mesolimbic

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mesolimbic system

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2013/09/30 23:25:50」(JST)

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Mesolimbic dopaminergic and serotonergic pathways.

The mesolimbic pathway is a dopaminergic pathway 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. The mesolimbic dopamine system is widely believed to be a "reward" pathway, but that hypothesis is not universally accepted.

Anatomy

The following structures are considered to be a part of the mesolimbic pathway:

Ventral Tegmental Area

The ventral tegmental area (VTA) is a part of the midbrain. It consists of dopaminergic, GABAergic, and glutamatergic neurons. The VTA communicates with the nucleus accumbens via the medial forebrain bundle.

Nucleus Accumbens

The nucleus accumbens is found in the ventral striatum and is composed of medium spiny neurons. It is subdivided into limbic and motor subregions known as the shell and core. The medium spiny neurons receive input from both the dopaminergic neurons of the VTA and the glutamatergic neurons of the hippocampus, amygdala, and medial prefrontal cortex. When they are activated by these inputs, the medium spiny neurons' projections release GABA onto the ventral pallidum. The release of dopamine in this structure drives the mesolimbic system.

Amygdala

The amygdala is a large nuclear mass in the temporal lobe anterior to the hippocampus. It has been associated with the assignment of emotions, especially fear and anxiety. There are two, one in each temporal lobe, and their functions may be lateralized.

Hippocampus

The hippocampus is located in the medial portion of the temporal lobe. It is known for its association with double memory (i.e., both procedural and declarative memory).

Bed Nucleus of the Stria Terminalis

Controversy over mesolimbic dopamine function

There is some controversy regarding dopamine’s role in the reward system. Three hypotheses—hedonia, learning, and incentive salience—have been proposed as explanations for dopamine’s function in the reward system. The hedonia hypothesis suggests that dopamine in the nucleus accumbens acts as a 'pleasure neurotransmitter'. In the late 1970s, it was found that some drugs of abuse involved dopamine activity, in particular in the nucleus accumbens, to cause the "high" or euphoric state. However, not all rewards or pleasurable things involve activation of the reward system, which may suggest that the mesolimbic pathway may not be just a system that works merely off enjoyable things (hedonia). Learning, on the other hand, deals with predictions of future rewards and association formation. Studies have shown that rats that had their ventral tegmental area and nucleus accumbens destroyed do not lose their learning capabilities, but rather lack the motivation to work for a reward. Incentive salience (wanting) stands out as a possible role for dopamine, as it regards this molecule as being released when there is a stimulus worth working hard for, thus making an individual work to get it. This is one of the reasons that dopamine transport has been extensively studied in ADD and ADHD. It is now widely understood that most people suffering from some form of attention deficit disorder most likely lack dopamine stimulation. This also explains why dopamine reuptake inhibitors and stimulants often dramatically improve symptoms of attention disorders. In self-administration studies, animals have been trained to give an operant response (lever press, nose poke, wheel turn, etc.) in order to obtain either a drug or a mate. It has been shown that the animals will continue to perform the required task until the reward is received, or fatigue sets in.

Clinical significance

Since the mesolimbic pathway is shown to be associated with feelings of reward and desire, this pathway is heavily implicated in neurobiological theories of addiction, schizophrenia, and depression. Drug addiction, the loss of control over drug use or the compulsive seeking and taking of drugs despite adverse consequences, with the four major classes of abused drugs (psychostimulants, opiates, ethanol, and nicotine) are due to increased dopamine transmission in the limbic system-each by different mechanisms. Like drug addiction, schizophrenia and depression have similar structural changes with dopamine transmission.

Other dopamine pathways

The other dopamine pathways are:

• mesocortical pathway
• nigrostriatal pathway
• tuberoinfundibular pathway

References

See also

• antipsychotic
• tardive dysphrenia

External links

UpToDate Contents

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English Journal

• A self-medication hypothesis for increased vulnerability to drug abuse in prenatally restraint stressed rats.

• Reynaert ML1, Marrocco J, Gatta E, Mairesse J, Van Camp G, Fagioli F, Maccari S, Nicoletti F, Morley-Fletcher S.
• Advances in neurobiology.Adv Neurobiol.2015;10:101-20. doi: 10.1007/978-1-4939-1372-5_6.
• Stress-related events that occur in the perinatal period can permanently change brain and behavior of the developing individual and there is increasing evidence that early-life adversity is a contributing factor in the etiology of drug abuse and mood disorders. Neural adaptations resulting from earl
• PMID 25287538

• Neonatal onset of leptin signalling in dopamine neurones of the ventral tegmental area in the rat.

• Naef L1, Gjerde E, Long H, Richard D, Walker CD.
• Journal of neuroendocrinology.J Neuroendocrinol.2014 Dec;26(12):835-43. doi: 10.1111/jne.12221.
• Leptin inhibits feeding by acting on hypothalamic and mesolimbic dopamine (DA) pathways involved in the homeostatic and hedonic control of energy balance. In the rodent, the neonatal period is characterised by high circulating leptin concentrations and an insensitivity to the anorectic effects of th
• PMID 25205242

• NMDA Receptor Blockade in the Prelimbic Cortex Activates the Mesolimbic System and Dopamine-Dependent Opiate Reward Signaling.

• Tan H1, Rosen LG, Ng GA, Rushlow WJ, Laviolette SR; Addiction Research Group.
• Psychopharmacology.Psychopharmacology (Berl).2014 Dec;231(24):4669-79. doi: 10.1007/s00213-014-3616-0. Epub 2014 May 29.
• RATIONALE: N-Methyl-D-aspartate (NMDA) receptors in the medial prefrontal cortex (mPFC) are involved in opiate reward processing and modulate sub-cortical dopamine (DA) activity. NMDA receptor blockade in the prelimbic (PLC) division of the mPFC strongly potentiates the rewarding behavioural propert
• PMID 24871699

Japanese Journal

• 脊髄損傷後の機能回復を支える大脳辺縁系と大脳皮質運動野の機能的神経結合

• 西村 幸男,伊佐 正
• 日本神経回路学会誌 20(3), 135-142, 2013
• … In addition, functional connectivity of the M1 with other structures belonging to the mesolimbic system was also strengthened. …
• NAID 130003385105

• 脳内モノアミン神経の構造と機能 : 特に、中脳辺縁ドーパミン神経系と情動について

• 吉田 眞美
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• HAPPINESS ASSOCIATED WITH NOH-MASKS MODULATES THE MESOLIMBIC REWARD SYSTEM: AN FMRI STUDY BASED ON NEUROAESTHETICS

• OSAKA Naoyuki,MINAMOTO Takehiro
• ＰＳＹＣＨＯＬＯＧＩＡ 54(4), 234-240, 2011
• We report a brain imaging study with fMRI in which participants were scanned while watching Noh masks with face expressions rated as happy. Among seventy standard masks previously rated by the partici …
• NAID 130001896343

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リンク元	「中脳辺縁系」
拡張検索	「mesolimbic fiber」

「中脳辺縁系」

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mesolimbic system, mesolimbic, mesocortical limbic system

「mesolimbic fiber」

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