Prefrontal Cortex

Abstract

The cortex of the anterior pole of the brain can be subdivided, histologically and physiologically, into three major parts. They have been most clearly identified and extensively investigated in the frontal lobe of the primate: (1) the primary motor cortex, a strip of agranular cortex rostral and adjacent to the central sulcus; (2) the premotor cortex, a conglomerate of cytoarchitectonically transitional areas, including the supplementary motor area (SMA); and (3) the prefrontal cortex, which constitutes the largest and most anterior of the three components and which, in the primate at least, has a prominent internal granular layer (IV) and for this reason is known as the granular frontal cortex. The three components can be well distinguished in the external convexity of the frontal lobe; in the cingulate and inferior (orbital) aspects of the lobe, the first two components are absent and the granular cytoarchitecture of the prefrontal cortex blends more or less gradually into that of limbic cortex behind it.