The term proisocortex refers to one of two types of neocortex defined on the basis of cytoarchitecture. The other is true isocortex. Proisocortex is transitional between true isocortex and periallocortex. It is found in portions of the cingulate gyrus, the insula, the parahippocampal gyrus, and the subcallosal gyrus ( Stephan-1975; Zilles-1990 ). See dysgranular insular cortex (Roberts) and retrosplenial dysgranular area ( Mesulam-1985 ). Updated 1 Oct 2024.