Mesolimbic pathway

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The mesolimbic pathway, sometimes referred to as the reward pathway, is a dopaminergic pathway in the brain. The pathway connects the ventral tegmental area, which is located in the midbrain, to the nucleus accumbens and olfactory tubercle, which are located in the ventral striatum. The release of dopamine from the mesolimbic pathway into the nucleus accumbens regulates incentive salience (i.e., motivation and desire) for rewarding stimuli and facilitates reinforcement and reward-related motor function learning; it may also play a role in the subjective perception of pleasure. The dysregulation of the mesolimbic pathway and its output neurons in the nucleus accumbens plays a significant role in the development and maintenance of an addiction.

Video Mesolimbic pathway

Anatomy

The mesolimbic pathway is a collection of dopaminergic (i.e., dopamine-releasing) neurons that project from the ventral tegmental area (VTA) to the ventral striatum, which includes the nucleus accumbens (NAcc) and olfactory tubercle. It is one of the component pathways of the medial forebrain bundle, which is a set of neural pathways that mediate brain stimulation reward.

The VTA is located in the midbrain and consists of dopaminergic, GABAergic, and glutamatergic neurons. The nucleus accumbens and olfactory tubercle are located in the ventral striatum and are primarily composed of medium spiny neurons. The nucleus accumbens is subdivided into limbic and motor subregions known as the NAcc shell and NAcc core. The medium spiny neurons in the nucleus accumbens 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.

Maps Mesolimbic pathway

Function

The mesolimbic pathway regulates incentive salience, motivation, reinforcement learning, and fear, among other cognitive processes.

The mesolimbic pathway is involved in motivation cognition. Depletion of dopamine in this pathway, or lesions at its site of origin, decrease the extent to which an animal is willing to go to obtain a reward (e.g., the number of lever presses for nicotine or time searching for food). Dopaminergic drugs are also able to increase the extent an animal is willing to go to get a reward, and the firing rate of neurons in the mesolimbic pathway increases during anticipation of reward. Mesolimbic dopamine release was once thought to be the primary mediator of pleasure, but is now believed to have only a minor role in pleasure perception.

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Clinical significance

The mesolimbic pathway and a specific set of the pathway's output neurons (i.e., D1-type medium spiny neurons within the nucleus accumbens) play a central role in the neurobiology of addiction. It is also implicated in schizophrenia and depression. Addiction, schizophrenia, and depression all involve distinct structural changes within the mesolimbic pathway.

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Other dopamine pathways

• Mesocortical pathway
• Nigrostriatal pathway
• Tuberoinfundibular pathway

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See also

• Antipsychotic
• Tardive dysphrenia

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References

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External links

Source of the article : Wikipedia