Functional Connectivity During Hand Tasks

Functional connectivity between surface electromyography (EMG) signals is still an unexplored area, mainly the study of directed coupling. The Partial Directed Coherence (PDC) technique has been used to analyze the direction of information flow on muscle networks. This work aims to use PDC to investigate the information flow during hand movements. The EMG signals were acquired from six muscles of the hand and forearm of 10 participants, during extension (FE) and flexion (FF) of the fingers. The average of PDCs was calculated and displayed as color maps. Two frequency bands were analyzed, 10–60 Hz and 60–400 Hz. In addition, the prevalence of flow direction between a muscle pair was inferred by paired Wilcoxon Non-Parametric Test. The results for FE movement showed a consistent direction of information flow from the First Dorsal Interosseous (FDI), Flexor Digitorium Superficialis (FDS), and Flexor Digitorium Profundus (FDP) to the Digitorum Extensor (ED). On the other hand, for FF movement, the coupling direction was from FDP to FDI. The functional connectivity pattern related to different movements can be promising in future applications as an assessment of post stroke subjects and human machine interface for rehabilitation purposes.