Topographical projections from the prefrontal cortex to the post-arcuate area in the rhesus monkey, studied by retrograde axonal transport of horseradish peroxidase.

The cells of origin of ipsilateral, prefrontal cortical projections to the post-arcuate area were studied in rhesus monkeys with the horseradish peroxidase (HRP) method. Following injections of HRP into the dorsal portion of the post-arcuate area, retrogradely labeled cells appeared in the arcuate area dorsal to the principal sulcus, while, following injections into its ventral portion, labeled cells appeared in the arcuate area ventral to the principal sulcus. They were pyramidal cells and lay mainly in the III layer, but small numbers of them were also found in the IV and V layers. In addition, HRP labeled cells were seen ipsilaterally in the banks of the cingulate sulcus.