CONNECTIONS OF NUCLEUS ACCUMBENS

Ag impregnation methods were used to discern some of the afferent fibers of the nucleus [in monkeys] and autoradiographic techniques were used to locate target areas of efferent projections. Afferents were predominately from the septum. Other sources of possible afferents were the mid cingulate gyrus and the ventral nucleus of the diagonal band. No argyrophilia was observed in the nucleus accumbens following transection of the fornix body, lesions of the anterior orbital frontal cortex or anterior cingulate gyrus. On the basis of grain counts made from autoradiographic studies, the nucleus accumbens projected predominately to the lateral hypothalmus. Counts above background were found in the cingulate gyrus, septum, ventral nucleus of the diagonal band, midline thalamic nuclei, habenula, caudate and substantia nigra. Efferent projections appeared to distribute to both limbic and extrapyramidal structures. Considering these connections and the functions reported by various workers, the nucleus accumbens may serve as a bridge between limbic and extrapyramidal motor systems effecting limbic influence in some movements.