Kinematic properties of real and pantomimed prehension movements in parietal patients

Abstract

To study how visuo-perceptual and visuo-motor processes contribute to action execution, we investigated kinematics of real and pantomimed prehension. Two parietal patients and 18 control participants performed pantomimed prehension followed by a session of real grasping. Participants gazed directly at the target object or at a fixation point (approx. 10 deg from the target) and were subjected to a 5-s visual occlusion. In the pantomimed prehension session, the target was removed during visual occlusion, while in the real grasping session, the target was not removed. Patient MFL, who was mainly damaged in dorso-dorsal stream, was more impaired during real grasping and showed improvement of grip scaling for pantomimed prehension especially in peripheral visual condition. Patient MCS whose lesion also includes ventro-dorsal stream did not show such improvement. The results suggest different roles of dorso- and ventro-dorsal streams in action execution.