Nucleus accumbens

Last revised by Rohit Sharma on 22 Oct 2022

The nucleus accumbens (plural: nuclei accumbentes) (colloquially known as the pleasure center) is a small region in the forebrain involved in the reward pathway and is therefore involved in impulse control disorders. It is considered part of the corpus striatum ventrale (ventral striatum).

The nucleus accumbens is part of the basal ganglia. It is not a separate structure and hence cannot be identified distinctly on cerebral specimens.

There appears to be ambiguity in terms of its relationship with the ventral striatum as some sources identify that the nucleus accumbens was formerly known as the ventral striatum, while others identify it as a part of the ventral striatum 1,2

The nucleus accumbens receives dopaminergic innervation from the ventral tegmental area (VTA) in the brainstem, glutaminergic from the prefrontal cortex (PFC) and orexinergic innervation from the lateral hypothalamus (LH) 2.

The predominant role of the nucleus accumbens is to influence planning and aversion based on pleasurable stimuli. This information is conveyed to the prefrontal cortex (PFC), lateral hypothalamus (LH) and the brainstem 1,2.

Dopaminergic innervation from the ventral tegmental area (VTA) and glutaminergic innervation from the PFC are responsible for the reward pathway for food, sex and music. The nucleus accumbens (NAc) also receives orexinergic projections from the LH which are thought to model the psychosomatic response to psychostimulant drugs 3.

The nucleus accumbens receives blood supply from the recurrent artery of Heubner, which is a branch of the medial lenticulostriate arteries 4.

The nucleus accumbens is too small to be visualized on MRI. Other features that make it difficult to visualize the nucleus accumbens are its proximity to the cerebral sinuses and pulsating arterioles.

On fMRI, the nucleus accumbens is activated when patients actively crave pleasurable stimulus and it is inactivated when the stimulus has been received 5.

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