ABSTRACT
This chapter summarizes available data on the afferent and efferent connections of the frontal lobe. It presents a novel approach that, by relying on an additional analysis of cortical cytoarchitecture, seeks to explain cortical function in light of the evolution of the cerebral cortex. Traditionally, the frontal lobe has been divided into three principal regions: precentral, premotor, and prefrontal. The precentral region is the classic motor cortex that gives rise to the corticobulbar and corticospinal tracts. In terms of thalamocortical connections, the precentral region receives input primarily from the ventrolateral and ventral posterior nuclei, while premotor areas are connected with the ventrolateral nucleus and nucleus X. According to the notion of dual origin of the cortex, the premotor and precentral areas of the frontal lobe in the rhesus monkey may be conceptualized as having evolved, by successive architectonic differentiation, from archicortical and paleocortical moieties.
