Reward and aversion systems of the brain as a functional unit. Basic mechanisms and functions

Abstract

Introduction. It is increasingly important to recognize the reward and aversion systems of the brain as a functional unit. A fundamental task of the mammalian brain is to assign an emotional/motivational valence to any stimuli by determining whether they are rewarding and should be approached or are aversive and should be avoided. Internal stimuli are also assigned an emotional/motivational valence in a similar fashion.

Objective. To understand the basic mechanisms and functions of the reward and aversion system of the brain.

Method. A bibliographical search was conducted in the Pubmed database using different key words. Documents on relevant aspects of the topic were selected.

Results. In the ventral tegmental area, dopaminergic (VTA-DA) neurons play a role in reward-dependent behaviors. It is also known that the inhibition of the VTA-DA neurons by GABAergic neurons contributes to a reward prediction error calculation that promotes behaviors associated with aversion. The ventral dopaminergic mesolimbic system and the nucleus accumbens are activated during reward and inhibited during aversions. The amygdala is activated during aversive behavior.

Discussion and conclusion. The reward/aversion system is highly relevant for survival, which is most likely its primary function. It is involved in important pathologies such as addiction, depression and autonomic and endocrine disturbances. Therefore, its knowledge has become of clinical importance.

Although great advances have been made in the knowledge of the basic mechanisms of the reward/aversion system, the detailed circuits within the VTA that mediate reward and aversion and the anatomical substrates are not completely clear.