What happens in our brains when we're afraid?

• Fear is necessary for survival and helps us escape dangerous situations
• However, some people experience irrational fears, lowering their quality of life
• Understanding how fear is processed in the brain can lead to better treatment for people with disorders characterised by fear

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Fear is a necessary response for survival in all living creatures, as it plays a crucial role in letting us know when we are in danger. In less dire situations, we may be startled by a loud noise or an unexpected object heading towards us, but this kind of fear is short-lived, and subsides quickly.

More than just a scare

A paper published in the journal Dialogues in Clinical Neuroscience defines anxiety as “a psychological, physiological, and behavioural state induced in animals and humans by a threat to well-being or survival, either actual or potential”. Anxiety is characterised by fear and can be experienced by anyone.

However, there are more severe cases of fear than the odd wince due to a bang or the slight worry experienced before meeting someone new. In people who suffer from anxiety disorders, fear becomes debilitating and lowers one's quality of life.

Social anxiety disorder (SAD) is one of the more serious instances of fear. In people with SAD, immense fear of non-life-threatening situations is constant.

A new study may help experts better understand how fear is processed in the brain, which may allow them to assist people with anxiety disorders.

Fear and the central amygdala

A team of researchers, led by Professor Bi Li of Cold Spring Harbor Laboratory, aimed to examine brain circuits that underlie fear. The study was centred around understanding the amygdala.

Researchers explained: “The central amygdala (CeA) is critically involved in a range of adaptive behaviours, including defensive behaviours.” Fear processing is one of the functions of the amygdala, but Professor Li and his team discovered that this part of the brain is also responsible for reward-based learning.

 Another surprising discovery made by the team is that the amygdala communicates with the Globus pallidus (the part of the brain responsible for movement).

The Globus pallidus was not previously seen by researchers as being associated with fear processing or memory. However, when researchers interrupted signals between these two parts of the brain in mice, the animals could not learn that a particular sound signalled unpleasant sensations. 

Controlling fear and anxiety sufferers

The findings of this study indicate that fear-processing circuits are vital when it comes to the learning of fear by the brain. In the process of learning fear, it is important for the brain to identify which situations to learn from, and to differentiate between what is threatening and what isn't. 

Professor Li and his team demonstrated that that fear learning may be adjusted, potentially giving people with anxiety disorders better control over overactive or inappropriate fear responses.