Visual feedback of a hand prepared to move modulates cortical motor activity.

Previous study has shown that observation of a movement leads to the activation of some of the same cortical motor regions that are stimulated when the movement is performed. This study aimed to determine whether visualization of a static hand would lead to the activation of the vision/action related system or if viewing a movement was essential to modulate the activity of cerebral motor areas. In our experimental procedure, motor cortical activity was measured using the lateralized readiness potential, a cortical motor potential generated partially in the primary motor cortex, when participants had to press a button with the right or left hand, which was either seen or not. We found that the lateralized readiness potential amplitude differed significantly between the two conditions, suggesting that visual feedback from the image of the hand is sufficient to modulate neural activity in the primary motor cortex.