The organization of the striatal projection fibers from the hippocampal formation (HF) was studied in the monkey with particular emphasis on specific projections of the ventral striatum. Retrograde tracers were injected into the five different regions of the ventral striatum such as the ventromedial caudate nucleus, ventral shell, central shell, and dorsal core of the nucleus accumbens (NA), and ventrolateral putamen. The ventromedial caudate nucleus and the shell of the NA received dense projections from the HF. Although the ventromedial caudate nucleus and the shell of the NA are both innervated by the HF, the shell receives the larger of these projections. This suggests that the HF is more strongly connected with the shell of the NA than with the ventromedial caudate nucleus. There are no differences between the ventral shell and central shell of the NA. Labeled neurons were mainly observed in the rostral parts of the dorsomedial CA1 and adjacent subicular complex (prosubiculum, subiculum, presubiculum, and parasubiculum) of the HF. These results suggest that the shell of the NA is the main converging site receiving hippocampal projections primarily related to integrating visuospatial and limbic information.
Basal Ganglia* ; Caudate Nucleus ; Haplorhini ; Hippocampus ; Neurons ; Nucleus Accumbens ; Primates* ; Putamen