Ventral pallidum

The Ventral Pallidum is a structure within the basal ganglia of the brain. It is an output nucleus whose fibres project to thalamic nuclei, such as the ventral anterior nucleus, the ventrolateral nucleus, and the medial dorsal nucleus. The Ventral Pallidum is a component of the limbic loop of the basal ganglia, a pathway involved in the regulation of motivation, behaviour, and emotions. It is involved in drug addiction.

Anatomy
The Ventral Pallidum lies within the basal ganglia, a group of subcortical nuclei. Along with the external segment of the Globus pallidus, it is separtated from other basal ganglia nuclei by the anterior commisure. Like the rest of the basal ganglia, its vascular supply is provided by the middle cerebral artery.

The Limbic loop
The Limbic loop is a functional pathway of the basal ganglia, in which the ventral pallidum is involved. It (and the Globus Pallidus internus and substantia nigra pars reticulata) receives input from the temporal lobes, and the hippocampus via the ventral striatum. The information is relayed to the medial dorsal and ventral anterior nuclei of the thalamus.

Role in Addiction
The Ventral Pallidum receives dopaminergic inputs from the ventral tegmental area, and GABAergic inputs from the nucleus accumbens . It is the relay nucleus from the nucleus accumbens to the medial dorsal nucleus. The nucleus accumbens projects to the medial dorsal nucleus via GABAergic medium spiny neurons. It is thus a component of the mesolimbic dopamine system, a pathway thought to be the major neural correlate of addiction. Addictive drugs facilitate dopamine release in this system

Additional Sources

 * Martin J.H. Neuroanatomy Text and Atlas. 3rd Edition 2003: Chapter 14