Amygdala is an almond-like structure present in the brain and is known to play an important role in human emotion, especially the fear and anxiety, and its’ respective resulting behavior. In this article we will look at what happens when amygdala is damaged.
What Is Amygdala?
Before we jump over to our concerned topic, let us first know briefly about what amygdala is. Amygdala comes from the Latin-Greek word, meaning “Almond”. The name comes from the fact that this structure looks like an almond and it is found in the brain.
The amygdala in the human brain is placed somewhat strategically at the dorsomedial part of the temporal lobe, anteriorly (in the front) of the Hippocampus and very close to the tail of the Caudate nucleus. It is placed near to the hypothalamus and also the brainstem.
Amygdala ranges from 1 cm to 4 cm, average of about 1.8 cm, and has extensive connection with the brain. This includes, the neighbouring structures like hippocampus, basal ganglia, entorhinal cortex, brainstem, thalamus and hypothalamus. Amygdala is also connected well with the limbic system and other associative cortex, prefrontal cortex, and basal forebrain. Therefore, its stimulation is known to bring a major effect to the entire brain.
Amygdala is well known to play an important role in human emotions, especially fear and anxiety and its respective resulting behavior. Stimulation of the amygdala in the human, produces a feeling of fear and anger. This is because, this structure is located near the brainstem, where the sympathetic pathway is located, to produce all physiological reflexes when we are angry or scared. Apart from this, the extreme proximity of amygdala and hippocampus makes us to believe that amygdala has some form of memory functions too. And in fact, it has memory functions too. However, it is more towards the memory of producing anxiety and fear.
Amygdala is also important for sexual function by vomeronasal organ-detected pheromones. Sex-related hormone is secreted by the hypothalamus in respond to the amygdala. Moreover, amygdala, also has a role in the reward system, where positive emotion is elicited.
What Happens If Amygdala Is Damaged?
Now, what happens if amygdala is damaged? In case of monkeys, the bilateral (both, there is one left and one right amygdala) lesion of amygdala demonstrated that there is a massive reduction of fear and aggression and the monkeys became more friendly, sexually and also non-sexually towards other monkeys.
Then, what is the case in humans? Same is the case here too. There is a reduction of fear and aggression in the person if the amygdala gets damaged. However, there is also something more to it. Bilateral lesion of amygdala also causes the affected person to have an impaired ability to interpret emotional aspect of facial expression. A damage to the amygdala is linked to autism. Amygdala has a potential relationship with the social ability of a human being, although more studies on this is required.
A case study has found that the damage to a woman’s amygdala is not only associated with merely a decrease in the experience of fear, but the absence of fear altogether. However the study concluded that the woman showed a wide range of all other emotion; which suggest that the crippling effect of the damage to the amygdala is limited only to the experience of fear.