Connections of the ventral granular frontal cortex of macaques with perisylvian premotor and somatosensory areas: Anatomical evidence for somatic representation in primate frontal association cortex

In macaque monkeys with injections of tritiated amino acids or horseradish peroxidase in the ventrolateral granular frontal cortex, we observed extensive anterograde and retrograde labeling of the premotor and somatosensory cortex in and around the lateral sulcus. Comparable labeling was not present with large and small control injections of the dorsal granular cortex. Cytoarchitectonic evaluation of the perisylvian cortex in the three cases examined in detail indicated that labeled areas included the ventral premotor cortex (area 6V); the precentral opercular and orbitofrontal opercular areas (PrCO and OFO); the second somatosensory area (S‐II); the opercular cortex immediately anterior to S‐II, possibly corresponding to area 2 of the S‐I complex; and the central part of the insular cortex, including portions of the granular and dysgranular insular fields (Ig, Idg). Labeling was particularly dense and extensive in areas 6V, S‐II, and OFO. Lighter labeling was also present in the rostral inferior parietal lobule (areas 7b and POa).