Role of the left and right supplementary motor areas in memory-guided saccade sequences.

Six right-handed patients with a lesion affecting the left (3 patients) or right (3 patients) supplementary motor area were studied using single and sequential memory-guided saccade paradigms. Accuracy of single saccades was preserved in both groups, compared to control subjects, and the chronology of saccade sequences was disturbed in the group with the left lesion but not in the group with the right lesion. The results suggest that neither side of the supplementary motor area is involved in spatial memory, and that the left supplementary motor area plays a greater role in motor sequencing than does the right supplementary motor area.