Experiencing a frightening event is something that people never forget. People remember such events for decades when other happy events become difficult to recall. Why does this happen? A team of neuroscientists has found the answer.
The team of experts from Tulane University School of Science and Engineering and Tufts University School of Medicine carried out experiments on mice to find the answer. They have been studying the formation of fear memories in the emotional hub of the brain - the amygdala - and now have a theory behind the mechanism.
The peer-reviewed study has been published in Nature Communications.
The researchers found that stress neurotransmitter norepinephrine, also known as noradrenaline, facilitates fear processing in the brain by stimulating a certain population of inhibitory neurons in the amygdala to generate a repetitive bursting pattern of electrical discharges.
This bursting pattern alters the frequency of brain wave oscillation in the amygdala from a resting state to an aroused state that promotes the formation of fear memories, said the neurologists.
Lead researcher and Tulane cell and molecular biology professor Jeffrey Tasker gave an example of armed robbery to explain it.
"If you are held up at gunpoint, your brain secretes a bunch of the stress neurotransmitter norepinephrine, akin to an adrenaline rush," professor Tasker was quoted as saying in a release published by Tulane University on the research.
"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," he added.
