The normal population performs certain bimanual tasks with the hands behaving in similar ways even when each hand has a different task. Lateralization of bimanual coordination emerges by seven years of age, but the tendency exists to deviate in the direction of the dominant hand's task. Patients who have undergone corpus collastomy for intractable epilepsy show some impairment of bimanual coordination. This study compares the bimanual performance of individuals with callosotomies with normal subjects in two experimental situations. The first task involved moving both hands simultaneously; one hand was required to clear a 10.1 cm high barrier located either to the right or left of midline. The second task was a two handed aiming test. The results showed a significant difference in the times of right and left hand to reach peak amplitude of trajectories when the barrier was on the left (p< .05). The trajectories of the normal subjects demonstrated smooth uniform performance by both hands as predicted by earlier studies. The experimental group demonstrated less uniform trajectories overall with the hands appearing to behave more independently than those of the control group. This suggests the importance of the corpus callosum in mediating certain voluntary bimanual movements.
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