Brain reward system: what is it and how does it work?

The functioning of the human brain may seem chaotic due to its complexity, but the truth is that everything that happens in it obeys a logic: the need for survival.

Of course, such an important issue has not been neglected by natural selection, and that is why our nervous system includes many mechanisms that allow us to stay alive: the regulation of body temperature, the integration of visual information, the control of breathing, etc. All these processes are automatic and we cannot voluntarily intervene on them.

But... What happens when what brings us closer or closer to death has to do with actions learned through experience? In those cases, which are not predicted by evolution, an element known as the brain's reward system acts.

What is the reward system?

The reward system is a set of mechanisms made by our brain and that allows us to associate certain situations with a sensation of pleasure. In this way, from these learnings we will tend to try that in the future the situations that have generated that experience reappear.

In a way, the reward system is what allows us to locate objectives in a very primary sense. Because human beings are exposed to a wide variety of situations for which biological evolution has not prepared us, these Mechanisms reward certain actions over others, making us learn as we go what is good for us and what is not it is.

Thus, the reward system is closely linked to basic needs: it will make us feel very rewarded when we find a place that contains water when we have not drunk too long, and it will make us feel good when we bond with someone friendly.

Its function is to ensure that, whatever we do, and no matter how varied our actions and behavioral options, let us always have as a reference a compass that points consistently towards certain sources of motivation, instead of anywhere.

Where does the reward circuit pass?

Although everything that happens in our brain happens very quickly and receives feedback from many other regions of the nervous system, to better understand how the reward system works Its operation is often simplified by describing it as a circuit with a clear beginning and end: the mesolimbic path, characterized among other things by its importance in it a neurotransmitter called dopamine.

The beginning of this chain of information transmission is located in an area of ​​the brain stem called the ventral tegmental area. This region is related to the basic survival mechanisms that are automated with the lower part of the brain, and from there they rise to the limbic system, a set of structures known to be responsible for generating emotions. Specifically, the nucleus accumbens, is associated with the appearance of the sensation of pleasure.

That mixture of pleasant emotions and a sensation of pleasure passes to the frontal lobe, where the information is integrated in the form of more or less abstract motivations that lead to planning sequences of voluntary actions that allow getting closer to the objective.

Thus, the reward circuit begins in one of the most basic and automated places in the brain and goes going up to the frontal lobe, which is one of the places most related to learning, flexible behavior and the decision making.

The dark side: addictions

The reward system allows us to remain connected to a sense of pragmatism that allows us to survive while we can choose between various options for action and we do not have to stick to automatic and stereotyped behaviors determined by our genes (something that happens, for example, in ants and insects in general).

However, This possibility of leaving us a margin of maneuver when it comes to choosing what we are going to do also has a risk called addiction. Actions that are initially voluntary and fully controlled, such as choosing to try heroin, may become the only option left to us if we become addicted.

In these cases, our reward system will only be activated by consuming a dose, leaving us totally incapable of feeling satisfaction for something else.

Of course, there are many types of addictions and the one that depends on the use of heroin is one of the most extreme. However, the mechanism underlying all of them is fundamentally the same: the reward center remains "hacked" and becomes a tool that guides us to a single objective, making us lose control over what what do we do.

In the case of substance use, certain molecules can directly interfere with the reward circuit, causing it to undergo a transformation in a short time, but addictions can also appear without drug use, simply from the excessive repetition of certain behaviors. In these cases, the substances that produce changes in the reward system are neurotransmitters and hormones that our own body generates.

The ambiguities of addiction

The study of the reward system makes us wonder where the boundary is between addiction and normal behavior. In practice it is clear that a person who sells all of her belongings to sell drugs has a problem, but if we take into account that addictive behaviors can appear without taking anything and that occur from the functioning of a brain system that operates in all people constantly, it is not easy to establish the threshold of addiction.

This has led, for example, to talk about love as a kind of addiction Relatively benign: the reward system is activated when we interact with certain people and stops responding as much when they are no longer present, at least for a while. Something similar happens with mobile phone and internet addiction: Maybe if we don't take it very seriously it is simply because it is socially accepted.

Bibliographic references:

• Govaert, P.; de Vries, L.S. (2010). An Atlas of Neonatal Brain Sonography: (CDM 182–183). John Wiley & Sons.
• Moore, S.P. (2005). The Definitive Neurological Surgery Board Review. Lippincott Williams & Wilkins.
• Parent, A.; Carpenter, M.B. (nineteen ninety five). "Ch. 1". Carpenter's Human Neuroanatomy. Williams & Wilkins.