Visual feedback discordance mediates changes in brain activity and effective connectivity: A stroke fMRI dynamic causal modeling study

In this study we investigated the effect of visual feedback discordance in Virtual Reality (VR) on brain activity. Fifteen subjects with chronic stroke moved the less-affected hand with concomitant feedback through a VR hand model corresponding to the ipsilateral (veridical) or contralateral side (mirrored). Visual feedback discordance (mirrored-feedback) was associated with an increase in ipsilesional (iM1) sensorimotor cortex activity (ipsilateral to movement). Effective connectivity analysis using dynamic causal modeling (DCM) revealed a facilitatory effect of mirrored-feedback on the interaction between bilateral posterior parietal cortices and iM1. These results indicate that mirrored-feedback training may enhance brain activity in the ipsilesional cortical motor system, likely driven by parietal areas. These neural changes may be important substrates for fostering neuroplasticity and behavioral benefits induced by mirror therapy.