Frontal cortical regions projecting to the dorsal aspect of area 46 (area 46d) and the dorsal premotor cortex (PMd) in macaques

Abstract

Physiological studies revealed that the PMd and area 46d are commonly involved in planning action. Anatomical studies revealed that these two areas are interconnected with cortico-cortical connections. In this study, we examined whether the PMd and area 46d would also receive shared inputs from other frontal cortical areas, and, if this is the case, how neurons projecting to these areas would be distributed. To achieve these goals, we injected two fluorescent tracers into the PMd and area 46d of macaque monkeys. Analyzing location of neurons labeled with each tracer revealed frontal cortical areas containing both neurons projecting to the PMd and to area 46d. These regions were located in the cingulate cortex (area 24, 23), the medial frontal cortex, and the fundus of the superior limb of the arcuate sulcus. We also found that neurons projecting to the PMd or area 46d were distributed less than 500 micrometers in a majority of cases. These results revealed that the PMd and area 46d receive shared inputs from these frontal cortical areas and that neurons projecting to the PMd and area 46d exist in close proximity, suggesting that the local circuits play an important role for the PMd and area 46d to execute information processing in an integrated manner. [J Physiol Sci. 2008;58 Suppl:S192]