Some connections of the entorhinal (area 28) and perirhinal (area 35) cortices of the rhesus monkey. I. Temporal lobe afferents.

In this investigation the efferent projections from ventral temporal neocortical and limbic cortical areas to the entorhinal and perirhinal cortices have been investigated in the rhesus monkey using silver impregnation methods. It was observed that virtually all ventral temporal neocortical areas contribute some afferents to the transitional zones of periallocortex (perirhinal and prorhinal cortices) forming the walls of the rhinal sulcus. These areas in turn project medially to the entorhinal cortex and hippocampus. Additional direct sources of afferent input to the entorhinal cortex were found to originate in Brodmann's areas 51, 49 and 27, and Bonin and Bailey's areas TF and TH. These connections have been characterized as final relays in multisynaptic cortico-cortical pathways linking the entorhinal cortex and, ultimately, hippocampus to the association areas of the frontal, parietal, temporal, and occipital lobes.