New brain networks are active after right MCA stroke when moving the ipsilesional arm

To determine whether, like the paretic arm, movement of the ipsilesional arm after middle cerebral artery (MCA) stroke is associated with widespread neural activation changes in areas anatomically and functionally connected to the lesion.

In this fMRI experiment, seven patients with right MCA stroke and seven healthy control subjects performed a series of movements with their (nonparetic) right hand. Subjects either mimicked a visual display (visually guided) or generated the same motor task after a visual start signal (self-monitored). A multivariate linear discriminant analysis was used to determine the combinations of brain regions of interest (ROIs) that demonstrated maximum differences in activation between healthy and stroke subjects. The analysis was repeated within subject groups to differentiate self-monitored and visually guided movement.

There was a significantly different network of neural regions recruited for movement with the nonparetic, ipsilesional arm in patients with stroke vs healthy control subjects. The anterior cingulate cortex was significantly more active when patients execute self-monitored movement than visually guided movement, suggesting changes in attentional processing required for the two tasks. The lesioned hemisphere was significantly more active in patients with stroke using the nonparetic arm than in control subjects during visually guided movement.

These results support a model of widespread bihemispheric reorganization in the motor system after a focal right hemisphere lesion. Attentional demands of self-monitored movement may be much greater than visually guided movement in patients, possibly impacting rehabilitation protocols for these patients.