Unilateral and bilateral digital mirror visual feedback with different movement types modulate mu oscillations in individuals with stroke.

OBJECTIVE

Mirror visual feedback (MVF) simulates motor execution of the affected hand and therefore potentially recruits motor areas in the affected hemisphere for individuals with stroke. However, whether and how digital form of MVF modulates oscillatory activities in individuals with stroke remain unclear. We investigated the neural mechanisms underlying digital MVF combined with different movement types in healthy controls and individuals with stroke using electroencephalography (EEG).

METHODS

The participants performed a motor task with different combinations of MVF forms and movement types, including: (1) the bimanual training (BT) condition, (2) the unilateral MVF with unimanual training (UMUT) condition, (3) the unilateral MVF with bimanual training (UMBT) condition, and (4) the bilateral MVF with bimanual training (BMBT) condition. We investigated cortical excitability in motor regions by examining mu (9-14 Hz) power attenuation.

RESULTS

Both the healthy and stroke groups showed pronounced mu power suppression in the central regions contralateral to unilateral MVF in the UMUT condition, indicating enhanced cortical excitability induced by digital MVF. Additionally, we found larger mu power attenuation in the affected hemisphere in both the UMUT and BMBT conditions than in the UMBT condition in the stroke group. Moreover, the individuals with stroke with better motor ability of the affected hand showed larger mu power attenuation in the affected hemisphere, and a higher degree of mu-power lateralization shifted toward the affected hemisphere in the BMBT condition.

CONCLUSIONS

Our electrophysiological findings provide neural evidence that digital MVF can facilitate cortical recruitment in the affected motor regions in individuals with stroke.