Ventral pallidum
Encyclopedia
The Ventral Pallidum is a structure within the basal ganglia
Basal ganglia
The basal ganglia are a group of nuclei of varied origin in the brains of vertebrates that act as a cohesive functional unit. They are situated at the base of the forebrain and are strongly connected with the cerebral cortex, thalamus and other brain areas...

 of the brain
Brain
The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...

. It is an output nucleus whose fibres project to thalamic nuclei, such as the ventral anterior nucleus
Ventral anterior nucleus
-Inputs and outputs:The ventral anterior nucleus receives neuronal inputs from the basal ganglia which includes the substantia nigra and the globus pallidus. It also has inputs from the cerebellum. It sends out neuronal input to the supplementary motor cortex and to primary motor...

, the ventrolateral nucleus
Thalamus
The thalamus is a midline paired symmetrical structure within the brains of vertebrates, including humans. It is situated between the cerebral cortex and midbrain, both in terms of location and neurological connections...

, and the medial dorsal nucleus
Medial dorsal nucleus
The medial dorsal nucleus is a large nucleus in the thalamus.It is believed to play a role in memory.-Anatomy:...

.
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
Basal ganglia
The basal ganglia are a group of nuclei of varied origin in the brains of vertebrates that act as a cohesive functional unit. They are situated at the base of the forebrain and are strongly connected with the cerebral cortex, thalamus and other brain areas...

, a group of subcortical nuclei. Along with the external segment of the Globus pallidus
Globus pallidus
The globus pallidus also known as paleostriatum, is a sub-cortical structure of the brain. Topographically, it is part of the telencephalon, but retains close functional ties with the subthalamus - both of which are part of the extrapyramidal motor system...

, 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
Middle cerebral artery
-External links:*...

.

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
Globus pallidus
The globus pallidus also known as paleostriatum, is a sub-cortical structure of the brain. Topographically, it is part of the telencephalon, but retains close functional ties with the subthalamus - both of which are part of the extrapyramidal motor system...

 and substantia nigra pars reticulata
Substantia nigra
The substantia nigra is a brain structure located in the mesencephalon that plays an important role in reward, addiction, and movement. Substantia nigra is Latin for "black substance", as parts of the substantia nigra appear darker than neighboring areas due to high levels of melanin in...

) receives input from the temporal lobes, and the hippocampus
Hippocampus
The hippocampus is a major component of the brains of humans and other vertebrates. It belongs to the limbic system and plays important roles in the consolidation of information from short-term memory to long-term memory and spatial navigation. Humans and other mammals have two hippocampi, one in...

 via the ventral striatum
Ventral striatum
The ventral striatum is generally considered that part of the striatum that is connectionally associated with limbic structures, such as the amygdala, hippocampus, midline thalamus, and certain regions of the prefrontal cortex...

. The information is relayed to the medial dorsal
Medial dorsal nucleus
The medial dorsal nucleus is a large nucleus in the thalamus.It is believed to play a role in memory.-Anatomy:...

 and ventral anterior
Ventral anterior nucleus
-Inputs and outputs:The ventral anterior nucleus receives neuronal inputs from the basal ganglia which includes the substantia nigra and the globus pallidus. It also has inputs from the cerebellum. It sends out neuronal input to the supplementary motor cortex and to primary motor...

 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
Nucleus accumbens
The nucleus accumbens , also known as the accumbens nucleus or as the nucleus accumbens septi , is a collection of neurons and forms the main part of the ventral striatum...

 to the medial dorsal nucleus
Medial dorsal nucleus
The medial dorsal nucleus is a large nucleus in the thalamus.It is believed to play a role in memory.-Anatomy:...

. The nucleus accumbens projects to the medial dorsal nucleus via GABAergic medium spiny neurons. It is thus a component of the mesolimbic dopamine system
Mesolimbic pathway
The mesolimbic pathway is one of the dopaminergic pathways in the brain. The pathway begins in the ventral tegmental area of the midbrain and connects to the limbic system via the nucleus accumbens, the amygdala, and the hippocampus as well as to the medial prefrontal cortex...

, a pathway thought to be the major neural correlate of addiction. Addictive drugs facilitate dopamine
Dopamine
Dopamine is a catecholamine neurotransmitter present in a wide variety of animals, including both vertebrates and invertebrates. In the brain, this substituted phenethylamine functions as a neurotransmitter, activating the five known types of dopamine receptors—D1, D2, D3, D4, and D5—and their...

release in this system

Additional Sources

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