Cortical connections of the anterior (F5a) subdivision of the macaque ventral premotor area F5.

We traced the cortical connections of the anterior sector (F5a) of the macaque ventral premotor (PMv) area F5 and compared them with those of the adjacent F5 sectors, F5c and F5p. F5a displays a very dense "intrinsic" connectivity with F5c and F5p, premotor connections limited to F4 and F6/pre-SMA, relatively robust prefrontal connections with areas 46v and 12, and dense connections with rostral opercular frontal areas. Outside the frontal cortex, connections of F5a are dense with the SII region, relatively robust with inferior parietal areas PFG and AIP, weak with the inferior parietal area PF, and moderate with area 24. The comparison with data from injections in F5c and F5p showed that F5a, though sharing some common parietal connections with the other F5 sectors, displays several characterizing features providing robust evidence for its connectional distinctiveness. The present study provides evidence for a general organization of the PMv similar to that of the medial and dorsal premotor cortex, with F5a representing a pre-PMv area. Specifically, the present data suggest that F5a is a privileged site of integration, in the PMv, of parietal sensory-motor signals with higher-order information originating from prefrontal, rostral frontal opercular areas, and F6/pre-SMA. The results of this integration can be then broadcasted to the adjacent F5 sectors for the generation and control of hand actions and cognitive motor functions.