The Ventral tegmental Area (VTA) is a collection of neurons situated at the center of the midbrain. The area functions as a sort of receptor core, receiving messages from other parts of the brain as to how efficiently basic human needs are being met. It is the region where many pleasurable feelings are born, and plays an important role in cognition, impulses, drug addiction, and mental illness.
The ventral tegmental area rests on the floor of the midbrain, close to the center. It is the origin of two of the brain's major dopamine pathways: the mesocortical pathway and the mesolimbic pathway. Three other, less significant dopamine channels also have their sources in the this area: the mesodiencephalic, the mesostriatal, and the mesorhombencephalic pathways.
When this part of the brain gets messages indicating how and if various needs are being satisfied, dopamine neurons respond appropriately. They become the messaging system by which it transmits communication to the nucleus accumbens, another area of the brain that sits in front of the ventral tegmentum. Once in the nucleus accumbens, dopamine levels increase, enhancing pleasurable feelings and thereby "rewarding" the behaviors through which the basic needs are met.
In the science of addiction, the activities in the ventral tegmental area are of great importance. This is the area of the brain that is directly stimulated by the presence of stimulant drugs. Cocaine, for example, affects this area with intensity, initiating the production of dopamine and creating the drug's satisfying sensations. The brain cannot immediately distinguish between good rewards and bad rewards as it only registers the pleasure of the feelings. This pleasure inspires the brain to want more of the drug and continue the ecstatic high associated with waves of dopamine production.
Mental illness can also be born in the ventral tegmental area. Normal functioning with the mesocortical and mesolimbic pathways may become interrupted, instigating any number of psychological problems. The most common are schizophrenia, attention deficit hyperactivity disorder (ADHD), and Parkinson's disease.
The VTA also processes messages from the emotional center of the brain, the amygdala. The VTA is charged with ensuring the body stays safe and satisfied, so messages involving fear are taken quite seriously. The VTA develops techniques to condition the body against fearful situations, motivates feelings of security, and creates avoidance strategies that ensure survival.