Figure 4

A primate right hand grip. A group of neurons that creates a representation of the external world or the own body may resemble a 3 dimensional coordinate system. The object of attention (the berry) might be like the origin (the crossing of the x-, y- and z-line). During the reaching maneuver, the right hemisphere receives no primary visual information about the hand. In gripping, the ipsilateral (right) hemisphere receives some visual information (the tip of the thumb and approximately half of the berry). The decussation line primarily follows the thumbnail cuticle. Right hemisphere information about the tip of the thumb, proprioception due to conjugate eye movements and left hemisphere information (touch, proprioception, vision, and motor signals related to the right arm/hand) may create many dimensions in such a coordinate system, contributing to the precision of the hand.