What is the amygdala?
The amygdala (corpus amygdaloideum) is a sub-region within the limbic system, consisting of two bean-sized clusters of nerve cells. Through the connection with other brain regions, the meaning of various signals is evaluated here and these are then projected from the amygdala (together with the hippocampus) to the cerebral cortex via branched pathways.
What is the function of the amygdala?
The main function of the amygdala is to evaluate memory functions such as memories with emotional content. The amygdala plays a particularly important role in the development of fear:
When a situation is classified as threatening or dangerous based on experience, the information that is passed on from the corpus amygdaloideum to other areas of the brain changes. As a result, for example, the neurotransmitters acetylcholine, dopamine, serotonin and norepinephrine as well as the stress hormones adrenaline and cortisol are increasingly released. This signals to the body that something significant and potentially dangerous is happening. These signals are then compared with memories by the amygdala. If this comparison signals “danger”, fear arises and the body reacts with increased alertness and perhaps also with flight reactions.
Where is the amygdala located?
The amygdala is a stem part of the end brain. It is located near the tip of the temporal lobe (temporal lobe) and protrudes towards the front end of the inferior horn of the lateral ventricle (cavity filled with cerebrospinal fluid). The amygdala is divided into several core groups by fine lamellae and is connected to the parahippocampal gyrus (part of the cerebral cortex surrounding the hippocampus). There is also a connection with the area olfactoria, the olfactory center.
What problems can the amygdala cause?
Damage to the amygdala leads, for example, to memories being evaluated without their emotional content.
In Urbach-Wiethe syndrome – a relatively rare, hereditary disorder – calcium is deposited on the vessels of the amygdala. The people affected cannot or can hardly recognize, describe or reproduce the emotional expression of fear.
Due to degenerative processes, the storage of so-called engrams (memory traces) is no longer possible because the circuits to the cerebral cortex are disturbed. Degenerative changes are seen, for example, in Alzheimer’s disease or through alcohol abuse, which leads to Korsakow’s disease.
Epileptic seizures sometimes begin in the amygdala.
