hippocampus
n. (pl.
hippocampi) a seahorse-shaped part of the forebrain, in the basal medial region of the temporal lobe, that is important for declarative memory and learning. Because of its resemblance to a ram’s horn, 19th-century neuroanatomists named it Ammon’s horn (cornu ammonis; CA) for the horn of the ram that represented the Egyptian deity Ammon. Parts of the hippocampus were then labeled CA1, CA2, CA3, and CA4; these designations are still used for the different regions of the hippocampus. See hippocampal formation; Papez circuit. —hippocampal
adj.