The term area Iapm (macaque) refers to the posteromedial agranular insular area, a subdivision of the orbitomedial prefrontal cortex (macaque). It is defined on the basis of internal structure and connectivity. Located in the posterior part of the orbital gyri, Iapm is one of two areas constituting the medial agranular insular region. The other is area Iam (macaque). The lamina rara revealed by Nissl stain is a defining feature of area Iapm. Other significant features are fiber plexi in the external pyramidal layer (III) and the internal pyramidal layer (V) that bracket the lamina rara stained for cholinesterase, and very few cells that stain for parvalbumin. Horizontal fibers in the molecular layer of the cerebral cortex (I) also distinguish it from some neighboring areas ( Carmichael-1994 ). Its equivalent in the human is area Iapm ( Ongur-2003 ). As a component of insulo-orbital cortex, its equivalent in the rat and mouse would be in the agranular insular cortex.