What Happens to the Brain When We Get Scared?
Updated: Aug 24, 2022
Everyone gets scared; fear is an unavoidable fact of life. Typically, fear is considered an unpleasant experience, but as we say goodbye to Halloween for another year its easy to see that some individuals seek out scary experiences, and the hyper-arousal that comes with it, on purpose.
What is Fear?
Fear is a fundamental natural reaction caused by stimulus we perceive as dangerous, painful, or harmful. Fear is an essential role in survival; successfully running and hiding from potentially dangerous predators allows for the survival of that individual. A lot of fearful experiences can be justified and are valid reasons for being scared (e.g. a physical threat such as a home intruder), whilst some fearful reactions to experiences can be inappropriate (e.g. jump scares in scary movies).
We are all familiar with the physical aspects of fear such as increased breathing and heart rate, tightened muscles, and goose bumps etc. Metabolically the body also undergoes experiences such as a surge of adrenaline and blood glucose levels spiking. These reactions are referred to as the fight or flight response and it all begins in the brain.
What Happens in the Brain?
Fear reactions start in a part of the brain called the amygdala. The amygdala is an almond shaped structure in the brain that forms part of the limbic system. The amygdala plays an important role in processing emotions, it does this through triggering activity in the hypothalamus the pituitary gland is activated which in turn secretes hormones into the blood stream.
The division of the nervous system responsible for flight or flight responses (the sympathetic nervous system) activates the adrenal gland which gives the bloodstream a dose of epinephrine (adrenaline). The body also releases cortisol in response to these changes which causes the rise in blood pressure, blood sugar, and white blood cells and turns fatty acids into energy for the body to use if needed.
Hormones such as adrenaline and noradrenaline prepare the body’s muscles for action and boost lung and heart activity, reduce stomach and intestine activity (which results in the feeling of “butterflies”), prevents the production of tears and saliva, dilates the pupils, and results in tunnel vision and concentrated hearing.
Important parts of the brain during this fear response are the hippocampus and prefrontal cortex which assess the presenting threat. These sections help us decide whether our fear response is justified or not. If the hippocampus and prefrontal cortex evaluate the fear response as inappropriate they can dampen the amygdala’s activity.
This dampening of the fear response can explain why some people enjoy scary movies as the “thinking” sections of their brains can override the automatic fear response. This results in the feeling of a rush of fear before rationalized calming.
Whilst many people only experience fear response towards genuine threats and controlled stimulus such as scary movies, for a lot of people daily abnormal levels of fear and anxiety leads to distress and dysfunction in everyday life. As such effective treatments for fear and anxiety (e.g. exposure therapy) are incredibly important.