Figure 4.

Effects of the virtual lesions of the left or right PMv on the fingertip positioning. Side view of the manipulandum showing the distribution of the fingertip positions for the thumb (black circles) and the index finger (white circles). The two graspable surfaces of the manipulandum were superimposed to represent the thumb and index fingertip positions on the same graph. The subject’s hand came from the right side of the figure. The ellipses represent the area in which 95% of the fingertip positions were found. A, Distribution of the thumb and index fingertip positions for 30 control trials in one subject. Note that the index finger contact points were always slightly farther than those of the thumb. B, A virtual lesion of the left PMv increased significantly both the horizontal distance between the thumb and index finger contact points and their variability. C, Similar effects, although less pronounced, of a virtual lesion of the right PMv on fingertip positions and distributions.