New research works out how the brain is involved in processing fear, which could potentially lead to new treatment options for people with mental health disorders.
Fear can be both useful and dangerous: it can protect people from danger by stimulating a ‘fight or flight’ response, yet it could also cause serious psychological discomfort and even mental health problems. The National Institute of Mental Health has explained that when the response of fear lasts longer than what is normally expected in a situation, this can interfere with an individual’s well-being and daily functioning – this is known as an anxiety disorder.
Because our brains are quite similar to that of animals, scientists have studied on animal models to to try and find out what exactly causes fear to be processed by the brain. For example, after researching on animals it was found that a mass of gray matter in the brain called amygdala plays a key role in processing emotions, emotional behavior, and motivation, and that the elongated ridges on the floor of each lateral ventricle of the brain (the hippocampus) is heavily involved in dealing with memory and emotions. The amygdala and hippocampus work with the hypothalamus by directly exchange signals when an individual recognizes emotional stimuli to deal with everything to do with memory and emotions.
When researchers tested their findings on humans, they surgically inserted electrodes into the amygdala and hippocampus of nine participants, who were asked to watch scenes from horror movies. From this, it was found that the had a form of medication-resistant epilepsy and the seizure activity in the electrode placements were high, showing that there is “direct evidence that the amygdala first extracts emotional relevance and then sends this information to the hippocampus to be processed as a memory.”
One of the researchers, Zheng, explains the findings in more detail:
“Neurons in the amygdala fired 120 milliseconds earlier than the hippocampus, It is truly remarkable that we can measure the brain dynamics with such precision. Further, the traffic pattern between the two brain regions are controlled by the emotion of the movie; a unidirectional flow of information from the amygdala to the hippocampus only occurred when people were watching fearful movie clips but not while watching peaceful scenes.”
Finally, I would like to end on a comment by neurologist Dr Jack Lin
“This is the first study in humans to delineate the mechanism by which our brain processes fear at the circuitry level. This has huge implications for treating neuropsychiatric disorders. For example, current drugs available to treat anxiety disorder bind to large areas of the brain, leading to unwanted side effects. Our hope is that we will one day be able to target and manipulate the precise amygdala-hippocampal circuit involved in processing negative emotions while preserving positive ones.”
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