ANATOMIC ORGANIZATION OF THE BASILAR PONTINE PROJECTIONS FROM PREFRONTAL CORTICES IN RHESUS-MONKEY

In our ongoing attempt to determine the anatomic substrates that could support a cerebellar contribution to cognitive processing, we investi gated the prefrontal cortical projections to the basilar pens. A detai led understanding of these pathways is needed, because the prefrontal cortex is critical for a number of complex cognitive operations, and t he corticopontine projection is the obligatory first step in the corti copontocerebellar circuit. Prefrontopontine connections were studied u sing the autoradiographic technique in rhesus monkey. The pontine proj ections were most prominent and occupied the greatest rostrocaudal ext ent of the pens when derived from the dorso-lateral prefrontal convexi ty, including areas 8Ad, 9/46d, and 10. Lesser pontine projections wer e observed from the medial prefrontal convexity and area 45B in the in ferior limb of the arcuate sulcus. In contrast, ventral prefrontal and orbitofrontal cortices did not demonstrate pontine projections. The p refrontopontine terminations were located preferentially in the parame dian nucleus and in the medial parts of the peripeduncular nucleus, bu t each cortical area appeared to have a unique complement of pontine n uclei with which it is connected. The existence of these corticopontin e pathways from prefrontal areas concerned with multiple domains of hi gher-order processing is consistent with the hypothesis that the cereb ellum is an essential node in the distributed corticosubcortical neura l circuits subserving cognitive operations.