The term limen insula refers to a superficial feature of cerebral cortex, namely, the surface of the junction between the insula, limbic lobe and frontal lobe in the human ( Mai-1997 ) and the macaque ( Mesulam-1982 ). More specifically, in the human it is the rostral surface of the junction of the anterior long gyrus of the insula with the piriform cortex of the anterior parahippocampal gyrus of the limbic lobe and basal forebrain of the frontal lobe. Identified by dissection, its medial border on the ventral surface of the brain is with the olfactory tubercle, which in primates is commonly referred to as the 'anterior perforated substance' ( Duvernoy-1992 ). The limen insula has no topological equivalent in the rat or mouse. Updated 24 May 2024.