The Origin of Fear


For those who choose to observe it, it’s “spooky time” again. Each year in October, many of us do our darndest to scare the willies out of each other and ourselves. We watch scary movies, visit “haunted” houses, and search for the most frightening costumes with the goal of experiencing a little bit of that most universal of emotions: fear.

Most of us know why we experience fear; it’s our bodies’ way of getting us ready for a threat to our lives or livelihood. But, how does the whole system work?

The human fear response starts in the portion of the brain called the amygdala – its purpose is to detect the emotional importance of external stimuli. It activates whenever we see a human face with emotion or anything else that can be perceived as a threat. For instance, if we are walking down a path and see a wild dog, the amygdala immediately perceives the dog as a threat and activates our “fight or flight” response leading to bodily changes such as enhanced brain activity, dilated pupils, accelerated breathing and heart rate, and increased blood flow to our muscles. After the amygdala activates, the brain’s hippocampus goes to work to interpret the perceived threat, determining whether it is real. To explain, the sight of a wild dog on your path is perceived by the amygdala as a threat; however, the hippocampus and prefrontal cortex understand that the dog is on a leash handled by an owner. The threat response is deactivated as the dog is no longer scary.

This explains our universal fear of the dark and unknown. When we hear a “strange” sound outside such as a tapping on the window at night, the amygdala activates but the hippocampus cannot instantly determine that the sound is NOT a threat due to the dark. Only when we determine that the “tapping” on the window was a tree branch blowing in the wind, can the hippocampus cancel the fear response. The amygdala also acts much faster than the hippocampus, leading to instances when we are “surprised” by a friend, causing our heart to race before the hippocampus recognizes the actual situation.

Just know that the feeling of dread you experience listening to the mysterious scratching at your bedroom door or the face you see leering from the shadows in the middle of the night, could be nothing more than uncertainty run amok. Do you investigate … or hide beneath the covers?

Happy Halloween.


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