27 September 2023

Why fear is seared into our brains

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Barri Bronston* says neuroscientists have discovered a mechanism that explains why we often have to live with the constant memory of traumatic experiences, while other events fade with time.

Experiencing a frightening event is likely something you’ll never forget.

Why does it stay with you when other kinds of occurrences become increasingly difficult to recall with the passage of time?

Neuroscientists from the Tulane University School of Science and Engineering and Tufts University School of Medicine have been studying the formation of fear memories in the emotional hub of the brain — the amygdala.

They believe they have found the mechanism that makes fearful events stick with us.

In a nutshell, the researchers found that the stress neurotransmitter, norepinephrine, also known as noradrenaline, facilitates fear-processing in the brain by stimulating a certain population of inhibitory neurons in the amygdala.

This generates a repetitive bursting pattern of electrical discharges.

This bursting pattern of electrical activity changes the frequency of brain wave oscillation in the amygdala from a resting state to an aroused state that promotes the formation of fear memories.

Published recently in Nature Communications, the research was led by Tulane Cell and Molecular Biology Professor, Jeffrey Tasker, who is the Catherine and Hunter Pierson Chair in Neuroscience, and his PhD student, Xin Fu.

Professor Tasker used the example of an armed robbery.

“If you are held up at gunpoint, your brain secretes a bunch of the stress neurotransmitter norepinephrine, akin to an adrenaline rush,” Professor Tasker said.

“This changes the electrical discharge pattern in specific circuits in your emotional brain, centred in the amygdala, which in turn transitions the brain to a state of heightened arousal.

“That facilitates memory formation, in this case fear memory, since it’s scary.

“It is the same process, we think, that goes awry in PTSD and makes it so you cannot forget traumatic experiences.”

This research was led by Professor Tasker’s laboratory and was conducted in collaboration with the Jonathan Fadok laboratory of Tulane and the Jamie Maguire laboratory of Tufts.

*Barri Bronston is a publicist for the Tulane University of Louisiana, a private research university based in New Orleans.

This article first appeared on the Science Daily website.

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