The term area 31 refers to a cytoarchitectural subdivision of the part of cingulate cortex that is located largely in the precuneus on the medial surface of the parietal lobe. It belongs to the posterior cingulate cortex. In the human it arches around the caudal boundaries of area d23 and area v23 caudal to the splenium of the corpus callosum, and it has two parts: area d31 of the dorsal posterior cingulate cortex and area v31 of the ventral posterior cingulate cortex. The macaque area 31 corresponds to area d31 of the human; the macaque has no area corresponding architectonically to area v31. ( Vogt-2012 ). Equivalents in the rat and mouse may be present in the cingulate/retrosplenial cortex ( Paxinos-2001 ).