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Information about Nucleus Accumbens

Brain: Nucleus accumbens
Nucleus accumbens not labeled, but labels are provided for caudate, putamen, and septum pellucidum.
Medial surface. (Nucleus accumbens is very roughly in the area of the 34.)
Latinnucleus accumbens septi
NeuroNameshier-259
MeSH Nucleus+Accumbens
Dorlands/Elsevier n_11/12580142
The nucleus accumbens (NAcc), also known as the accumbens nucleus or as the nucleus accumbens septi (Latin for nucleus leaning against the septum), is a collection of neurons within the forebrain, located where the head of the caudate and the anterior portion of the putamen meet just lateral to the septum pellucidum.
The nucleus accumbens can be divided into two structures -- the nucleus accumbens core and the nucleus accumbens shell. These structures have different morphology and function.
The nucleus accumbens and the olfactory tubercle collectively form the ventral striatum, which is part of the basal ganglia [1].

This nucleus is thought to play an important role in reward, laughter, pleasure, and addiction.

Cell types

The principal neuronal cell type found in the nucleus accumbens is the medium spiny neuron. The neurotransmitter produced by these neurons is gamma-aminobutyric acid (GABA), one of the main inhibitory neurotransmitters of the central nervous system. These neurons are also the main projection or output neurons of the nucleus accumbens.

While 95% of the neurons in the nucleus accumbens are medium spiny GABA-ergic projection neurons, other neuronal types are also found such as large aspiny cholinergic interneurons.

Output and input

The output neurons of the nucleus accumbens send axon projections to the ventral analog of the globus pallidus, known as the ventral pallidum (VP). The VP, in turn, projects to the mediodorsal (MD) nucleus of the dorsal thalamus, which projects to the prefrontal cortex. Other efferents from the nucleus accumbens include connections with the substantia nigra and pontine reticular formation. Major inputs to the nucleus accumbens include prefrontal association cortices, basolateral amygdala, and dopaminergic neurons located in the ventral tegmental area (VTA), which connect via the mesolimbic pathway. Thus the nucleus accumbens is often described as one part of a cortico-striato-thalamo-cortical loop.

Dopaminergic input from the VTA is thought to modulate the activity of neurons within the nucleus accumbens. These terminals are also the site of action of highly-addictive drugs such as cocaine and amphetamine, which cause a manifold increase in dopamine levels in the nucleus accumbens. In addition to cocaine and amphetamine, almost every drug abused by humans has been shown to increase dopamine levels in the nucleus accumbens.

Research

In the 1950s, Olds and Milner implanted electrodes into the septal area of the rat and found that the rat chose to press a lever which stimulated it. It continued to prefer this even over stopping to eat or drink. This suggests that the area is the 'pleasure center' of the brain.[2]

Although the nucleus accumbens has traditionally been studied for its role in addiction, it plays an equal role in processing many rewards such as food, sex, and video games. A recent study found that it is involved in the regulation of emotions induced by music [3] , perhaps consequent to its role in mediating dopamine release. It also has roles in timing, and has long been considered to be the limbic-motor interface (Mogensen).

References

1. ^ [1]
2. ^ Olds J, Milner P (1954). "Positive reinforcement produced by electrical stimulation of septal area and other regions of rat brain". J Comp Physiol Psychol 47 (6): 419-27. PMID 13233369.  article
3. ^ Menon, Vinod & Levitin, Daniel J. (2005) ''The rewards of music listening: Response and physiological connectivity of themesolimbic system." NeuroImage 28(1), pp. 175-184

External links

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Human brain - Limbic system
Amygdala • Cingulate gyrus • Fornicate gyrus • Hippocampus • Hypothalamus • Mammillary body • Nucleus accumbens • Olfactory System •Orbitofrontal cortex • Parahippocampal gyrus
Caudate (Latin for tail, and closely related to caudal and coda) can refer to:
  • Caudate nucleus
  • Caudate lobe of liver
  • Cauda equina
  • Members of the Caudata order.

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putamen is a structure in the middle of the brain, which, together with the caudate nucleus forms the dorsal striatum.

The putamen is a portion of the basal ganglia that forms the outermost part of the lenticular nucleus.
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The septum pellucidum (also called the septum lucidum) is a thin, triangular, vertical membrane that separates the lateral ventricles of the brain. It separates the anterior horn of the left and right lateral ventricles.
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Latin}}} 
Official status
Official language of: Vatican City
Used for official purposes, but not spoken in everyday speech
Regulated by: Opus Fundatum Latinitas
Roman Catholic Church
Language codes
ISO 639-1: la
ISO 639-2: lat
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NeuroNames is a system of nomenclature for the human and/or macaque brain.

It is maintained by the University of Washington and is a part of a tool called "BrainInfo". BrainInfo helps one identify structures in the brain.
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Medical Subject Headings (MeSH) is a huge controlled vocabulary (or metadata system) for the purpose of indexing journal articles and books in the life sciences. Created and updated by the United States National Library of Medicine (NLM), it is used by the MEDLINE/PubMed
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Elsevier, the world's largest publisher of medical and scientific literature, forms part of the Reed Elsevier group. Based in Amsterdam, the company has substantial operations in the UK, USA and elsewhere.
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In neuroanatomy, a nucleus is a central nervous system structure that is composed mainly of gray matter, and that acts as a hub or transit point for electrical signals in a single neural subsystem.
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septum (Latin: something that encloses; plural Septa) is a partition separating two cavities or spaces. Examples include:
  • Nasal septum: the cartilage wall separating the nostrils of the human nose.

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Neurons (also known as neurones and nerve cells) are electrically excitable cells in the nervous system that process and transmit information. In vertebrate animals, neurons are the core components of the brain, spinal cord and peripheral nerves.
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Caudate (Latin for tail, and closely related to caudal and coda) can refer to:
  • Caudate nucleus
  • Caudate lobe of liver
  • Cauda equina
  • Members of the Caudata order.

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putamen is a structure in the middle of the brain, which, together with the caudate nucleus forms the dorsal striatum.

The putamen is a portion of the basal ganglia that forms the outermost part of the lenticular nucleus.
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The septum pellucidum (also called the septum lucidum) is a thin, triangular, vertical membrane that separates the lateral ventricles of the brain. It separates the anterior horn of the left and right lateral ventricles.
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Olfaction (also known as olfactics) refers to the sense of smell. This sense is mediated by specialized sensory cells of the nasal cavity of vertbrates, and, by analogy, sensory cells of the antennae of invertebrates.
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striatum is a subcortical part of the telencephalon. It is the major input station of the basal ganglia system. Anatomically, the striatum is the caudate and the putamen.

History


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The basal ganglia (or basal nuclei) are a group of nuclei in the brain interconnected with the cerebral cortex, thalamus and brainstem. Mammalian basal ganglia are associated with a variety of functions: motor control, cognition, emotions and learning.
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42 (1), 43-55. doi: 10.1111/1468-5906.t01-1-00160
18. ^ Moreira-Almeida Alexander, Lotufo Neto Francisco, Koenig Harold G. "Religiousness and mental health: a review" . Rev. Bras. Psiquiatr. [serial on the Internet]. 2006 September, cited 2007 June 21, 2007 ; 28(3): 242-250.
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An addiction is a recurring compulsion by an individual to engage in some specific activity, despite harmful consequences to the individuals health, mental state or social life.
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Location Basal Ganglia
Function inhibitory projection neuron

Morphology Spiny neuron
Presynaptic connections Cortex, thalamus, & brain stem
Postsynaptic connections Other basal ganglia

The medium spiny neurons
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Neurotransmitters are chemicals that are used to relay, amplify and modulate signals between a neuron and another cell. According to the prevailing beliefs of the 1960s, a chemical can be classified as a neurotransmitter if it meets the following conditions:

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Gamma-aminobutyric acid (usually abbreviated to GABA) is an inhibitory neurotransmitter found in the nervous systems of widely divergent species. It is the chief inhibitory neurotransmitter in the central nervous system and also in the retina.
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A synapse is cholinergic if it uses acetylcholine as its neurotransmitter.

Cholinergic means "related to the neurotransmitter acetylcholine", and is typically used in a neurological perspective. The parasympathetic nervous system is entirely cholinergic.
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An interneuron (also called relay neuron, association neuron or bipolar neuron) is a term used to describe a neuron which has two different common meanings.
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The globus pallidus (Latin for "pale globe") is a sub-cortical structure of the brain. It is a major element of the basal ganglia system. In this system, it is a major element of the basal ganglia core, consisting of the striatum and its direct targets: globus pallidus and
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The globus pallidus (Latin for "pale globe") is a sub-cortical structure of the brain. It is a major element of the basal ganglia system. In this system, it is a major element of the basal ganglia core, consisting of the striatum and its direct targets: globus pallidus and
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For the computer game developer, see Thalamus Ltd.


The thalamus (from Greek θάλαμος = bedroom, chamber, IPA= /ˈθæləməs/) is a pair and symmetric part of the brain.
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prefrontal cortex is the anterior part of the frontal lobes of the brain, lying in front of the motor and premotor areas. Cytoarchitectonically, it is defined by the presence of an internal granular layer IV (in contrast to the agranular premotor cortex).
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The substantia nigra (Latin for "black substance", Soemering) or locus niger is a heterogeneous portion of the midbrain, separating the pes (foot) from the tegmentum (covering), and a major element of the basal ganglia system.
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amygdalae (Latin, also corpus amygdaloideum, singular amygdala, from Greek
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The ventral tegmentum or the ventral tegmental area (VTA) (tegmentum, Latin for covering) is part of the midbrain, lying close to the substantia nigra and the red nucleus.
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