Cerebral tonsil: structure and functions

Surprise, fear, anguish, affection, affection, joy, excitement … All of these words denote different emotions that we all feel in our everyday life..

These are reactions we have to stimuli that can come both from the outside (e.g. seeing a spider, a baby, or communicating your long-awaited ascension) and from within the person himself (a thought or a memory that makes you suffer or feel happy). These reactions, at the cerebral level, depend on a series of circuits capable of organizing and linking perception and emotion, the main system being responsible the limbic system, and within this system being the amygdala one of the nuclei. main.

In this article we will focus on this structure, the amygdala, in order to visualize what it is and some of its main functions.

What is the amygdala?

The amygdala is a subcortical structure located in the inner part of the medial temporal lobe. This element has connections with the vast majority of the brain, being a nucleus of particular importance that can affect the entire nervous system and the functionality of the body.

It is a key element for survival, because its main function is to integrate emotions into the corresponding response patterns, Provocation of a response at the physiological level or preparation of a behavioral response. It is also responsible for coordinating the areas that notice the somatic expression of emotion and the cerebral cortex in charge of conscious feeling, so it plays a very important role in assessing the emotional significance of experiences.

The amygdala is therefore the main core of emotional control and feelings in the brain, also controlling responses to satisfaction or fear. Their connections not only produce an emotional response, but due to their attachment to the frontal lobe, they also allow behavioral inhibition.

However, the amygdala is not just a “piece” of the human brain, with a predictable and well-known pattern of functioning. In fact, none of the structures in the brain are like this, but in the case of the amygdala it is even more evident, given that is linked to many other areas of the central nervous system. It is a complex structure, being an almond shaped structure located in the limbic system of the brain. It is made up of different parts, so it is sometimes referred to as the amygdala complex.

Parts of the amygdala complex

As we said, the amygdala is not a uniform structure, but is divisible into several subelements. These include the following:

1. Corticomedial nuclei

This part of the amygdala complex has a great implication in the absorption of pheromones, participating largely in the control of male and female sexual behavior. It also participates in hormonal control and the satiety response when ingested.

2. Basolateral nuclei

Its main implication is to control the intake by the feeling of satiety. Likewise, their involvement in achieving and learning learned emotional responses, such as fear reactions to different stimuli, is paramount.

3. Central core

This nucleus is most involved in the expression of the emotional response, Affecting both the physiological level, producing the sensations and the physical reactions that cause emotions and we have a great participation in the autonomic nervous system, as well as behavioral in allowing the performance of behaviors that respond to the sensations that produce perceptions.

Likewise, this core also affects the genesis and maintenance of feelings, which differ from emotions in that they are patterns of thought and psychophysiological reactivity sustained over time and less specific to a particular situation.

Functions of the tonsillar complex

As mentioned, the amygdala is a complex structure and vital for survival, participate in and be linked to a large number of psychological and physiological phenomena. Here are a few:

1. Integration of emotions and autonomous responses

The amygdala manages the emission or inhibition of emotional responses with great precision both consciously and unconsciously, its function being more studied and one of the most relevant. It allows you to associate feelings of gratification or aversion to your experiences. Participates in both positive emotions and reactions of joy or happiness and other emotions of a more adaptive nature, as we will see in the next point.

2. Fear management and fight / flight response

In this regard, one of the main functions of the amygdala and the fact that this is a key part of survival is fear management. At the phylogenetic level, this nucleus has allowed the survival of our species, because it is what allows us to react after perceiving a stimulus potentially threatening to physical integrity, stimulating or inhibiting the fight / flight response. In fact, injuries to the amygdala can lead to extremely aggressive reactions and loss of fear, with all the repercussions that the absence of this feeling can have.

3. Emotional learning

Associative and conditioned learning is also strongly influenced by the performance of the amygdala. This structure allows the choice of strategies to be applied in the presence of stimuli, as well as the detection of situations in which these strategies are also applicable. This is due to the link between emotion and cognition, as well as maintaining motivation by linking one’s own goals to specific feelings.

4. Memory

In addition to the learning process, the amygdala also affects the structuring of memories. This is due to the association of memories with emotional states, which allow greater connection and fixation of the material to be remembered, allowing its consolidation.

Indeed, even when the hippocampus fails and does not allow certain memories to be stored, the amygdala allows a certain emotional memory of a situation to be preserved, so it is possible, for example, that we are very afraid of dogs. (emotional memory) without remembering why it happened (due to the stress he experienced during a traumatic event with a dog, this “narrative” memory of what happened was not preserved).

5. Regulation of sexual behavior

Sexual behavior is also influenced by the action of the amygdala. In addition to allowing the association of different stimuli with pleasure, the emotional bond between individuals and their association with the maintenance of intimate relationships are due among other structures to the tonsillar complex.

6. Aggression

The amygdala is also linked to aggression. Studies to date indicate that dysfunction of it can lead to the loss of reactions of aggression and self-defense, while hyperstimulation of the tonsil complex causes extremely aggressive and violent reactions.

7. Saturation response

Another aspect in which the amygdala has some influence is in the control of ingestion, contributing to a large extent in the maintenance of bodily homeostasis through its influence on the perception of satiety.

Bibliographical references:

  • Kandel, ER; Schwartz, JH and Jessell, TM (2001). Principles of neuroscience. Fourth edition. McGraw-Hill Inter-American. Madrid.

  • Méndez-Bértolo, C .; Moratti, S .; Toledano, R; López-Sosa, F .; Martínez-Álvarez, R .; Mah, YH; Vuilleumier, P .; Gil-Nagel, A. and Strange, BA (2016). “A Fast Track to Fear in the Human Amygdala”, Nature Neuroscience.

  • Nieuwenhuys, Voogd and van Huijzen (2009). The human central nervous system. 4th edition. Pan American Medical Editorial. Madrid.

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