Modulation of sensorimotor cortical dynamics and proprioceptive processing induced by virtual reality-based mirror feedback during bilateral robot-assisted arm movement.

This study investigated frequency-specific cortical activity associated with different mirror feedback (MF) tasks during bilateral robot-assisted arm movement, using a virtual reality-based mirror system and electroencephalography. Eighteen healthy right-handed participants performed bimanual robot-assisted wrist-extension movements, with the passive hand driven by the active hand via a bimanual robot-assisted training device. Four experimental conditions were tested: congruent MF, incongruent MF, static virtual mirrored hand, and blank screen. Our results demonstrated that both congruent and incongruent MF elicited sustained activation of the mirror neuron system, as reflected by prolonged alpha event-related desynchronization (ERD). In the low-beta band, MF tasks enhanced proprioceptive processing, evidenced by stronger ERD in centroparietal and parietal regions relative to the blank screen and static hand conditions during the first 2000  ms after movement onset. Additionally, attenuation of beta rebound in frontocentral and parietal regions under MF conditions suggested continued motor cortical engagement beyond movement termination. Selective modulation in the high-beta band was observed in the congruent MF condition, with significantly greater ERD in bilateral posterior parietal cortices and the left posterior parietal cortex relative to static hand and blank screen conditions, indicating enhanced visuomotor integration when visual feedback was congruent with motor output. Overall, these findings reveal that VR-based MF not only sustains mirror neuron system activation and enhances proprioceptive feedback but also modulates post-movement beta dynamics and facilitates visuomotor integration. The observed frequency-specific oscillatory signatures provide neurophysiological evidence supporting the integration of VR-based MF into rehabilitation protocols aimed at improving motor and sensory function, particularly for patients with stroke.