Experience of agency during movement observation causes lateralized cerebral activations

It has long been established that execution and observation of human movement share a common cerebral network. This knowledge is employed for visual-based motor rehabilitation strategies such as mirror therapy or video therapy. The analogy between both therapy approaches, especially the question of eliciting of lateralized cerebral activations, was frequently assumed, but had never been addressed explicitly. For this purpose, 15 healthy right-handed subjects were instructed to observe and perform index finger-thumb opposition sequences under direct or mirrored visual control while being scanned with fMR. Imaging analysis was performed using SPM8 (FDR, p < 0,01). Lateralized cerebral activations in precuneus were only observed during movement mirroring, but not during movement observation of an otherwise identical visual stimulus. Contrary, movement observation of a right or a left hand elicit a symmmetric visual activation. These findings demonstrate that the occurance of lateralized cerebral activation is crucially dependent on the demand of agency and have important implications for the use of mirror and video therapy after stroke.