Mirror feedback in virtual reality elicits ipsilesional motor cortex activation in chronic stroke patients

We studied if mirror-visual feedback, presented in virtual reality (VR), could bolster the activity of the lesioned motor cortex in chronic stroke patients. 5 stroke subjects performed a simple finger movement using the non-paretic hand. During fMRI scanning, an MRI-compatible VR-motion capture interface was used to record their hand movement and actuate in real-time virtual hand models, which were presented in 1st person perspective as virtual feedback. Virtual hands´ motion was manipulated by either actuating the hand model corresponding to the moving (unaffected) hand (veridical feedback) or the opposite (mirrored) virtual hand. Two additional types of feedback, in which the virtual hands were replaced with moving non-anthropomorphic shapes, served as control conditions. Subjects maintained consistent movement kinematics across conditions. In each of the 5 stroke subjects, mirrored feedback led to significant activation of the ipsilesional sensorimotor cortex, despite the affected hand remaining motionless during the task. An additional control experiment and conjunction analysis confirmed that the part of the motor cortex that was activated by mirrored feedback overlapped with the area of motor cortex involved in movement production of the affected hand. Our data suggest that mirrored visual feedback may be a feasible modality that can be used to recruit select brain regions in stroke patients as a means of facilitating neural reorganization and recovery.