The amygdala is a subcortical structure that is part of the limbic system. It is therefore involved in experiencing, processing and controlling various emotions. In addition, the amygdala is involved in many everyday functions of the brain.

The emotion most commonly associated with the amygdala is fear. Fear is an innate emotion, and already exists in babies when they unexpectedly hear a loud noise. The reaction that babies show is known as the startle reflex, and consists of blinking the eyes and contracting various muscles. During this reflex, activity is found in the amygdala. However, it would be too easy if the amygdala only became active during the emotion of fear. Activity is also seen in the amygdala when attention is focused on a particular emotion. There is a simple experiment to investigate this:

People are asked to evaluate well-known people as being 'good' or 'bad'. When asked to say how 'bad' a particular person is, the amygdala becomes active when seeing a person who is generally seen as bad (so, for example, when seeing a picture of Hitler). When asked to say how 'good' someone is, the amygdala does not become active when seeing a bad person, but becomes active when seeing a good person (e.g. when seeing a pop star).

In addition to the above reactions to emotions, the amygdala is also involved in certain expressions of emotion such as anger. When the amygdala is stimulated, it triggers a fight response. In this way, even the most peace-loving person can suddenly turn into a fighting creature.

The amygdala is also activated by the pons during dreaming. This is the reason why there are often many emotions in dreams. There is a theory that says that dreaming is nothing more than an attempt by the brain to process abnormal information. When you sleep you lie flat, in contrast to your posture during the rest of the day. This posture is interpreted as a position of flying or falling. According to this theory, this is the reason why so many people dream of free-falling or flying. This theory is called the activation-synthesis hypothesis.

Author: Myrthe Princen (translated by Pauline van Gils)

Image: Marcel Loeffen

In these articles you can see the amygdala in action in different contexts:
Don't judge a book by its cover
Brain basics
Brain basics: fear in the brain
Tripping terror: psychedelics and fear
Babies smell their mother's fears
Who's afraid of....?
Horror, my brain and I