The term anterior parahippocampal gyrus (PHGa) refers to the more rostral of two components of the parahippocampal gyrus (PHG) defined by topology in the human ( Insausti-2012 ) and the macaque ( Martin-2000 ). It is composed of three histologically distinct areas of cerebral cortex. From anterior to posterior they include the piriform cortex (PIR), presubiculum, and entorhinal cortex ( NeuroNames ). No topologically equivalent area exists in the smooth cortex of the rat or mouse ( Swanson-2004 Hof-2000 ). Updated 7 Jul 2026.