Cortical Integration of Simple Somatosensory and Visual Input

Introduction Primates, probably more than most other mammals, have developed a host of complex behaviors that require integration across sensory systems and between sensory systems and the motor system. One such ability is goal- directed reaching. This ability requires the brain to generate body centered coordinates for conjugal eye and hand movements. Thus, there should be regions of the brain, particularly the neocortex, that have access to both visual and somatic inputs, as well as information regarding eye position. One likely site of this multimodal integration is posterior parietal cortex (areas 5 and 7a). Studies in non-human primates indicate that neurons here have somatic receptive fields, and respond to wrist and arm movements, and reaching and grasping [1-3]. Further, neurons in this region participate in integration of visual inputs regarding target location and kinesthetic information regarding the position of the limbs in space [5]; instructed movements [6]; and attenti