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The reward system of the brain: how does it work?

The reward system of the brain: how does it work?

January 23, 2024

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's 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 the breathing, etc. All these processes are automatic and we can not voluntarily intervene on them.

But ... what happens when what brings us closer or less to death has to do with actions learned through experience? In those cases, which are not foreseen 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 that allows us to associate certain situations with a sense of pleasure. In this way, from these learnings We will tend to try that in the future the situations that have generated this experience will occur again .

In some way, the reward system is what allows us to locate objectives in a very primary sense. As human beings are exposed to a variety of situations for which biological evolution has not prepared us, these mechanisms reward certain actions over others, making us learn on the fly what is good for us and what does not. is.


Thus, the reward system is closely linked to basic needs: it will make us feel very rewarded to find a place that contains water when we have not drunk for 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 however varied our actions and behavioral choices may be, we always have a compass that points consistently towards certain sources of motivation, rather than anywhere.

Where does the reward circuit go?

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 pathway, characterized, among other things, by the importance of a neurotransmitter called dopamine.


The principle of this chain of transmission of information is located in an area of ​​the brainstem 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 go up to the limbic system, a set of structures known to be responsible for the generation of emotions. Specifically, the nucleus accumbens, is associated with the appearance of the sensation of pleasure .

This mixture of pleasant emotions and pleasure sensation goes 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 approaching the objective.

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

But nevertheless, this possibility of leaving us a margin of maneuver when it comes to being able to choose what we are going to do also has a risk called addiction . Actions that are initially voluntary and fully controlled, such as the choice to try heroin, can be the only option left to us if we become addicted.

In these cases, our reward system will only be activated when consuming a dose, leaving us totally unable to feel 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 is "hacked" and becomes a tool that guides us to a single objective, causing us to lose control over what we do.

In the case of the consumption of substances, certain molecules can interfere directly in the circuit of rewards, 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 the neurotransmitters and hormones that our own body generates.

The ambiguities of addiction

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

This has led, for example, to talk about love as a kind of relatively benign addiction: the reward system is activated by relating to certain people and stops responding when it is no longer present, at least for a while. Something similar happens with the addiction to mobile phones and the Internet: perhaps if we do not take it very seriously it is simply because it is socially accepted.


Expectation and Reward (January 2024).


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