The term area v23a refers to the more rostral of two parts of area v23 in the human and the macaque. Defined on the basis of multiple criteria, it is located in the human in the isthmus of the cingulate gyrus between area 26 of the retrosplenial area and area v23b. In the macaque it is located similarly, except that the macaque has no area 26, so it directly abuts the splenium of the corpus callosum ( Vogt-2012 ).