The patterns of afferent innervation of the core and shell in the “Accumbens” part of the rat ventral striatum: Immunohistochemical detection of retrogradely transported fluoro‐gold

Recent data have emphasized the neurochemically distinct nature of subterritories in the accumbens part of the rat ventral striatum termed the core, shell, and rostral pole. In order to gain a more comprehensive understanding of how afferents are distributed relative to these subterritories, immunohistochemical detection of retrogradely transported Fluoro‐Gold was carried out following iontophoretic injections intended to involve selectively one of the subterritories. The data revealed that a number of cortical afferents of the medial shell and core originate in separate areas, i.e., the dorsal peduncular, infralimbic, and posterior piriform cortices (to medial shell) and the dorsal prelimbic, anterior agranular insular, anterior cingulate, and perirhinal cortices (to core). The lateral shell and rostral pole are innervated by cortical structures that also project either to the medial shell or core. The orbital, posterior agranular insular, and entorhinal cortices, hippocampus, and basal amygdala were observed to innervate the accumbens in a topographic manner. Following core injections, strong bilateral cortical labeling was observed. Few labeled cortical cells were observed contralaterally following injections in the medial shell. Intermediate numbers of labeled neurons were observed in contralateral cortices following lateral shell injections.