UNIMANUAL MOTOR LEARNING IMPAIRED BY FRONTOMEDIAL AND INSULAR LESIONSIN MAN

We correlated impaired unimanual motor learning with the lesion site i n 53 patients with chronic lesions predominantly of the frontal lobe. The lesions were assessed using computed tomography (CT), then transfe rred to standard templates of nine slices parallel to the canthomeatal plane and digitized with a raster matrix of 3 mm by 3 mm width. The l earning task was to track a moving target on a computer screen with a dot guided by the preferred hand, while the horizontal coupling betwee n hand movement and screen was inverted. The mean tracking error was r ecorded over eight successive trials of 80 s duration. If the mean err or of the last three trials was not lower than that of the first three trials, impaired motor learning was assumed. We correlated performanc e and lesion with a contingency table analysis for each raster element . Impaired motor learning was associated with a lesion within the supp lementary motor area and adjacent anterior cingulate, and within the a nterior insular region. Our results indicate that these regions are cr itical for motor learning and functional plasticity in man. Our data s upport activation patterns obtained with positron emission tomography.