The term parahippocampal amygdalar transition area (PHA) refers to a topologically and histologically defined area of the anterior parahippocampal gyrus (PHGa) of the limbic lobe (LLB) located ventral to the subdivision of the periamygdalar area that is defined on the basis of cytoarchitecture. It is located in the ventral portion adjacent to the basolateral nuclear group ( Amaral-1992 ).