Microsurgical and Fiber Tract Anatomy of the Nucleus Accumbens

The nucleus accumbens (NAc) has been a target for deep brain stimulation (DBS) in the treatment of depression and obsessive-compulsive disorder (OCD).

To examine the anatomy and connections of the NAc using a fiber dissection technique.

Ten human brains and 2 whole cadaveric heads were examined by fiber dissection technique and ×6 to ×40 surgical magnification. The NAc was examined from the lateral, medial, superior, and inferior sides to define its fiber connections and relationships with adjacent cortical and subcortical structures. Magnetic resonance imaging (MRI) with 1-mm slices was used to define its neuronavigation coordinates.

Eight tracts, the uncinate fasciculus, cingulum, stria medullaris thalami, fornix, diagonal band of Broca, stria terminalis, medial olfactory stria, and forceps minor, form a capsule around the anterior, inferior, and medial sides of the NAc. The uncinate fasciculus connects along the inferior and adjacent part of the medial side of the NAc, the cingulum and diagonal band along the medial surface, the medial olfactory stria along the posteromedial and adjacent part of the inferior surface, the forceps minor along the anteromedial surface, and the stria terminalis, fornix, and stria medullaris along the posterosuperior surface. The subcortical gray matter related to the NAc includes the septal nuclei, indusium griseum, substantia innominata, caudate nucleus, and hypothalamus. The cortical areas communicating with and overlying the NAc are reviewed.

An increased understanding of the fiber connections and neural relationships of the NAc should allow more accurate DBS targeting for the treatment of psychiatric disorders.