Sensory Sources of Body Perception

Information about the spatial structure and configuration of one's body is provided by vision, somato-sensory afferences, and monitoring of motor commands. Vision of one's body enters the brain by the same pathways as vision of any other object. Direct

Encyclopedia of the Human Brain Volume 1

Copyright 2002, Elsevier Science (USA).

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sight of one's own body is limited to the limbs and the front of the trunk but does not basically differ from vision of other person's bodies. Mirrors, photography, and electronic recording provide ample opportunity for seeing one's own body as completely as it can be seen by anyone else. Vision provides a view of one's own body that is very similar to how it can be seen by external observers.

Somatosensory afferences from cutaneous surface receptors subserve primarily the reaction to and recognition of external stimuli, but tactile sensations can also be analyzed with respect to their localization on the body. One can also touch oneself. Tactual exploration of one's own body differs from exploration of external objects by the coincidence of tactile sensations from touching and touched body parts. This coincidence can serve as a clue for recognizing one's own body as being the object of touch.

In contrast to surface receptors, afferences from mechanoreceptors in deep skin layers, joint capsules, Golgi tendon organs, and muscle spindles are predominantly used for proprioception. Proprioception comes from the interior of the body and differs fundamentally from the way in which one's body can be perceived by another person.

Data from the physiology of motor control and perception strongly suggest that "efference copies'' of motor commands can be monitored and compared with proprioceptive feedback from motor execution. In routine behavior we are not aware of motor commands as being different from motor execution, but motor commands may rise to consciousness when there is discrepancy between the command and its execution.

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