The term insulo-orbital cortex (IOC) refers to a portion of cerebral cortex (CTX) that spans the junction of the agranular insular cortex (INSa) and the agranular orbitofrontal cortex of the human ( Zilles-2004; Ongur-2003 ) and the macaque ( Mesulam-1982; Carmichael-1994 ). Having neither an external granular layer (II) nor an internal granular layer (IV) both parts are agranular cortex ( Mesulam-1984 ). Equivalent agranular areas are found In the rat (Swanson-2004 ) and mouse ( AMBA-2024 ). Their equivalents to the orbital components of the human and macaque IOC are also located on the frontoventral surface of the cerebral cortex (CTX). Thus, in rodents,.the parts of IOC are both topologically and histologically equivalent to the IOC of primates. Updated 24 Mar 2025.