Discovery reveals how scary memories stick

A new study shows how the “fight or flight” chemical works with memory — and points the way to treating PTSD.

Neuroscientists from Tulane and Tufts believe they have discovered how memories of fear get seared into the emotional center of the brain, potentially staying sharper even as other memories begin to fade.

In their study, published in Nature Communications, the researchers found that a neurotransmitter called norepinephrine — critical to the body’s “flight or fight” response — stimulates a specific group of neurons in the amygdala, causing them to pulse electrical discharges repeatedly.

That pulsing action changes the frequency of brain wave patterns, which in turn cause the fear memories to be created.

“Switching between different brain and behavioral states is necessary to adapt to an ever-changing environment,” the researchers wrote. 

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

Jeffrey Tasker

Those state changes are accompanied by prominent changes in neural activity — like the pulsing amygdala neurons.

“If you are held up at gunpoint, your brain secretes a bunch of the stress neurotransmitter norepinephrine, akin to an adrenaline rush,” Jeffrey Tasker, a professor of cell and molecular biology at Tulane, said

“This changes the electrical discharge pattern in specific circuits in your emotional brain, centered in the amygdala, which in turn transitions the brain to a state of heightened arousal that facilitates memory formation, fear memory, since it’s scary. This is the same process, we think, that goes awry in PTSD and makes it so you cannot forget traumatic experiences.”

The discovery could provide crucial insight into how to treat PTSD, depression, and other psychological disorders. 

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