The nucleus accumbens beyond the anterior commissure: implications for psychosurgery

The nucleus accumbens (Acc) is a basal forebrain structure integrated in the dopaminergic cerebral rewarding circuits and implicated in some neuropsychiatric disorders. It has become a target for deep brain stimulation for some of these disorders when refractory to medical treatment. However, it is controversial as to which target is the best and similar results have been achieved with the stimulation of neighboring structures such as the bed nucleus of the stria terminalis (BNST). Previous studies have established the stereotactic anatomy of the human Acc, but some difficulties remain concerning its precise posterior limit, which is assumed to be at the level of the anterior commissure (AC). It is our purpose to clarify the anatomy of this zone, given the importance of its exact identification in psychosurgery.

A total of 16 Acc were collected by autopsy, fixed, dissected, embedded and cut in coronal 5-µm slices. The slices were stained with hematoxylin and eosin, marked with anti-D1 and anti-D2 antibodies and analyzed under a microscope.

The human Acc has the same cellular structure as the dorsal striatum, except in its posterior subcommissural part where voluminous neurons prevail, similar to and contiguous with the BNST.

The Acc is longer than previously described, with a sub- and postcommissural extension behind the AC, continuous with the BNST.