The term insulo-orbito-temporopolar complex refers to the piriform cortex and three adjacent areas that form an architectonic unit in the primate cerebral cortex surrounding the rostroventral end of the limbic lobe. The sequences of areas, which radiate from the piriform cortex at the limen insula, include: 1) the agranular insula, dysgranular insula and granular insula; 2) a similar sequence of agranular, dysgranular and granular areas that extend into the orbital gyri; and 3) a comparable sequence extending into the temporopolar region ( Mesulam-1984 ).