The Effects of Brain Lesions on the Learning Performance of a Bimanual Co-Ordination Task

Abstract

The ability to learn a task requiring the precise co-ordination of movements of the left and right arm with one another was investigated in 40 patients with verified lesions in various sectors of the cerebral cortex and in 20 control subjects. The results show that patients with left-sided cerebral lesions are significantly inferior to normal subjects in their ability to learn, as well as in the proficiency ultimately achieved in a bimanual task. Patients with right-sided cerebral lesions show only minor deficiencies in learning during practice — however, the degree of proficiency ultimately achieved is not significantly different from that of a normal subject group. The results further indicate that there is a significant improvement with practice in the control group, as well as in the patients with left- and with right-sided cerebral lesions. However, patients with left-sided lesions show less improvement (relative to the score obtained in the initial trial) than patients with right-sided lesions or normal subjects. Finally, the results show that the highest percentage of patients with abnormal scores in the performance of a bimanual task is represented by the patients with parietal lobe lesions. In addition the deficiencies encountered in the patient group are not contingent upon the presence of clinically detectable abnormalities of motor and/or sensory function. Some theoretical interpretations of the findings are discussed.