The term inferior occipital gyrus refers to the most ventral of the human occipital gyri defined on the basis of topology ( Duvernoy-1992 ). It is listed in the glossaries of Mai-1997 and of Talairach-1988, where it is annotated: "the exact identification... is often difficult." Neither author labels it in atlas illustrations of the human occipital lobe. In the macaque it is defined as the portion of the occipital lobe bounded laterally by the inferior occipital sulcus, medially by the occipitotemporal sulcus and posteriorly by the inferior calcarine fissure ( Martin-2000 ). It has no topological equivalent in the macaque or in the smooth cerebral cortex of the rat or mouse ( NeuroNames ).