KINEMATICS OF GOAL-DIRECTED ARM MOVEMENTS IN NEGLECT - CONTROL OF HAND IN-SPACE

The present study investigated unrestrained, three-dimensional arm mov ements during goal-directed pointing in five patients with clinically manifest neglect to targets positioned either in the center or the lef t and right hemispace. Five patients with unilateral right hemispheric lesions without neglect and six healthy subjects served as controls. All subjects were able to point to these targets. Terminal accuracy of pointing did not differ between the three groups along the horizontal , vertical and anterior-posterior axis. Subjects' hand trajectories di d not reveal direction-specific deviations from a straightline hand pa th. Our data show that deviations in the trajectories toward the ipsil esional side are not characteristic for patients with spatial neglect. We argue that exploratory and goal-directed motor behavior might not share the same egocentric, body-centered reference frame. A spatial re ference frame for exploratory behavior is disturbed in patients with n eglect resulting in a failure to explore the contralesional part of sp ace by eye or limb movements. Its failure does not induce a spatial bi as in hand trajectory formation during goal-directed arm movements in peripersonal space. Such deviations of reaching or pointing rather see m to be characteristic for patients with optic ataxia. (C) 1997 Elsevi er Science Ltd.