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 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.
- 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.
- 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
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:
- Pierce RC, Kumaresan V. 2006. The mesolimbic dopamine system: The final common pathway for the reinforcing effect of drugs of abuse? Neuroscience and Biobehavioral Reviews 30:215-38
- Zhang TA, Maldve RE, Morrisett RA. 2006. Coincident signaling in mesolimbic structures underlying alcohol reinforcement. Biochemical Pharmacology 72:919-27
- Purves D et al. 2008. Neuroscience. Sinauer 4ed. 754-56
- Van den Heuval DMA, Pasterkamp RJ. 2008. Getting connected in the dopamine system. Progress in Neurobiology 85:75-93
- Laviolette SR. 2007. Dopamine modulation of emotional processing in cortical and subcortical neural circuits: evidence for a final common pathway in schizophrenia? Schizoprenia Bulletin 33:971-981
- Diaz J. 1996. How Drugs Influence Behavior: A Neurobehavorial Approach. Prentice Hall
- Janhunen S, Ahtee L. 2007. Differential nicotinic regulation of the nigrostriatal and mesolimbic dopaminergic pathways: Implications for drug development. Neuroscience and Biobehavioral Reviews 31:287-314