Cortical Connections of the Macaque Caudal Ventrolateral Prefrontal Areas 45A and 45B

Abstract

We have found that the 2 architectonic subdivisions of the prefrontal area 45, 45A and 45B, display connectivity patterns that clearly distinguish them from one another and from their neighboring architectonic areas. Area 45A is primarily connected to the frontal areas 45B, 12l, caudal 12r, 12o, 10, rostrodorsal 46, 9/8B, 44, 8/FEF (frontal eye field), and the SEF (supplementary eye field), temporal area IPa, and unique among all the studied areas, to the superior temporal polysensory (STP) area and auditory parabelt areas. Area 45B displayed much stronger frontal connections with the oculomotor areas 8/FEF, 8r, and the SEF than those of area 45A, primary connections with areas 12l, caudal 12r, 12o, and 8B, and unlike area 45A, with areas ventrorostral 46, rostral 12r, 12m, and 13m. Temporal connections were all virtually confined to areas IPa, intermediate TEa/m, and TE. Additional labeling was found in lateral intraparietal area. Our data suggest that 45A and 45B are 2 distinct areas, possibly playing a differential role in nonspatial information processing: area 45A corresponds to the prefrontal sector for which a role in communication behavior and homology with the human area 45 was proposed, whereas area 45B is a distinct prearcuate area, possibly affiliated to the oculomotor frontal system.

Selectivity for Three-Dimensional Shape and Grasping-Related Activity in the Macaque Ventral Premotor Cortex

“…Moreover the presence of visualdominant neurons encoding 3D object information in F5a also provides a functional interpretation of the concept of pre-premotor cortex, as suggested by Gerbella et al (2010): the pre-premotor F5a sector is clearly much more visual than the other F5 sectors, where previous studies have observed no visual-dominant neurons (Raos et al, 2006). Fluet et al (2010), however, also described the presence of "sensory" (visual-dominant) neurons in F5.…”

Anatomical Evidence for the Involvement of the Macaque Ventrolateral Prefrontal Area 12r in Controlling Goal-Directed Actions

“…The criteria used to define the injection sites and identify FB, DY, BDA, FR, and LYD labeling have been described in previous studies (Luppino et al, , 2003Rozzi et al, 2006;Gerbella et al, 2010Gerbella et al, , 2011. All the injection sites used in this study were completely restricted to the cortical gray matter, involving the entire cortical thickness or at least the middle cortical layers.…”

“…Connections with the parietal and premotor cortex have been observed by Barbas (1988) and Saleem et al (2008) after tracer injections placed in the middle of area 12r but not by Gerbella et al (2010) after injections placed caudally in this area. Indeed, the connections of AIP and F5a with area 12r observed by Borra et al (2008) and Gerbella et al (2011) did not involve the entire extent of this area, only the intermediate part.…”

“…The reaction product was intensified with cobalt chloride and nickel ammonium sulfate. In this same case, two series of each fifth section were processed to visualize FR and BDA, or LYD and BDA, respectively, using the double-labeling protocol described in detail by Gerbella et al (2010). Briefly, the sections were first processed to visualize BDA, except for a shorter incubation period in the ABC solution (overnight), and then BDA was stained brown using DAB.…”

Single neurons in monkey prefrontal cortex encode volitional initiation of vocalizations

“…Recent studies suggest a monkey homologue of Broca's area (BA 44 and 45) in the vlPFC of rhesus monkeys. Although much less developed, BA 44 and 45 in macaques share a similar anatomy in terms of cytoarchitectonics and cortico-cortical connections with human Broca's area [24][25][26][27] . In addition, functional commonalities have emerged over the past years.…”