Performance of complex arm movements and facial-movement sequences after cerebral commissurotomy.

Two patients with presumed complete midline section of the interhemispheric commissures and two patients with partial section were asked to copy complex arm movements and facial-movement sequences. Their performance was compared with our previously published findings on these tasks for patients with unilateral removals from the frontal, temporal or parietal region. On the arm-movement task, the commissurotomized patients were impaired equally with either the left or right arm and were as poor at performing this task as patients with excisions of left parietal cortex. On the face-movement task, commissurotomized patients performed very poorly, scoring significantly lower than all excision groups. There was no significant difference on either task between the performance of the patients with partial and those with complete sections.