The term hippocampal complex refers to the functionally defined combination of gray and white matter components that make up the seahorse-shaped structure revealed by dissection on the floor of the lateral ventricle in the human ( Shaw-1997 Glasser-2016 ) and the macaque ( Martin-2000 ). ('hippocampus' is Latin for 'seahorse'.) Part of the cerebral cortex, the hippocampal complex is an infolding of the part of hippocampus in the ventral part of the limbic lobe into the lateral ventricle. It consists of three predominantly gray matter structures: the dentate gyrus, CA fields, and subiculum, and two predominantly white matter structures: the alveus and fimbria ( Carpenter-1983 ). While some authors refer to the transitional area of the CA1 field into the subiculum as a histologically separate structure ( Carpenter-1983 Paxinos-2009a ), that area, the presubiculum, does not appear in a functional segmentation of the human cerebral cortex ( Glasser-2016 ). In primates the HPC is a relatively flat structure the rostral end of which abuts the amygdala and curves medially to form the uncus. In rodents, where it constitutes a much greater portion of the cerebral cortex it curves up caudally into a C-shaped structure. Updated 18 Jun 2024.