EEG based analysis of lower limb exercise for neurorehabilitation according to the linkage between motor execution and visual feedback in immersive VR: A feasibility study with healthy adults

Stroke causes physical dysfunction due to brain damage, leading to aftereffects, such as hemiplegia. Until now, a lower limb rehabilitation system was developed by us to help patients to restore leg function owing to brain plasticity in neurorehabilitation. Visual Feedback (FB) in the system, together with a mechanical assistant for lower limb, linked to the motor execution is presented to form a FB learning model matching the motor execution and its imagination. This feasibility study on the healthy subjects aims to apply the knowledge to rehabilitation program in the future. Meanwhile, the feasibility study aims to investigate the effect of linked visual FB on the imagination of motor execution and furthermore, to clarify an effective design of visual FB conditions focusing on the similarity between visual FB and motor execution. The experiments under three different conditions were conducted using the system: (i) no visual FB, (ii) with visual FB and motion in the FB different from motor execution, (iii) with visual FB and motion in the FB closer to motor execution. Electroencephalogram (EEG) was performed as an indicator to evaluate the imagination of motor execution, being the reduction of EEG values during motion recall - Event Related Desynchronization (ERD) mainly used. According to the results, by comparing (i) and (ii), significantly greater ERD in (ii) verified that visual FB helps acquire the imagination of motor execution (p = 0.028). Moreover, between (ii) and (iii), ERD in β-band were significantly greater in (iii) (p = 0.028), but no significant difference showed for ERD in α-band (p = 0.600) that further confirmation might be needed. In conclusion, the linkage between visual FB and motor execution was verified in this study, which helps to acquire the imagination and may be related with brain recovery.