lipps, Eric J. Perreault
Identifying Motor Units in Longitudinal Studies with High-Density Surface Electromyography

We investigated the possibility to identify motor units (MUs) with high-density surface electromyography (HDEMG) over experimental sessions in different days. 10 subjects performed submaximal knee extensions across three sessions in three days separated by one week, while EMG was recorded from the vastus medialis muscle with high-density electrode grids. The shapes of the MU action potentials (MUAPs) over multiple channels extracted from HDEMG decomposition were matched across sessions by cross-correlation. Forty and twenty percent of the MUs decomposed could be tracked across two and three sessions, respectively (average cross correlation 0.85 ± 0.04). The estimated properties of the matched motor units were similar across the sessions. For example, mean discharge rate and recruitment thresholds were measured with an intra-class correlation coefficient (ICCs) >0.80. These results strongly suggest that the same MUs were indeed identified across sessions. This possibility will allow monitoring changes in MU properties following interventions or during the progression of neuromuscular disorders.

Eduardo Martinez-Valdes, Francesco Negro, Christopher M. Laine, Deborah L. Falla, Frank Mayer, Dario Farina
Transfer Learning for Rapid Re-calibration of a Myoelectric Prosthesis After Electrode Shift

For decades, researchers have attempted to provide patients with an intuitive method to control upper limb prostheses, enabling them to manipulate multiple degrees of freedom continuously and simultaneously using only simple myoelectric signals. However, such controlling schemes are still highly vulnerable to disturbances in the myoelectric signal, due to electrode shifts, posture changes, sweat, fatigue etc. Recent research has demonstrated that such robustness problems can be alleviated by rapid re-calibration of the prosthesis once a day, using only very small amounts of training data (less than one minute of training time). In this contribution, we propose such a re-calibration scheme for a pattern recognition controller based on transfer learning. In a pilot study with able-bodied subjects we demonstrate that high controller accuracy can be re-obtained after strong electrode shift, even for simultaneous movements in multiple degrees of freedom.

Cosima Prahm, Benjamin Paassen, Alexander Schulz, Barbara Hammer, Oskar Aszmann
EMG Discrete Classification Towards a Myoelectric Control of a Robotic Exoskeleton in Motor Rehabilitation

Myoelectric control constitutes a promising interface for robot-aided motor rehabilitation therapies. The development of accurate classifiers and suitable training protocols for this purpose are still challenging. In this study, eight healthy participants underwent electromyography (EMG) recordings while they performed reaching movements in four directions and five different hand movements wearing an exoskeleton on their right upper-limb. We developed an offline classifier based on a back-propagation artificial neural network (ANN) trained with the waveform length as time-domain feature extracted from EMG signals to classify discrete movements. A maximum overall classification performance of 75.54 % ± 5.17 and 67.37 % ± 8.75 were achieved for reaching and hand movements, respectively. We demonstrated that similar or better classification results could be achieved using a small number of electrodes placed over the main muscles involved in the movement instead of a large set of electrodes. This work is a first step towards a discrete decoding-based myoelectric control for a motor rehabilitation exoskeleton.

N. Irastorza-Landa, A. Sarasola-Sanz, F. Shiman, E. López-Larraz, J. Klein, D. Valencia, A. Belloso, F. O. Morin, N. Birbaumer, A. Ramos-Murguialday

Characterization and Modulation of Neurophysiological Signals: Investigation of the Human Neuromuscular System Using Human Reflexes: Past, Present and the Future

Frontmatter
Difficulties Faced in Standardized Receptor Stimulation and in Standardized Analysis of Muscle Responses to a Stimulus

This presentation will cover the methods used to investigate neuronal circuitries between peripheral receptors and skeletal muscles in human subjects. There are a number of problems regarding reflex studies using experimental animals. There are also problems in the recording and analysis aspects of these experiments. To overcome these problems we have utilized precisely-controlled mechanical or electrical stimuli to activate receptors and single motor units from human muscles. We also used classical and novel methods to analyze the results to indicate neuronal networks.

Kemal S. Türker
The Reflex Circuitry Originating from the Cutaneous Receptors of the Hand to the First Dorsal Interosseus Muscle

In this study, we aimed to use both the probability- and frequency-based analyses methods simultaneously to examine cutaneous silent period induced by strong electrical currents. Subjects were asked to contract their hand muscles so that single motor unit discharged at a rate of approximately 8 Hz. Strong electrical stimuli were delivered to the back of the hand and induced cutaneous silent period in all units. It was found that the duration of the cutaneous silent period (CSP) was significantly longer when the same data were analysed using frequency-based analysis method compared with the probability-based methods.

Kemal S. Türker, Mehmet C. Kahya
Reflex Circuitry Originating from the Muscle Spindles to the Tibialis Anterior Muscle

In this study we investigated whether the reflex excitatory and inhibitory inputs to motor neuron pools are uniformly or differentially distributed. We found that the distribution of monosynaptic excitatory (H-reflex) and reciprocal inhibitory inputs to different size motor neurons fitted gamma distributions with different skew values. This result can be interpreted as due to a differential distribution of afferent inputs on motor neurons.

Utku S. Yavuz, Francesco Negro, Robin Diedrichs, Kemal S. Türker, Dario Farina
Jaw Reflexes Originating from the Periodontal and Muscle Spindle Receptors to the Jaw Muscles

We investigated the jaw reflexes using both the probability- and the discharge rate-based analysis methods. While recording the masseter muscle activity, computer controlled slow-rate “push” and rapid rate “tap” stimuli were delivered to the upper right central incisor before and during local anesthetic block. While preceding local anesthesia, the tap stimuli induced inhibitory reflex responses; during local anesthetic block, the same stimulus induced excitatory and inhibitory reflex responses. The push stimuli generated a combination of inhibitory and excitatory responses that disappeared during the local anesthetic block. We found that the discharge rate-based method was better for indicating the duration of earlier responses and the existence, sign, and duration of later responses.

G. Yılmaz, P. Uginčius, K. S. Türker

Empowering and Quantifying Neurorehabilitation: Biomechanics and Movement Analysis in Rehabilitation (I)

Frontmatter
Stance Sub-phases Gait Event Detection in Real-Time for Ramp Ascent and Descent

This article presents a real-time gait event/phase detection system for control subjects and lower limb amputees during ramp ascent (RA) and ramp descent (RD) using a single wearable sensor. Development of the algorithm is based on the shank angular velocity in the sagittal plane and linear acceleration signal in the shank longitudinal direction. System performance was evaluated with nine control subjects (CS) and one transfemoral amputee (TFA) and the results were validated with foot-switches. Results were promising for Initial-Contact (IC) and Toe-Off (TO) across all the subjects. Higher mean differences were found out for Foot-Flat start and Heel-Off, particularly in the case of TFA due to the difference in kinematics behavior compared to CS. Success detection rate of 99.7 % was achieved for RA and RD in both groups.

Hafiz F. Maqbool, Muhammad A. B. Husman, Mohammed I. Awad, Alireza Abouhossein, Nadeem Iqbal, Abbas A. Dehghani-Sanij
Is Clinical Gait Analysis Useful in Guiding Rehabilitation Therapy Decisions in Patients with Spinal Cord Damage?

This is a retrospective open cohort case series that describes biomechanical data provided by three dimensional gait analysis (3DGA) in adults with incomplete spinal cord damage (ISCD) and outlines how the recommendations helped optimize rehabilitation therapy. 3DGA data were collected on 40 adults over 17 years of age with SCD due to traumatic or non-traumatic causes. Following clinical assessment and placement of retroflective markers, patients walked barefoot at preferred speed along a 10 m walkway as per clinical protocol. 3DGA data suggests the most common gait deviation in patients with ISCD occurs in the sagittal plane with compensations made in the transverse plane. These data guided therapy options in many of the patients in this study, at times suggesting alternate methods of treatment to those originally posed by the referrer.

Anna Murphy, Barry Rawicki, Stella Kravtsov, Peter New
Phonatory and Articulatory Correlates in Kinematic Neuromotor Degeneration

Degenerative neuromotor diseases, as Parkinson’s (PD) produce important correlates in phonation and articulation, which may be used in pathology monitoring and grading. The study is intended to describe how phonation and articulation correlates in simple exercises may be used to monitor PD. Specifically, phonation bursts, mandibular and lingual tremor, or velopharyngeal switch failures may be detected in formant spectrograms by estimating articulation kinematics from the first and second formants. Estimations of these correlates in PD patients and control subjects are compared to establish the statistical relevance of the methodology.

C. Carmona-Duarte, P. Gómez-Vilda, R. Plamondon, V. Rodellar-Biarge, D. Palacio-Alonso, M. A. Ferrer-Ballester, J. B. Alonso-Hernández
Analysis and Quantification of Upper-Limb Movement in Motor Rehabilitation After Stroke

It is extremely difficult to reduce the relations between the several body parts that perform human motion to a simplified set of features. Therefore, the study of the upper-limb functionality is still in development, partly due to the wider range of actions and strategies for motor execution. This, in turn, leads to inconsistent upper-limb movement parameterization. We propose a methodology to assess and quantify the upper-limb motor execution. Extracting key variables from different sources, we intended to quantify healthy upper-limb movement and use these parameters to quantify motor execution during rehabilitation after stroke. In order to do so, we designed an experimental setup defining a workspace for the execution of the action recording kinematic data. Results reveal an effect of object and instruction on the timing of upper-limb movement, indicating that the spatiotemporal analysis of kinematic data can be used as a quantification parameter for motor rehabilitation stages and methods.

R. Mariana Silva, Emanuel Sousa, Pedro Fonseca, Ana Rita Pinheiro, Cláudia Silva, Miguel V. Correia, Sandra Mouta

Empowering and Quantifying Neurorehabilitation: Biomechanics and Movement Analysis in Rehabilitation (II)

Frontmatter
Effect of Motor-Cognitive (Dual Task) Rehabilitation Program on Gait Biomechanics in Parkinson’s Disease: Case Study

In some pathologies with impaired control gait, the dual task execution even worse these gait alterations, as in Parkinson’s Disease (PD) occurs. The aim of this paper is to present the effects of a rehabilitation program that integrates dual tasks in gait rehabilitation and prepare patients to move functionally in complex environments in a person with PD. 3D photogrammetry system and two force platform were used for the registering of kinematic and kinetic parameters, respectively. The main variables that have improved after the proposed program are: speed gait (54.87 %), step length (52.01 %), stride length (43.48 %), double support time (37.36 %), flexo-extension hip range of motion (36.08 %) and vertical reaction force at the heel contact moment (23 %). The inclusion of complex environments representative of daily life activities in gait rehabilitation is useful for improving the performance of walking when parkinsonian gait impairment is suffered.

Constanza I. San Martín, José M. Tomás, Pilar Serra-Añó
Reliability of Functional Principal Components Decomposition of Ground Reaction Forces in Post-stroke Patients

Analysis of Ground Reaction Forces is a non-invasive useful tool for the analysis of gait in post-stroke patients. The analysis of ground reactions forces in post-stroke patients is difficult due to the large variability of the shape of the force curves, making very difficult an analysis of the different events of the gait pattern, as has been common practice for years. Functional Principal Components, allows the analysis of the fitting coefficients to a sample of curves better describing the variability of the whole set. In this contribution, this type of analysis has been made, and the reliability of the measurements has been obtained, demonstrating the usefulness of the approach.

María-José Vivas-Broseta, Juan-Manuel Belda-Lois
Interactive Locomotion of Mechanically Coupled Bipedal Agents: Modeling and Experiments

This paper investigates the interactive locomotion for physically coupled bipedal agents using a human-human object carrying experiment and a simple mathematical model. The model is based on the Spring Loaded Inverted Pendulum (SLIP) and on the assumption that the coupling can be modeled as a spring-damper. By setting appropriate parameters, the model can achieve stable walking gaits and coordinated foot-fall patterns. Human-human interactive locomotion data are also analyzed in order to evaluate how the model can be useful to investigate humans’ interaction. The kinematic study of how the rigid coupling between two humans can influence their own behaviour is presented for the first time to our knowledge. Moreover a good match between experimental and model data emerges from the comparison between several gait parameters.

Jessica Lanini, Alexis Duburcq, Auke Ijspeert
Interference During Simultaneous Performance of a Motor and Cognitive Task Involving the Upper Extremity After Stroke

After stroke, the ability to perform two tasks concurrently is diminished, which may contribute to less pronounced gains on activity level after rehabilitation. The current study investigated whether upper extremity dual-task performance is compromised after stroke, as a first step towards examining whether cortical stimulation can reduce dual-task interference. Twenty stroke patients performed a single motor task (tapping targets), single cognitive task (memorising digits) and dual motor-cognitive task. Although motor performance was better when performing the dual-task compared to the single tapping task, it was at the expense of cognitive performance. These findings suggest upper extremity cognitive-motor interference after stroke. In ongoing work, we are investigating the potential role of cortical stimulation to improve motor and cognitive dual-task performance.

G. B. Prange-Lasonder, V. Robles-García, S. Brown, J. H. Buurke, J. Whitall, J. H. Burridge

Empowering and Quantifying Neurorehabilitation: Advances in Understanding Human Movement and Motor Interactions (I)

Frontmatter
Human Movement Execution Control Combined with Posture Control—A Neurorobotics Approach

The human-derived sensorimotor control concept DEC (for Disturbance Estimation and Compensation) is here considered with three issues: (1) DEC can be used in a modular control architecture for multi-DoF applications. (2) DEC can easily be implemented on humanoid robotics platforms that have human-inspired sensors and force-controlled actuations. (3) Comparing different bio-inspired control concepts with each other on the same robot helps to define criteria for human-likeness of control algorithms—with potential benefits for user acceptance in assistive robotics.

T. Mergner, V. Lippi
Efficacy of Cardiovascular Activity in Stroke Rehabilitation Therapy

We aim to optimize post-stroke motor control rehabilitation therapy via integration of cardiovascular activity. Although stroke therapy ranges from months to years for some stroke patients, the majority of neurological recovery occurs within the first three months. Afterwards, neurological recovery occurs at a reduced rate for a period of up to one year. Current studies report that cardiovascular activity increases synaptic plasticity by affecting synaptic structure and potentiating synaptic strength, strengthening neurogenesis, metabolism and vascular function. Integrating cardiovascular activity in post-stroke motor control rehabilitation therapy may restore two-way communication between the central nervous system and extremities via growth of alternative central nervous system pathways; thus, resulting in improved motor control in both upper and lower extremities. We hypothesize that the neurotrophic factors engendered by cardiovascular activity significantly fortify descending motor pathways. In part one, functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) quantify the level of brain activity resulting from upper extremity movement and lower extremity movement in two cohorts, each cohort consisting of four members. In part two, cohort one will perform 30 min of cardiovascular activity prior to 30 min of upper and lower extremity strength training five times a week for a total of three months. During this period, cohort two will perform only 30 min of upper and lower extremity strength training five times a week. In part three, fMRI and EEG will quantify the level of brain activity resulting from upper extremity movement and lower extremity movement in both cohorts. After data collection, juxtaposition of functional magnetic resonance images in conjunction with electroencephalograms during day one and during day ninety will occur in order to quantify the significance of cardiovascular activity integration in post-stroke motor control rehabilitation therapy.

Javier Rodriguez, Emel Demircan
Modelling Collaborative Strategies in Physical Human-Human Interaction

Systematic analysis of the mechanisms of physical human-human interaction (pHHI) requires adequate computational modelling framework. Recently differential game theory models—a multi-agent counterpart of optimal control—have been used to analyse sensorimotor collaborative strategies. A task can be defined by a pair of quadratic cost functionals (one per partner). The ‘plant’ is constituted by the two partners’ body dynamics plus their mechanical links (if any). Every partner has his/her own sensory system. In analogy with single-agent dynamics, we assume that each partner maintains an internal model or state observer of own and partner’s dynamics. The framework naturally incorporates the effects of noisy or incomplete sensory information about own body state. Different interaction strategies can be simulated, ranging from ‘optimal’ collaboration (Nash equilibrium) to no collaboration (two separate LQG controllers). We compared the model predictions with an experimental scenario in which two partners have partly conflicting goals—a reaching task with different via-points. This framework also reproduces behaviours—like ‘slacking’—that are typical of the robot-human interaction in robot-assisted adaptation or rehabilitation trials.

Vinil Thekkedath Chackochan, Vittorio Sanguineti
Soft Robots that Mimic the Neuromusculoskeletal System

In motor control studies, the question on which parameters human beings and animals control through their nervous system has been extensively explored and discussed, and several hypotheses proposed. It is widely acknowledged that useful inputs in this problem could be provided by developing artificial replication of the neuromusculoskeletal system, to experiment different motor control hypothesis. In this paper we present such device, which reproduces many of the characteristics of an agonistic-antagonistic muscular pair acting on a joint.

Manolo Garabini, Cosimo Della Santina, Matteo Bianchi, Manuel Catalano, Giorgio Grioli, Antonio Bicchi
Predictive Framework of Human Locomotion Based on Neuromuscular Primitives and Modeling

Synthesizing human movement in computational neuro-mechanical models is a complex problem. In this study, we describe a predictive framework that combines computational models of neural, sensory and mechanical processes. Our proposed formulation facilitates the transition towards the design of a new class of bio-mimetic assistive devices that do not rely on explicit representations of task-specific motor control models.

Massimo Sartori, José González-Vargas, Strahinja Došen, José L. Pons, Dario Farina

Empowering and Quantifying Neurorehabilitation: Advances in Understanding Human Movement and Motor Interactions (II)

Frontmatter
Towards a Better Understanding of Stability in Human Walking Using Model-Based Optimal Control and Experimental Data

This paper investigates different possible stability criteria of human walking and their correlation to the nature of the real motion. The analysis is performed using human motion capture data and a precise dynamic 3D model of human walking with 34 DOF and physical contact constraints.

Katja Mombaur, C. Javier Gonzalez, Martin L. Felis
Gait Abnormalities of Above Knee Amputees During Late Swing Phase, Is It a Design Deficiency or Compensatory Strategy?

The paper reports on an intervention crossover study with repeated measures with two different prosthetic knees during two weeks adaptation period over the ground walking. The heel linear velocities of a transfemoral amputee (TFA) was measured to evaluate possible gait deficiency during heel-contact (HC). The result showed that during late swing phase just before the HC, amputee must have advanced preparation of the residual limb to adjust heel velocity for placement. The knee and the hip kinematics for reduction of the heel velocities during HC is paramount. The Knee flexion in late swing is essential to avoid impact during HC. Such mechanism does not exist in current prosthetic knees, therefore, heavy damping is necessary on the foot-heel to avoid impact.

A. Abouhossein, M. I. Awad, C. Crisp, A. A. Dehghani-Sanij, N. Messenger, T. D. Stewart, O. M. Querin, R. Richardson, D. Bradley
A Novel Controller for Bipedal Locomotion Integrating Feed-Forward and Feedback Mechanisms

It has been recognized that bipedal locomotion is controlled using feed-forward (e.g., patterned) and feedback (e.g., reflex) control schemes. However, most current controllers fail to integrate the two schemes to simplify speed control of bipedal locomotion. To solve this problem, we here propose a patterned muscle-reflex controller integrating feed-forward control with a muscle-reflex controller. In feed-forward control, the pattern generator is modeled as a Matsuoka neural oscillator that produces four basic activation patterns that mimic those extracted experimentally via electromyograms (EMGs). The associated weights of the patterns for 16 Hill-type musculotendon units (MTUs) are calculated based on a predictive model of muscle excitations under human locomotion. The weighted sums of the basic activation patterns serve as the pre-stimulations to muscle-reflex control of the Hill-type MTUs actuating a 2D-simulated biped. As a result, the proposed controller enables the biped to easily regulate its speed on an even ground by only adjusting the descending input. The speed regulation does not require re-optimizations of the controller for various walking speeds, compared to pure muscle-reflex controllers.

Xiaofeng Xiong, Massimo Sartori, Strahinja Dosen, José González-Vargas, Florentin Wörgötter, Dario Farina
A Preliminary Comparison of Stepping Responses Following Perturbations During Overground and Treadmill Walking

The aim of this study was to compare stepping responses during overground and treadmill walking with two balance assessment robots that apply perturbations to the subject’s pelvis. The results show high similarity of both approaches. Both devices reproduce similar experimental conditions in the unperturbed walking as well as in perturbed walking.

Matjaž Zadravec, Andrej Olenšek, Zlatko Matjačić

Empowering and Quantifying Neurorehabilitation: Clinical Needs and Prospects of Neurorehabilitation Technology in Stroke

Frontmatter
Effectiveness of Interventions to Decrease the Physical and Mental Burden and Strain of Informal Caregivers of Stroke Patients: A Systematic Review

Informal caregivers (IC) play a crucial role in the care for post stroke patients. As this care radically changes IC’s lives, it is necessary to decrease the risk of caregiver burden and strain through specific programs that provide support. The aim of this systematic review was to investigate the effect of interventions on the burden and strain of IC of stroke patients. In total, 12 clinical trials were included, with a large variability in interventions and characteristics of the patients and their IC. Although the interventions had a positive effect in some studies, it is still not clear what type of intervention could decrease the burden and strain of the IC of stroke patients.

E. Rubbens, L. De Clerck, E. Swinnen
Effect of Providing Ankle-Foot Orthoses in Patients with Acute and Subacute Stroke: A Randomized Controlled Trial

Despite frequent application of ankle-foot orthoses (AFOs), little scientific evidence is available to guide AFO-provision early after stroke. A randomized controlled trial was conducted to study the effects of AFO-provision in (sub-) acute stroke patients. Primary aim: to study effects of the actual provision of AFOs on functional outcomes. Secondary aim: to study whether the point in time at which an AFO is provided (early (week 1) or delayed (week 9)), influences these effects. Thirty-three subjects were included and walking speed, balance (Berg Balance Scale, BBS) and independence of walking (Functional Ambulation Categories, FAC) were measured. Positive effects of AFO-provision were found two weeks after provision, both when provided early (significant effects on all outcome measures) or late (BBS p = 0.011, FAC p = 0.008). Comparing the early and delayed group showed that early provision resulted in extra improvements on BBS (+5.1 points, p = 0.002) compared to late provision.

Corien D. M. Nikamp, Jaap H. Buurke, Job van der Palen, Hermie J. Hermens, Johan S. Rietman
User Acceptance of a Balance Support System that Enables Unsupervised Training of Balance and Walking in Stroke Survivors

A balance support system is developed with the goal to evoke unsupervised training of balance and walking in stroke survivors. The system is attached to the pelvic area and is developed to be used on a treadmill. It is based on the working principle of a therapist who only provides support at times the patient needs it. When support is not needed, the subject is able to move freely over the treadmill. In this study, we focus on the potentials and limitations of such a system from the user’s point of view. Results indicate that the system has high potential: user acceptance is rated as ‘good’ (SUS score = 76.8). Limitations lie mainly in the fact that subjects were concerned that controlling the system was too difficult with one functional hand.

J. A. M. Haarman, J. Reenalda, P. Lammertse, J. H. Buurke, H. van der Kooij, J. S. Rietman
Upper Extremity Training with CUREs Robot in Subacute Stroke: A Pilot Study

We developed a robot, CUREs (Chulalongkorn University Rehabilitation robotic Exoskeleton system), for upper extremity rehabilitation. Five subacute stroke patients participated in this pilot study. All patients had severe upper extremity weakness (Brunnstrom stage I and II, Fugl–Meyer Assessment Upper Extremity score, motor function, are from 4 to 10). They participated in 30 min of conventional upper extremity training and 30 min of robotic training, 5 days per week for 2 consecutive weeks. The Fugl–Meyer Assessment Upper Extremity Scale was improved after 2 weeks training in all participants. However, the Motor Assessment Scale was not changed. In the future, we plan to conduct a 4 week randomized–controlled trial study to compare the rehabilitation outcome between CUREs robot with conventional therapy in stroke patient.

Wasuwat Kitisomprayoonkul, Pim Bhodhiassana, Viboon Sangveraphunsiri
Preliminary Extraction of Themes from a Review About User Perspectives on Assistive Technology for the Upper Limb After Stroke

Use of assistive technology to support the upper extremity of stoke survivors seems promising. Attention for the needs and preferences of the end-user from the start of the design is crucial to avoid device abandonment. The aim of this study was to gain insight into the factors that play a role in the successful use of upper extremity assistive technology in rehabilitation and daily life activities of stroke survivors through a systematic analysis of the literature. Six qualitative studies have been retrieved from PubMed, Scopus, CINAHL, Embase, PsycINFO and additional reference tracking. Analysis of user expressions resulted in the specification of three overarching themes: accessibility, usage and personalization.

A. L. van Ommeren, G. B. Prange-Lasonder, J. S. Rietman, P. H. Veltink, J. H. Buurke

Empowering and Quantifying Neurorehabilitation: Clinical Needs and Prospects of Neurorehabilitation Technology in SCI

Frontmatter
Usability of the Combination of Brain-Computer Interface, Functional Electrical Stimulation and Virtual Reality for Improving Hand Function in Spinal Cord Injured Patients

This work assesses the usability of a system that combines a brain-computer interface, a functional electrical stimulator and a virtual feedback with the aim of promoting neuroplasticity. The system has been tested in a patient with C5 D ASIA spinal cord injury, who performed 5 sessions with the device as well as exertion, clinical and usability tests.

Manuel Bayon-Calatayud, Fernando Trincado-Alonso, Eduardo López-Larraz, Luis Montesano, José Luis Pons, Ángel Gil-Agudo
Kinematic Indices for Upper Extremity Assessment After Spinal Cord Injury: A Case of Study

A 38-year-old man, with incomplete spinal cord injury at the C6 level, classified as American Spinal Injury Impairment Scale C (AIS), right-handed, participated in a study for assessing the upper extremity functionality in an objective way by means of a set of kinematic indices for quantifying upper extremity ability and dexterity. Along his rehabilitative treatment, the participant was evaluated twice over 6 weeks, with the main objective of analyzing the upper extremity functional changes in the kinematic indices proposed between both assessments in relation to accuracy, agility, efficiency, coordination and smoothness movement characteristics during the performance of the drinking activity of daily living. Results: The kinematic indices proposed showed more functional changes within the patient that the clinical scales. Conclusion: Data from one subject showed important information on the feasibility and effectiveness of the kinematic indices for detecting upper extremity functional changes after incomplete spinal cord injury.

A. de los Reyes-Guzmán, I. Dimbwadyo-Terrer, V. Lozano-Berrio, S. Pérez, D. Torricelli, J. L. Pons, A. Gil-Agudo
Physiological Evaluation of Different Control Modes of Lower Limb Robotic Exoskeleton H2 in Patients with Incomplete Spinal Cord Injury

Gait rehabilitation robots are of increasing importance in neurorehabilitation. The aim of this study is to assess the effects of Exo-H2 on metabolic cost in patients with incomplete SCI while walking with two control modes, compared with unassisted walking. Three patients with incomplete SCI participated in the study and three walking tests were conducted in randomized order with two control modes and unassisted gait while recording the oxygen consumption and prior and after blood pressure, heart rate, VAS of pain and fatigue was obtained. As conclusion, our results suggest that the gait robotic assistance with Exo-H2 is more physiological when is selected compliant mode.

Soraya Pérez-Nombela, Antonio J. del-Ama, Guillermo Asín-Prieto, Elisa Piñuela-Martín, Vicente Lozano-Berrio, Diego Serrano-Muñoz, Ángel Gil-Agudo, José L. Pons, Juan C. Moreno
Muscle Activity and Coordination During Robot-Assisted Walking with H2 Exoskeleton

Nowadays, exoskeletons have been introduced for empowering walking in military, industrial and rehabilitation settings. Several companies are commercializing these devices, but there is a lack of understanding of their effects on muscle activations and coordination. The objective of this article is to investigate the impact on muscle activation and user effort during ambulatory, robotic-assisted walking. Compared with free walking, our results suggest that robotic assistance with the Exo-H2 lower limb exoskeleton may result in increased muscle activation. Muscular timing experienced unspecific changes with respect to unassisted walking. Further research is needed to unveil the mechanical interaction between the robot and the lower limbs and the underlying motor adaptations in response to robot-assisted walking.

Antonio J. del-Ama, Guillermo Asín-Prieto, Elisa Piñuela-Martín, Soraya Pérez-Nombela, Vicente Lozano-Berrio, Diego Serrano-Muñóz, Fernando Trincado-Alonso, José González-Vargas, Ángel Gil-Agudo, José L. Pons, Juan C. Moreno
Modelling Neuromuscular Function of SCI Patients in Balancing

A novel neuromechanical model for investigating patient-specific lower limb movement dynamics after spinal cord injury (SCI) is presented. The model is designed in joint space and takes into account muscle neuromechanics. Application of the model is demonstrated in the application of a balancing task.

Hsien-Yung Huang, Ildar Farkhatdinov, Arash Arami, Etienne Burdet

Empowering and Quantifying Neurorehabilitation: Interpersonal Rehabilitation Games

Frontmatter
Motivation and Exercise Intensity in Competition and Cooperation Between a Patient and Unimpaired Person in Arm Rehabilitation

This paper presents four arm rehabilitation games played by a patient together with their friend, relative or therapist. One game involves competition, two involve cooperation, and one is played alone by the patient. All four games were tested by 29 participants with arm impairment for 3 min per game. In-game motivation and exercise intensity were examined. The most promising results were achieved with the competitive game, which shows the highest level of exercise intensity and high motivation, but only in participants who enjoy competition. Furthermore, playing with a friend or relative appears to be more motivating than playing with a therapist, though this likely depends on the game design.

Maja Goršič, Imre Cikajlo, Domen Novak
Towards Pervasive Motor and Cognitive Rehabilitation Strategies Mediated by Social Interaction

This paper introduces the concept of socially mediated interventions targeting specific deficits anywhere, in public spaces beyond the hospital/clinical context. Such concept would provide affordable and engaging experiences carefully designed to promote social interaction and affordable pervasive interventions without the ‘rehabilitation tag’ associated. Several playful group activities supported by haptic robots have been conducted to determine how people perceive this type of approach. This paper presents a set of playful group activities piloted to start testing the feasibility of the concept.

Hoang H. Le, Martin J. Loomes, Rui C. V. Loureiro
Collaborative Gaming to Enhance Patient Performance During Virtual Therapy

We present a collaborative training game, based on a novel task where the participants are virtually but dynamically coupled and require collective actions for successful task completion. This can be considered a new type of interpersonal interaction which both increases player motivation during training (compared to single-player participation) and also intrinsically balances the skill levels of the two partners without the need for an additional procedure. This is achieved by a temporary averaging, during collaboration, of the individual performance’s which leads to a more balanced playing field and challenge point being set for both partners.

Michael Mace, Paul Rinne, Nawal Kinany, Paul Bentley, Etienne Burdet
Flowing to the Optimal Challenge: An Adaptive Challenge Framework for Multiplayer Games

Rehabilitation training is a key component in the treatment of patients with neurological disorders such as stroke and spinal cord injury. A key parameter in rehabilitation is to have a high level of intensity during training—that is, training where a patient performs a high number of repetitions under high levels of mental and physical effort. To address the need for increased intensity during training we propose the use of robotic devices to deliver training in multiplayer environments. Robotic devices have the potential to train multiple patients simultaneously under the supervision of a single therapist. However, when more than one patient is involved in training, for example during a competitive game, the differences in skill level become an important factor to consider. Here we discuss the implications of two-player competitive games for rehabilitation training. We focus our discussion in training for the upper extremity and frame our ideas in the context of the flow concept—from the field of psychology—and the challenge point framework—from the field of motor learning. We discuss how the introduction of an additional player, with different skill level, can affect these concepts and how we can use Dynamic Difficulty Adaptation methods to address possible issues. We hypothesize that multiplayer environments, with appropriate adjustments for difficulty, increase the intensity and motivation of training by expanding the flow zone of trainees.

Jaime E. Duarte, Kilian Baur, Robert Riener

Empowering and Quantifying Neurorehabilitation: Gaming and Rehabilitation

Frontmatter
Assessing the Gaming Experience of an Applied Game for Rehabilitation of the Arm and Hand Function: A Feasibility Study

The present pilot study assessed the feasibility, in terms of gaming experience, of using a first prototype of a self-developed mixed-reality system for rehabilitation of the arm and hand function. Results showed that the hybrid game approach is well accepted by Cerebral Palsy children and adults with stroke/acquired brain injury. Further research is needed to improve the current prototype and to investigate the clinical value of the applied game.

Anke I. R. Kottink, Gerdienke B. Prange-Lasonder, Johan S. Rietman, Jaap H. Buurke
Combining EEG and Serious Games for Attention Assessment of Children with Cerebral Palsy

Electroencephalography (EEG) is an electrophysiological monitoring method to record the electrical activity of the brain in a not invasive manner, with low cost hardware, using wireless communication and with high temporal resolution. Serious Games (SG) have demonstrated their effectiveness as a therapeutic resource to deal with motor, sensory and cognitive disabilities. We have considered the combination of both techniques for attention assessment in children with cerebral palsy (CP). In this short paper we present a new approach for the development of a SG based on a Brain Computer Interface (BCI).

F. J. Perales, E. Amengual
INTERPLAY—Advanced Console for the Playful Rehabilitation of Children with Neuromotor Disabilities

INTERPLAY is a project that proposes the development of an advanced console that suits the motor and cognitive level of the user. The main objectives of the motor rehabilitation are to reduce disability, increase functional ability and, consequently, promote social participation. Adapted peripherals were specially developed for users with motor impairments to enable them the access to the adapted rehabilitation games. The peripherals are based on inertial sensors and superficial electromyography for the measurement of body posture and muscle activation. In addition, a gaze tracking device will quantify the child’s level of attention during the game. The system will allow the therapist to design and import customized rehabilitation protocols consisting of sequences of games to exercise 3 body segments (head, trunk, and upper limbs) and perform movements in the frontal, sagittal and transverse axis. The therapist will be able to select specific difficulty levels for each subject and stage of the therapy and to monitor the evolution of the child throughout the work sessions. Patients with severe deficiencies of movement, posture and expression, among others, will use in their everyday life this system both at home and/or at care centers. In this paper, we present the therapies design concepts, rehabilitation system architecture, and implementation results.

A. Clemotte, M. A. Velasco, R. Raya, R. Ceres, P. Andradas, C. Talegón, M. A. Íñigo, N. Rando, L. Zumárraga, J. Arambarri, E. Rocon
ViTAS Gaming Suite: Virtual Therapy Against Stroke

Stroke is the leading cause of disability in Western Society, and rehabilitation is a fundamental support to ensure the best possible recovery of stroke patients after acute disease. To support and enhance conventional therapies we have developed a virtual rehabilitation gaming suite called ViTAS. ViTAS replicates some of the tests performed in clinical contexts, thus making the integration between virtual and traditional rehabilitation completely straightforward. We have collected the opinion of 35 clinicians with different degree of experience, following a customized self-report questionnaire. The results showed high acceptance of clinicians to use ViTAS system in rehabilitation. We conclude that ViTAS could become an essential supplement to standard post-stroke rehabilitation protocols.

Diego Dall’Alba, Iris Dimbwadyo, Stefano Piazza, Enrico Magnabosco, Giovanni Menegozzo, Paolo Fiorini
Game-Based Assessment in Upper-Limb Post-stroke Telerehabilitation

ArmAssist is a low-cost robotic system for post-stroke upper-limb rehabilitation based on serious games. The system incorporates a set of games for assessment, the ArmAssist Assessment (AAA). AAA provides a fast, quantitative and automatic evaluation of the arm function and allows a remote monitoring of the progress of the patient and an automatic adaptation of the therapy; all of them essential elements for partially unsupervised or remote rehabilitation. Apart from usability and motivational components, demonstrating the clinical meaningfulness of this assessment is crucial in order to be considered useful. Current study shows a statistically significant correlation of the AAA with three widely-used clinical tests, the Fugl-Meyer Assessment (FMA), the Action Research Arm Test (ARAT) and the Wolf Motor Function Test (WMFT). These results look promising and are expected to be improved with currently ongoing improvements in the system.

Cristina Rodríguez-de-Pablo, Andrej Savić, Thierry Keller
NAO Robot as Rehabilitation Assistant in a Kinect Controlled System

In this paper NAO robot is presented as a Home Rehabilitation assistant; Machine Learning is used to classify the data provided by a Kinect RGB-D sensor in order to obtain a Home Exercise Monitoring System which aims at helping physicians controlling patient at home rehabilitation.

I. Rodríguez, A. Aguado, O. Parra, E. Lazkano, B. Sierra
Hand Rehabilitation with Toys with Embedded Sensors

We describe here a novel platform for hand rehabilitation through exer-games. It is based on a mobile device on which the game is run combined with a modular adaptive architecture that senses fingers pressure and communicates with the mobile device in real-time. Exer-games designed to increase fingers mobility are plaid with the device touch-screen display. Fingers force is trained through exer-games whose input is the pressure exerted by the patient on an adequate object. The object hides a modular micro-architecture that samples pressure and transmit it in real-time, through wireless connection, to the device. Preliminary usability results from thirteen children and their parents are reported.

N. A. Borghese, R. Mainetti, J. Essenziale, E. Cavalli, E. M. Mancon, G. Pajardi
Assessment of Exergames as Treatment and Prevention of Dysgraphia

The dysgraphic disorder is usually underestimated and belatedly diagnosed. The need of prevention and early intervention focused on prewriting exercises emerges from the literature. We explore exergames to supply this need, together with an adequate assessment module of the training results. The exergames were designed in collaboration with clinicians and were tested on 16 kindergarten children. The movement data collected have allowed to provide some preliminary indexes of evaluation, that have shown to be consistent with the qualitative evaluation of the teachers. The use of the mobile application as a school exercise obtained positive feedback.

N. A. Borghese, C. Palmiotto, J. Essenziale, R. Mainetti, E. Granocchio, B. Molteni, D. Sarti, T. Guasti, N. Stucchi, A. Pedrocchi, S. Ferrante
Examining VR/Robotic Hand Retraining in an Acute Rehabilitation Unit: A Pilot Study

Current service delivery models limit treatment time and length of hospital stay during the period of post-ischemic heightened neuronal plasticity when intensive training may optimally affect recovery. Prioritization for rehabilitation of independence in transfers and ambulation, negatively impacts the provision of intensive hand and upper extremity therapy. Our pilot data show that we are able to integrate intensive, targeted hand therapy that uses robotics and a library of gaming activities into the routine of an acute rehabilitation setting. Our system has been specifically designed to deliver hand training when motion and strength are limited. The system uses adaptive algorithms to drive individual finger movement, gain adaptation and workspace modification, and haptic and visual feedback from mirrored movements. The data establishes a foundation for a future clinical trial to investigate the potential benefits of robot-assisted gaming during the early phase of recovery.

Alma Merians, Mathew Yarossi, Jigna Patel, Qinyin Qiu, Gerard Fluet, Eugene Tunik, Sergei Adamovich
Serious Game and Wearable Haptic Devices for Neuro Motor Rehabilitation of Children with Cerebral Palsy

Cerebral palsy (CP) is a group of disorders that affect the development of movement and posture, resulting in limited activities. To optimize pediatric neuro-rehabilitation and to complement conventional occupational therapies, serious game based therapies for upper limb (UL) rehabilitation have been developed or adapted for the pediatric field during recent years. In this work, we present the design and development of UL rehabilitation scenario for CP patients, based on Serious Games (SG) and enhanced by immersive virtual reality (VR) with haptic feedback to increase engagement and provide rich, congruent multi-sensory feedback during virtual interaction.

Ilaria Bortone, Daniele Leonardis, Massimiliano Solazzi, Caterina Procopio, Alessandra Crecchi, Lucia Briscese, Paolo Andre, Luca Bonfiglio, Antonio Frisoli

Empowering and Quantifying Neurorehabilitation: Experimental Approaches for Restoring Hand Function

Frontmatter
Introduction of an EMG-Controlled Game to Facilitate Hand Rehabilitation After Stroke

Stroke survivors often have difficulty creating the proper muscle activation patterns to perform functional tasks. We have developed an electromyographically (EMG)-controlled game to assist stroke survivors in rehabilitating activation patterns. Players must produce specific EMG patterns in order to move a cursor throughout a computer screen. We ran a pilot study with neurologically intact subjects playing the game on three separate days. Significant carryover in improvement of activation was seen from one day to the next.

Mohammad Ghassemi, Rajiv Ranganathan, Alex Barry, K. Triandafilou, Derek Kamper
Learning Interference in Dynamic Manipulation with Redundant Degrees of Freedom

One important dimension of sensorimotor rehabilitation is motor practice to induce adaptation to new and improved movement patterns. Previous studies have shown that motor adaptation in a novel, directional dynamic context induces interference on the learning of a subsequent task. However, little data exist about how such interference affects the low-level coordination pattern of the end-effectors in the presence of biomechanical redundancy. We addressed this question by using a novel experimental design based on velocity-dependent torque perturbations delivered by haptic devices during three-finger dynamic manipulation tasks. We found that the finger force patterns in the initial stages after context switch was modulated by the preceding contexts, exhibiting higher energy cost. These findings provide insights to improving protocols for sensorimotor rehabilitation.

Qiushi Fu, Marco Santello
Pinching Performance of a Spinal Cord Injured Patient with Exo-Glove with Respect to the Tendon Route Design

Exo-Glove is a soft wearable robotic hand to assist hand function of people who have paralysis of the hands. Exo-Glove is compactly structured with soft fabrics and adapts an under-actuation concept. Pinch performance is defined, and the variation of the pinching performance with Exo-Glove with respect to the tendon route design is shown through an experiment. A subject with spinal cord injury participated in the experiment. As shown by the experimental result, Exo-Glove provides adequate pinching performance, and the tendon routing of Exo-Glove severely affects its pinching performance.

Hyunki In, Brian Byunghyun Kang, Kyu-Jin Cho
The SoftHand Pro: Translation from Robotic Hand to Prosthetic Prototype

This work presents the translation from a humanoid robotic hand to a prosthetic prototype and its first evaluation in a set of 9 persons with amputation. The Pisa/IIT SoftHand is an underactuated hand built on the neuroscientific principle of motor synergies enabling it to perform natural, human-like movements and mold around grasped objects with minimal control input. These features motivated the development of the SoftHand Pro, a prosthetic version of the SoftHand built to interface with a prosthetic socket. The results of the preliminary testing of the SoftHand Pro showed it to be a highly functional design with an intuitive control system. Present results warrant further testing to develop the SoftHand Pro.

Sasha B. Godfrey, Matteo Bianchi, Kristin Zhao, Manuel Catalano, Ryan Breighner, Amanda Theuer, Karen Andrews, Giorgio Grioli, Marco Santello, Antonio Bicchi

Rehabilitation Robotics and Neuroprosthetics: Wearable Human-Robot Interfaces for Upper Limb Functional Recovering

Frontmatter
Wearable Elbow Exoskeleton Actuated with Shape Memory Alloy

This paper presents a wearable rehabilitation exoskeleton for the elbow joint with two degrees of freedom (DOF), flexion-extension and pronation-supination, actuated with Shape Memory Alloy (SMA) based actuators. Due to the actuation system, the proposed exoskeleton presents a light weight, low noise, and is designed in a simple structure. The number of actuators and the preliminary designed was calculated based on a biomechanical simulation with a specific category of patients.

D. Copaci, A. Flores, F. Rueda, I. Alguacil, D. Blanco, L. Moreno
Intuitive Control of a Prosthetic Elbow

Many transhumeral amputees deplore the lack of functionality of their prosthesis, mostly caused by a counter-intuitive control strategy. This work is the first implementation of an automatic prosthesis control approach based on natural coordinations between upper limb joints and IMU-based humeral orientation measurement. One healthy individual was able to use the prosthetic elbow, fitted with a prosthetic forearm and attached to the subject’s upper arm, to point at targets with an encouragingly small error.

Manelle Merad, Étienne de Montalivet, Agnès Roby-Brami, Nathanaël Jarrassé
Interaction Force Estimation for Transparency Control on Wearable Robots Using a Kalman Filter

A wearable robot is constantly in contact with its user. To measure and control the human–robot interaction force is important to properly and safely perform tasks together with the wearer, such as walking and load carrying. To avoid the burdensome integration of force sensors at the human–robot attachments, we propose the use of a Kalman filter to perform data and sensor fusion to estimate the interaction force. We demonstrate the impact of real world issues on the measurement estimation and evaluate its performance in hardware. Preliminary simulation and experimental results demonstrate that good measurement prediction and control performance may be achieved with such an estimator.

Thiago Boaventura, Lisa Hammer, Jonas Buchli
Validation of a Gravity Compensation Algorithm for a Shoulder-Elbow Exoskeleton for Neurological Rehabilitation

In this paper we validate a gravity compensation algorithm for a novel shoulder-elbow exoskeleton, aimed at compensating the device weight during the execution of rehabilitation exercises. Along with the description of the exoskeleton, we present the results of the validation of the algorithm on data acquired in static and dynamic trials, in unloaded conditions. Results showed good performance of the algorithm in calculating the gravity torque of each joint, suggesting the possibility to implement rehabilitation exercises in which a specific net amount of assistive torque is provided to the user’s joints.

S. Crea, M. Cempini, M. Moisè, A. Baldoni, E. Trigili, D. Marconi, M. Cortese, F. Giovacchini, F. Posteraro, N. Vitiello
A Robot-Assisted Neuro-Rehabilitation System for Post-Stroke Patients’ Motor Skill Evaluation with ALEx Exoskeleton

Robotic Neuro Rehabilitation has been proved to be effective for motor recovery and less demanding for therapists. During a therapy, the aim of the task is to maximize the patient’s effort with respect to his/her clinical status and motor abilities, improving at the same time his/her impaired movements. In this paper, we propose a framework for performance evaluation of post-stroke subjects able to provide assistance-as-needed based on their motor skills during a therapy session with an upper-limb robotic exoskeleton.

F. Stroppa, C. Loconsole, S. Marcheschi, A. Frisoli
Rhythmic Movements After a Stroke: A Different Motor Primitive Should Receive a Dedicated Training

This paper reports two experiments that we recently conducted. The first established that upper-limb rhythmic and discrete movements are differentially affected after a stroke, reinforcing the statement that these two movements form two fundamentally different motor primitives. The second focused on the development of a specific robot-assisted therapy for rhythmic movements, targeting assistance-as-needed. We claim that rhythmic movements deserve such as specific therapy, since they are part of the daily motor repertoire and belong to a different class of movements as the discrete ones.

Patricia Leconte, Renaud Ronsse
Multimodal Control Architecture for Assistive Robotics

This document present a multimodal control architecture for assistive robotics which try to minimize the possible aleatory error during the grasping process by means of visual servoing techniques. Through the gaze tracking information provided by the Tobii Pro Glasses 2 the user is capable to interact with the system in order to select the desirable object as well as indicate the intention to grasp it. At the same time, employing the 6DoF optical tracking information provided by the OptiTrack V120:Trio, the system defines the position to reach and also supervises the movement of the robot to detect some deviation in the trajectory execution.

José M. Catalán, Jorge A. Díez, Arturo Bertomeu-Motos, Francisco J. Badesa, Nicolás Garcia-Aracil
Rationale of an Integrated Robotic Approach for Upper Limb Functional Rehabilitation

Upper limb motor impairment often causes long-term disability in stroke patients and implies limitations in activities of daily living. Several studies tested robotic devices for proximal or distal upper limb rehabilitation and reported results principally focused on specific treated district without significant global effects. We propose a novel approach that integrates a hand distal effector in task-oriented arm training for upper limb functional rehabilitation. Four chronic stroke patients underwent to an intensive rehabilitative treatment using a robotic device that provides arm weight support and assistance of the hand closing/opening within specific setting in virtual reality. After treatment improvements in upper limb functional scales and in kinematic and pressure assessments were observed, highlighting effects on global upper limb motor performance and distal motor control. Furthermore a decrease in resting motor threshold and a reduction in silent period recorded from unaffected hemisphere were evident, suggesting a potential cortical reorganization.

G. Sgherri, G. Lamola, C. Fanciullacci, M. Barsotti, E. Sotgiu, D. Leonardis, C. Procopio, B. Rossi, A. Frisoli, C. Chisari
Novel Mixed Active Hand Exoskeleton and Assistive Arm Device for Intensive Rehabilitative Treatment for Stroke Patients

This paper presents a novel rehabilitative platform designed to provide a functional upper-limb task specific training for hemiparetic chronic stroke patients. The system provides arm weight support and robotic assistance of the hand closing/opening skill. A graphical interface allows clinicians to administer different virtual reality scenarios and to customize training tasks providing progressive complexity based on patients motor skills. In order to assess motor function recovery along the whole treatment, objective performance metrics have been extracted and analyzed, showing an overall improvement of upper limb motor function after the treatment period.

Michele Barsotti, Edoardo Sotgiu, Daniele Leonardis, Giada Sgherri, Giuseppe Lamola, Chiara Fanciullacci, Caterina Procopio, Carmelo Chisari, Antonio Frisoli
Design of a Prono-Supination Mechanism for Activities of Daily Living

This paper describes the design process of a mechanism for assisting the movements of pronation and supination of the forearm. The device is designed to be part of an assistive robotic exoskeleton, which is being developed within the AIDE project. The distinctive feature of this mechanism is that it satisfies a number of technical requirements needed to perform activities of daily living such as eating or serving water from a bottle. This will need a special approach in order to modify and adapt commercial and generic components for the requested application, so that it results in an inexpensive and reliable device.

Jorge A. Díez, Andrea Blanco, José M. Catalán, Francisco J. Badesa, José M. Sabater, Nicolas Garcia-Aracil

Rehabilitation Robotics and Neuroprosthetics: Soft Wearable Robotics: Potential for Neurorehabilitation

Frontmatter
MAXX: Mobility Assisting teXtile eXoskeleton that Exploits Neural Control Synergies

Exosuits are a promising robotic approach to assist individuals with motor impairment while being lightweight and unobtrusive. However, these systems have limitations since they can neither provide high levels of assistance nor continuous support. Due to the lack of rigid structures, exosuits are also not able to provide contentious stability. Our goal was to reduce the limitations of such systems by determining an optimal exosuit architecture. Therefore, we conducted an extensive analysis of neural, kinetic and kinematic variables during several lower limb motor tasks. Our multi-articular exosuit MAXX (Mobility Assisting textile eXoskeleton) supports the weight of a person without collapsing, provides stability, and applies the forces needed to move the joints.

Kai Schmidt, Robert Riener
Soft Printable Pneumatics for Wrist Rehabilitation

Stroke is a leading cause of disability worldwide. Rehabilitation is necessary to recover from such disability. However due to growing manpower constraints and greying populations, patients receive limited rehabilitative care. In recent years, soft robotics is slowly becoming more popular as a choice of technology for robot-assisted rehabilitation. Traditional methods of fabricating soft actuators typically require the use of mold-casting, which is a multi-step process. Therefore, this work aimed to adopt a single-step printable pneumatics technique to fabricate soft bending actuators for wrist rehabilitation. The printed pneumatic actuator showed increased bending curvature and force output with greater input air pressure. Based on our preliminary testing, we found that the soft wrist rehabilitation device, based on soft actuators developed using a printable pneumatics approach, is able to guide the wrist model and the human wrist through flexion-extension motions.

H. K. Yap, H. Y. Ng, C. H. Yeow
Use of an Actuated Glove to Facilitate Hand Rehabilitation After Stroke

Stroke survivors often experience long-term upper extremity impairment. This can greatly impair activities of daily living. Repetitive practice of task-oriented training is thought to be beneficial for rehabilitation, but task practice can be limited by poor hand motor control. The objective of this study is to use a soft robotic glove to facilitate hand therapy of stroke survivors. Participants, all of whom will have experienced a stroke less than one year prior to enrollment, will complete 18 one-hour sessions, consisting of 20 min of passive stretching followed by 40 min of active task practice while wearing the device. To date two subjects have finished all training sessions. The device was well tolerated and improvements were observed. The study is ongoing.

Ning Yuan, Kelly Thielbar, Li-Qun Zhang, Derek G. Kamper
Design and Preliminary Testing of a Soft Exosuit for Assisting Elbow Movements and Hand Grasping

Most of the currently available exoskeletons for upper limbs are constrained by limited portability, ergonomics, weight and, energy-wise, autonomy. Moreover, their high cost makes them available only for the most affluent users, ruling out the majority of the population in need. By replacing rigid aluminum links and transmissions with fabrics and bowden cables, we can both cut down the cost of the assistive device and design it to be portable, comfortable and lightweight. We present the design and a preliminary testing of a soft exosuit for assisting elbow flexion/extension and hand open/close. Our system comprises two proximally located tendon-driving actuators, and two textile-based frames that route the tendons and transmit forces to the human joints, namely an elbow sleeve and a glove. A preliminary test on a healthy subject is presented with an adaptive controller that achieves good tracking accuracy despite of the system’s non-linear and time-varying dynamics.

M. Xiloyannis, L. Cappello, B. Khanh Dinh, C. W. Antuvan, L. Masia

Rehabilitation Robotics and Neuroprosthetics: Next Generation Bionics

Frontmatter
The Quest for a Bionic Hand

Replacing a missing upper limb with a functional one is an ancient need and desire. The need for a versatile prosthetic limb with intuitive motor control and realistic sensory feedback is huge and its development is absolutely necessary for the near future. In this paper, our recent results about the possibility to stimulate afferent nerves by using intraneural implants are briefly summarized. We showed that using this approach it is possible to restore the bidirectional connection between a dexterous hand prosthesis and the nervous system. The user was also able to improve his ability to provide useful motor commands over time. This finding can open up interesting opportunities for sensory restoration in prosthetic hands.

Silvestro Micera
Prosthetic Control by Lower Limb Amputees Using Implantable Myoelectric Sensors

When a lower extremity is lost the primary and obvious effect is the loss of the mechanical support of weight bearing when standing and walking. Additionally there are loses of sensation for the lost leg, the sensation for interaction of the leg with its environment as well the central nervous system motor control of the leg in response to these sensations and for the purpose of locomotion. All of these losses affect quality of live negatively in many different ways, a parameter that is accepted valid for economic decision making since its improvements are highly associates with increased mobility. Reestablishing the central nervous system connection of bionic prosthesis is the next lower limb prosthetic challenge. Here we present the first cases of amputees gaining voluntary control of commercially available microprocessor controlled lower limb prosthesis using implantable myoelectric sensors.

Kristleifur Kristjansson, Jona S. Sigurdardottir, Atli Ö. Sverrisson, Stefan P. Sigurthorsson, Olafur Sverrisson, Arni Einarsson, Knut Lechler, Thorvaldur Ingvarsson, Magnus Oddsson
A MyoKinetic HMI for the Control of Hand Prostheses: A Feasibility Study

In an attempt to overcome the several limitations of currently available/investigated human-machine interfaces (HMI) for the control of robotic hand prostheses, we propose a new HMI exploiting the magnetic field produced by magnets implanted in the muscles. As a magnet is implanted in a muscle it will travel with it, and its localization could provide a direct measure of the contraction/elongation of that muscle, which is voluntarily controlled by the individual. Here we present a proof of concept of a single magnet localizer, which computes on-line the position of a magnet in a certain workspace. In particular, the system comprises a pair of magnetic field sensors mounted on custom printed circuit boards, and an algorithm that resolves the inverse magnetic problem using the magnetic dipole model. The accuracy and the repeatability of our system were evaluated using six miniature magnets. Ongoing results suggest that the envisioned system is viable.

Sergio Tarantino, Francesco Clemente, Diego Barone, Marco Controzzi, Christian Cipriani
User Centered Design and Usability of Bionic Devices

User Centered Design of bionic and assistive devices is growing in importance as many technologies are now moving from lab concepts to certified medical products for use in daily life. The enthusiasm to develop new technologies often focuses on the scientific requirements but often very practical user requirements are over looked. This presentation discusses the role of user centered design in bionics development and how this relates to usability in use. The presentation frames the importance of usability and user centered design on technology acceptance, generally by users, but also with focus on technology acceptance and adoption by older age adults.

L. W. O’Sullivan, V. Power, A. de Eyto, J. Ortiz

Rehabilitation Robotics and Neuroprosthetics: Advances in Limb Prosthetics

Frontmatter
Does Sensory Feedback in Prosthetic Hands Provide Functional Benefits in Daily Activities of Amputees?

In an attempt to investigate the value of artificial somatosensory feedback in upper limb prostheses we designed a novel, modular feedback system and paired it with a battery of clinically-relevant tests. Three transhumeral amputee subjects, wearing dexterous myoelectric hands, participated in the study. The obtained objective as well as subjective performance outcomes indicate that the benefits of feedback might be seen only in dexterous, delicate tasks.

M. Marković, L. F. Engels, M. Schweisfurth, S. Došen, D. Wüstefeld, D. Farina
Synergy-Based Myocontrol of a Two Degree of Freedom Robotic Arm in Children with Dystonia

We tested the ability of a synergy-based myocontrol scheme to achieve simultaneous, continuous control of two degrees of freedom (DOFs) of a robotic arm that reproduces the child’s movement (or intention of movement), using muscle synergies extracted from muscles recorded during both isometric contractions and unconstrained flexion-extension movements of elbow and shoulder joints in the horizontal plane. The aim of the current work was to validate the feasibility and the efficacy of the synergy-based approach for multi-DOF robotic control in children with dystonia, compared to the simple muscle-pair method typically used in commercial applications. The proposed synergy-based scheme showed a better performance compared to the traditional muscle-pair approach, both in dynamic and isometric conditions. The current study represents a crucial successful first step toward synergy-based working solutions for children with dystonia.

Francesca Lunardini, Claudia Casellato, Terence D. Sanger, Alessandra Pedrocchi
Dynamic Stimulation Patterns for Conveying Proprioceptive Information from Multi-DOF Prosthesis

The aim of this study was to investigate the ability of the amputees to understand and identify proprioceptive feedback information presented by a set of dynamic stimulation patterns. The feedback relied on spatial coding of electrotactile stimuli, provided by a multichannel electrical stimulator, over custom designed array electrodes. Four stimulation patterns representing opening, closing, pronation and supination of a prosthetic hand were defined to mimic the change of the corresponding prosthesis degree of freedom. The psychometric evaluation on three amputee subjects confirmed that the four proposed dynamic stimulation patterns can be distinguished successfully after a short training.

Milica Isaković, Matija Štrbac, Minja Belić, Goran Bijelić, Igor Popović, Milutin Radotić, Strahinja Došen, Dario Farina, Thierry Keller
Evoking Referred Sensations of Missing Digits by Electro-Tactile Stimulation: Preliminary Tests

Sensory feedback is an important component in a prosthetic device. However, due to technological limits, current prosthetic digits aimed to treat partial hand amputations do not provide individuals with cutaneous touch feedback. In this work, we propose to employ electro-tactile stimulation to promote, by the application of stimulation electrodes on the palm, sensations relative to the missing digits. The promising findings of tests on 20 able-bodied participants are presented in this abstract.

Marco D’Alonzo, Ahmed I. K. Alsaqqa, Marco Controzzi, Christian Cipriani
Investigation into Energy Efficiency and Regeneration in an Electric Prosthetic Knee

Powered lower limb prosthesis are facing energy and efficiency challenges. This article presents an investigation into reducing the energy losses and increasing the efficiencies of energy regeneration for a powered prosthetic knee during level ground walking. The results showed that the regeneration and overall system efficiencies would dramatically increase if the negative mechanical load in the braking quadrants are within the regenerative zone of the motor. This approach reduced the energy losses in the stance and swing phases and increased the possibility of harvesting more negative mechanical energy during level ground walking.

M. I. Awad, A. Abouhossein, B. Chong, A. A. Dehghani-Sanij, R. Richardson, D. Moser, S. Zahedi

Rehabilitation Robotics and Neuroprosthetics: Neuromechanical Modeling for Wearable Assistive Technologies

Frontmatter
A Model of Human Non-stepping Postural Responses as the Basis for a Biomimetic Control Strategy for Robot-Assisted Balance

We present an optimal feedback model of human standing balance that answers three open questions related to the complexity, energy requirements, and robustness of the control architecture and that will serve as the basis for a biomimetic control strategy for robot-assisted balance.

Maarten Afschrift, Joris De Schutter, Ilse Jonkers, Friedl De Groote
Optimizing Wearable Assistive Devices with Neuromuscular Models and Optimal Control

The coupling of human movement dynamics with the function and design of wearable assistive devices is vital to better understand the interaction between the two. Advanced neuromuscular models and optimal control formulations provide the possibility to study and improve this interaction. In addition, optimal control can also be used to generate predictive simulations that generate novel movements for the human model under varying optimization criterion.

Manish Sreenivasa, Matthew Millard, Paul Manns, Katja Mombaur
Combining a 3D Reflex Based Neuromuscular Model with a State Estimator Based on Central Pattern Generators

A neuromuscular model (NMC) presented by H. Geyer and extended by S. Song shows very interesting similarities with real human locomotion. The model uses a combination of reflex loops to generate stable locomotion and is able to cope with external disturbances and adapt to different conditions. However, to our knowledge no works exist on the capability of the model to handle sensory noise. In this paper, we present a method for designing Central Pattern Generators (CPG) as feedback predictors, which can be used to handle large amount of sensory noise. We show that the whole system (NMC + CPG) is able to cope with a very large amount of noise, much larger than what the original system (NMC) could handle.

T. J. H. Brug, F. Dzeladini, A. R. Wu, A. J. Ijspeert
Subject-Specificity via 3D Ultrasound and Personalized Musculoskeletal Modeling

This study combines experimental-based and model-based methodologies for accessing in vivo musculoskeletal function in healthy individuals. We use ultrasound and dynamometer technologies to derive subject-specific muscle parameters including muscle isometric force, optimal fiber length and tendon slack length. We then assess the impact of subject-specificity on the electromyography-driven simulation of walking of the composite musculoskeletal system.

Massimo Sartori, Jonas Rubenson, David G. Lloyd, Dario Farina, Fausto A. Panizzolo
An In Vitro Approach for Directly Observing Muscle-Tendon Dynamics with Parallel Elastic Mechanical Assistance

Lower-limb exoskeletons are a promising tool for restoring or augmenting locomotion performance. While engineering advances have led to marked improvements on the machine side of the human machine interface, fundamental aspects of the physiological response of the human user remain unknown—especially at the level of individual leg muscles. One complication is that it is difficult to make direct measurements from muscles in humans without being invasive. Here we offer a novel benchtop approach by introducing a ‘smart’ robotic interface into the framework of biological muscle-tendon work loop experiments in order to simulate the local dynamical environment muscles experience in vivo during locomotion with exoskeleton assistance. Using this framework we demonstrate that providing force in parallel with a muscle-tendon using an ‘exo-tendon’ can have unintended consequences, disrupting the ‘tuned’ spring-like mechanics of the underlying biological muscle tendon unit.

Gregory S. Sawicki, Benjamin D. Robertson
Toward Balance Recovery with Active Leg Prostheses Using Neuromuscular Model Control

We seek to improve balance recovery in amputee gait by taking advantage of the advent of active leg prostheses. Toward this goal, we use inspiration from biology to identify reflex-like control strategies that stabilize gait, refine these strategies in simulations of amputee locomotion, and evaluate the resulting controllers in experiments with human subjects wearing custom prototypes of active leg prostheses. Our results so far indicate that reflex-like control can improve balance recovery over existing control strategies used in active leg prostheses. However, further research on the hardware realization of the control is needed to more rigorously evaluate its potential benefit to amputee locomotion.

Hartmut Geyer, Nitish Thatte, Helei Duan

Rehabilitation Robotics and Neuroprosthetics: Motor Neuroprosthetics

Frontmatter
Clinical Trial Protocol for Analyzing the Effect of the Intensity of FES-Based Therapy on Post-stroke Foot Drop

Positive assistive and therapeutic effects of FES have been proved for post-stroke subjects suffering from foot drop. However, the published studies are very heterogeneous in terms of methodology, therapy duration, session duration and session frequency, where most studies rely on intensive FES-based therapy. In this document a clinical protocol is proposed for analyzing the effect of medium and low intensity of FES-based therapy. The protocol is designed to be used with a surface multi-field FES system and it is based on available studies on literature and preliminary results with chronic post-stroke subjects. The proposed clinical trials could help determining the minimum necessary FES-based therapy intensity for obtaining positive therapeutic results.

Eukene Imatz-Ojanguren, Haritz Zabaleta, David Valencia-Blanco, Jovana Malešević, Milos Kostić, Thierry Keller
TMR Improves Performance of Compensatory Tracking Using Myoelectric Control

We explored the performance of a glenohumeral TMR (targeted muscle reinnervation) patient in controlling the activity of two reinnervated muscles of the chest and back during a compensatory tracking task that implied quick switches of activity between the two muscles. The same task was conducted in intact-bodied subjects, using either the wrist flexor/extensor muscles (innervated by the nerves were used as donors in the TMR patient) or the chest/back muscles that were re-innervated in the patient following the TMR. As expected, the intact-bodied subjects showed better control performance when using the wrist muscles than when using the chest and back muscles. Using the reinnervated chest and back muscles, the TMR patient performed similarly in the compensatory task than the able-bodied subjects when they used wrist muscles and his performance was superior than that of the able-bodied subjects using their chest and back muscles for control. These results indicate that the control properties have been improved through TMR.

Meike A. Schweisfurth, Tashina Bentz, Strahinja Došen, Jennifer Ernst, Marko Marković, Gunther Felmerer, Oskar C. Aszmann, Dario Farina
Injectable Stimulators Based on Rectification of High Frequency Current Bursts: Power Efficiency of 2 mm Thick Prototypes

To overcome the miniaturization bottleneck imposed by existing power generation/transfer technologies for implantable stimulators, we have proposed a heterodox electrical stimulation method based on local rectification of high frequency (≥1 MHz) current bursts delivered through superficial electrodes. We have reported 2 mm thick addressable injectable stimulators, made of off-the-shelf components, that operate according to this principle. Since a significant amount of high frequency power is wasted by Joule heating, the method exhibits poor energy efficiency. In here we have performed a numerical case study in which the presence of the above implant prototypes is simulated in an anatomically realistic leg model. The results from this study indicate that, despite low power transfer efficiency (~0.05 %), the power consumed by the external high frequency current generator is low enough (<4 W) to grant the use of small portable batteries.

Laura Becerra-Fajardo, Roser Garcia-Arnau, Antoni Ivorra
Quasi-Static Control of Whole-Arm Motions with FES

This paper introduces a quasi-static method for controlling reaching movements of a paralyzed human arm using FES. A subject-specific model was estimated from experimental data collected from a single subject with a high cervical spinal cord injury who uses a functional electrical stimulation neuroprosthesis. We tested a controller based on this model that maps desired shoulder and elbow joint positions to muscle stimulation commands. The controller tracked the desired lateral direction of hand movements well but did not track forward/backward or vertical movements well. The lateral position of the hand was not greatly affected by the direction of movement given identical stimulation commands, which supports the hypothesis that velocity information is not required for tracking slow hand movements.

Eric M. Schearer, Derek N. Wolf, Robert F. Kirsch
Hybrid Robotic System for Reaching Rehabilitation After Stroke: Reporting an Usability Experimentation

The combined use of functional electrical stimulation and robotic exoskeleton in a hybrid rehabilitation system represents a promising research field for rehabilitation of the motor functions after stroke. In this work, we report the results obtained in a study carried out with a hybrid robotic system for reaching rehabilitation. The system was tested in two sessions with one chronic stroke subject.

F. Resquín, J. González-Vargas, J. Ibañez, I. Dimbwadyo, S. Alves, L. Torres, L. Carrasco, F. Brunetti, J. L. Pons

Rehabilitation Robotics and Neuroprosthetics: FES and Wearable Robot Systems in Rehabilitation and Assistance of Locomotion

Frontmatter
Dynamic Optimization of a Hybrid Gait Neuroprosthesis to Improve Efficiency and Walking Duration: A Simulation Study

The walking duration of gait restoration systems that use functional electrical stimulation (FES) is severely limited by the rapid onset of muscle fatigue. Alternatively, fully actuated orthoses can also be employed to restore walking in paraplegia. However, due to the high power consumption of electric motors the walking duration of such devices are limited by the charge of the batteries. This paper proposes that a hybrid system, which uses FES and an actuated orthosis, is capable of achieving greater walking durations than an FES only system and more energetically efficient than a lower-limb exoskeleton. This is illustrated through results of optimizations of a musculoskeletal gait model for three actuation cases: FES only, electric motors only, and a hybrid system. The presented results illustrate that a hybrid system may be capable of greater walking durations than FES-based systems while using half the energy of a lower-limb exoskeleton.

Nicholas A. Kirsch, Naji A. Alibeji, Mark Redfern, Nitin Sharma
Preliminary Experiments of an Adaptive Low-Dimensional Control for a Hybrid Neuroprosthesis

Hybrid neuroprostheses that use both electric motor drives and functional electrical stimulation for the restoration of walking in persons with paraplegia have a promising potential. However, the hybrid actuation structure introduces effector redundancy, making the system complex and difficult to control. In this paper, preliminary experimental results of a recently developed low-dimensional controller, which is inspired from the muscle synergy principle, are presented. The experiments were performed on an able-bodied subject in a configuration where only one leg is actuated in a cycling manner while the contralateral leg was fixed.

Naji A. Alibeji, Nicholas A. Kirsch, Nitin Sharma
The Potential of Inertial Sensors in Posture, Gait and Cycling FES-Assistance

In this communication we will present some general approaches developed in our team and recent results involving inertial measurement units (IMU) in FES-controllers for lower-limb movement assistance in different situations of sensory-motor deficiencies. We will discuss some of the challenges to met in order to achieve robust adaptive controllers.

Christine Azevedo Coste, Benoît Sijobert, Christian Geny, Jérôme Froger, Charles Fattal
Online Monitoring of Muscle Activity During Walking for Bio-feedback and for Observing the Effects of Transcutaneous Electrical Stimulation

This contribution describes a method for real-time analysis of muscle activity over the gait cycle while simultaneously applying Functional Electrical Stimulation (FES) to the assessed muscles. Inertial sensors at the foot are used for real-time gait phase detection in order to synchronize the stimulation with the gait. An EMG analysis has been performed to cancel out stimulation artifacts, to filter the data and to extract the voluntary EMG activity. This corrected EMG signal has been rectified and low-pass filtered to produce an envelope that was parameterized as a function of the Gait Cycle Percentage (GCP). The volitional EMG activity profile has been averaged over five strides and can be presented as a moving average over the exercise duration. Initial evaluation with healthy subjects showed that this procedure is feasible to detect the expected volitional muscle activity profiles also during active electrical stimulation.

Nathan D. Bunt, Juan C. Moreno, Philipp Müller, Thomas Seel, Thomas Schauer
Walking Assistance Through Impedance Control of a Lower-Limb Exoskeleton

This paper presents a control approach of a lower limb exoskeleton by modulating the original impedance of the wearer’ swinging leg to reduce the muscular efforts. The proposed method ensures compensation of the damping and gravity effects of the wearer’s leg to desired levels offering though the possibility to adapt the lower limb wearer’s impedance as a function of the gait phase evolution. The performance of the proposed approach is evaluated by carrying out experiments with two healthy subjects. The EMG activities of the extensor muscles spanning the knee-joint are used as assesment criteria. The results show that the muscular activities required to perform the same flexion/extension movements are effectively reduced by providing lower desired joint damping and stiffness with exoskeleton’s assistance.

Weiguang Huo, Samer Mohammed, Yacine Amirat

Rehabilitation Robotics and Neuroprosthetics: Novel Technologies and Natural Sensory Feedback for Phantom Limb Pain Modulation and Therapy

Frontmatter
Natural Sensory Feedback for Phantom Limb Pain Modulation and Therapy

Phantom limb pain (PLP) is a frequent consequence of amputation, and it is notoriously difficult to treat. Despite isolated reports of success, no medical/non-medical treatments have been beneficial on more than a temporary basis. Recent evidence suggests that the pathophysiological mechanism of PLP is related to neuroplastic changes in the cortex. While the majority of the treatments currently offered seek to actively suppress the pain, the EU consortium ‘EPIONE’ will challenge the status-quo of PLP treatment by actively creating natural, meaningful sensations that will restore the neuroplastic changes in the cortex and thereby control and alleviate pain. The consortium will develop dedicated, technological solutions and test these in multi-center clinical trials within Europe and the US.

Winnie Jensen
Evaluation of the Effect of Sensory Feedback on Phantom Limb Pain in Multi-center Clinical Trials

The EPIONE consortium aims to evaluate the effect of artificial sensory stimulation using an operant conditioning paradigm as a therapy for Phantom Limb Pain (PLP). A uniform therapy /assessment protocol was developed for a multi-center study to evaluate the effect of the therapy on their (1) Phantom Limb Pain, (2) psychological state and (3) sensory motor cortical map. Participating subjects complete several phases of assessment. Post hoc analyses will compare results from testing done before, during, and after therapy. Outcomes of the intervention aim to improve the current understanding of pain and the psychophysical effects of pain management, which will progress the pilot therapy program toward a fully developed PLP solution.

Ken Yoshida, James Malec, Caleb Comoglio, Kristine Mosier, Romulus Lontis, Knud Larsen, Xavier Navarro, Winnie Jensen
On Biocompatibility and Stability of Transversal Intrafascicular Multichannel Electrodes—TIME

Transversal intrafascicular multichannel electrodes (TIME) have been developed to interface with peripheral nerves after upper limb amputation. Intended use is the electrical stimulation of the median and ulnar nerve to deliver sensory feedback during phantom limb pain treatment and artificial hand control. Miniaturized electrode arrays were developed on polyimide substrates with thin film metallization using sputtered iridium oxide as electrode coating. Here, we report on the essential requirements including biocompatibility, mechanical and stimulation stability that have been investigated before permission was granted by the legal authorities to conduct subchronic first-in-man clinical trials. Explants have been investigated to identify possible first failure points and optimize the devices for chronic implantation.

Thomas Stieglitz, Tim Boretius, Paul Čvančara, David Guiraud, Thomas Guiho, Victor Manuel Lopez-Alvarez, Xavier Navarro
On the Use of Intraneural Transversal Electrodes to Develop Bidirectional Bionic Limbs

The development of more effective approaches for controlling dexterous hand prostheses is an important area of research currently addressed by several groups with the aim of improving the quality of life of amputees. It is particularly important to establish a fast, intuitive, bidirectional flow of information between the user’s nervous system and the smart artificial device. Among the possible solutions to achieve this goal, interfaces with the peripheral nervous system, namely intraneural electrodes, are considered the most adequate choice. In this paper, the results achieved so far by using thin-film transversal intraneural electrodes for neural recording and stimulation are summarized. These findings show that these interfaces are a valuable solution for neural writing while long-term neural recording is still challenging. Further experiments are necessary to better understand how to address this issue.

Silvestro Micera, Stanisa Raspopovic, Francesco Petrini, Jacopo Carpaneto, Calogero Oddo, Jordi Badia, Thomas Stieglitz, Xavier Navarro, Paolo M. Rossini, Giuseppe Granata
Advanced 56 Channels Stimulation System to Drive Intrafascicular Electrodes

A wearable, 56-channel stimulator was developed and successfully tested to drive multichannel intrafascicular electrodes. It is able to safely elicit sensory afferent signals through the activation of 4 Time-4H intrafascicular electrodes. The STIMEP embeds not only the pulse generator but also a software that ensures: (i) real time control by a hand-prosthesis, (ii) embedded procedures for sensation mapping interfaced with a PC software, (iii) impedance follow-up, (iv) real-time safety management.

T. Guiho, D. Andreu, V. M. López-Alvarez, P. Cvancara, A. Hiairrassary, G. Granata, L. Wauters, W. Jensen, J. L. Divoux, S. Micera, T. Stieglitz, X. Navarro, D. Guiraud

Biological Signal Analysis: Neural Signal Processing of the Pathological Brain

Frontmatter
Analysis of Functional Connectivity During an Auditory Oddball Task in Schizophrenia

The aim of this study was to evaluate neural coupling patterns in schizophrenia (SCH) patients and healthy controls during an auditory oddball task. Two measures of functional connectivity were applied to 28 SCH patients and 51 healthy controls to characterize electroencephalographic (EEG) activity. Specifically, magnitude squared coherence (MSC) and the imaginary part of coherency (ICOH) were computed for five frequency bands: theta, alpha, beta-1, beta-2 and gamma. The results showed a statistically significant modulation increase in MSC and ICOH for controls with respect to SCH in the theta band, and a decrease in ICOH for the beta-2 band. Furthermore, controls showed more significant changes from the baseline and active task windows than SCH patients. Our findings suggest that SCH patients show coupling abnormalities during an auditory oddball task compared to healthy controls.

P. Núñez, J. Poza, A. Bachiller, J. Gomez-Pilar, C. Gómez, A. Lubeiro, V. Molina, R. Hornero
Event-Related Phase-Amplitude Coupling: A Comparative Study

The aim of this study was to explore the coupling among neural oscillations in different frequency bands using two approaches: conventional phase-amplitude coupling (PAC) and a novel event-related PAC. Both measures were applied to the electroencephalographic activity from 20 healthy volunteers. The results showed that the phase of alpha band modulated gamma power. Event-related PAC measures the coupling between frequency rhythms without losing of temporal resolution. Therefore, it may provide further insights into the characterization of brain dynamics.

A. Bachiller, J. Gomez-Pilar, J. Poza, P. Núñez, C. Gómez, A. Lubeiro, V. Molina, R. Hornero
Assessment of Effective Connectivity in Alzheimer’s Disease Using Granger Causality

Alzheimer’s disease (AD) is a neurological disorder accompanied by cognitive impairment. A complete understanding of the neurological processes involved in AD is a leading challenge in brain research. In this study, resting-state magnetoencephalography (MEG) activity from 36 AD patients and 26 healthy controls was evaluated by means of Granger Causality (GC), an effective connectivity measure that provides an estimation of the information flow between brain regions. Our results showed widespread increments in connectivity in delta (δ, 1–4 Hz) band. On the other hand, decrements in connectivity patterns were found for theta (θ, 4–8 Hz), beta (β, 13–30 Hz), and gamma (γ, 30–65 Hz) bands. These findings strength the disconnection hypothesis in AD, and reveal GC as a useful parameter for AD characterization.

Celia Juan-Cruz, Carlos Gómez, Jesús Poza, Alberto Fernández, Roberto Hornero
Visual Detection of High Frequency Oscillations in MEG

High Frequency Oscillations (HFOs, >80 Hz) are events that have been linked to the seizure onset zone (SOZ). Few studies have identified HFOs in noninvasive EEG and MEG signals due to the high signal-to-noise ratio (SNR) required, but beamforming-based virtual sensors (VS) can increase SNR. We computed the beamforming-VS as a grid inside the brain volume model for 200 s MEG signals. Events of interest (EOIs) exceeding a threshold were automatically determined as well as the area of interest, where EOIs occurred more frequently. Finally HFOs inside the area of interest were selected and compared with simultaneous iEEG recordings.

Carolina Migliorelli, Joan F. Alonso, Sergio Romero, Miguel A. Mañanas, Rafal Nowak, Antonio Russi
On Recalibration Strategies for Brain-Computer Interfaces Based on the Detection of Motor Intentions

Coupling motor intentions decoded from cortical activities with coherent proprioceptive feedback is of interest for the motor rehabilitation of neurological patients with lesions in the central nervous system. For these interventions to be effective, repeated sessions need to be carried out to achieve functional long-lasting plastic changes of cortical circuits. Electroencephalography-based Brain-Computer Interfaces typically show significant decreases in accuracy when used across multiple sessions with fixed parameters. Therefore, it is important to look for optimal strategies to recalibrate these classifiers. Here we compare different recalibration strategies for systems decoding motor intentions based on electroencephalographic data of neurological patients.

J. Ibáñez, E. López-Larraz, E. Monge, F. Molina-Rueda, L. Montesano, J. L. Pons

Biological Signal Analysis: Data Mining and Physiological Signal

Frontmatter
A Stress Classification System Based on Arousal Analysis of the Nervous System

Detection of an increment in stress levels is a step towards improving the quality of people’s lives, especially in the case of people with intellectual disabilities, as they have fewer resources to deal with this situation. This paper presents a biophysical stress classification system that is able to classify the detected stress situations at three intensity levels: low, medium and high. Furthermore, the system distinguishes between continued stress and a momentary alert depending on the subject’s arousal. The system uses two non-invasive physiological signals for the classification: the galvanic skin response and the heart rate variability. The experiment shows that the proposed system is able to detect and classify the different stress states achieving an accuracy of 97.5 % with a 0.9 % FN rate.

R. Martínez, J. Abascal, A. Arruti, E. Irigoyen, J. I. Martín, J. Muguerza
Spectral Regression Kernel Discriminant Analysis for P300 Speller Based Brain-Computer Interfaces

This study proposes a novel classification algorithm for enhancing the performance of online P300 Speller based Brain-Computer Interface (BCI) applications. The key element of the algorithm is an ensemble of spectral regression kernel discriminant analysis (SRKDA) classifiers, an optimized version of the well-known KDA. The method was tested with the III BCI Competition dataset IIa and results were compared with LDA and the winner of the competition. Reached accuracies outperforms both of them for 5 and 15 sequences, making the proposed method a suitable alternative for this kind of applications.

Víctor Martínez-Cagigal, Pablo Núñez, Roberto Hornero
Supervised + Unsupervised Classification for Human Pose Estimation with RGB-D Images: A First Step Towards a Rehabilitation System

A system has been developed to detect postures and movements of people, using the skeleton information provided by the OpenNI library. A supervised learning approach has been used for generating static posture classifier models. In the case of movements, the focus has been done in clustering techniques. These models are included as part of the system software once generated, which reacts to postures and gestures made by any user. The automatic detection of postures is interesting for many applications, such as medical applications or intelligent interaction based on computer vision.

A. Aguado, I. Rodríguez, E. Lazkano, B. Sierra
Switch Mode to Control a Wheelchair Through EEG Signals

This paper presents a switch strategy to control the movement of a Brain-Controlled Wheelchair. After the activation of a Motor Imagery task, an advance movement is started and kept until the same task stop it. This way, users with an unstable control of their EEG could be aided in handling the wheelchair.

F. Velasco-Álvarez, A. Fernández-Rodríguez, R. Ron-Angevin
The Biosignal C.A.O.S.: Reflections on the Usability of Physiological Sensing for Human-Computer Interaction Practitioners and Researchers

Wearable technologies and low-cost hardware platforms for physiological data sensing are rapidly growing. However, biosignal sources pose usability and acceptability challenges, which can negativelly affect the users’ experience and performance when working with systems that incorporate physiological sensing. This paper analyses and presents practical considerations about the use of biosignals, highlighting aspects that practitioners and novice researchers should be aware of when designing their systems, especially in real-world use cases. Common biosignal modalities are characterised according to a proposed multidimensional taxonomy (C.A.O.S.), devised to characterize physiological data sources and balancing expectations around their use in human-computer interaction.

Hugo Plácido da Silva

Biological Signal Analysis: Human Gait Simulation for Exoskeleton Design and Patient Adaptation

Frontmatter
Evaluation of Motion/Force Transmission Between Passive/Active Orthosis and Subject Through Forward Dynamic Analysis

Forward dynamic analysis of the acquired gait of subjects assisted by either passive or active knee-ankle-foot orthoses and crutches is used to evaluate the motion and force transmission between orthosis and subject depending on the connecting stiffness. Unlike inverse dynamic analysis, this approach allows to consider the subject’s limbs and the assistive devices as different entities, so that their relative behavior may be studied. The quality of motion transmission and the intensity of interface forces are evaluated for a range of connecting stiffness values, so that those providing the best trade-off between both aspects can be identified.

Francisco Mouzo, Urbano Lugris, Javier Cuadrado, Josep M. Font-Llagunes, Francisco J. Alonso
Model-Based Optimization for the Design of Exoskeletons that Help Humans to Sustain Large Pushes While Walking

In order to be useful in daily life, lower limb exoskeletons have to be able to provide support not only for nominal situations, such as level ground walking, but also for the recovery from extreme situations. In this paper, we investigate which torques a lower leg exoskeleton would have to produce in order to allow a person to recover from large perturbations or pushes that may occur while walking. We propose a model-based optimization approach that takes into account dynamic models of the human and the exoskeleton as well as experimental data of humans being pushed. Using optimal control and a least squares objective function we compute the joint torques that exoskeletons of different masses and mass distributions would have to produce in order to make the person follow the recorded recovery trajectories of healthy subjects and which loads would occur in the structure. The results of these computations can serve as guidelines for the design of future lower limb exoskeletons.

R. Malin Schemschat, Debora Clever, Matthew Millard, Katja Mombaur
Neuromusculoskeletal Models of Human-Machine Interaction in Individuals Wearing Lower Limb Assistive Technologies

This abstract outlines how musculoskeletal modeling formulations driven by electrophysiological recordings can be used to understand the complex dynamics of human-machine interaction in healthy and impaired individuals wearing lower limb orthoses. We investigate two scenarios. The first involves a healthy individual walking with a powered exoskeleton. The second involves an impaired individual walking with a passive knee-ankle-foot orthosis. We demonstrate how offline and online modeling can be used for predicting the individual’s neuromusculoskeletal responses to the devices connected in parallels to their limbs.

Massimo Sartori, Guillaume Durandau, Dario Farina
Design, Analysis and Simulation of a Novel Device for Locomotion Support

Active ankle foot orthoses (AAFOs) can be found in the literature exhibiting promising results in the rehabilitation of people with gait disabilities. However none of the referred solutions was yet able to successfully surface the market as a new off-the-shelf product. There are several reasons for that, being probably the most important one the high level of customization that is still required both at the technical and at the user level. In this work, a novel concept of an AAFO is proposed that due to its particular design characteristics is thought to considerably reduce technical customization needs and hence presenting some advantages towards the creation of a new commercial product. An in silico CAD model is developed as proof-of-concept and a kinematic analysis is performed to evaluate motion performance and specific torque-velocity requirements.

Rita Cardoso, Miguel T. Silva

Biological Signal Analysis: BCI Driven Approaches for Motor-Cognitive Rehabilitation After Stroke

Frontmatter
An Associative Brain-Computer-Interface for Acute Stroke Patients

An efficient innovative Brain-Computer-Interface system that empowers chronic stroke patients to control an artificial activation of their lower limb muscle through task specific motor intent has been tested in the past. In the current study it was applied to acute stroke patients. The system consists in detecting the movement-related cortical potential (MRCP) using scalp electrodes as the patient attempts to perform a dorsiflexion task. This is translated into the control command for an electrical stimulator to generate a stimulus to the nerve that innervates and thus activates the prime mover (tibialis anterior). This activation is precisely and individually timed such that the sensory signal arising from the stimulation reaches the motor cortex during its maximum activation due to the intention. The output of the motor cortical area representing the dorsiflexor muscles was significantly enhanced in all patients tested following a single session of 30 repetitions. All patients were able to perform the intervention with minimal training and very few repetitions, making this a feasible new efficient approach for restoration of motor function in stroke patients. Such few necessary applications of the protocol make it a unique approach in comparison to available techniques and paves the way for at home use devices.

N. Mrachacz-Kersting, A. J. T. Stevenson, S. Aliakbaryhosseinabadi, A. C. Lundgaard, H. R. Jørgensen, K. Severinsen, D. Farina
Brain Computer Interfaces for Cognitive Rehabilitation After Stroke

We summarize the achievements of the EU FP7 funded project CONTRAST on cognitive rehabilitation after stroke. We developed a neuropsychological algorithm to assign patients to specific, personalized neurofeedback training to improve cognitive function, namely attention, declarative memory, inhibitory control, and working memory. Further, BCI technology was integrated into a remote control set-up, such that therapists can supervise simultaneously multiple patients at their home during BCI-based neurofeedback training. Phase I studies with subacute and chronic stroke patients demonstrated the potential of our approach such that patients were able to learn regulation of the respective brain activity and improved in the targeted cognitive function. Phase II studies are necessary to consolidate our findings.

Andrea Kübler, Sonja Kleih, Donatella Mattia

Biological Signal Analysis: Indirect Measures of Brain Activity: A Window into the Mind

Frontmatter
Short-Term Effects of Real-Time Auditory Display (Sonification) on Gait Parameters in People with Parkinsons’ Disease—A Pilot Study

Parkinson’s disease PD patients frequently experience gait impairments. Auditory input has been shown to be an effective measure to benefit critical gait aspects related to the timing and initiation of movement. An instrumented shoe insole device for real-time sonification of gait has been developed for rehabilitation purposes (SONIGait). The objective of the present pilot study was to gain insight about possible effects of SONIGait on gait parameters in PD patients. Five PD patients participated in this pilot study and completed three series of trials with and without sonification. Spatio-temporal gait parameters were recorded during these trials. The outcomes revealed an increase in walking velocity and cadence along with other gait parameters between pre- and posttest. These data indicate that sonification affects gait parameters and fosters (short-term) learning effects in PD patients. Thus, SONIGait may be a suitable measure to promote gait rehabilitation in PD in the future.

Anna-Maria Gorgas, Lena Schön, Ronald Dlapka, Jakob Doppler, Michael Iber, Christian Gradl, Anita Kiselka, Tarique Siragy, Brian Horsak
Articulation Characterization in AD Speech Production

Alzheimer’s Disease (AD) produce important clues in speech, which may be used in pathology monitoring and grading. The study is intended to model which aspects of articulation may be affected more, and to which extent. Comparing speech from AD patients versus control subjects produced in animal naming, certain characteristics may be observed, encoding fluency and formant dynamics. Kullback-Leibler Divergence from formant velocity distributions is sought to work as a possible biomarker in AD monitoring tasks.

P. Gómez-Vilda, M. K. López de Ipiña, V. Rodellar-Biarge, D. Palacios-Alonso, M. Ecay-Torres
Non-invasive Biosignal Analysis Oriented to Early Diagnosis and Monitoring of Cognitive Impairments

In this paper some of novel and low-cost methodologies are analysed for most common cognitive impairments: Alzheimer disease, Parkinson and Essential Tremor. These methodologies allow us to obtain information from the brain in an indirect form, without needing to do neither invasive nor expensive or long-time tests. We will present handwriting and speech as interesting biomarkers for the early detection and monitoring of cognitive impairments and detail possible fields of application, with real experiments carried-out at the Hospital Donostia (Spain) in several past and current projects.

K. López-de-Ipiña, J. Solé-Casals, U. Martinez de Lizarduy, P. M. Calvo, J. Iradi, M. Faundez-Zanuy, A. Bergareche
Eye-Tracking Data in Visual Search Tasks: A Hallmark of Cognitive Function

Vision is an active process in that detailed representations of our visual world are only built from actively scanning our eyes with a series of saccades and fixations. The process of actively scanning a visual scene while looking for something in a cluttered environment is known as visual search. The study of visual search processes not only offers a unique opportunity to gain fundamental insights into visual information processing in the human brain, but also opens new avenues to assess cognitive function. In this work, we show that it is possible to unveil the strategies pursued by subjects to solve visual tasks by investigating dynamical aspects inherent to eye-tracking data in a generalized N-dimensional feature domain.

Vicente Pallarés, Mar Hernández, Laura Dempere-Marco

Biological Signal Analysis: Feedback Systems for Rehabilitation and Assistance

Frontmatter
An Auditory Feedback System in Use with People Aged +50 Years: Compliance and Modifications in Gait Pattern

Aging leads to gait impairments, which increases the risk for falls. In this study the impact of the auditory feedback system SONIGait on gait parameters in elderly persons was investigated. Twenty-one participants walked at self-selected speed with four variations of real-time auditory feedback of their plantar pressure. Repeated measures ANOVA was utilized to determine changes in time-distance parameters between walking without feedback and four feedback variations. After walking, they completed a questionnaire about their appraisal of the SONIGait system and the four different feedback modalities. There was a significant reduction in gait velocity (0.142 ± 0.04 m/s; p < 0.001) and prolongation of step time (0.02 ± 0.005 s; p < 0.001) during walking with SONIGait. No significant preference for any of the feedback variations was observed. Most participants evaluated the system SONIGait positively. Thus, real-time auditory feedback may be used in gait rehabilitation and may support an older person’s gait stability.

Theresa Fischer, Anita Kiselka, Ronald Dlapka, Jakob Doppler, Michael Iber, Christian Gradl, Anna-Maria Gorgas, Tarique Siragy, Brian Horsak
Supplementary Haptic Framework for Dexterous Rehabilitation

In this work we propose a supplementary haptic framework for dexterous training during rehabilitation. Based on a variety of goal-oriented tasks in a form of puzzles and a set of specifically designed objects, we aim to improve the dexterity and the sense of touch of the impaired hand and fingers w.r.t. different shapes and shape features, such as curved surfaces, edges, vertices and holes. Central to our framework is the Modular Haptic Stimulus Board (MHSB). Within the MHSB elementary shapes can be combined into a large variety of complex shape patterns. This, in turn, enables us to recreate a large set of simple environmental scenarios and to suit a large set of goal-oriented tasks. Through such modular design the framework is suitable for goal-directed training on different complexity levels in a variety of scenarios, such as haptic object discrimination, haptic memory exercises and haptic search. Based on a multimodal recording setup, including haptic glove [1], Vicon system, a microphone and video, the framework provides the necessary infrastructure for automatic evaluation of recovery progress and a detailed movement analysis. Based on this analysis, objects or tasks that pose most problems during training can be automatically included in the future training schedule. A preliminary study with healthy individuals has been conducted to test the framework. Clinical trials still need to be conducted.

Alexandra Moringen, Helge Ritter
Cortical and Muscle Response to Focal Vibro-Tactile Stimuli

This paper investigates cortical responses to vibro-tactile stimuli. EEG was recorded in two conditions: when vibrations were applied focally on the muscle during relaxation and during muscle contraction. Mu and beta waves analysis of the EEG signals suggest that vibrations applied before the contraction increases the stretch of the muscle, thus improving its output performance. Further analysis of the vibrations applied during the muscle contraction shows cortical activation while modulating vibro-tactile stimuli to stabilise muscle performance.

Tijana Jevtic, Aleksandar Zivanovic, Rui C. V. Loureiro

Biological Signal Analysis: Role of Input Synergies for Rehabilitation

Frontmatter
The Role of Inputs Combination to Enhance the Internal Model and Body Control Ability

The role of attention in formulating the input-signals to the CNS toward enhancing the motor-control ability in human is unclear. Here we hypothesized that the distance between the arms in alignment to the frontal center of a person, and the voluntary shifting of his visual attention play roles in enhancing the internal model and the body-control ability. To examine this, six participants were introduced to dual-steering-device. Using the device, we can modulate the participant’s visual attentions and arms distance while performing various tasks. Major muscles and brain activities of the participants were monitored using EMG, and fNIRS. The results were compatible with our hypothesis: users could inhibit muscular activities in the passive movements with increasing distance of the arms and with a visual focus on the inhibited arm. We believe that this study can add important contributing factors in designing rehabilitation program by adjusting the possible input-combination to enhance the internal-model.

Fady Alnajjar, Fatimah Harib, Shaima AlAmeri, Asma Almarzoqi, Matti Itkonen, Hiroshi Yamasaki, Nazar Zaki, Shingo Shimoda
Feeling of Bodily Congruence to Visual Stimuli Improves Motor Imagery Based Brain-Computer Interface Control

Motor imagery based Brain-Computer Interface (BCI) utilizes an electrophysiological phenomenon of EEG power decrease in alpha frequency band, but its larger inter-subject variability limits the practical use. Here we tested three types of visual feedback objects in BCI from abstract to realistic scenarios during motor imagery to see its effect on self-induced changes of EEG power decrease. Double case study in hemiplegic stroke participants was also conducted to check its feasibility as neuro-facilitatory technique on the motor system. We found that a first person perspective of realistic visual feedback, which copies the participant’s mental image, assisted the user to perform motor imagery resulting in generation of large EEG power decrease. The same result was found also in hemiplegic stroke patients. This study has clear implications for both the mechanism of mental process of motor imagery and the influence of feedback type on BCI performance.

Junichi Ushiba, Shotaro Miyashita, Takashi Ono, Koji Aono, Mitsuhiko Kodama, Yoshihisa Masakado
The Repertoire of Brain Synchronized States Accounts for Stroke Recovery

We demonstrate the first experimental evidence that fluctuations in electroencephalographic (EEG) resting-state connectivity are associated with recovery from stroke. We found that fluctuations in instantaneous brain states, quantified as the variance in EEG phase synchronized states, were correlated with motor-related subscores in the Functional Independence Measure, which estimates the recovery of activities of daily living (ADL) in stroke patients. The results suggest that the dynamic repertoire of spontaneous large-scale phase synchronization networks constrains functional networking and accounts for the ADL recovery.

Keiichi Kitajo, Yutaka Uno, Noriaki Hattori, Teiji Kawano, Yuka O. Okazaki, Megumi Hatakenaka, Ichiro Miyai
Is Modular Control of Cycling Affected by Learning? Preliminary Results Using Muscle Biofeedback

Cycling training is used in neurorehabilitation to promote motor recovery in people affected by neurological impairments, such as spinal cord injury and stroke. Visual biofeedback, normally based on cadence or load, can be used in combination with cycling exercise to inform the patient about his/her physical performance. We wanted to test the effectiveness of an alternative biofeedback variable, based on muscle activity (EMG), to induce a change in muscle coordination. Preliminary results on 2 subjects show that single muscle biofeedback can be successfully used to change the neuromuscular control of pedaling, without altering the typical modular structure during the learning process.

Diego Torricelli, Daniel Nemati Tobaruela, Cristiano De Marchis, Filipe Barroso, José L. Pons

Biological Signal Analysis: Modular Control in Healthy and Pathologic Subjects

Frontmatter
Posture Dependent Spatiotemporal Modulation of Dynamic Torques During Sit-to-Stand Movements

Flexibility of patterned multi-joint movements, such as sit-to-stand (STS) motions, is an important factor to ensure the stable behaviors in daily life. Knowledge on detailed mechanism to modulate the pattern of motion is, however, limited so far. Here, quantitative variations of spatiotemporal modular structure of dynamic torques during STS motions were analyzed using complex principal component analysis. The result showed that modulation of two simple parameters could account for the posture-dependent pattern changes, i.e., magnitude of control signal and temporal phase of the torques in the modules. The role of synergistic sensory input from the initial posture on spatiotemporal organization of the motion pattern was suggested.

Hiroshi Yamasaki, Shingo Shimoda
Different Temporal Structure of Muscle Synergy Between Sit-to-Walk and Sit-to-Stand Motions in Human Standing Leg

Humans do not only perform individual motion separately, but they transit motions from one to another. It has been widely known that human sit-to-stand and walking motions are composed of four and five muscle synergies, but it is not clarified how humans utilize these muscle synergies to generate sit-to-walk motion. This study conducted a measurement experiment to identify muscle synergy structure in standing leg during the sit-to-walk motion. Results showed that the same muscle synergy of sit-to-stand and walking could explain sit-to-walk motion. Three of four synergies in sit-to-stand was not significant different but the last synergy was adaptively changed in order to shorten the time of postural stabilization to initiate stepping motion.

Qi An, Hiroshi Yamakawa, Atsushi Yamashita, Hajime Asama
Changes in Muscle Synergy Organization After Neurological Lesions

The role of the cerebral cortex and the cerebellum in determining the spatiotemporal characteristics of the muscle activation patterns is still largely unknown. Recent studies suggest that the coordination of the muscles relies on flexible combinations of a few muscle synergies. We aim at gaining new insights on the neural organization of the muscle patterns for reaching by using multidimensional decomposition algorithms to identify muscle synergies in patients with damage to the cerebral cortex and to the cerebellum. Understanding the changes in the modular organization of the motor system after neurological lesions is highly relevant for upper limb rehabilitation because it may lead to the development of novel objective and quantitative indicators of motor impairment directly related to a specific pathophysiology.

Denise J. Berger, F. Ferrari, A. Esposito, M. Masciullo, M. Molinari, F. Lacquaniti, Andrea d’Avella
Muscle Synergy Analysis in Transtibial Amputee During Ramp Descending Activity

The highest number of amputees are elderly transtibial in developed countries. Walking on inclined surfaces is a crucial activity. The aim of this study was to investigate the difference in healthy, elderly amputee’s intact (IL) as well as prosthetic leg (PL) using muscle synergy analysis. Non-negative matrix factorization (NNMF) was performed to divide the surface electromyographic (sEMG) data obtained from 6 upper knee and 4 shank muscles into muscle synergy (S) and activation coefficient profile (C) during ramp descending (RD) activity. S comparison showed a reasonable correlation in healthy and amputee groups. This suggests synergistic activation of the same group of muscles by the central nervous system (CNS). However, C showed to be statistically significantly different in some regions of the amputee’s gait cycle (GC). The difference could be resulted by muscles alteration due to lack of force tolerance and proprioceptive feedback from PL as well as the type of prosthesis used by the amputee. This information will be useful in future development of myoelectric prostheses and rehabilitation.

P. Mehryar, M. S. Shourijeh, A. A. Dehghani-Sanij

Biological Signal Analysis: Muscle Synergies: Towards Clinically Oriented Applications

Frontmatter
Evaluation of a Pose-Shared Synergy-Based Isometric Model for Hand Force Estimation: Towards Myocontrol

In this work the authors investigated whether the muscle synergies concept could improve the isometric hand force estimation. Electromyographic (EMG) activity from 9 arm muscles and hand forces applied at the Light-Exos Exoskeleton end-effector were recorded during isometric contractions in several workspace points lying on the parasagittal plane crossing the shoulder joint. The muscle synergies were extracted in two different ways according to the statements that the muscle primitives are ‘Arm Pose Related’ or ‘Arm Pose Shared’. From the pre-processed EMG signals the authors then estimated the hand forces using three methods. The results showed that the muscle synergy concept improves the isometric force estimation paving the way for a synergy-based myoelectric control.

Domenico Buongiorno, Francesco Barone, Denise J. Berger, Benedetta Cesqui, Vitoantonio Bevilacqua, Andrea d’Avella, Antonio Frisoli
Muscle Synergies Indices to Quantify the Skilled Behavior in Human

Muscle synergy interprets the neural strategy adopted by the central nervous system (CNS) to simplify the coordination of muscles recruitments when performing useful movements. The computational mechanism of defining the optimal muscle combinations, however, still debatable. Muscle synergy deals with muscle activations pattern and time-dependent variables. The synergy space defines the suitable combinations of muscles, and time-dependent variables vary in lower-dimensional space to drive the behavior. In this study, we investigated the role of the CNS to optimize muscle patterns when performing skilled behavior. We introduced two synergy indices: the synergy stability index that indicates the similarity of the recruited synergies, and the synergy coordination index that indicates the size of the synergy space. The results on automatic posture response experiments on seven healthy participants show that both indices are positively correlated with the overall balance skill of the participants. Results suggest the optimal mechanisms adopted by the CNS to recruit muscles.

Fady Alnajjar, Shingo Shimoda
Towards a Myoelectrically Controlled Virtual Reality Interface for Synergy-Based Stroke Rehabilitation

Recent studies endorse the use of robotic and virtual reality (VR) systems for rehabilitation. Myoelectric (EMG) signals have been used for prosthetic control but their application to rehabilitation has been limited so far. Here we present a novel approach using an EMG controlled VR interface to test the synergistic organization of the neural control of arm movements in healthy subjects. EMG control offers the possibility to manipulate visual feedback according to the subject’s muscle activity and to test effects of simulated interventions on the human neuromuscular system that are either compatible or incompatible with the synergies. Such EMG controlled VR interface may open up new possibilities for rehabilitation as it offers the possibility to provide assistance tailored to the individual changes in synergistic organization.

Denise J. Berger, Andrea d’Avella
FES-Drop-Foot Correction: From Pre-programmed Patterns to Online Modulation

In this communication we will present on going work in our team and recent results towards the improvement of FES-controllers for drop-foot correction in post-stroke survivors. We will insist on challenges to met the way to more adaptive systems. Most of the results have been already published and we try here to make a synthesis in order to explain our general framework.

Christine Azevedo Coste, Benoît Sijobert, Jérôme Froger
A Biologically-Inspired Robust Control System for Myoelectric Control

We review recent studies that aimed at designing an intuitive and robust myoelectric control system for transradial amputees. The methods developed assume that the forearm muscles are controlled in a synergistic manner and capture this synergistic structure hidden in the electromyographic signal patterns by factorization algorithms. We have shown that this system is capable of providing robust control over multiple degrees of freedom relying on 6 electrodes only and that it is robust to electrode shift. However, a pure factorization approach may result in some unwanted movements when the user is willing to activate only one function, which is mitigated by combining a synergistic controller with pattern recognition.

S. Muceli, I. Vujaklija, N. Jiang, S. Amsuess, B. Graimann, O. C. Aszmann, D. Farina

Posters

Frontmatter
Effect of Attention Variation in Stroke Patients: Analysis of Single Trial Movement-Related Cortical Potentials

We have previously developed a Brain-computer interface (BCI) for neuromodulation based on movement related cortical potentials (MRCP). Since successful induction of plasticity is dependent on the attention of the user, the aim of this study was to analyze the changes in MRCPs during imposed attentional shifts in patients. We recorded EEG signals from Cz and its surrounding channels in seven chronic stroke patients, who were asked to attempt ankle dorsiflexion in two subsets of 30 repetitions. Each subset was separated from the other by an auditory oddball task comprised of three tones. Patients were asked to detect the target tone by pressing a button. Nine temporal features were extracted from single trial MRCPs and compared between the two subsets of dorsiflexion that were interspersed by the oddball task. The amplitude of the MRCP negativity, pre-movement slopes, pre-movement variability and movement detection latency and accuracy changed significantly when attention was diverted from the main task of dorsiflexion. This has significant implications for BCIs designed to induce plasticity since detection failure will result in inappropriate device control.

S. Aliakbaryhosseinabadi, V. Kostic, A. Pavlovic, S. Radovanovic, D. Farina, N. Mrachacz-Kersting
Do not Move! Entropy Driven Detection of Intentional Non-control During Online SMR-BCI Operations

Correct classification of motor imagery tasks is not the only requirement of a Brain-Computer Interface (BCI) based on Sensorimotor Rhythms (SMR). Indeed, a SMR-BCI controlling an external device (e.g., robotic prostheses) needs to reliably detect even if the user is in the so-called Intentional Non-Control (INC) state. In this work, we propose a novel approach to online detect INC and thus, to reduce undesired delivered commands during SMR-BCI operations. Results with six healthy subjects show that the proposed INC detection framework does not affect the online BCI performance and, more importantly, it reduces the number of unintentionally delivered BCI commands with respect to a traditional approach (in average 42.7 ± 13.76 % less).

L. Tonin, A. Cimolato, E. Menegatti
Stimulation Waveforms for the Selective Activation of Baroreceptor Nerve Fibers in the Cervical Vagus Nerve

The recruitment of large nerve fibers before small fibers is an issue in many neuromodulation applications. It may, e.g., cause the larynx to be activated by vagus nerve stimulation (VNS) at lower thresholds than required for activation of clinically relevant fibers, such as baroreceptors. We here present results from two animals, indicating that a custom waveform, combining known techniques, can activate the baroreflex with suppressed laryngeal activation, as compared to rectangular pulses. Such selective baroreflex activation with tolerable side-effects could potentially help advance VNS as a treatment modality in resistant hypertension.

Thomas N. Nielsen, Johannes J. Struijk, Cristian Sevcencu
Motor Unit Coherence at Low Frequencies Increases Together with Cortical Excitability Following a Brain-Computer Interface Intervention in Acute Stroke Patients

This study aims at investigating the neurophysiological correlates of increased cortical excitability following a Brain-Computer interface based intervention in three acute stroke survivors. The analysis was performed on high-density EMG signals recorded from the Tibialis Anterior muscle. All patients showed an increased excitability in the motor cortex area of interest following the BCI intervention. Moreover, coherence between motor unit spike trains increased in the frequency band 1–5 Hz, suggesting an increase in the common oscillatory drive to the target muscle.

Margherita Castronovo, N. Mrachacz-Kersting, F. Landi, HR. Jørgensen, K. Severinsen, D. Farina
Response of Spinal Excitability to Different Short-Lasting Motor Tasks: Preliminary Results

Understanding the origin of muscle fatigue is essential for optimizing neuro-rehabilitation treatments. Fatigue is tasks dependent and its neural substrates have been deeply addressed for isometric contractions. However, we recently showed differences in the silent periods generated at cortical or spinal levels after brief maximal rate finger tapping or isometric force tasks, advocating for a cortical but not spinal origin of fatigue for repetitive movements. Here we extend our previous findings by exploring another spinal cord circuits, as well as analyzing the modification of the compound muscle action potential. We use electric cervicomedullary stimulation (n = 7) and the recording of the compound muscle action potential, always at the time of fatigue. Once more our results suggest a different place of fatigue onset for each type of task. Fatigue evoked by maximal rate finger tapping does not have its origin at spinal cord level.

Antonio Madrid, Verónica Robles-García, Yoanna Corral-Bergantiños, Josep Valls-Solé, Antonio Oliviero, Javier Cudeiro, Pablo Arias
Effect of Electrode Size on Amplitude Estimation of HDsEMG Maps

The purpose of this work is to evaluate the effect of the electrode size on recorded High Density surface electromyography (HDsEMG) maps. We recorded the sEMG signals using a grid of electrodes (16 × 8) placed on biceps brachii (5 mm inter electrode distance, IED). Each instantaneous map was interpolated using the 2D Sinc function to obtain a “continuous” map (CM, with 10,000 samp/m). To simulate acquisition with different electrode sizes, each CM was filtered with a circular averaging filter (2–10 mm diameter) and re-sampled with 10 mm IED. Inverse transfer function to compensate the effect of electrode size was applied on each map. The results suggest that greater electrode size implies higher error of power (RMS2) of each map values with respect to the CM. The error of power estimation introduced by electrode size is smaller than the error due to IED.

P. Cattarello, S. D. H. Soedirdjo, B. Afsharipour, R. Merletti
Processing of Motor Performance Related Reward After Stroke

Performance dependent reward activates the striatum, a key region of the reward system. However, stroke patients were identified to show reduced brain activations to rewarding feedback in cognitive tasks when compared to healthy age-matched controls. This was reflected in impaired reinforcement learning. Whether their response to reward derived from preceding motor performance is also reduced, is, however, still unknown. Using functional magnetic resonance imaging, striatal activity linked to performance dependent monetary reward was measured during the training of a repetitive arc-tracking task. Pilot results of nine stroke patients and nine age-matched healthy individuals point towards a tendency for reduced responsiveness of ventral parts of the striatum in stroke patients, while the dorsal striatum, although to a smaller extent, shows an opposite trend. This is of particular interest as ventral striatal activation was found to be the key factor for successful overnight consolidation in an earlier study using a similar task.

Mario Widmer, Andreas R. Luft, Kai Lutz
Muscle Activation Variability Is Inversely Correlated with Walking Speed

Individuals with motor impairments typically walk at much slower speeds than their unimpaired counterparts, yet their gait data is still evaluated against the relatively faster gait of healthy subjects. Therefore a good understanding of unimpaired gait at extremely slow speeds is needed for comparison. Studies have shown that walking at very slow speeds is quantitatively different from self-selected walking speed. These modifications can be observed at different levels (kinetic, kinematic, electromyographic). In order to better understand the changes in walking at extremely slow speeds, we recorded seven subjects walking at their preferred speed and at speeds ranging from 0.11 m/s to 0.61 m/s. In this study, we analyzed changes in muscle activations and quantified their variability using the Pearson correlation coefficient. Confirming previous observation, we show that both the inter- and intra-subject variability of muscle activities increases with decreases in walking speed, with a more pronounced effect for proximal muscles. The inter-subject correlation of muscle activities also suggests a modular organization of muscle activities in three functional blocks at normal speed. This modular organization vanishes with decreasing walking speed following a proximo-distal gradient.

F. Dzeladini, A. Grappe, C. Simpson, A. R. Wu, A. Ijspeert
Spatial Facilitation of Reciprocal Inhibition and Crossed Inhibitory Responses to Soleus Motoneurons During Walking

In humans, short-latency crossed spinal inhibitory reflexes are elicited in the contralateral soleus (cSOL) muscle following stimulation of the ipsilateral posterior tibial nerve (iPTN). To date, the spinal interneurons mediating the cSOL inhibition are unknown. This study investigated whether the Ia inhibitory interneurons in the disynaptic reciprocal inhibition pathway mediate the short-latency cSOL inhibition. Following combined stimulation of the iPTN and the contralateral common peroneal nerve (cCPN), we quantified the spatial facilitation of the ongoing electromyography (EMG; Experiment 1) or the test H-reflex (Experiment 2) in the cSOL during walking. There was a significant increase in the cSOL inhibition when the two stimuli were elicited in combination compared to that expected from the algebraic sum of the two if elicited separately. It is therefore likely that the Ia inhibitory interneurons in the disynaptic reciprocal inhibitory pathway contribute to the short-latency cSOL inhibitory reflex.

Andrew J. T. Stevenson, Svend S. Geertsen, Jens B. Nielsen, Natalie Mrachacz-Kersting
Probabilistic Locomotion Mode Recognition with Wearable Sensors

Recognition of locomotion mode is a crucial process for control of wearable soft robotic devices to assist humans in walking activities. We present a probabilistic Bayesian approach with a sequential analysis method for recognition of locomotion and phases of the gait cycle. Our approach uses recursive accumulation of evidence, as biological systems do, to reduce uncertainty present in the sensor measurements, and thus improving recognition accuracy. Data were collected from a wearable sensor, attached to the shank of healthy human participants, from three locomotion modes; level-ground walking, ramp ascent and ramp descent. We validated our probabilistic approach with recognition of locomotion in steady-state and gait phases in transitional states. Furthermore, we evaluated the effect, in recognition accuracy, of the accumulation of evidence controlled by increasing belief thresholds. High accuracy results achieved by our approach, demonstrate its potential for robust control of lower limb wearable soft robotic devices to provide natural and safe walking assistance to humans.

Uriel Martinez-Hernandez, Imran Mahmood, Abbas A. Dehghani-Sanij
Simulation of Rehabilitation Therapies for Brachial Plexus Injury Under the Influence of External Actuators

This work presents the modeling of the MX-64 and RX-64 servomotors from Robotis® and the analysis of their influence in some biomechanical movements for the rehabilitation of the upper brachial plexus injury. The model of each motor was introduced in a musculoskeletal model of the upper limb in order to compare their response and contribution in the movements made by a patient. The results have verified the feasibility of using these servomotors in an exoskeleton for the rehabilitation process of the injury.

Luis J. Monge Chamorro, Cecilia E. García Cena, Marie André Destarac, Roque Saltarén Pazmiño
Effects of Balance Training with Resistance Function on Center of Mass Trajectory and Muscle Co-contraction

We hypothesized that the balance training with a resistance function may engender effective rehabilitative balance training outcomes, compared to the balance training without a resistance function. The aim of the current study was to evaluate our hypothesis through the measurement of the alterations of the center of mass (COM) trajectory and muscle co-contraction characteristics (co-activation of muscles in the same motion) in balance training with/without a resistance function. Nine subjects with no musculoskeletal or nervous system-related diseases participated. We applied a resistance function to the subjects for 9 weeks and controlled them via our test platform customized for balance training. The results show that COM trajectory and muscle co-contraction were effectively improved after 3 or 6 weeks in balance training with a resistance function, compared to a non-resistance one. The finding indicates that our hypothesis is potentially true. For a strong conclusion, however, additional validations and investigations are necessary.

Leila Alizadeh Saravi, Sung-Jae Lee, Dohyung Lim
Relation Between Functional Movement and Kinematics in Robot Assisted Reach Exercise for Chronic Stroke Survivors

In recent years, robot-assisted exercise has been used as a therapeutic intervention to improve upper limb function of stroke survivors. The purpose of this study is to investigate the relation between functional movement and kinematics in robot assisted reach exercise for chronic stroke survivors. The robot assisted reach exercise was performed in a test bed during 40 min for 16 chronic stroke survivors. The training test bed consisted of one Whole Arm Manipulator (WAM) and one projective display device. The Action Research Arm Test (ARAT) was used to measure functional movement and kinematics (movement time) was analyzed based on the performance of a reaching movement toward 3 targets. ARAT was positively correlated with movement time in 3 targets. In addition, stepwise linear regression analysis revealed that the movement time toward a contralateral target (target 1) was the explanatory variable closely associated with the functional movement, i.e., ARAT.

Ki Hun Cho, Won-Kyung Song
Motor Control Training Enhances Reactive Driving in Stroke—A Pilot Study

Impairments in motor control but not strength affect reactive driving performance in older adults [1]. Stroke significantly impairs motor control that could contribute to deficits in driving ability. The goal of this study was to compare whether strength training or motor control training could improve reactive driving following stroke. Participants were randomly assigned to either strength or motor control training. Both groups received a total of 12 h of training over 2 weeks in 4 sessions with increasing intensity. We tested reactive driving performance before and after the training. The motor control group showed significant decrease in premotor, and motor times (p < 0.05), and significant decrease in brake pedal error (p < 0.05), as compared with the strength training group. This finding suggests that post-stroke driving rehabilitation will benefit from motor control training.

Neha Lodha, Agostina Casamento-Moran, Evangelos A. Christou
BiMU—Inertial Sensors and Virtual Reality Games for the Rehabilitation of the Upper Limb in Cerebral Palsy

BiMU is a platform for computer access and rehabilitation of the upper limb through virtual reality (VR) games. It adapts to the motor and cognitive level of the user and its main goal is improving the efficiency of traditional therapies: reducing disability, increasing functional ability, and promoting social participation. BiMU’s peripheral consists of two wireless inertial measurement units that are attached to the forearm and upper arm and measure their movement. This information is used to control the movement of the cursor and perform click actions. In this paper, we present a pilot study that aimed to improve the quality of a specific movement: the forearm supination. The participants wore the BiMU system and played a series of VR games that recorded their performance. BiMU allows users computer access and a new mode of interactive occupational therapy. Moreover, it registers physical parameters and task performance measures that can be used by therapists to design customized rehabilitation protocols consisting of sequences of games to exercise specific functional movements and to monitor the evolution of the child throughout the work sessions.

M. A. Velasco, B. Valle, R. Raya, A. Clemotte, R. Ceres, M. G. Bueno, E. Rocon
Targeted Dance Program for Improved Mobility in Multiple Sclerosis

Multiple sclerosis (MS) is a disease of the central nervous system with impaired communication between the brain and the body. Walking impairment is prevalent in MS. There is no documented evidence for improving walking agility or smoothness of movements in exercise interventions for those with MS. We report the results of a classical ballet based targeted dance program on clinical measures of balance, posture, and ataxia as well as a quantitative measure of smoothness of gait. The results demonstrate statistically significant improvements in all measures.

A. M. Scheidler, A. L. Tisha, D. L. Kinnett-Hopkins, Y. C. Learmonth, R. Motl, C. López-Ortiz
Upper-Limb Motion Analysis in Daily Activities Using Wireless Inertial Sensors

The Activities of Daily Living (ADL) are used to refer the daily self care activities. Stroke survivors usually experience an impairment in the functionality limbs being affected their independent life. A complete assessment of a patient implies functional and analytic evaluation. However, the joints range cannot be always measured due to the complexity of the patient limbs. The aim of this paper is to present the results acquired from a new tool being able to quantify objectively the functional level of joints movement during ADLs. Twelve healthy subjects had participated in this trial. Four ADL were performed to measure and evaluate the maximum range reached in those activities.

A. Bertomeu-Motos, I. Delegido, S. Ezquerro, L. D. Lledó, J. M. Catalan, N. Garcia-Aracil
Reflex Response Modelling of Exoskeleton-User Interaction

An exoskeleton can help older aged adults stay independent for a longer time by augmenting their torque at weakened joints. Predictive models are useful to develop an exoskeleton and assess the effect of exoskeleton s on the user. Existing models that predict the effect of the exoskeleton on the user use a pre-defined motion which does not change when the forces applied by the exoskeleton change. In our work, we capture the effect of the exoskeleton on the user’s motion by a fitted muscle reflex model and a musculoskeletal model. The model explains the motion deviation with respect to a base motion, as opposed to a steady pose. In an experiment a base motion is perturbed with an external torque. The resulting predicted motion correlates well with the measured motion. As the response of a mechanical system due to forces is well known, the dynamic interaction, incorporating changes in the motion, between an exoskeleton and its user can be predicted with the reflex model.

Bas J. de Kruif, Emilio Schmidhauser, Konrad S. Stadler, Leonard O’Sullivan
Adaptation of Stepping Responses During Perturbed Walking in Neurologically Impaired Subject

This work investigates adaptation of stepping responses when neurologically impaired subject is subjected to repeated perturbations while walking. Balance assessment robot in combination with treadmill (BAR-TM) and Optitrack camera were used to deliver well repeated perturbations and to track foot placement respectively. Results show that when neurologically impaired subject is repeatedly subjected to identical perturbations we may expect adaptation period at the beginning of session when gait parameters change before they settle. We could speculate that in order to evoke repeatable postural responses during balance training patients should be subjected to limited number of exercises that would allow them to surpass adaptation period and focus on repeating the movement after it stabilizes.

Andrej Olenšek, Matjaž Zadravec, Nika Goljar, Zlatko Matjačić
Delivering Remote Rehabilitation at Home: An Integrated Physio-Neuro Approach to Effective and User Friendly Wearable Devices

There is a global shortage of manpower and technology in rehabilitation to attend to the five million new patients who are left disabled every year with stroke. Neuroplasticity is increasingly recognized to be a primary mechanism to achieve significant motor recovery. However, most rehabilitation devices either limit themselves to mechanical repetitive movement practice at a limb level or focus only on cognitive tasks. This may result in improvements in impairment but seldom translates into effective limb and hand use in daily activities. This paper presents an easy-to-use, wearable upper limb system, SynPhNe (pronounced like “symphony”), which trains brain and muscle as one system employing neuroplasticity principles. A summary of clinical results with stroke patients is presented. A new, wireless, home-use version of the solution architecture has been proposed, which can make it possible for patients to do guided therapy at home and thus have access to more therapy hours.

Subhasis Banerji, John Heng, Alakananda Banerjee, P. S. Ponvignesh, Daphne Menezes, Robins Kumar
Pseudo-Online Detection of Intention of Pedaling Start Cycle Through EEG Signals

This work studied different electrode configurations and processing windows for detecting the intention of pedaling initiation. Furthermore, data were pseudo-online analyzed. The main goal was to find alterations in the mu and beta frequency bands where event-related synchronization and desynchronization (ERS/ERD) is produced. The results show an improvement using time before and after the movement onset rather than until the movement onset.

M. Rodríguez-Ugarte, Á. Costa, E. Iáñez, A. Úbeda, J. M. Azorín
How Many EEG Channels Are Optimal for a Motor Imagery Based BCI for Stroke Rehabilitation?

The optimal number of EEG channels is a controversial issue for motor imagery based BCIs for stroke rehabilitation. In this study, we compared the BCI performance with 63, 27 and 16 channels of EEG on three stroke patients across 10 to 24 sessions, and demonstrated that the 16 channels montage yields similar classification error (21.3 ± 11.6, 10.5 ± 6.6 and 16.0 ± 12.6 % for these patients respectively) to montages with larger number of channels. This is important for practical applications in stroke rehabilitation, since fewer channels means lower cost, less preparation time and easier maintenance.

Ren Xu, Brendan Z. Allison, Rupert Ortner, Danut C. Irimia, Arnau Espinosa, Alexander Lechner, Christoph Guger
Non-supervised Feature Selection: Evaluation in a BCI for Single-Trial Recognition of Gait Preparation/Stop

Is presented a non-supervised method for feature selection based on similarity index, which is applied in a brain-computer interface (BCI) to recognize gait preparation/stops. Maximal information compression index is here used to obtain redundancies, while representation entropy value is employed to find the feature vectors with high entropy. EEG signals of six subjects were acquired on the primary cortex during walking, in order to evaluate this approach in a BCI. The maximum accuracy was 55 and 85 % to recognize gait preparation/stops, respectively. Thus, this method can be used in a BCI to improve the time delay during dimensionality reduction.

Denis Delisle-Rodriguez, Ana Cecilia Villa-Parra, Alberto López-Delis, Anselmo Frizera-Neto, Eduardo Rocon, Teodiano Freire-Bastos
Spectral Entropy and Vector Machines Support for Imagined Motion Detection in Brain-Computer Interfaces

Brain-Computer Interfaces (BCI’s) aim to create a channel of communication between a person and a device without any physical action on the environment by the user. There are several BCI systems, some of them focusing on motor actions by the user. Various techniques exist for such BCI systems, such as extraction of the power in different frequency bands. These techniques have proven to be useful but require extensive training by the end user and the creation of new models every time other user intends to use the system. In this paper we present a new method based on spectral entropy to detect changes in motor area and their possible application in the detection of imagined movement. The successes obtained with this technique is about 76 %.

Fabio R. Llorella, Gustavo Patow, José M. Azorín
An EEG-Based Brain-Machine Interface to Control a 7-Degrees of Freedom Exoskeleton for Stroke Rehabilitation

Brain machine interfaces (BMIs) have previously been utilized to control rehabilitation robots with promising results. The design and development of more dexterous and user-friendly rehabilitation platforms is the next challenge to be tackled. We built a novel platform that uses an electro-encephalograpy-based BMI to control a multi-degree of freedom exoskeleton in a rehabilitation framework. Its applicability to a clinical scenario is validated here with six healthy subjects and a chronic stroke patient using motor imagery and movements attempts. Therefore, this study presents a potential system to carry out fully-featured motor rehabilitation therapies.

A. Sarasola-Sanz, E. López-Larraz, N. Irastorza-Landa, J. Klein, D. Valencia, A. Belloso, F. O. Morin, M. Spüler, N. Birbaumer, A. Ramos-Murguialday
Preliminary EEG Characterisation of Intention to Stand and Walk for Exoskeleton Applications

Wearable lower limb exoskeletons aim to mobilize and improve the quality of life of people with lower limb paralysis. However, all the current commercially available exoskeletons require good upper limb function to operate them effectively. This limits their use for people with higher-level impairments, such as tetraplegia. In this paper we investigate the possibility of being able to decode from the user’s brain signals, their intention to perform various actions, including standing up and walking, with a view to eventually controlling an exoskeleton with a brain-computer interface. As such, we present some preliminary results that show statistically significant changes in Mu band power, when preparing to execute movements and during the execution of movements.

Alex Zervudachi, Eric Sanchez, Tom Carlson
Task Influence on Motor-Related Cortical Signals: Comparison Between Upper and Lower Limb Coordinated and Analytic Movements

Changes in cortical signals related to motor planning processes have been widely studied in the past. However, no studies so far have investigated the intra-subject differences in these signals between analytical and coordinated upper limb and lower limb cue-based movements. Here, data from healthy subjects is analyzed to research this aspect. The statistical analysis carried out with data from 7 subjects indicates that statistically significant differences were observed between premotor cortical activities of upper and lower limb movements. Specifically, higher amplitudes of the contingent negative variation pattern were observed for lower-limb tasks. Such results may be due to complexity in movement task planning. BCI devices could take advantage and be improved with the knowledge provided.

A. Martínez-Expósito, J. Ibáñez, F. Resquín, J.L. Pons
An Empirical Study of Factorization Methods to Quantify Motor Synergies

This paper presents a study investigating robustness of three factorization methods in identifying muscle and kinematic synergies in healthy population. Results showed that Principal Component Analysis (PCA) and Non-Negative Matrix Factorization (NNMF) have comparable empirical performances, both outperforming Independent Component Analysis (ICA). However, PCA showed a faster training time, giving it an edge over NNMF.

Navid Lambert-Shirzad, H. F. Machiel Van der Loos
Decoding Muscle Excitation Primitives from Slow Cortical Potentials During Knee Flexion-Extension

Linear decoders have been successfully applied to extract human limbs kinematics from low-frequency cortical modulations. In this, intermediate descending motor pathways are absorbed in the regression. Here we propose the use of linear decoders to map cortical function to the spinal function (muscle primitive-level), thus shortening the transmission distance and reducing the dimensionality of the decoding of a large number of muscles. Our first results show that it is possible to accurately reconstruct muscle primitives computed from knee flexion-extension and to successfully detect muscle activity during repetitive cyclic movements.

A. Úbeda, M. Sartori, A. J. del-Ama, Á. Gil-Agudo, J. M. Azorín, D. Farina
Recommendations for Games to Increase Patient Motivation During Upper Limb Amputee Rehabilitation

Videogame based approaches are a motivating way to increase entertainment for upper limb amputees during neuromuscular rehabilitation training. Thereby myoelectric signals needed to control the prosthesis are intuitively trained and the functional gain of the prosthesis is increased. This study compares the intrinsic motivation between upper limb amputees and age and gender matched able-bodied participants after playing different videogames. Participants had to fill in two questionnaires in order to evaluate their attitude regarding videogame based rehabilitation and their intrinsic motivation. Results show higher investment of patients during the games and give a suggestion of what the ideal game for neuromuscular prosthetic control training might look like.

Cosima Prahm, Fares Kayali, Agnes Sturma, Oskar Aszmann
Rehabilitation Robot in Primary Walking Pattern Training for SCI Patient at Home

Attention has recently been focused on incomplete spinal cord injuries (SCI) caused by pressure on portions of the white matter conduction pathway, such as the pyramidal tract. In this paper, we focus on a training robot designed to assist with primary walking-pattern training, helping patients relearn the basic functions of the usual walking pattern. It is particularly intended for those with incomplete-type SCI to the central spine, who are capable of standing by themselves but not of performing walking motions. The mechanism of the robot was modified to be simple and lightweight with the expectation of home use. The machine was tested with six normal senior subjects before the tests with SCI patients to verify the exercise strength which is suitable to the elderly or patient and the stability of standing position which is important for walking with preventing falling.

Taisuke Sakaki, Toshihiko Shimokawa, Nobuhiro Ushimi, Koji Murakami, Yong-Kwun Lee, Kazuhiro Tsuruta, Kanta Aoki, Kaoru Fujiie, Ryuji Katamoto, Atsushi Sugyo
A Comprehensive Training Mode for Robot-Mediated Upper Limb Rehabilitation

Defining rehabilitation robots behavior during training exercises is necessary for their optimum performance. In this work, a comprehensive training mode for an upper limb rehabilitation robot, the UHP (Universal Haptic Pantograph) is presented. The proposed mode, which is divided in three phases, focuses on upper limb extension allowing the task to be adapted to the recovery state of the patient and ensuring exercise completion. Experimental validation of the training mode is carried out with the upper limb rehabilitation robot UHP.

Aitziber Mancisidor, Asier Zubizarreta, Itziar Cabanes, Pablo Bengoa, Je Hyung Jung
Learning Motor Coordination Under Resistive Viscous Force Fields at the Joint Level with an Upper-Limb Robotic Exoskeleton

In the field of rehabilitation robotics, few researchers have been focusing on the problem of controlling motor coordination in post-stroke patients. Studies on coordination learning, when the robotic devices act at the joint level on multiple interaction points, as in the case of exoskeletons, are lacking. For this reason, we studied on 10 healthy subjects the possibility of learning a non-natural inter-joint coordination while performing a pointing task. This coordination was induced by a 4-DOF robotic exoskeleton, applying resistive force fields at the joint level. Preliminary results showed the capability of our controller to modify human healthy natural coordination after exposition to the fields and generalization of these effects to movements which were never exposed to these constraints.

Tommaso Proietti, Agnès Roby-Brami, Nathanaël Jarrassé
Improving Upper Extremity Impairments with Tongue Driven Robotic Assisted Rehabilitation: A Pilot Study

Stroke is one of the leading causes of long-term disability in the United States with many survivors unable to participate in rehabilitation. We have developed a novel rehabilitation paradigm for the upper extremity (UE) that uses a Tongue Drive System (TDS) to control a robotic device (HandMentor (HM)) while engaging with a game-like user interface for stroke survivors. This pilot study demonstrates that the TDS-HM intervention elicits improvements in motor performance that transfer to reduced upper extremity impairments and improvements in quality of life for moderately to severely impaired stroke survivors.

S. N. Housley, D. Wu, S. Belagaje, M. Ghovanloo, A. J. Butler
Upper Limb Robot Assisted Rehabilitation Platform Combining Virtual Reality, Posture Estimation and Kinematic Indices

Upper limb rehabilitation is critical for patients affected by spinal cord injury (SCI). Currently, robotics and Virtual Reality (VR) have changed the way in which rehabilitation therapies are provided. However, a still unreached precondition for these systems is the precise and practical estimation of limb posture and an objective evaluation of patient’s improvement. In this manuscript we present an upper limb rehabilitation platform combining VR, patient posture estimation and objective kinematic indices. This manuscript describes the software platform and criteria which integrate the modules of the system. We report preliminary results of the kinematic indices and platform usability by practitioners.

D. Scorza, A. de Los Reyes, C. Cortés, A. Ardanza, A. Bertelsen, O. E. Ruiz, A. Gil, J. Flórez
User Requirements in Multimodal System Design and Robotics

Gathering end users requirements at the development phase of innovative systems is a critical but often over looked feature of design. This paper presents the outcome of five focus groups undertaken to determine the key user needs for a novel state of the art modular multimodal system that can be customized and adapted to the needs of people with complex disabilities. Users discussed their desires for the system, their preferences for control, the use of a wearable upper limb exoskeleton, and finally usability factors were outlined. Future research will focus on target end users validating the iterative prototypes that emerge from this user centered design approach.

Jean Daly Lynn, Elaine Armstrong, Suzanne Martin
A Novel Exoskeleton for Continuous Monitoring of the Upper-Limb During Gross Motor Rehabilitation

The development of exoskeletons and wearable robots has caught the attention of the academic community in recent years due to its high potential in Neurorehabilitation. In addition to this, exoskeletons have found commercial use in motion assistance, military, labour and industrial applications. Most of the exoskeletons that have been proposed in the literature are designed for the lower-limbs due to the motivation of providing mobility to stroke and SCI patients, however there are few developments for upper-limbs. This paper presents a novel upper-limb exoskeleton that provides four degrees-of-freedom (henceforth denoted as DoF) per each arm, where 4 DoF and 1 DoF are given to the shoulder and elbow, respectively. Closed-form solutions for the inverse and forward kinematics of the exoskeleton are determined, and by using accelerometers, this work obtains the pose and orientation of the exoskeleton in real-time. The experimental work includes healthy subjects that wear the exoskeleton for daily use activity, while the device monitors their motion and reachable workspace, which are compared to statistical parameters found in the literature. Simulations and numerical examples are performed in order to compare the results obtained in the experiments in order to verify their plausibility.

Eduardo Piña-Martínez, Ricardo Roberts, Ernesto Rodriguez-Leal, Jose H. Flores-Arredondo, Rogelio Soto
Psychophysiological Measurements in a Robotic Platform for Upper Limbs Rehabilitation: First Trials

This paper examines psycho-physiological measurements in a group of healthy volunteers and the usefulness of this information. The aim is the characterization of the psychophysiological state during the performance of active therapy with the robotic platform, E2REBOT, for upper limb rehabilitation, which we have developed. Psycho-physiological assessment was performed by means of the Self-Assessment Manikim (SAM) test and physiological signals (heart rate variability, skin conductance, and skin temperature) were obtained in this first trial with E2REBOT. The protocol design and the results of the experiments obtained are presented. Results suggest that is possible to quantitatively characterize the psycho-physiological state of an individual who interacts with the E2REBOT robot.

P. F. Viñas, M. Hernández, J. Pérez-Turiel, J. C. Fraile, A. Cuadrado, R. Alonso, M. Franco-Martin
The CP Walker for Strength Training in Children with Spastic Cerebral Palsy: A Training Program Proposal

Eccentric and explosive strength training have the potential to stimulate in-series sarcomere addition in children with cerebral palsy (CP), as previously seen in typically developing children. This adaptation would enable greater muscle power generation. Similarly to previously used ankle robotic therapy, we believe the CPWalker robotic platform is an optimal tool as it may deliver individualized eccentric and explosive strength training during gait and under highly controlled conditions. Thus, a proposal for an 8 week CPWalker training program for children with CP is described.

Teresa Martín Lorenzo, Sergio Lerma Lara, Cristina Bayón, Oscar Ramírez, Eduardo Rocon
A Preliminary Test of a Portable Prototype System of FES Foot Drop Correction and Gait Measurements with a Hemiplegic Subject

In this study, a portable prototype system of FES foot drop correction and gait measurements was tested with a hemiplegic subject to develop FES rehabilitation system for gait of hemiplegic subjects. The prototype system consisted of a tablet-type device and 2 inertial sensors and an electrical stimulator. The system worked properly during walking with FES foot drop correction and foot inclination angles, stride time and gait event timings were obtained. Measurement of gait information during rehabilitation training can be useful to evaluate the training effect.

Takashi Watanabe, Shun Endo, Ryusei Morita, Katsunori Murakami, Naomi Kuge
A Novel Robotic Walker for Over-Ground Gait Rehabilitation

Recovery from impaired gait of stroke patients is in increasing need. Conventional robotic gait rehabilitation systems based on treadmill restrict pelvic horizontal motion and lack of presenting natural gait patterns with actual foot contact on the ground. To overcome these limitations, we proposed a novel robotic walker for gait rehabilitation. It consists of an active omni-directional mobile platform and a body weight support (BWS) unit to assist gait motions. The control algorithm automatically executes force assistance during gait. 3 healthy young subjects were recruited to evaluate force assistance of robotic walker. Recorded assistive forces of the walker to pelvis showed beneficial influence.

Jing Ye, Francisco A. Reyes, Haoyong Yu
Energy Consumption and Cardiorespiratory Load During Lokomat Walking Compared to Walking Without Robot-Assistance in Stroke Patients: Preliminary Results

Energy consumption and cardiorespiratory load were assessed during 3 different walking conditions (Lokomat, treadmill and overground walking) in stroke patients. Preliminary results demonstrated that Lokomat walking was significantly less oxygen demanding than treadmill, but not overground walking. No significant differences in heart rate and minute ventilation were found. Further research with sufficient sample size and additional analyses will be performed to draw firm conclusions.

Nina Lefeber, Eva Swinnen, Marc Michielsen, Stieven Henderix, Eric Kerckhofs
Experiences in Four Years of HAL Exoskeleton SCI Rehabilitation

In 2012 the neurologic controlled exoskeleton Hybrid assistive limb (HAL) was introduced in the spinal cord injury unit of the university hospital Bochum. Until now 20 acute and 40 chronic injured SCI patients (AIS A-D) have been treated for a three-month body weight supported treadmill training paradigm wearing HAL with a daily intervention. Here we report the feasibility, safety and outcome aspects. All subjects improved due to their functional walking abilities without wearing HAL. The training was feasible, safe and suitable in acute and chronic SCI patients. No severe adverse events were recorded.

D. Grasmücke, O. Cruciger, R. Ch. Meindl, Th. A. Schildhauer, M. Aach
Control of a Robot Using Brain Computer Interface to Aid in Rehabilitation

In this paper, we develop methods to assist people with disability to control robot using brain computer interface. Using a new technique based on action grammar, robot is able to carry out tasks such as opening a door knob simply by recognizing the intention of the user. To successfully implement this concept we have developed techniques that help articulated robot to become spatially aware. We provide a set of actions which can be combined using action-grammar that is modelled using stationary Markov decision process. We demonstrate our methodology using two tasks (i) screw-insertion and (ii) door-opening.

Pramod Chembrammel, Thenkurussi Kesavadas
Preliminary Evaluation of a Wearable Soft-Robotic Glove Supporting Grip Strength in ADL

In the ongoing ironHand (iH) project, a wearable soft-robotic glove, the iH system, is being developed to support the hand during daily functioning. This study gives a first insight in the potential effect of the glove in daily life. Preliminary results show that participants can increase their pinch grip strength with assistance of the glove, but functional tasks were performed slower with the glove compared to performing these tasks without the glove. Overall, usability of the iH system was perceived as good. More research is needed to determine the impact of the iH system in daily life.

B. Radder, G. B. Prange-Lasonder, A. I. R. Kottink, L. Gaasbeek, K. Sletta, J. Holmberg, T. Meyer, J. H. Buurke, J. S. Rietman
User Acceptance of a Therapeutic System that Enables Hand Training Exercises in a Motivating Environment

In this study, a wearable soft-robotic glove that is connected to a computer with therapeutic software to train hand function (the ironHand therapeutic system, iH TS) is introduced. This study explored usability of the iH TS after first use without receiving instructions from researchers. The results on the System Usability Scale (SUS) are promising for acceptance of the iH TS in daily life (mean SUS score = 66.4). More research is needed to determine user acceptance and the effects of the therapeutic hand exercises after a longer acquaintance period.

B. Radder, G. B. Prange-Lasonder, A. I. R. Kottink, L. Gaasbeek, J. Holmberg, A. Melendez-Calderon, J. H. Buurke, J. S. Rietman
Combining Soft Robotics and Brain-Machine Interfaces for Stroke Rehabilitation

Stroke is a devastating condition with profound implications for health economics and resources worldwide. Recent works showed that the use of brain-machine interfaces (BMI) could help movement improvements in severely affected chronic stroke patients. This work shows the feasibility and use of a Soft Orthotic Physiotherapy Hand Interactive Aid (SOPHIA) system, able to provide more intense rehabilitation sessions and facilitate the supervision of multiple patients by a single Physiotherapist. The SOPHIA device is controlled by a BMI system and has a lightweight design and low cost. Tests with researchers showed that the system presents a reliable and stable control, besides being able to actively open the volunteers’ hands.

Patricia A. Vargas, Fabricio Lima Brasil, Alistair C. McConnell, Marta Vallejo, David W. Corne, Adam A. Stokes, Renan Cipriano Moioli
Simulation of the Length Change in Muscles During the Arm Rotation for the Upper Brachial Plexus Injury

This work presents a 3D upper limb musculoskeletal model and the simulation of arm rotation for the case of a healthy human subject and one with upper brachial plexus injury (UBPI). Then, the length change in muscles and range of movement was obtained and compare for both cases. The results show a notable difference between the two cases and can be used to define an effective rehabilitation therapies for this injury.

Marie André Destarac, Cecilia E. García Cena, Roque Saltarén Pazmiño
Analysis of Optimal Control Problem Formulations in Skeletal Movement Predictions

Predictions of human movements to study control strategies or to investigate human-orthosis interaction require the solution of the kinematic redundancy by solving a dynamic optimization problem. Direct collocation is a promising method to solve these problems. However, the convergence of collocation methods is sensitive to problem formulation. We therefore compare different optimal control problem formulations to predict the motion of a planar two-link model with foot-ground contact. The use of implicit dynamic formulations minimizing accelerations or jerks facilitated the convergence over other formulations. The use of automatic differentiation and an appropriate time scale had a large influence on computation time.

Gil Serrancolí, Joris De Schutter, Friedl De Groote
From Spiking Motor Units to Joint Function

This abstract proposes a modeling methodology that enables reconstructing ankle joint mechanical function from muscle motor unit spike trains decomposed from high-density electromyography signals. The abstract outlines methods and results and discusses the implication that this approach can have for enhancing our understanding of the neuro-mechanical processes underlying human movement.

Massimo Sartori, Utku S. Yavuz, Cornelius Frömmel, Dario Farina
Towards Behavioral Based Sensorimotor Controller Design for Wearable Soft Exoskeletal Applications

This study presents the assessment of ankle-foot gait abnormalities and estimation of neuromuscular control for maintaining gait dynamic stability and avoid falls. Control signals are modelled as the rate of change in the body COM acceleration as an input and the COP velocity as an output. Experiments show that the toe foot condition is least stable than inverted and normal walk at loading phase. However, the overdamped motor output response, equally stable for the three undamped input instabilities, shows the robustness of our proposed motor controller. Results show that our novel neuromotor inspired controller, based on behavioral I/O signals, is robust and suitable for the assessment of exoskeletal stability and control of wearable soft robotic applications.

Imran Mahmood, Uriel Martinez-Hernandez, Abbas A. Dehghani-Sanij
Hybrid Robotic System Simulation for the Exploration of Novel Control Strategies

The combined use of the functional electrical stimulation (FES) with robotic devices known as Hybrid Robotic System emerges as a promising solution to improve rehabilitation therapies after neurological injuries (e.g. stroke). This work presents a first step towards the implementation of a Hybrid Robotic System simulation platform that could allow exploring several control strategies to improve its performance. The results show the feasibility of the platform to deploy several control strategies that combines FES and robotic devices.

H. Barbouch, F. Resquin, J. González-Vargas, N. Khraief-Hadded, S. Belghith, J. L. Pons
First Results on the Joint Use of E2Rebot and Gradior to Improve Cognitive Abilities

In this paper we present the results of the first clinical trials conducted to evaluate the usefulness of the joint use of E2Rebot and Gradior to improve cognitive abilities in subjects with ABI, dementia and schizophrenia. E2Rebot is a cost-effective robotic platform for active assistance in the rehabilitation of patients suffering upper limb impairment as a consequence of ABI (Acquired Brain Injury). Gradior is a training and neuro-psychological rehabilitation software used in more than 450 centers at national and international level within the social and health sector. The results obtained in the quantitative study showed a general improvement in the average scores on cognitive tests although the differences are not statistically significant. This result encourages us to undertake a broader study with a greater number of subjects and longer in time.

J. Pérez-Turiel, M. Franco-Martin, J. C. Fraile, E. Parra, P. Viñas
Microsoft Kinect-Based System for Automatic Evaluation of the Modified Jebsen Test of Hand Function

The design and test of a Microsoft Kinect-based system for automatic evaluation of the Modified Jebsen Test of Hand Function (MJT) is presented. The MJT was administered to 11 chronic stroke patients (both the dominant and non-dominant hand). MJT completion times were evaluated by a therapist using a stopwatch and automatically by use of the Kinect-based system. The ground truth times were assessed based on visual inspection of video-recordings. Analysis of the agreement between the MJT times estimated by the two methods generally showed better agreement between the ground truth times and the times estimated by the Kinect-based system compared to the agreement between the ground truth times and the times obtained by the therapist.

Daniel Simonsen, Erika G. Spaich, Ole K. Andersen
Chair Kinematics, A Novel Criteria for Frailty Status Classification

A quarter to a half of people over 85 years are estimated to be frail by 2050. There is an urge to tackle this syndrome to assess the risk for an elderly to become frail. Performance tests such as the 30-s chair stand test (30-s CST) are a cornerstone for detecting early decline. Predictions are based on the number of repetitions instead of how they are performed. Latest advances show that kinematics from chair-related transitions are able to track frailty status. Here, the most interesting parameters for the 30-s CST extracted from the literature are presented. A classification tree was used to assess which ones identify better frailty. Finally, this study provides a set of four parameters to classify a subject regarding the frailty status more accurately than the current 30-s CST outcome. This novel information could help clinicians to undertake the corresponding actions to prevent this syndrome.

N. Millor, M. Gómez, P. Lecumberri, A. Martínez-Ramírez, J. Martiricorena, M. Izquierdo
Gait Exercise Program with a Low-Tech Device for Children with Severe Cerebral Palsy: Physiologic and Neuromotor Effects

Cerebral Palsy is a group of permanent disorders of posture and movement that cause activity limitation due to non-progressive disturbances on the developing brain. The assisted bipedestation programs are typically used on this condition to decrease bone fragility and to promote muscle function, weight bearing and autonomic functions. The aim of this study was to evaluate a gait exercise program using a low-tech walker, to identify the effects on muscle tone, range of motion, and heart rate in children with Cerebral Palsy. The results showed significant changes in heart rate immediately after using the device however, no changes were found in muscle tone and range of motion. Future studies should test the long-term effects of this device on this population.

P. Barría, E. Tapia, A. Andrade, A. Bandera, A. Moris, H. Henriquez
Adaptive Arm Weight Support Using a Cable-Driven Robotic System

Many stroke and spinal cord injured (SCI) patients suffer from a paretic arm movement, which can be characterized by a limited shoulder flexion. We consider a possibility to assist the patient in slow arbitrary arm flexions within a large range of motion. To address this issue, we propose a shoulder flexion dependent weight support during robot-assisted therapy of the upper limb. Inverse static models of the cable-driven robotics and the passive human arm are used to estimate the required forces at the ropes to flex the upper arm in order to compensate a given percentage of the arm weight. Our results show that conventional constant rope forces during a therapy may produce an over- or undercompensated weight support, whereas the proposed adaptive approach achieves a desired larger range of motion.

Sven Knuth, Arne Passon, Frank Dähne, Andreas Niedeggen, Ingo Schmehl, Thomas Schauer
Top 50 Cited Articles in Neurorehabilitation by Transcranial Magnetic Stimulation: A Bibliometric Analysis

A systematic bibliometric analysis of TMS in neurorehabilitation. Current and future basic research lines and their clinical applications are highlighted.

F. Hanna, J. Alfonso-Beltrán
‘VRComponent’: A Virtual Reality Software for Neuro-Rehabilitation with Robotics Technologies

Autonomous robots that are interfaced with virtual or augmented reality gaming are increasingly being developed to provide repetitive intensive practice to promote increased compliance and facilitate better outcomes in neurorehabilitation therapies. These therapist robots, equipped with a set of sensors and actuators for monitorizing the environment, allows health professionals to supervise the recovery of patients with serious disability. In this paper, a new system for supervising neuro-rehabilitation therapies using autonomous robots is presented. The therapy explained in this work is based on a set of virtual reality games developed by using robotics technologies, such as RGB-D camera and depth image processing. Three different virtual reality games have been developed in the application to gain better outcomes during the therapy, each one focuses on a typical exercise: ‘Touch the apple’, ‘Follow the path’ and ‘Imitate the dance’. Both, the virtual reality games and the main robotics technologies for their development, are explained in this paper.

Christopher Ávila, Luis Manso, Pablo Bustos Garcia de Castro, Pedro Núñez

Workshops

Frontmatter
Cutaneomuscular Spinal Reflex Activity as a Biomarker of Motor Dysfunction and Neurorehabilitation After Incomplete Spinal Cord Injury

Cutaneomuscular afferent information is essential for voluntary motor tasks such as gait and balance. After spinal cord injury (SCI) changes in sensorimotor activity are involved in recovery of limited motor function. Here we present a review of clinical neurophysiological measures that quantify sensorimotor dysfunction and which have the potential to benchmark the therapeutic effect of cutaneous stimulation during SCI neurorehabilitation. Specifically we will show that long-latency cutaneous reflex and cutaneomuscular conditioned H-reflex techniques can quantify spinal neuronal activity and the presence of either adaptive or maladaptive motor control mechanisms after incomplete SCI. In conclusion, the development of neurorehabilitation programs in combination with cutaneomuscular stimulation protocols is a viable strategy not only to promote motor recovery but to prevent maladaptive neuroplasticity such as spasticity after SCI.

Julio Gómez-Soriano, Stefano Piazza, Diego Serrano-Muñoz, Gerardo Ávila-Martín, Iriana Galán-Arriero, Julian S. Taylor
Promising Tools in Neurorehabilitation: Portable Non-invasive Brain Stimulation Techniques

The neurophysiological techniques that can induce plasticity or simply modulate cortical excitability or produce interference with normal brain activity and behavior are known as neuromodulation techniques. The interest in using neuromodulation techniques in neurorehabilitation has sharply increased in the last years. Moreover, as neurorehabilitation can be a long process, portability of these approaches start to be considered important. I will briefly introduce non- invasive neuromodulation techniques, discuss the rationale for their use in neurorehabilitation, and address the problem of choosing the optimal technique for a given purpose focusing the attention on the possibility to be used “at home”.

Antonio Oliviero
On Correlation Between the Neural Drive to Muscles and Multichannel Surface Electromyogram Amplitudes

Amplitude of surface electromyogram (EMG) has often been used as a measure of neural drive sent to skeletal muscle, especially for assessment of muscle co-activations. In this study, we analyze correlation between the multichannel EMG amplitudes and cumulative motor unit spike train (CST) as assessed by decomposition of surface EMG of writ flexors and extensors in 27 Parkinsonian tremor patients. We demonstrate that in involuntary contractions surface EMG amplitudes vary significantly with the location of the measuring electrodes and that the first principal component of the EMG amplitudes correlates with the CST only in about one third of cases studied and when its relative energy is high.

Damjan Karlatec, Aleš Holobar
Functional Connectivity and Magnetoencephalography

This century is about brain. Not surprisingly, two megaprojects, the “Brain Activity Map Project” (USA) and the “Human Brain Project” (EU) with a total budget over a few billions euros, have been initiated across the Atlantic and mobilized many of the best and most renowned neuroscientists. They both aims to answer open questions for Neuroscience, such as: Is there an underlying functional architecture to the brain’s networks?, What is the functional connectivity diagram of a circuit?, What are the long-range interactions that underlie cognitive functions and behaviour? or What are the paths of information flow?. Such questions are related to the so-called “functional connectivity”, it reflects the statistical interdependencies between two physiological signals, providing information about functional interactions between the corresponding brain regions. Over the last years it has been increasingly used in neuroscience. Specifically, in the study of electrophysiological recordings such as Magnetoencephalography (MEG) and Electroencephalography (EEG).

P. Cuesta, R. Bajo, J. García-Prieto, L. Canuet, F Maestú
Prospects of Neurorehabilitation Technologies Based on Robust Decoding of the Neural Drive to Muscles Following Targeted Muscle Reinnervation

Latest advances in neurorehabilitation technologies provide users with reliable mechatronic devices. Nonetheless, the control capabilities of these systems are limited to techniques that rely on indirect measures of neural information using EMG signals. We foresee that the combination of targeted muscle reinnervation (TMR) and high-density EMG electrodes supported by advanced blind source separation techniques (BSS) can substantially enhance current neurorehabilitation solutions. TMR provides access to the nerve activity by connecting nerves to muscles, used as biological amplifiers. Control would benefit from richer information content directly related to spinal motor neuron activity. The motor neuron firing statistics is obtained by applying advanced decomposition algorithms on the multi-channel EMGs from the targeted reinnervated muscles. It is expected that the control of these systems will be more dexterous and precise.

Ivan Vujaklija, Silvia Muceli, Konstantin Bergmeister, Oskar C. Aszmann, Dario Farina
Adaptive-Oscillator-Based Control Strategy for Gait Rehabilitation Robots

In the field of gait rehabilitation robotics, it is very important to provide synchronous assistance during walking. In this paper, a novel control strategy based on an adaptive oscillator is proposed. The adaptive oscillator estimates the stride percentage of gait based on the gait events information, which is detected in real time with a hidden Markov model (HMM). Synchronous reference trajectories for the robot are then generated with a look-up table. An impedance controller is implemented to provide assistance based on the synchronous reference. The proposed synchronization method is implemented in a portable knee-ankle-foot robot and tested in 15 healthy subjects. The experimental results demonstrate that the proposed control strategy is efficient in achieving human–robot synchronization and feasible for rehabilitation robotics application.

Gong Chen, Haoyong Yu
Bioinspired Controller Based on a Phase Oscillator

Oscillatory behavior is important for tasks such as walking and running. We are developing methods to add energy to enhance or vary the oscillatory behavior based on the phase angle. Both the amplitude and frequency of oscillation can be modulated by adjusting the forcing function based on the sine and cosine of the phase angle. Pendulum systems are simulated using our phase controller. We show that a double-pendulum can be controlled using an oscillator.

Thomas G. Sugar, Sangram Redkar
An Active Compliant Knee Joint for Gait Assistance: Design and Characterization

Wearable lower-limb powered othoses represent valid tools for assisting people affected by gait disorders given their capability to actively sharing the workload of energetically expensive tasks of activities of daily living, contrarily to passive lower-limb orthoses or braces. In this abstract we present the design of an active knee orthotic joint, endowed with a novel series elastic actuator, and the experimental characterization of its torque controller. Experimental results demonstrated that the performance of the active knee joint are suitable for assisting locomotion-related activities of mildly impaired people.

Matteo Fantozzi, Andrea Parri, Francesco Giovacchini, Tingfang Yan, Silvia Manca, Mario Cortese, Nicola Vitiello
Compliant Lightweight Actuator Designs for Robotic Assistance and Rehabilitation Exoskeletons

This paper presents the design of a compliant, lightweight and adaptable active ankle foot orthosis (AAFO) and two iterations of the conceptual design of an active knee actuator. The actuators are designed to keep their torque to weight as low as possible. The adaptability of the AAFO allows adjusting the device to different patients, without the need of customized versions. The knee actuators are designed for 2 exoskeleton prototypes that will be used for assistance of people with muscle weakness and for gait rehabilitation of incomplete spinal cord injury (iSCI) patients.

Dirk Lefeber, Marta Moltedo, Tomislav Bacek, Kevin Langlois, Karen Junius, Bram Vanderborght
Dynamic Balance Assessment During Pathological Bipedal Walking

In this paper we present a set of dynamic balance responses following perturbation applied in the right direction to a selected subject suffering from chronic hemiparesis by a newly developed Balance Assessment Robot. The responses are grossly similar to those previously observed in neurologically intact individuals in terms of stepping characteristics and repeatability, however distinct changes characteristic for hemiparesis that are subject-specific were also identified.

Zlatko Matjačić, Matjaž Zadravec, Nika Goljar, Andrej Olenšek
Individualization of Gait Therapy Through Patient-Tailored Trajectory Generation

This extended abstract presents the work being done in a project aimed at developing a mobile robotic system for individualized gait rehabilitation. As an important component of the individualisation of robot-assisted gait therapy, a method for “patient-tailored” trajectory generation was developed. This method provides the therapist with “healthy-like” walking patterns, dependent on the patient’s height and the desired cadence and walking speed, and allows the therapist to adapt the given trajectories in an intuitive graphical way to fit better the specific patient’s gait abilities.

Santiago Focke Martinez, Olena Kuzmicheva, Danijela Ristić-Durrant, Axel Graeser
The Role of Corticomuscular Transmission in Movement Execution

Current research in corticomuscular transmission, e.g. by assessing corticomuscular coherence during movement execution, has mainly focused on frequencies higher than 10 Hz. However, the effective bandwith of force generation at the spinal level has been proved to be below this frequency threshold. Recent studies are increasingly showing the importance of low-frequency modulations as a cortical control input in movement execution. Still, the presence of motion and muscular artifacts can significantly bias the role of slow cortical potentials. This work addresses current works that characterize corticomuscular motor pathways and discusses the effective bandwidth (in relation to force generation) of the corticomuscular drive to serve as base for present and future debate on the behavior of corticomuscular transmission in movement execution.

Andrés Úbeda
Muscle Synergies: A Compact Way to Describe and Restore Neuromuscular Coordination

In this abstract we present the potentialities of muscle synergy analysis, according to the most recent and debated functional interpretations. We also provide some ideas on the use of the synergy approach beyond the classical descriptive modalities, in order to enhance the biologically inspiration of current neurorehabilitation techniques.

Diego Torricelli, José Luis Pons
Electrical Modulation of Cerebral Cortex Activity: Mechanisms and Applications

To further understand the mechanisms underlying non-invasive brain stimulation techniques we studied the modulatory effect of electric fields in vitro in cortical slices that express slow oscillations (<1Hz). We found a that a fine control of the emergent oscillatory frequency can be obtained by means of regulation of the intensity and direction of the electric field. Besides this, electric fields influence the propagation behavior of slow oscillations and display a strong impact on the horizontal speed and on the regularity of the oscillation.

M. V. Sanchez-Vives, M. D’Andola, P. Boada-Collado, M. Giulioni, J. F. Weinert

AITADIS Workshops

Frontmatter
Pseudo-online Multimodal Interface Based on Movement Prediction for Lower Limbs Rehabilitation

Patients with physical disabilities can benefit from robotic rehabilitation since it can provide more control, accuracy and variety of training modes. This improves the efficiency of the patient’s rehabilitation. This work presents a multimodal platform for acquisition and processing of EEG and EMG signal with inertial sensors data in order to detect lower limb movement intentions. A pseudo-online technique was also developed. Experiments were conducted with 5 healthy subjects performing lower limb motor tasks and an experimental protocol is proposed. In the future, this interface will be integrated in an active knee orthosis for robotic rehabilitation. The results obtained show that the system is capable to acquire, process and classify the signals synchronously. The movement intention was evaluated taking into account EEG and EMG signal together with a OR logic, detecting $$60.0\pm 21.2\,\%$$60.0±21.2% of movement intentions. The movement anticipation achieved $$881.5\pm 136.3$$881.5±136.3 ms based on EEG signal and $$137.6\pm 77.5$$137.6±77.5 ms based on EMG signals.

T. Botelho, D. Soprani, C. Carvalho, P. Rodrigues, P. Schneider, A. Frizera-Neto, A. Ferreira
Experiences in Development and Application of Simplified Technologies for Rehabilitation and Gait Analysis

We focus in developing and applying simplified low-cost technologies that allow an approach to rehabilitation process and make it accessible to the most number of subjects. We present two cases: the mechanical equipment for gait stimulation, and the computer system for gait analysis. In both cases we have developed technologies that are being applied with patiens with terapeutical results in concordance with literature. Statistical validation is being performed. These experiences provide access to rehabilitation technologies to a significant amount of patients, professionals and institutions.

Fernando Salvucci, Ricardo Garbayo, Carolina Fernández Bizcay, Rafael Kohanoff
Quasi-static Tests on a Low Cost Polymer Optical Fiber Curvature Sensor

Joint angle measurement is broadly used for understanding human kinematics and different techniques have been proposed throughout several years. Conventional techniques for joint angle assessment are generally costly, bulky and intrusive or have poor portability. Wearable solutions based on inertial measurement unities usually suffer from external perturbations. Considering that polymer optical fiber (POF) is highly flexible, and that is a low cost technology with great immunity from electromagnetic perturbations, a POF based curvature sensor is a promising alternative. This paper presents quasi-static experiments on a curvature sensor. Lateral section on the fiber is made to improve sensor sensibility. Results show a relation between the section dimensions and the hysteresis and signal to noise ratio. Although the hysteresis reduces for proper lateral section dimensions, it is always present due the polymer viscoelasticity. Future studies will aim at modelling and compensating such phenomena for achieving greater precision in angular measurements.

Arnaldo G. Leal Junior, Lucas G. Webster, Anselmo Frizera Neto, Maria José Pontes
Comprehensive Environmental Intervention for Cerebral Palsy Based on the International Classification of Functioning, Disability and Health

The International Classification of Functioning, Disability and Health provides a useful model to guide the complex aspects of assessment for Assistive Technology. Evaluations based on the ICF help professionals to comprehend the patient’s needs and prioritize goals for intervention. The aim of this study was to demonstrate how to incorporate the ICF framework in the treatment of a patient with severe Cerebral Palsy, with particular focus on Environment Factors, mainly Assistive Technologies to achieve optimal functioning. The study design was single-case interventional type. The study variables were the Environmental Factors included in the ICF Core Sets for children with CP. These factors were evaluated with the ICF-based tools and other standardized measures. After the assessment, the rehabilitation team designed a Comprehensive Environmental Intervention, which consisted in Assistive Technologies implementation and environmental modifications. At the end of intervention, the patient’s achievements were considerable, with improvements on six ICF Categories related to environmental factors.

P. Barría, V. Schiariti, A. Andrade, A. Bandera, H. Henriquez, A. Moris
Proposal for Clinical Validation of Lower Limb Robotic Exoskeleton in Patients with Incomplete Spinal Cord Injury

The most important aspect in rehabilitation of incomplete spinal cord injury (iSCI) is the possibility to recover walking ability. Lower limbs exoskeletons are of increasing importance in neurorehabilitation of SCI patients to achieve gait with this type of robotic device. In this work, a longitudinal, prospective and observational study, single-blind, randomized and multi-center design is proposed to assess the effectiveness of H2 exoskeleton in incomplete SCI.

Soraya Pérez-Nombela, Antonio J. del-Ama, Ángel Gil-Agudo, Mónica Alcobendas-Maestro, Fernando López-Díaz, Jesús Benito-Penalva, José L. Pons, Juan C. Moreno
Serious Game for Post-stroke Upper Limb Rehabilitation

Stroke is a considerable cause of disability worldwide. A common motor recovery goal in physical therapy is to promote and enhance symmetry in motor patterns involved in daily functional tasks, aiming to prevent learned nonuse of the paretic side. The aim of this work is the development of a serious game for upper limbs training in stroke persons. This assistive technology is composed of a Kinect v2 combined with sEMG. We propose an integrated approach that includes three key factors: (a) fully immersive virtual environment with virtual body representation; (b) interaction with virtual objects; and (c) a biofeedback of arm movements of the patient through sEMG. The results show that the virtual reality environment here proposed is able to promote muscle activation in elbow flexion-extension movements, with average hit rate of 94.51 % (right arm), 93.1 % (left arm) and 85.67 % (both arms).

Nicolás Valencia, Vivianne Cardoso, Anselmo Frizera, Teodiano Freire-Bastos
Wearable Robotic Walker for Gait Rehabilitation and Assistance in Patients with Cerebral Palsy

Cerebral Palsy (CP) is the most common cause of permanent serious physical disability in childhood. New strategies are needed to help promote, maintain, and rehabilitate the functional capacity of children with severe level of impairment. The main objective of this work is to present a Human-Robot interaction strategy for overground rehabilitation to support novel robotic-based therapies for CP rehabilitation. This strategy is implemented in a new Wearable Robotic Walker named CPWalker. In our approach, legs’ kinematics information obtained from a Laser Range Finder (LRF) sensor is used to detect the user’s locomotion intentions and drive the robotic platform. During a preliminary validation we observed that this approach enabled the robot to continuously follow the human velocity and provided body weight support during gait.

Carlos A. Cifuentes, Cristina Bayon, Sergio Lerma, Anselmo Frizera, Luis Rodriguez, Eduardo Rocon
Effects of the Use of Functional Electro-Stimulation (FES) on the Physiological Cost, Speed and Capacity of Gait After Stroke

Hemiplegia is one of the most common impairments after stroke and contributes significantly to reduce gait performance. Gait recovery is a major objective in the rehabilitation program for stroke patients. Stroke survivors can exhibit abnormally elevated oxygen consumption during walking. Have tried different therapies and approaches to improve motor function, one of which is the use of electrical stimulation functional. The aim of this study is to establish the effects of FES on gait speed and physiological cost of patients with hemiplegia, and the ability of the march and the degree of patient satisfaction.

S Mercante, E Cersósimo, C Letelier, S Cacciavillani
Evaluating Cognitive Mechanisms During Walking from EEG Signals

In this work, three different cognitive mechanisms were analyzed during gait. First, a real-time index of attention level was obtained in real-time. The detection of starting and stopping indices was also evaluated. Finally, the detection of obstacle appearance allows increasing safety during experiments providing a stop command when necessary. The results obtained indicate that it is possible to generate commands related to the patient’s mental state. These commands allow users to be more implicated in their therapies and thus improve their performance.

E. Iáñez, Á. Costa, A. Úbeda, E. Hortal, M. Rodríguez-Ugarte, J. M. Azorín
Non-supervised Feature Selection: Evaluation in a BCI for Single-Trial Recognition of Gait Preparation/Stop

Is presented a non-supervised method for feature selection based on similarity index, which is applied in a brain-computer interface (BCI) to recognize gait preparation/stops. Maximal information compression index is here used to obtain redundancies, while representation entropy value is employed to find the feature vectors with high entropy. EEG signals of six subjects were acquired on the primary cortex during walking, in order to evaluate this approach in a BCI. The maximum accuracy was 55 % and 85 % to recognize gait preparation/stops, respectively. Thus, this method can be used in a BCI to improve the time delay during dimensionality reduction.

Denis Delisle-Rodriguez, Ana Cecilia Villa-Parra, Alberto López-Delis, Anselmo Frizera-Neto, Eduardo Rocon, Teodiano Freire-Bastos
Defining Therapeutic Scenarios Using Robots for Children with Cerebral Palsy

For children with Cerebral Palsy, occupational and physical therapy are intervention mechanisms that support their development in areas of motor, cognitive, sensory, communicative, social and emotional functioning. Moreover, with recent advances in robotics, protocols using robots are ideal to make an impact in these interventions. The proposal of this paper is to present a first approach to the definition of therapeutic scenarios using robots for the rehabilitation processes of children with cerebral palsy. In order to specify these scenarios, a pilot test is presented, where the therapeutic aims for four children with motor disability (cerebral palsy) are formalized. Likewise, the functional requirements of the robots are defined, as well as a proposal for evaluation of the objectives. This process has been done with children attending their scheduled therapy at the Neuro-Rehabilitation Center “SURGIR” in Cali–Colombia.

Jaime A. Buitrago, Eduardo F. Caicedo Bravo
An Approach to a Phase Model for Steady State Visually Evoked Potentials

One of the most used signals in Brain Machine Interfaces (BMI) is the Steady State Visually Evoked Potentials (SSVEP). In a SSVEP-based BMI, a visual stimulus that flickers in a constant frequency is presented to the user, and the system has to detect if the user is gazing the stimulus. Usually the stimulus is a rectangular signal and there are no clear criteria for select the duty cycle, which is generally fixed to 50 %. We propose a model for SSVEP that links the phase and amplitude variations in function of the duty cycle for a specific frequency. This model can be adjusted using only the phase of the SSVEP signal and it could improve the SSVEP-based BMI by selecting the duty cycle. The model was fixed for SSVEP responses in a man who is 39 years old. The mean absolute error below 0.3 rad shows that the model predicts the phase in the majority of the used frequencies.

Jaiber Cardona, Eduardo Caicedo, Wilfredo Alfonso, Ricardo Chavarriaga, José del R. Millán
Velocity Dependant Spasticity Detection for Active Exoskeleton Based Therapies

In this paper a method to detect velocity-dependant spasticity is shown. The implementation and test were performed using the ankle joints of a six degrees of freedom exoskeleton. In this first stage of the project all subjects are healthy and have no difficulty in walking. The subjects left the ankle joint relaxed while sat down and did not rest the heel on the floor. Force sensors are used in order to measure the interaction forces between the exoskeleton and de human limb. The sensors were located in the foot sole under the subject’s forefoot and in the instep brace. A variable oscillator is used to generate the angle reference signal and to vary the frequency thereof. The presence of spasticity was detected based on the interaction force information and the joint movement was decreased in speed.

R. Mendoza-Crespo, R. Soto, J. L. Pons
Bioinspired Hip Exoskeleton for Enhanced Physical Interaction

Exoskeletons are becoming one of the most promising devices to improve quality of life to injured patients to regain ability to walk. Bioinspired designs in exoskeletons could increase adaptability as well as minimal interference to perform gait movements. An important issue regarding the design of this devices is the hip joint. This work presents a design of a bioinspired hip exoskeleton for enhanced physical interaction, which is based on the motion analysis model, taking into account bioinspired design criterion, and also concepts of wearable robots. As future work, both, the 3D prototyping of this device to evaluate the gait performance, and the actuators selection are considered.

Diego Casas, Marcela Gonzalez Rubio, Miguel Montoya, Wilson Sierra, Luis Rodriguez, Eduardo Rocon, Carlos A. Cifuentes
Inclusive Approach for Developing a Robotic Vehicle for Disabled Children

Self mobility plays a key role in early childhood development. Several devices has been proposed but most of them are prohibitive for low income families in development countries. Includ.ING project proposes the inclusive development of a low cost robotic vehicle for children with motor disabilities. Four operation modes and several sensing functions were defined for the platform. This paper present the design and early results with the developed platform.

H. Fernández, G. Mercado, V. González, F. Bunetti
Metadaten
Titel
Converging Clinical and Engineering Research on Neurorehabilitation II
herausgegeben von
Jaime Ibáñez
José González-Vargas
José María Azorín
Metin Akay
José Luis Pons
Copyright-Jahr
2017
Electronic ISBN
978-3-319-46669-9
Print ISBN
978-3-319-46668-2
DOI
https://doi.org/10.1007/978-3-319-46669-9