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The Science of Fear

Haloween1Think of Halloween and FEAR comes to mind. From the scary horrors of the darkest of our imagination to just the thought of pestering children knocking on your door! We’ve all been there. Facing our worst nightmares. Heart starts racing. Palms sweating. Stomach turning. But what is fear?

Fear has been with us since the dawn of time. Promoting survival, fear allows the animal kingdom to handle threats through the well-known fight-or-flight response. Faced with danger we either attack and escape or freeze- whatever is best for our survival. So, through evolution, those who feared the “best” survived, reproduced and passed their fears on to their children.

Haloween2So does being a scared-y cat makes you a dream catch?

Not quite. Over the course of time, fear began to evolve in human society. Alongside our rooted survival-fears, we began to develop our own personal fears. Our personal experiences unconsciously shape what we fear, meaning we now have the potential of being scared of anything – from bananas to zebras.

So, with so many potential fears surrounding us, the body’s response to these possible fearful stimuli must be controlled.

Our brains translate information about a fearful scenario – i.e. ghosts, ghouls, upcoming deadlines- and decide the right course of action. The resulting hormonal responses in the body leads to the standard fearful feelings we all know and loath.

Haloween3Advancements in imaging, such as magnetic resonance imaging (MRI) and positron emission tomography (PET), have helped show the key areas of the brain involved – identifying the Amygdala as fear central. This evolutionarily conserved, almond-shaped group of neurons, located deep within the brain is essential for emotion, decision-making and memory – all crucial features of fear.

The amygdala can be activated by a variety of stimuli that entices any of our senses. As the hub of fear, it is believed to process information about the threat, assesses the level of fear, bringing about an appropriate response. Many studies have confirmed the role of the amygdala in fear using visual stimuli.

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Amygdala activation shown using MRI

Conscious fear responses provoked by images of common phobias like snakes and spiders occurs alongside amygdala activation. Interestingly, in the absence of conscious stimuli, the amygdala still becomes activated. In these experiments, subjects were again shown the images but only momentarily so they never actually became aware of the threat. However they still suffered impeding fear alongside enhanced amygdala activity.

So with the amygdala being incredibly crucial for fear on all levels of our consciousness, what would life be like without the amygdala?

Well we are actually able to see. A few years ago a case came to light of a 44 year-old woman who was essentially fearless.

Referred to as “SM”, the woman suffered from an incredibly rare, less then 300 cases ever reported, genetic disorder called Urbach-Wiethe Disease. The disorder affects the extracellular matrix, the cells scaffold, meaning the symptoms vary drastically between cases. Usually the disease causes hardening of the brain and, in the case of SM, progressive degeneration of the amygdala.

The case of SM proved to be a unique way to continue exploring the amygdala. SM’s response to situations, from exposure to her once personal fears, a visit to the world’s scariest house to endless viewing of horror films, shown she failed to experience any sort of fear.

Haloween5While this may seem wonderful, we need to remember fear is essential for survival. Never the attacker, SM has found herself as the victim of numerous crimes in her lifetime, including being threatened at knife point and being involved in an abusive relationship. During these horrific ordeals, while feeling emotions like anger, she has never felt fear. Without amygdala function, SM is vulnerable, unable to sense looming threats

So this Halloween, when you feel fear trickling down your spine, remember the most terrifying fear is not being able to feel fear itself!

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Post by: Claire Wilson

Some references to sink your fangs into over Halloween

  • Feinstein, J.S., et al., The Human Amygdala and the Induction and Experience of Fear. Current Biology, 2011. 21(1): p. 34-38.
  • Ohman, A., The role of the amygdala in human fear: automatic detection of threat. Psychoneuroendocrinology, 2005. 30(10): p. 953-8.[1]
  • Ohman, A., et al., On the unconscious subcortical origin of human fear. Physiol Behav, 2007. 92(1-2): p. 180-5.

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