Advances in Physarum Machines

Slime mould Physarum polycephalum is a macroscopic amoeba-like organism whose ability to ‘compute’ the solutions to complex problems ranging from logic to computational geometry has led to its extensive use as an unconventional computing substrate. In slime mould computing devices—‘Physarum machines’—data may be imparted to the organism via stimulation with chemical, optical, mechanical or electrical sources and outputs are generally behavioural, chemical or/and electrical. This chapter examines the biological basis of a slime mould’s ability to perceive and act upon input data and the mechanisms that contribute towards the output we interpret as computation. Furthermore, various research methods for slime mould cultivation, electrophysiological measurement and hybridisation with exogenous substances are discussed. The data presented here provides an essential foundation for the computer scientist wishing to fabricate their own Physarum machines.

In the recent years, computer scientists have been inspired by biological systems for computational approaches, in particularly with respect to complex optimization and decision problems. Nature provides a wealth of evolved solutions to such challenges. As evolved by natural selection, biological processes are robust and able to successfully handle failures as well as attacks to survive and propagate. Biological systems are mostly distributed systems that coordinate to make decisions without central control. An example par excellence for such a biological system is given by slime molds. In this context, Physarum polycephalum emerged as a model organism which has attracted substantial interest in the recent years. In this chapter, I present new approaches to cultivate this organism, with the goal to establish a multipurpose experimental platform for biological information processing.

We overview families of Boolean logical gates and circuits implemented in computer models and experimental laboratory prototypes of computing devices made of living slime mould Physarum polycephalum. These include attraction gates, based on chemo-tactic behaviour of slime mould; ballistic gates, employing inertial movement of the slime mould’s active zones and a repulsion between growing zones; repellent gates, exploited photo avoidance of P. polycephalum; frequency gates, based on modification of electrical potential oscillations frequency in protoplasmic tubes; fluidic gates, where a tactical response of the protoplasmic tubes is used for the actuation of two- and four-input logical gates and memory devices; and circuits based on quantitative transformations which completely avoids spatial propagation, branching and crossings in the design of circuits.

Physarum polycephalum has been shown to be a biological computer, capable of solving problems through morphological computation. We present laboratory experiments where Physarum was investigated as a component of electronic or wet-ware computers. We find that $$I-T$$I-T electronic signals consistent in time-scale with shuttle transport can be recorded with a sensitive Keithley electrometer. The memristor is a novel non-linear stateful resistor with great promise in neuromorphic computing. We demonstrate that Physarum gives $$I-V$$I-V curves consistent with a memristor and that this response is located in the living cytosol part of the organism (as opposed to the gel outer-body or slime layer). We model the Physarum as an active memristor (a memristor combined with a battery), where the living Physarum metabolism provides energy.

We discuss hybrid systems where the slime mould is interfaced with organic electronics devices. We demonstrate the realisation of slime mould Schottky diodeSchottkydiode and organic electrochemical transistorElectrochemical transistor. A central part of the chapter is dedicated to the integration of the Physarum into organic memristive deviceMemristivedevice, an electronic element with synapse-like properties. We describe an architecture and working principles of the hybrid devices and variations of their electrical and optical properties as a result of the interaction with slime mould. We demonstrate that the slime mould is a smart candidate for the implementation of functional properties of smart living systems into electronic devices.

Electronic and nanoelectronic systems implementing a Physarum-inspired computing architecture are presented. The system is designed to solve computationally demanding problems. The core of the electronic system consists of a capacitor network with star topology. Charging and discharging of the capacitors under charge conservation mimics the spatiotemporal dynamics of an amoeboid organism, exhibiting the sophisticated ability of exploring a solution space. Small fluctuations inherently involved in electronic devices are used to explore solution space. We constructed electronic Physarum and successfully demonstrated solution search capability through finding solutions of optimization problems including constraint satisfaction problem and satisfiability problem. Nanoelectronics implementation of the electron Physarum using electron Brownian ratchet devices is proposed toward the ultra-small system operating ultra-low power consumption. A unique feature of the system is that the system acquires spontaneous solution search capability from unavoidable fluctuation in nanostructure and nanodevices. Recent research results of fabrication and characterization of electron Brownian ratchet device using semiconductor nanowire are described.

We retrospectively examine and offer new perspectives on the hybridisation of slime mould Physarum polycephalum with metallic nanoparticles for the purpose of creating semi-organic, semi-artificial unconventional computing devices. Nanoparticle suspensions were successfully introduced into the plasmodium of P. polycephalum via feeding—i.e. exploitation of natural endocytotic mechanisms—and microinjection; nanoparticle uptake, intracellular distribution and excretion were thoroughly examined with light, electron and confocal microscopy. Slime mould was found to be extremely permissive to hybridisation with several biocompatible nanoparticle varieties, exhibiting few or no deleterious health effects following exposure. Hybridisation with nanoparticles was found to significantly alter the organism’s conductivity, resting potential and membrane potential dynamics through non-invasive electrophysiological measurement. The applications of the knowledge uncovered, which range from nanotoxicology research to emerging neurological disease therapies to novel bio-inspired computer design are relevant to all fields of scientific inquiry where biology, computing, medicine and nanotechnology meet.

A storable whole-cell biosensor has been a challenge in the whole-cell biosensor research. We developed a long-term storable whole-cell biosensor using the true slime mould, Physarum polycephalum, for toxicity detection. The cell is interfaced to a microfluidic device with impedance measurement system. The oscillatory activity of the cell when exposed to various concentrations of 2,4-dinitrophenol (DNP) is investigated. It has been demonstrated that the Physarum cell can be dry-stored in the device for months and used as bionsensor after revived with rehydration. This is the first implementation of storable whole-cell biosensor for toxicity detection use, and it suggests that the development of long-term storable, and potentially portable, whole-cell biosensor for general toxicity prescreening is possible.

The chemotaxis behaviour of the plasmodial stage of the true slime mould Physarum polycephalum was assessed when given a binary choice between two volatile organic chemicals (VOCs) placed in its environment. All possible binary combinations were tested between 19 separate VOCs selected due to their prevalence and biological activity in common plant and insect species. The slime mould exhibited positive chemotaxis towards a number of VOCs with the following order of preference: farnesene $$> \beta $$>β-myrcene $$>$$> tridecane $$>$$> limonene $$>$$> p-cymene $$>$$> 3-octanone $$> \beta $$>β-pinene $$>$$> m-cresol $$>$$> benzylacetate $$>$$> cis-3-hexenylacetate. For the remaining compounds no positive phototaxis was observed in any of the experiments, and for most compounds there was an inhibitory effect on the growth of the slime mould. By assessing this lack of growth or failure to propagate it was possible to produce a list of compounds ranked in terms of their inhibitory effect: nonanal $$>$$> benzaldehyde $$>$$> methyl benzoate $$>$$> linalool $$>$$> methyl-p-benzoquinone $$>$$> eugenol $$>$$> benzyl alcohol $$>$$> geraniol $$>$$> 2-phenylethanol. This analysis shows a distinct preference of the slime mould for non-oxygenated terpene and terpene like compounds (farnesene, $$\beta $$β-myrcene, limonene, p-cymene and $$\beta $$β-pinene). In contrast terpene based alcohols such as geraniol and linalool were found to have a strong inhibitory effect on the slime mould. Both the aldehydes utilised in this study had the strongest inhibitory effect on the slime mould of all the 19 VOCs tested. Interestingly 3-octanone which has a strong association with a “fungal odour” was the only compound with an oxygenated functionality where Physarum Polycephalum exhibits distinct positive chemotaxis. We utilise the knowledge on chemotactic assays to route Physarum “signals at a series of junctions. By applying chemical inputs at a simple T-junction we were able to reproducibly control the path taken by the plasmodium of Physarum. Where the chemoattractant farnesene was used at one input a routed signal could be reproducibly generated i.e. Physarum moves towards the source of chemoattractant. Where the chemoattractant was applied at both inputs the signal was reproducibly split i.e. at the junction the plasmodium splits and moves towards both sources of chemoattractant. If a chemorepellent was used then the signal was reproducibly suppressed i.e. Physarum did not reach either output and was confined to the input channel. This was regardless of whether a chemoattractant was used in combination with the chemorepellent showing a hierarchy of inhibition over attraction. If no chemical input was used in the simple circuit then a random signal was generated, whereby Physarum would move towards one output at the junction, but the direction was randomly selected. We extended this study to a more complex series of T-junctions to explore further the potential of routing Physarum. Although many of the “circuits were completed effectively, any errors from the implementation of the simple T-junction were magnified. There were also issues with cascading effects through multiple junctions. This work highlights the potential for exploiting chemotaxis to achieve complex and reliable routing of Physarum signals. This may be useful in implementing computing algorithms, design of autonomous robots and directed material synthesis. In additional experiments we showed that the application of chemoattractant compounds at specific locations on a homogeneous substrate could be used to reliably control the spatial configuration of Physarum.

To achieve fine control of Physarum polycephalum-based computing devices, a diverse library of plasmodium modulators is required. In this chapter, we review our recent findings on the application of genetically transformed plant roots as a chemomodulatory platform for Physarum. Hairy roots produced by genetic transformation with Agrobacterium rhizogenes are a metabolically productive source of bioactive plant compounds. Transgenic roots of the medicinal plant Valeriana officinalis were developed by stable integration of A. rhizogenes root-inducing genes into the plant genome. An axenic hairy root line was massively propagated in vitro and the culture biomass was characterized in Physarum plasmodium. Hairy roots elicited a robust, positive chemotactic response and augmented maze-solving behavior. In a simple plasmodium circuit, introduction of hairy roots stimulated the oscillation patterns of the slime molds surface electrical potential. We propose that the V. officinalis root culture platform is a sustainable source of modulatory biomass for the development of future slime mold computing devices.

We show how the slime mould can be used as a chemical sensor and investigate how the organism combines different sensory information. We have produced a biosensor using protoplasmic tubes of Physarum which is capable of detecting various biologically active chemicals in the local environment; this progress is akin to developing a biological nose using the organism’s natural sensing ability.

To make an electronic wetware device doing something useful we need sensors to input information, wires to transfer information between distant parts of the devices, and an oscillator to act as a clock and synchronise the device. We show how slime mould wires, optical colour and tactile sensors and oscillators can be made. A Physarum wire is a protoplasmic tube. Given two pins to be connected by a wire, we place a piece of slime mould at one pin and an attractant at another pin. Physarum propagates towards the attractant and thus connects the pins with a protoplasmic tube. A protoplasmic tube is conductive, it can survive substantial over-voltage and can be used to transfer electrical current to electronic loads. We demonstrate experimental approaches towards programmable routing of Physarum wires with chemoattractants and electrical fields, show how to grow the slime mould wires on almost bare breadboards and electronic circuits, and insulate the Physarum. We evaluate feasibility of slime-mould based colour sensors by illuminating Physarum with red, green, blue and white colours and analysing patterns of the slime mould’s electrical potential oscillations. We define that the slime mould recognises a colour if it reacts to illumination with the colour by a unique changes in amplitude and periods of oscillatory activity. In laboratory experiments we found that the slime mould recognises red and blue colour. The slime mould does not differentiate between green and white colours. The slime mould also recognises when red colour is switched off. We also map colours to diversity of the oscillations: illumination with a white colour increases diversity of amplitudes and periods of oscillations, other colours studied increase diversity either of amplitude or period. We design experimental laboratory implementation of a slime mould based tactile bristles, where the slime mould responds to repeated deflection of bristle by an immediate high-amplitude spike and a prolonged increase in amplitude and width of its oscillation impulses. We demonstrate that signal strength of the Physarum tactile bristle sensor averages near six for an immediate response and two for a prolonged response. Finally, we show how to make an electronic oscillator from the slime mould. The slime mould oscillator is made of two electrodes connected by a protoplasmic tube of the living slime mould. A protoplasmic tube has an average resistance of 3 MOhm. The tube’s resistance is changing over time due to peristaltic contractile activity of the tube. The resistance of the protoplasmic tube oscillates with average period of 73 s and average amplitude of 0.6 MOhm. We present experimental laboratory results on dynamics of Physarum oscillator under direct current voltage up to 15 V and speculate that slime mould P. polycephalum can be employed as a living electrical oscillator in biological and hybrid circuits.

We report the progress of using the plasmodium of Physarum as a biological electronic component. We provide blue prints of experimental prototypes of Physarum wires and analyse their transfer function, discuss how lifespan of a Physarum can be increased. We overview our experimental laboratory results on using Physarum wires with buffers and evaluate a potential of Physarum wires to transmit digital and analogue data. We argue that the Physarum wires could be used as alternative electronic components for future bio-electric hybrid computers and electronic devices.

Microbial fuels cells (MFCs) are bio-electrochemical transducers that generate energy from the metabolism of electro-active microorganisms. The organism Physarum polycephalum is a species of slime mould, which has demonstrated many novel and interesting properties in the field of unconventional computation, such as route mapping between nutrient sources, maze solving and nutrient balancing. It is a motile, photosensitive and oxygen-consuming organism, and is known to be symbiotic with some, and antagonistic with other, microbial species. In the context of artificial life, the slime mould would provide a biological mechanism (along with the microbial community) for controlling the performance and behaviour of artificial systems. In the following experiments it was found that Physarum did not generate significant amounts of power when inoculated in the anode. However, when Physarum was introduced in the cathode of MFCs, a statistically significant difference in power output was observed.

Through a range of laboratory experiments, we measure plasmodial membrane potential via a non-invasive method and use this signal to interface the organism with a digital system. This digital system was demonstrated to perform predefined basic arithmetic operations and is implemented in a field-programmable gate array (FPGA). These basic arithmetic operations, i.e. counting, addition, multiplying, use data that were derived by digital recognition of membrane potential oscillation and are used here to make basic hybrid biological-artificial sensing devices. We present here a low-cost, energy efficient and highly adaptable platform for developing next-generation machine-organism interfaces. These results are therefore applicable to a wide range of biological/medical and computing/electronics fields.

What searching strategies the slime mould adopts when exploring three-dimensional terrains? How optimal are transport routes approximated by the slime mould’s protoplasmic tubes? Do the routes built by slime mould on 3D terrains match real-world transport routes? We conducted laboratory experiments with Nylon terrains of USA and Germany. We used the slime mould to approximate route 20, the longest road in USA, and autobahn 7, the longest national motorway in Europe. We found that slime mould builds longer transport routes on 3D terrains, comparing to flat substrates yet sufficiently approximates man-made transport routes studied. We demonstrated how nutrients placed in destination sites affect performance of slime mould and shown how the slime mould navigates around elevations. In cellular automaton models of the slime mould we shown that the variability of the protoplasmic routes might depends on physiological states of the slime mould.

P. polycephalum imitates development of man-made transport networks of a country when configuration of nutrients represents major urban areas. We employ this feature of the slime mould to imitate Mexican migration to USA, which is the World’s largest migration system. In laboratory experiments with 3D Nylon terrains of USA we analyse development of migratory routes from Mexico-USA border to ten urban areas with high concentration of Mexican migrants. From results of laboratory experiments we extract topologies of migratory routes, and highlight a role of elevations in shaping the human movement networks.

Solving complex optimization problems by using biological computing substances, such as the plasmodium of Physarum polycephalum, is lately a commonly proposed technique. Moreover, as the successful evaluation of modern human-made motorways in several countries has been demonstrated, the same is expected when using that biological computer for transport networks built in historical time periods. To accelerate the computations a Cellular Automata model, proposed previously, that can approximate the computing abilities of the plasmodium has been used. Here the area of Balkans was considered, so as to evaluate the Roman road network built during the imperial period (1st century BC–4th century AD) which was of paramount significance in terms of maintaining the East territories of the Roman Empire under control. The results produced in the laboratory experiments and those delivered by the proposed model successfully approximate segments of the actual Roman road network. Exploring the efficiency of Physarum-based computers and bio-inspired algorithms can lead to an unconventional, interdisciplinary method that will be implemented in the field of archaeological research.

The plasmodium of true slime mould Physarum is a unicellular and multinuclear giant amoeba. Recent studies revealed that the plasmodium has computational abilities, and such studies are mainly performed based on the behaviours of the plasmodium in a closed space. However, there are not many studies on the behaviours of the plasmodium in an open space, though such studies may be more important in understanding the computational adaptability and intelligence of the organism. In this chapter, we thus analysed the behaviours of the plasmodium in an open space, and as a result we found some power laws in the cell motility and exploratory behaviour by the unicellular organism. These results showed how the plasmodium realises effective exploration in an open space, at the same time giving a clue to understand how cells in general adapt itself to an open environment.

The slime mould is efficient in imitating formation of man-made road networks, where major urban areas are sources of nutrients. We used a similar approach to grow slime mould on a three-dimensional template of Moon to speculate on potential colonization scenarios. The slime mould imitated propagation of colonisation in an exploratory mode, i.e. without any definite targets. Additional transportation hubs/targets were added after the initial network was formed, to imitate the development of colonies in parallel to slime mould growth.

We review a few models of adaptive circuits based on memory circuit elements and inspired by the adaptive behavior of the unicellular organism Physarum subjected to periodic temperature and humidity variations. Memory circuit elements are resistors, capacitors and inductors with memory whose state depends on the history of signals applied. When these devices are subjected to a time-dependent input their states demonstrate an adaptive functionality that can be used, e.g., to mimic the adaptation of biological systems to a time-dependent environment. Similar to experimental observations, these circuits demonstrate learning and anticipation to future signal (environmental) changes. This work shows the potential of memory circuit elements to model various biological processes in different setups and their use in a new type of adaptive electronics.

The giant single-celled slime mould Physarum polycephalum has inspired developments in bio-inspired computing and unconventional computing substrates since the start of this century. This is primarily due to its simple component parts and the distributed nature of the ‘computation’ which it approximates during its growth, foraging and adaptation to a changing environment. Slime mould functions as a living embodied computational material which can be influenced by external stimuli. The goal of exploiting this material behaviour for unconventional computation led to the development of a simple multi-agent approach to the approximation of slime mould behaviour. The basis of the model is a simple dynamical pattern formation mechanism which exhibits self-organised formation and subsequent adaptation of collective transport networks. The system exhibits emergent properties such as relaxation and minimisation and it can be considered as a virtual material, influenced by the external application of spatial concentration gradients. In this chapter we give an overview of this multi-agent approach to unconventional computing. We describe its computational mechanisms and different generic application domains, together with concrete example applications of material computation. We examine the potential exploitation of the approach for computational geometry, path planning, combinatorial optimisation, data smoothing and statistical approximation applications.

It has been established that Physarum polycephalum slime-mould organisms retain the time-period of a regular pulse of brief stimuli. We ask whether a period can equally well be imparted not via regular pulses, but via more general periodic functions—for example via stimulus intensity varying sinusoidally with time, or even varying with time as a function with unknown period (whence the organisms not merely retain the period, but in a sense compute it); we discuss this theoretically, and also outline, though defer to future work, an experimental investigation. As motivation, we note that the ability to determine a function’s period is computationally highly desirable, not least since from such ability follow methods of integer factorization. Specifically, the phenomena described herein afford a novel (albeit inefficient), non-quantum implementation of Shor’s algorithm; inefficiency aside, this offers interesting, alternative perspectives on approaches to factorization and on the computational uses of Physarum.

Behavioral diversity is one of the universal features for all animals but missing in artificial machines. Behavioral diversity enables animals to explore alternative behaviors and avoid to getting stuck in a dead-end situation due to severe environmental changes. Plasmodium of true slime mold (Physarum polycephalum) is one of the splendid models to investigate behavioral diversity of animals. We introduce a constructive approach to understand the versatile and adaptive behaviors of the plasmodium using a simulation model. The results obtained shed a new light on how to design artificial system in ways that allow behavioral diversity and purposeful behavior, e.g., chemotaxis or phototaxis.

A novel Score-based Physarum Learner algorithm for learning Bayesian Network structure from data is introduced and shown to outperform common score based structure learning algorithms for some benchmark data sets. The Score-based Physarum Learner first initializes a fully connected Physarum-Maze with random conductances. In each Physarum Solver iteration, the source and sink nodes are changed randomly, and the conductances are updated. Connections exceeding a predefined conductance threshold are considered as Bayesian Network edges, and the score of the connected nodes are examined in both directions. A positive or negative feedback is given to the edge conductance based on the calculated scores. Due to randomness in selecting connections for evaluation, an ensemble of Score-based Physarum Learner is used to build the final Bayesian Network structure.

Since the appearance of slime mould-inspired network design applications, it has attracted the attention of many researchers from all over the world. In this chapter, we provide an overview of a variety of slime mould-inspired applications on graph-optimization problems. We will focus more on the mathematical model inspired by slime mould, develop a novel Energy Propagation model, and also covers its applications to many graph optimization problems. Some examples of such applications include Shortest Path Tree Problem (SPT), Supply Chain Network Design (SCNP), Maze Problem and Multi-source Multi-sink Minimum Cost Flow Problem.

Slime mould computers have been used to solve graph-theoretical problems like mazes and evaluate man-made transport networks. For the laboratory experiments that demonstrate these computing capabilities, slime mould is first starved and then introduced to an area with attractants placed on key positions. The behaviour of slime mould during these laboratory experiments have been simulated by a model based on cellular automata (CAs). The advantages of a software model over the real slime mould are repeatability and faster productions of results. Using CAs can be justified by the emergence of global behaviour from local interactions, a rule that applies also on the real slime mould. The results of the model have been compared to the ones produced during laboratory experiments and found in good agreement both for maze solving and network designing. After thorough examination of the laboratory experiments an updated model was developed, which yielded more efficient networks. As the model was parametrized to produce slightly differentiated results, the effects of these parameters were studied.

Biological organisms have become an inspiration for many computer scientists in order to process and analyze complex engineering problems. A well known example of this success story departs from the application of plasmodium of Physarum to solving the shortest path problem as experimentally demonstrated in the case of a labyrinth as well as to other graph related problems. There are many modeling tools trying to mimic the behavior of Physarum. We consider a discreteDiscrete models and parallel model, namely cellular automataCellular automata (CA) based model implemented in hardwareHardware, which attempts to describe and, moreover, mimic the Physarum’s behavior in a mazeMazesolving. In order to take full advantage of the CA inherent parallelism, we implemented the model on a Field Programmable Gate Array (FPGA)Field programmable gate array . Two implementations were considered in order to accelerate the model’s response and improve the exactness of the experimental results. Their main difference subsists in the precision produced by the numerical representation of CA model parameters. The modeling efficiency of both approaches was compared depending on the resulting error propagation. The presented FPGA implementations accelerate considerably the performance of the CA algorithmHardwareacceleration when compared with its software based version. Finally, a Graphical Processing Unit (GPU)Graphical processing unit will exploit the prominent feature of parallelismParallel computing that CA structures inherently possess in contrast to the serial computers, thus accelerating the response of the proposed model in a more easy to be programmed fashion. As a result, these implementations can also be considered as a preliminary, parallel and accelerated CA-based Physarum Polycephalum hardware virtual lab, which reproduces the characteristics of the biological organism towards its application to the shortest-path problem and thus increases significantly the computational speed.

We propose two unconventional arithmetic circuits: adder and subtracter defined on finite p-adic integers. These circuits are theoretically implemented on the plasmodium of Physarum polycephalum. Adder and subtracter are designed by means of spatial configurations of several attractants and repellents which are stimuli for the plasmodium behaviour. As a result, the plasmodium could form a network of protoplasmic veins connecting attractants and original points of the plasmodium. Occupying new attractants is considered in the way of adders and leaving some attractants because of repelling is considered in the way of subtracters. On the basis of p-adic adders and subtracters we can design complex p-adic valued arithmetic circuits within a p-adic valued logic proposed by us.

We propose a game-theoretic simulation of motions of Physarum plasmodium. This simulation is based on the game of Go. We consider two syllogistic systems implemented as Go games: the Aristotelian syllogistic and performative syllogistic. In the Aristotelian syllogistic, the locations of black and white stones are understood as locations of attractants and repellents, respectively. In the performative syllogistic, we consider the locations of black stones as locations of attractants occupied by plasmodia of P. polycephalum and the locations of white stones as locations of attractants occupied by plasmodia of Badhamia utricularis. The Aristotelian syllogistic version of Go game is a coalition game. The performative syllogistic version of Go game is an antagonistic game.

Being a living substrate the slime mould does not halt its behaviour when a task is solved but often continues foraging the space thus masking the solution found. We propose to use temporal changes in compressibility of the slime mould patterns as indicators of the halting of the computation. Compressibility of a pattern characterises the pattern’s morphological diversity, i.e. a number of different local configurations. At the beginning of computation the slime explores the space thus generating less compressible patterns. After gradients of attractants and repellents are detected the slime spans data sites with its protoplasmic network and retracts scouting branches, thus generating more compressible patterns. We analyse the feasibility of the approach on results of laboratory experiments and computer modelling.

A new paradigm of decision-making is analyzed focusing on a binary choice, between two source of food, made by slime mould Physarum polycephalum. Mean-field and probabilistic approaches are developed and the results are compared to experiment.

Sensation and perception of the surrounding environment is an essential mechanism in enhancing survival by increasing opportunities for foraging, reproduction and avoiding predatory threats. The most complex and well developed sensory mechanism is vision, which is highly developed in mammalian neural systems. Simple organisms, such as the single-celled slime mould Physarum polycephalum possess no neural tissue yet, despite this, are known to exhibit complex computational behaviour. Could simple organisms such as slime mould approximate complex perceptual phenomena without recourse to neural tissue? We describe a multi-agent model of slime mould where complex responses to the environment such as Lateral Inhibition (LI) can emerge without any explicit inhibitory wiring, using only bulk transport effects. We reproduce the characteristic edge contrast amplification effects of LI using excitation via attractant based stimuli. We also demonstrate its counterpart behaviour, Lateral Activation (where stimulated regions are inhibited and lateral regions are excited), using simulated exposure to light irradiation. Long-term changes in population density distribution correspond to a collective representation of the global brightness of 2D image stimuli, including the scalloped intensity profile of the Chevreul staircase and the perceived difference of two identically bright patches in the Simultaneous Brightness Contrast (SBC) effect. We demonstrate a realistic perception of a greyscale scene generated by the movement trails of the agent population and explore how an artistic sketch-like perception can be achieved by purposefully distorting the sensory inputs to the agent population. This simple model approximates Lateral Inhibition, global brightness perception, and thus primitive vision, in a collective unorganised system without fixed neural architectures. This suggests novel collective mechanisms and sensors for use in distributed computing and robotics applications.

We present results into harnessing the memristive characteristics of Physarum polycephalum for computer music. Memristors are the recently discovered fourth fundamental passive circuit element that relates magnetic flux linkage and charge. Unlike the three established fundamental circuit elements, namely the capacitor, inductor, and resistor, the memristor is non-linear. The plasmodium of Physarum polycephalum is an amorphous unicellular organism that has been discovered to exhibit memristive qualities. We confirm findings that the protoplasmic tube of Physarum polycephalum exhibits memristive properties. We conduct a study that investigates how the memristive qualities of the organism may be used to generate musical responses to seed material. Following on, we briefly present an artefact of our research that takes the form of a piece of music composed for live performance. In the final section, we discuss our future work. Here we offer an insight as to how we plan on expanding the usability of Physarum-based memristors by stabilising the component and overcoming some of the constraints we present within this text.

Slime mould Physarum polycephalum is repelled by light. We inoculated a multi-electrode array (MEA)Multi-electrode array Physarum and discovered that the Physarum’s response to light was recordable as an electrical signal on the MEA—the response was identified aurally from sonificationSonification of the electrical data. In order to illustrate this result to the general public we decided to associate the sonified data responses with an emotion, which was then emoted by a robot ‘actor’ consisting of a mechanised robotic headRobotic head. The data was split into chunks; the chunks were given a polarity based on whether there was light (a repellent) or food (an attractant) and a level of arousal based on the volume of the chunk (power of the electrical signal): the chunks were then assigned an emotion using the circumplex modelCicumplex model of affect. The soundtrack of sonified responses to stimuli was then played alongside the robot emoting: the project was presented at the Living Machines exhibition at the Science Museum. The meaning of the sonified data was easily understandable by members of the public and to which they responded with enthusiasm and interest in scientific endeavours. Thus we suggest, although unconventional and not the most scientifically rigorous way of presenting data, there is a place for using humanity’s emotional responses to communicate experimental results to the general public.

This chapter presents an overview of the television and film work featuring myxomycetes before introducing The Creeping Garden, directed by Tim Grabham and Jasper Sharp, a rare example of an independently-produced feature-length documentary intended for a general audience that focuses on scientific subject matter. The issues surrounding the communication of factual information in visual and audial form about an organism that occupies a different timescale and perceptual world to humans is explored, before the various representational techniques of time magnification, sonification, musification and simulation are introduced as potential ways of providing new insights into the natural world.

bodymetries is an artistic project aimed at mapping the human body through amorphous intelligence. We present results of laboratory experiments, artistic installations and performances based on a generative algorithm, where the slime mould propagates on a human body making a virtual network giving a unique representation of the body features.

Slime mould Physarum polycephalum is large single cell with intriguingly smart behaviour. The slime mould shows outstanding abilities to adapt its protoplasmic network to varying environmental conditions. The slime mould can solve tasks of computational geometry, image processing, logics and arithmetics when data are represented by configurations of attractants and repellents. We attempt to map behavioural patterns of slime onto the cognitive control versus schizotypy spectrum phase space and thus interpret slime mould’s activity in terms of creativity.