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the region of fusion between the head of the caudate nucleus and the putamen, covered on its inferior aspect by the olfactory tubercle. Its former name nucleus accumbens septi ("a nucleus leaning against the septum") refers to a medial, hook-shaped expansion of this anteroventral region of the striatum, which curves under the floor of the frontal horn of the lateral ventricle and ascends for some distance into the ventral half of the septal region. Composed of a pars lateralis [TA] (lateral part [TA] or core region [TAalt]) and a pars medialis [TA] (medial part [TA] or shell region [TAalt]).
A limbic nucleus that sits at the ventral head of the striatum, contiguous with the caudate and putamen and adjacent to the olfactory tubercle. The nucleus accumbens is part of the ventral striatum nuclei. Synapses in the nucleus accumbens use dopamine as their neurotransmitter. Increasing the activity of these synapses (i.e., increasing the level of dopamine in the nucleus) leads to a rewarding or pleasurable sensation. This is thought to partly explain the addictive effect of those drugs, such as cocaine and amphetamine, that increase the level of dopamine in the nucleus accumbens.
See also: nucleus