Brain Anti-Reward Circuit: What It Is And How It Works

In neuroscience, the idea of ​​the reward circuit is widely known. It is the neurological basis behind the performance of pleasant behaviors, having an important role in the development of addictions.

However, it seems that there is a similar mechanism and contrary to this, a set of areas that are involved in producing unpleasant sensations when performing a certain behavior.

This set of areas has been called the anti-reward circuit And, although it should be said that research is still being carried out on what specific areas are involved and what exactly it is for, we are going to talk about this peculiar mechanism below.

• Related article: "Brain Reward System: What Is It and How Does It Work?"

The anti-reward circuit

One of the best known concepts in neurophysiology is the idea of ​​the reward circuit. This consists of a set of brain mechanisms to which it is attributed to associate certain situations with sensations of pleasure.

Thus, the brain learns to associate substances, behaviors or any other aspect with positive emotions, satisfaction and well-being

. It is thanks to this system that we feel motivated to carry out actions or consume substances that we know that they will give us pleasure, being a very important neurological component in the motivation.

As a counterpart to this system, the existence of another circuit has been proposed whose function would be to serve, in one way or another, as a regulator of behavior and mood. This is the anti-reward circuit, which consists of a network of brain regions that gives rise to negative physical and emotional emotions before certain events, substances and behaviors. In other words, in the same way that the reward system makes us feel pleasure, the anti-reward system makes us feel unhappy or, at the very least, less satisfied.

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Neurophysiological bases

The idea of ​​the anti-reward circuit is quite recent, and this is evidenced by the fact that that today little is known about how it works and what specific areas are involved in its activation. However, some brain regions that are suspected of being involved are known, as well as other biochemical bases that could explain their activation.

These areas would be certain regions of the amygdala and the terminal stria, close to the thalamus. Among the neurotransmitters involved we would have corticotropin, a substance that has a lot to do with amygdala as it seems that this structure is an important point in the release system of corticotropin. In addition to this neurotransmitter, others involved in the anti-reward circuit are dynorphin, norepinephrine, neuropeptide Y, and nociceptin.

These neurobiological bases of the anti-reward circuit can be related to some ideas discussed by Dean Burnett in his book “The Happy Brain” (2018). In that book, he comments that several investigations have detected abnormally high levels of corticotropin in the cerebrospinal fluid of people who have committed suicide. In addition, it is also commented that dynorphins have been linked very often with negative emotions, stress and depression.

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Emotional regulator?

Dynorphin and corticotropin are two neurotransmitters that cause the opposite effect of euphoria, that is, dysphoria. These two substances present in the brain and involved in the anti-reward circuit induce negative emotions and anxiety-depressive symptoms. Since our brain has the neuronal bases for this system and that it is not something acquired or the product of a disorder or neuropathology, What adaptive function does this peculiar circuit have?

Added to this unknown, it is worth mentioning the fact that it seems that the anti-reward circuit is activated in conjunction with the reward circuit. That is, our brain activates two systems that seem to be antagonistic, which raises even more mystery about the why of the existence of this system, since it comes to mean that we feel pleasure and dissatisfaction at it weather. Why does our brain need to activate two things that contradict each other?

The main function that the anti-reward circuit would have would be to regulate our mood. That is, when something activates our reward system, it is normal to feel satisfaction, euphoria and positive feelings, which if too exaggerated could translate into an episode of hypomania To avoid this, the anti-reward system is activated reducing pleasure, preventing us from getting too high and committing irresponsible acts.

The other function would be to keep the reward system operational. In our body there are multiple systems that carry out various functions and that, to adjust and regulate themselves, need an antagonistic system that acts as a counterweight. For example, the sympathetic and parasympathetic nervous systems perform opposite but coordinated functions, which serve for the body to maintain its homeostasis (p. g., inhibit or stimulate digestive activity). If one of the two failed, our body would go into crisis and we could manifest diseases.

So that, the anti-reward circuit would act to make sure the other system works properly, in addition to regulating behavior and adaptations of the individual to certain behaviors, substances and environmental events. By activating one and making the other rest, the cells are kept alive, avoiding overstimulation of one of the systems and, consequently, the decline of the organism.

And when does the imbalance happen? Both the reward system and its counterpart are closely related to addictions. The balance that both systems maintain is compromised when drugs are used in excess. A key element of addiction is the development of a negative emotional state during withdrawal. The neurophysiological basis of this negative emotional state derives from two processes: on the one hand, a reduction in activity in the reward system, and on the other, a greater activity in the circuit of anti-reward.

When we have been consuming an addictive substance for a long time, be it tobacco, alcohol or simply caffeine, it is normal that we end up developing tolerance to certain amounts. This means that in order to receive a kick, a “high”, it is necessary that we increase consumption. If we suddenly stop consuming or take less doses than our body is used to, we begin to feel negative emotions such as depression, apathy, irritability, in addition to other symptoms associated with the syndrome abstinence.

People addicted to substances have the problem that their reward system is no longer activated when consuming a certain amount of the drug, since he is hyposensitized. The problem is that if they stop taking the drug, as the anti-reward system is hypersensitized, in case they don't take the drugs or take less than they need, they start to feel very bad, making them more likely to use again to avoid suffer. This is one of the explanations of why addictions and their difficult abandonment.

It must be said that, despite the fact that more and more research is being done on the anti-reward circuit, the hypotheses behind the why of its peculiar operation and how it counteracts the effects of the reward system are very provisional. It is not known to what extent both systems, balanced, work in the brain of a healthy person without addiction, and it is also worth mentioning that the theories applied to people with drug dependence are in diapers. Likewise, it seems that it is an emotional regulator, or more specifically, a satisfaction regulator.