Ventral Tegmental Area: Anatomy, Functions And Disorders
The ventral tegmental area is a region of the midbrain , also known as the midbrain, which is very important due to its involvement in the reinforcement circuit, responsible for sensations of pleasure and motivated behavior. It is also involved in various other functions by sending projections to cortical and subcortical areas.
In this article we will describe the anatomical characteristics, The main functions and disorders associated with the ventral tegmental area We will focus mainly on the role that this structure plays in the brain reward system.
The concept “ventral tegmental area” refers to a set of neurons that are located at the base of the midbrain, the intermediate region of the brain stem. In Latin the word “tegmentum” means “covering” or “covering”; Therefore, the name highlights the fact that this area constitutes a layer of neurons that covers the midbrain.
Four principal cell nuclei have been identified in the ventral tegmental area: the paranigral nucleus, the parabrachial pigmentosa area, the retroflex parafascicular area, and the rostromedial tegmental nucleus. The dopaminergic neurons characteristic of this region of the brain are located mainly in the first two.
Along with the substantia nigra and the retrorubral field, also located in the midbrain, the tegmental area contains the majority of dopaminergic neurons of the brain. Dopamine is a neurotransmitter of the catecholamine class that is involved in increasing heart rate and learning through operant conditioning, among other aspects.
Dopaminergic neurons of the ventral tegmental area They are part of the mesocortical and mesolimbic systems While the mesocortical system connects this region with the frontal lobes, the mesolimbic system sends projections to the nucleus accumbens, a fundamental structure of the brain’s reward system, like the ventral tegmental area.
The mesocortical pathway plays a fundamental role in cognition ; In particular, it allows information about emotion and motivation to reach the frontal lobes. After receiving these inputs, the higher brain structures generate the responses that will be executed as a consequence.
However, the main functions of the ventral tegmental area are associated with its involvement in the brain reward system, also known as the reinforcement circuit, which begins with dopaminergic projections from neurons in this region. This pathway is closely related to the mesolimbic system.
The brain reward system
The ventral tegmental area is a key structure of the brain reward system, the biological basis of pleasure and behavioral motivation, since appetitive stimuli activate this region In this way, the reward circuit is involved in multiple behaviors, such as those related to food, sex or addictions.
When the body detects pleasurable stimulation, the ventral tegmental area sends dopaminergic projections to the nucleus accumbens. The increase in the concentration of the neurotransmitter in this area has a reinforcing effect on the behavior associated with obtaining pleasure or satisfaction.
When these inputs reach the cerebral cortex, the information obtained through the reinforcement circuit can be integrated and managed by higher cognitive functions. It is important highlight the reciprocity of the connections of the ventral tegmental area which allows continuous feedback between this structure and those to which it sends efferences.
Scientific research has identified several disorders that cause alterations in the dopaminergic pathways of which the ventral tegmental area is a part. In general, these types of disorders involve both the mesolimbic and mesocortical pathways, which are closely linked.
The neuropsychological disorders most frequently attributed to structural and/or functional problems in dopamine transmission They are Parkinson’s disease, attention deficit hyperactivity disorder and schizophrenia.
In the latter case, positive symptoms, such as hallucinations and delusions, are associated with alterations in the mesolimbic pathway. Failures in the mesocortical system produce negative symptoms, consisting of cognitive, emotional and motivational deficits.
On the other hand, the ventral tegmental area and the nucleus accumbens are the two regions of the nervous system in which the drugs and other potentially addictive substances have a more significant effect.
Alcohol, nicotine, cocaine, amphetamine and heroin, among others, have agonist effects on dopamine; This explains the physiological, motor and psychological consequences of the use of these substances, both in the short and long term, including addiction.
