From humans to amoeba, every living thing has an instinctive response to danger. Whether we’re surprised by someone creeping up on us, or by a sudden loud noise, we all know that familiar sensation where our heart starts to pound and our palms begin to sweat. But what is fear? And what’s happening in the brain when we feel fear?
A multitude of studies have sought to learn more about how our brains respond to fear. Many of these studies help us to develop new therapies and treatments for all kind of fear related disorders, such as post traumatic stress disorder (PTSD) and anxiety disorders. By having an objective way to measure the brain activity of those under some kind of threat, scientists are able to glean a better understanding of what happens when humans are exposed to fear.
How our brain responds to threats
When our brain responds to a perceived threat, many parts of the brain jump into action. However, it’s the structure known as the amygdala which is believed to be at the centre of the whole process. When we sense danger, this almond shaped bunch of neurons, which is buried deep within each medial temporal lobe, sends signals to other parts of the brain as a warning.
The amygdala was first identified as the brain’s ‘fear centre’ by scientists in the late 1880s, who noticed that monkeys whose amygdala had been damaged seemed to be relatively tame and didn’t exhibit fear when confronted with potential predators. Since then, many more studies have concluded that damage to the amygdala corresponds with lower than normal levels of fear.
Working in conjunction with other areas of the brain
However, while the amygdala does play a vital role in processing fear, it’s not a necessity. Researchers have also discovered that when the body is subjected to internal bodily threats, people with damaged amygdalae still respond. Furthermore, when subjects are asked to look at threatening images, activity is seen in not just the amygdala, but in the areas which are associated with language and memory, with this frontal lobe activity believed to be instrumental in assessing whether the perceived threat is genuine or whether it is merely a false alarm.
As with all studies, further research is needed to get a more complete picture of how our brains react in times of stress in order to further understand what goes wrong in the brains of people who respond abnormally to worrying situations.