How the brain represents the body: Insights from neurophysiology and psychology
To reach for the computer mouse, sit upright in a chair or hold a journal in order to read it, indeed, to do most of the actions that we commonly perform, we rely on a representation of the spatial configuration of the body. How and where in the brain is the body represented and what are the psychological properties of this body schema? In this article we review first the neurophysiology and then the psychology of the body representation. One finding that has emerged from both approaches is that the body representation is not merely a registration of proprioceptive inputs about joint angle. Instead, the brain contains a sophisticated model of the body that is continually updated on the basis of multimodal input including vision, somesthesis and motor feedback. Neurophysiological studies in the monkey brain show that parietal area 5 is a critical node for processing the body’s configuration. Neurons in area 5 combine signals from different modalities in order to represent limb position and movement. Psychological studies show that the body schema is used to cross-reference between different senses, as a basis for spatial cognition and for movement planning.