cerebral cortex [L, cerebrum + cortex, bark] , a layer of neurons and synapses (gray matter) on the surface of the cerebral hemispheres, folded into gyri with about two thirds of its area buried in fissures. It integrates higher mental functions, general movement, visceral functions, perception, and behavioral reactions. It has been classified in many different ways. More than 200 areas have been identified on the basis of differences in myelinated fiber patterns, as well as 47 separate function areas with different cell designs. For example, stimulation of the precentral cortex or motor area with electrodes causes contractions of voluntary muscles. Destruction of a motor speech area in the frontal operculum causes motor aphasia or speech defects despite healthy, intact vocal organs. Stimulation of the frontal area affects circulation, respiration, pupillary reaction, and other visceral activity. Also called pallium. See also cerebrum.
