Multimodal architectonic subdivision of the caudal ventrolateral prefrontal cortex of the macaque monkey

Abstract

The caudal part of the macaque ventrolateral prefrontal cortex (VLPF) is part of several functionally distinct domains. In the present study we combined a cyto- and a myeloarchitectonic approach with a chemoarchitectonic approach based on the distribution of SMI-32 and Calbindin immunoreactivity, to determine the number and extent of architectonically distinct areas occupying this region. Several architectonically distinct areas, completely or partially located in the caudal VLPF, were identified. Two areas are almost completely limited to the anterior bank of the inferior arcuate sulcus, a dorsal one-8/FEF-which extends also more dorsally and should represent the architectonic counterpart of the frontal eye field, and a ventral one-45B-which occupies the ventral half of the bank. Two other areas occupy the ventral prearcuate convexity cortex, a caudal one-area 8r-located just rostral to area 8/FEF and a rostral one-area 45A-which extends as far as the inferior frontal sulcus. Area 45A borders dorsally, in the proximity of the principal sulcus, with area 46 and, ventrally, with area 12. The present data show the existence of two distinct prearcuate convexity areas (8r and 45A), extending other architectonic subdivisions of the caudal VLPF and providing a new, multiarchitectonic frame of reference for this region. The present architectonic data, together with other functional and connectional data, suggest that areas 8/FEF, 45B and 8r are part of the oculomotor frontal cortex, while area 45A is a distinct entity of the VLPF domain involved in high-order processing of nonspatial information.

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

“…Ventrally, area 12r extends as far as the lateralmost part of the orbital surface, bordering, from rostral to caudal, areas 11l, 12m, and 12l, characterized by a relatively dense layer IV and a sublaminated layer V. Rostrally, in the proximity of the frontal pole, area 12r borders area 10, characterized by a dense layer IV and by vertical and horizontal cross striations of cells in layer III and V. Caudally, it borders area 45A, characterized by an evident increase in cell size from the upper to the lower part of layer III, a well-developed layer IV and a relatively dense layer V populated by small pyramids. As described by Petrides and Pandya (2002) and Gerbella et al (2007), this border corresponds with the infraprincipal dimple, when present.…”

“…The criteria and maps adopted for the areal attribution of the labeling were mostly similar to those adopted in previous studies (Rozzi et al, 2006;Borra et al, 2008;Gerbella et al, 2010Gerbella et al, , 2011. The prefrontal cortex was subdivided according to Carmichael and Price (1994), except for the caudal VLPF, which was subdivided according to Gerbella et al (2007). The labeling was attributed to the agranular frontal, cingulate, and opercular frontal areas according to architectonic criteria described previously (Matelli et al, 1985(Matelli et al, , 1991Belmalih et al, 2009).…”

“…The skull was trephined to remove the bone overlying the target region, and the dura was opened to expose the VLPF. The choice of the injection sites was based on identified anatomical landmarks, i.e., the inferior arcuate sulcus, the infraprincipal dimple, and the principal sulcus (PS), and using an average architectonic map of the caudal VLPF providing an estimate of the average location of areas 45A and 46v, with respect to these landmarks (Gerbella et al, 2007). These data were then used to estimate the location of the dorsal and the caudal borders of area 12r with areas 46v and 45A, respectively ( Fig.…”

Application of floating silicon-based linear multielectrode arrays for acute recording of single neuron activity in awake behaving monkeys

“…This is in line with anatomical data indicating that areas F5c/p contain a higher number of big pyramidal cells than prefrontal areas 46v and 12 (see figures 14 and 17 in ref. [10] and figure 22 in ref. [2]).…”

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

“…The criteria adopted for the areal attribution of the labeling observed in other cortical regions were mostly similar to those adopted in previous studies (Borra et al 2008;Gerbella et al 2010;Rozzi et al 2006). The ventrolateral prefrontal cortex was subdivided according to the cytoarchitectonic criteria described by Carmichael and Price (1994) and Gerbella et al (2007). In the inferior parietal lobule (IPL), the gyral convexity areas were defined according to Gregoriou et al (2006), whereas those of the lateral bank of the intraparietal sulcus (IPS) according to functional and connectional criteria described by Borra et al (2008).…”