INFLUENCE OF OBJECT SIZE ON PREHENSION IN LEUKOTOMIZED AND UNLEUKOTOMIZED INDIVIDUALS WITH SCHIZOPHRENIA

The aim of this study was to investigate the influence of schizophreni a and frontal leukotomy on the control and perceptual-motor coordinati on of reaching and grasping movements. Reaches to various-sized drinki ng glasses were videotaped for unleukotomized and leukotomized adults with schizophrenia, and for healthy age-matched controls. Kinematic an alyses showed that while the two patient groups moved more slowly than the controls, the proportion of overall movement time spent accelerat ing to reach peak velocity and the proportion of overall movement time spent decelerating before contact with the glasses was similar for al l 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 respons e to the various glass sizes. The frontal lesions of the leukotomized patients were not related to motor control deficits when compared to t he control schizophrenic patients. As well, the perceptual abilities o f the patients were adequate as evidenced by their ability to scale th eir grasp to glass size.