Influence of object size on prehension in leukotomized and unleukotomized individuals with schizophrenia.

The aim of this study was to investigate the influence of schizophrenia and frontal leukotomy on the control and perceptual-motor coordination of reaching and grasping movements. Reaches to various-sized drinking glasses were videotaped for unleukotomized and leukotomized adults with schizophrenia, and for healthy age-matched controls. Kinematic analyses showed that while the two patient groups moved more slowly than the controls, the proportion of overall movement time spent accelerating to reach peak velocity and the proportion of overall movement time spent decelerating before contact with the glasses was similar for all three groups. For grasp formation, the two patient groups, which did not differ, opened their hands wider than did the controls; however, all three groups opened their hands to the appropriate size in response to the various glass sizes. The frontal lesions of the leukotomized patients were not related to motor control deficits when compared to the control schizophrenic patients. As well, the perceptual abilities of the patients were adequate as evidenced by their ability to scale their grasp to glass size.