Influence of motor imagination on cortical activation during functional electrical stimulation

Abstract

<b>Objective</b> Motor Imagination (MI) and Functional Electrical Stimulation (FES) can activate the sensory-motor cortexthrough efferent and afferent pathways respectively. Motor Imagination can be used as a control strategy to activate FES through a Brain-computer interface as the part of a rehabilitation therapy. It is believed that precise timing between the onset of MI and FES is important for strengthening the cortico-spinal pathways but it is not known whether prolonged MI during FES influences cortical response.<p></p> <b>Methods</b> Electroencephalogram was measured in ten able-bodied participants using MI strategy to control FES through a BCI system. Event related synchronisation/desynchronisation (ERS/ERD) over the sensory-motor cortex was analysed and compared in three paradigms: MI before FES, MI before and during FES and FES alone activated automatically.<p></p> <b>Results</b> MI practiced both before and during FES produced strongest ERD. When MI only preceded FES it resulted in a weaker beta ERD during FES than when FES was activated automatically. Following termination of FES, beta ERD returns to the baseline level within 0.5 s while alpha ERD took longer than 1 s.<p></p> <b>Conclusions</b> When MI and FES are combined for rehabilitation purposes it is recommended that MI is practiced throughout FES activation period.<p></p> <b>Significance</b> The study is relevant for neurorehabilitation of movement.<p></p&gt