Asynchronous brain-computer interface with foot motor imagery

Electrophysiological studies on brain-computer interface (BCI) have shown that event-related desynchronization (ERD) and event-related synchronization (ERS) in a and β bands are connected with actual hand movement and motor imagery. However, how they related to actual foot movement and motor imagery are largely unclear. This study aimed to investigate the power modulation in a and β bands for right and left actual foot movements and motor imageries to determine whether these EEG features are applicable for BCI. Eight healthy, righthanded volunteers participated in the experiment. EEG data were recorded while each subject moved the left or right foot or imagined doing so. As a result, a band power on Cz did not show distinguishing features among the actual motor tasks, motor imagery tasks, or the no performance task. However, the observed difference in the degree of increment in the change rate of β band power (β-ERS) after tasks may be meaningful enough to recognize actual foot movement and that motor imagery. The results also confirm that there was no distinction between left and right foot and no laterality in the foot task. In conclusion, β-ERS on Cz after imagining foot tapping can be considered to be applicable for BCI control.