Brain Amygdala: structure and functions

A region of the brain that is responsible for making us feel emotions.

Surprise, fear, anguish, affection, affection, joy, excitement... All these words denote different emotions that we all feel on a daily basis..

They are reactions we have to stimuli that can come from outside (for example, seeing a spider, a baby or being told about your long-awaited promotion) or from inside the person (a thought or memory that makes you suffer or feel happy). These reactions, at brain level, depend on a series of circuits that are able to organize and connect perception and emotion, the main system in charge of this being the limbic system, and within this system the amygdala being one of the main nuclei.

In the present article we are going to 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 great majority of the encephalon, being a nucleus of special relevance that can affect the whole nervous system and the functionality of the organism.

It is a key element for survival, due to the fact that its main function is to integrate emotions with the brain. its main function is to integrate the emotions with the corresponding response patterns, provoking a response at a physical level.It is a key element for survival, because its main function is to integrate emotions with the corresponding response patterns, provoking a physiological response or the preparation of a behavioral response. It is also responsible for coordinating the areas that sense the somatic expression of emotion and the cerebral cortex in charge of conscious feeling, thus playing a very important role in the assessment of the emotional meaning of experiences.

The amygdala is, therefore, the main control nucleus of emotions and feelings in the brain, controlling and feelings in the brain, controlling also the responses of satisfaction or fear. Its connections not only produce an emotional reaction but, due to its link with the frontal lobe, it also allows the inhibition of behaviors.

However, the amygdala is not a simple "piece" of the human brain, with a predictable and well-known pattern of functioning. In fact, none of the structures of the brain are like this, but in the case of the amygdala this is even more evident, considering that it is related to many other areas of the brain. it is related 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, which is why it is sometimes also called the amygdaloid complex.

Parts of the amygdala complex

As mentioned above, the amygdala is not a uniform structure, but is divisible into several subelements.. Among them the following stand out:

1. corticomedial nucleus.

This part of the amygdala complex has a great implication in the uptake of pheromones, participating to a great extent in the control of both male and female sexual behavior. It is also involved in hormonal control and in the satiation response during feeding.

2. Basolateral nuclei

Its main participation is in the control of ingestion through the sensation of satiety.. Likewise, its involvement in the realization and learning of learned emotional responses, such as fear reactions to different stimuli, is essential.

3. Central nucleus

This nucleus is the one that has the greatest participation in the expression of the emotional response.It affects both at physiological level, producing the sensations and physical reactions that provoke emotions and having a great participation in the autonomic nervous system, as well as behavioral by allowing the realization of behaviors that respond to the sensations produced by the perceptions.

Likewise, this nucleus also affects the genesis and maintenance of feelings, which are different from emotions because they are patterns of thought and psychophysiological reactivity maintained over time and less specific to a particular situation.

Functions of the amygdaloid complex

As mentioned, the amygdala is a complex structure vital for survival, participating in and being linked to a large number of psychological and physiological phenomena.. Let us see some of them below:

Integration of emotions and autonomic responses 2.

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

2. Fear management and fight/flight reaction

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

3. Emotional learning

Associative and conditioned learning are also greatly influenced by the action of the amygdala.. This structure allows the choice of strategies to be applied in the presence of stimuli, as well as detecting situations in which these strategies are also applicable. This is due to the link between emotion and cognition, as well as in the maintenance of motivation by linking one's 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 a greater connection and fixation of the material to be remembered, allowing its consolidation.

In fact, 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, which is why it is possible, for example, to be very afraid of dogs (emotional memory) without remembering why this happened (due to the stress suffered in a traumatic event with a dog, that "narrative" memory of what happened has not been 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 bonding between individuals and its association with the maintenance of intimate relationships are due among other structures to the amygdalin complex.

6. Aggressiveness

The amygdala is also linked to aggression.. Studies so far indicate that a malfunction of the amygdala can lead to the loss of aggressive and self-defense reactions, while an overstimulation of the amygdala complex leads to extremely aggressive and violent reactions.

7. Satiation response

Another aspect in which the amygdala has some influence is in the control of intake, contributing greatly to the maintenance of body homeostasis through its influence on the perception of satiation.

Bibliographical references:

• Kandel, E.R.; Schwartz, J.H. & Jessell, T.M.. (2001). Principles of neuroscience. Fourth edition. McGraw-Hill Interamericana. Madrid.

• Méndez-Bértolo, C.; Moratti, S.; Toledano, R.; López-Sosa, F.; Martínez-Álvarez, R.; Mah, Y.H.; Vuilleumier, P.; Gil-Nagel, A. & Strange, B.A. (2016). "A fast pathway for fear in human amygdala", Nature Neuroscience.

• Nieuwenhuys, Voogd & van Huijzen (2009). The Human Central Nervous System. 4th Edition. Editorial Médica Panamericana. Madrid.