Anti-reward brain 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 pleasurable behaviors, playing an important role in the development of addictions.

However, there appears to be a similar and opposite mechanism to this, a collection of areas of the brain involved in producing unpleasant sensations when performing a certain behavior.

This set of zones has been called the anti-reward circuit. and, while it must be said that research is still being done to determine what particular areas are involved and what exactly they are used for, then we will talk about that particular mechanism.

    The anti-reward circuit

    One of the most well-known concepts in neurophysiology is the idea of ​​the reward circuit. It is a set of brain mechanisms that are attributed to associate certain situations with sensations of pleasure.

    This way, 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 perform actions or consume substances that we know will give us pleasure, being a very important neurological component in motivation.

    In return for this system, the existence of another circuit has been proposed, the function of which would be to serve, in one way or another, as a regulator of behavior and mood. It is the anti-reward circuit, which consists of a network of brain regions that cause negative physical and emotional emotions facing certain events, substances and behaviors. In other words, just as the reward system makes us feel happy, the anti-reward system makes us unhappy, or at least less satisfied.

      neurophysiological basis

      The idea of ​​the anti-reward circuit is fairly recent, and evidenced by the fact that little is known today about how it works and the specific areas involved in its activation. However, certain brain regions are known which are suspected to be involved, in addition to other biochemical bases which could explain their activation.

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

      These neurobiological bases of the anti-reward circuit can be linked to certain ideas discussed by Dean Burnett in the book “The Happy Brain” (2018). In this 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 said that dinorphins have often been linked to negative emotions, stress, and depression.

        Emotional regulator?

        Dinorphin and corticotropin are two neurotransmitters that cause the opposite effect of euphoria, i.e. 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 is the neural basis of this system and is not something acquired or the product of a disorder or neuropathology, what adaptive function has this particular circuit?

        Added to this unknown, it is worth mentioning the fact that it seems that the anti-reward circuit is activated at the same time as the reward circuit. That is, our brain activates two systems that appear to be antagonistic, which raises even more mystery about the existence of this system, because it means that we feel pleasure and dissatisfaction at the same time. Why does our brain need to activate two contradictory things?

        The main function of the anti-reward circuit would be to regulate our mood. That is, when something activates our reward system, the most normal thing is to experience satisfaction, euphoria, and positive feelings which, if overly exaggerated, could lead to an episode. hypomania. To avoid this, the anti-reward system is activated by reducing the pleasure, prevent us from climbing too high and committing irresponsible acts.

        The other function would be to keep the reward system operational. In our body, there are multiple systems which perform various functions and which, in order to adjust and regulate, need an antagonistic system which acts as a counterweight. For example, the sympathetic and parasympathetic nervous systems perform opposite but coordinated functions that serve to maintain the body’s homeostasis (for example, by inhibiting or stimulating digestive activity). If either of the two failed, our body would go into crisis and we could manifest diseases.

        Therefore, the anti-reward circuit would act to ensure that the other system is working properly, in addition to regulating behavior and the individual’s adaptations to certain environmental behaviors, substances and events. By activating one and resting the other, the cells are kept alive, preventing over-stimulation of one of the systems and, therefore, the breakdown of the organism.

        And when does the imbalance occur? Both the reward system and the quid pro quo are closely related to addictions. The balance maintained by the two systems is compromised when excessive drugs are consumed. A key part of addictions is the development of a negative emotional state during abstinence. The neurophysiological basis for this negative emotional state is derived from two processes: on the one hand, reduced activity in the reward system, and on the other, increased activity in the anti-reward circuit. .

        When we spend a lot of time consuming an addictive substance, be it tobacco, alcohol or just caffeine, the most normal thing is that we end up developing a tolerance to certain amounts. This means that to receive a blow, a “rise”, it is necessary to increase the consumption. If we suddenly stop consuming or take fewer doses that our body is used to, we start to experience negative emotions such as depression, listlessness, irritability, as well as other symptoms associated with withdrawal syndrome.

        Drug addicts have the problem that the reward system is no longer activated by consuming a certain amount of the drug., because it is hyposensitized. The problem is, if they stop taking the drug because the anti-reward system is hypersensitive, if they don’t take the drug or take less than they need, they start to feel really bad, they are therefore more inclined to start over. consume to avoid suffering. This is one of the reasons why addictions and their abandonment are so difficult.

        It should be noted that, while more and more research is being conducted on the anti-reward circuit, the assumptions behind why it peculiarly works and how it counteracts the effects of the reward system are very tentative. It is not known how well the two balanced systems work in the brain of a healthy, non-addictive person, and it should also be noted that the theories applied to people with drug addiction are in diapers. Likewise, it appears as an emotional regulator, or more precisely, a satisfaction regulator.

        Bibliographical references

        • Wiedacker, K., Kim, S., Nord, C., Rua, C., Rodgers, C. & Voon, V. (2020). Avoiding Monetary Losses: A Functional Ultra-High Magnetic Resonance Imaging Field Study of Human Avenula. Cortex
        • Gardner, Eliot. (2011). Addiction and the reward and anti-reward pathways of the brain. Advances in psychosomatic medicine. 30. 22-60. 10.1159 / 000324065.

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