Why do memories of fear leave such strong imprints in the brain?

An individual’s memories of experiences and events are not all processed the same way within the brain. Some memories are fleeting. Some memories may linger but are eventually extinguished. Some memories are permanently stored, and recalled when triggered. Why is there such variability in the consolidation of memories?

The formation of memories in response to fear has been of particular interest to a team of neuroscientists from the Tulane University School of Science and Engineering, New Orleans, and Tufts University School of Medicine, Boston. The scientists believe that they may have identified the mechanism for the processing of fear-associated memories in an area of the brain which is known to be associated with processing and experiencing emotions –- the amygdala.

Tulane cell and molecular biology professor Jeffrey Tasker led the research, along with his PhD student Xin Fu. They found that the processing of fear is mediated by the stress neurotransmitter norepinephrine, also known as noradrenaline. It stimulates specific inhibitory neurons in the amygdala, generating repetitive bursts of electrical activity.

The burst pattern of electrical discharges changes the frequency of oscillation of brain waves in the amygdala. It takes the amygdala from a resting state to an aroused state. That transformation facilitates the consolidation of memories associated with fear. 

Tasker explains these events using armed robbery as an example. “If you are held up at gunpoint, your brain secretes a bunch of the stress neurotransmitter norepinephrine, akin to an adrenaline rush,” he says in a statement. “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 study is published in the journal Nature Communications.

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About the Author

Dr. Faith Coleman

Faith A. Coleman MD
Dr. Coleman is a graduate of the University of New Mexico School of Medicine and holds a BA in journalism from UNM. She completed her family practice residency at Wm. Beaumont Hospital, Troy and Royal Oak, MI, consistently ranked among the United States Top 100 Hospitals by US News and World Report. Dr. Coleman writes on health, medicine, family, and parenting for online information services and educational materials for health care providers.

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