Motor and parietal cortex activity responses to mirror visual feedback in patients with subacute stroke: An EEG study

• Mirror visual feedback (MVF) inhibits the excitability of the contralateral primary motor cortex (M1) for subacute stroke. • The attenuated low mu suppression in sensorimotor cortex may serve as a biomarker of MVF for subacute stroke rehabilitation. • The findings have rehabilitation implications for clinical application of MVF on subacute stroke. To elucidate the immediate electrophysiological effects of mirror visual feedback (MVF) combined with or without touch task in subacute stroke. Subacute stroke patients and healthy controls were recruited to participate in four grasping tasks (MVF or no MVF, combined with rubber ball or no ball) under electroencephalogram (EEG) monitoring. Event-related desynchronization (ERD) /event-related synchronization (ERS) and the lateralization index (LI) were utilized to observe the electrophysiological effects. MVF reduced ERD suppression in the contralateral primary motor cortex (M1) of stroke patients. This reduction was observed in the low mu band for the contralateral parietal cortex during pure MVF. The laterality effects in the low mu band under MVF was noted in M1 for stroke patients and in the parietal cortex for all participants. MVF inhibits the excitability of the contralateral M1 for subacute stroke. MVF inhibit activities in the contralateral M1 and parietal cortex, and reestablished hemispheric balance in the low mu band. MVF has an instantaneous effect on subacute stroke by inhibiting the excitability of the contralateral sensorimotor cortex. The attenuated ERD in the low mu band in contralateral M1 and parietal cortex may serve as biomarkers of MVF for stroke rehabilitation.