Brain cells compete to promote or suppress traumatic memories, scientists say

Researchers from the National Institute on Alcohol Abuse and Alcoholism (NIAAA) say they have discovered that brain cells actually compete to either suppress or promote traumatic memories, the National Institutes of Health reported on May 26. 

These findings were revealed in a study conducted on mice in order to better understand human conditions such as post-traumatic stress disorder (PTSD), anxiety disorders, and even associated mental health issues including alcohol abuse which can arise from a traumatic event. 

NIAAA Director Dr. George F. Koob explained that over time the distress that comes with experiencing trauma can subside overtime for some causing trauma memories to be less triggering. 

"For other people who have experienced trauma, however, the fearful memories persist, and can adversely affect their ability to engage in everyday activities. These fearful memories can continue even though a person may repeatedly encounter cues associated with a traumatic experience without harm. The current study sheds light on the specific neural circuits that may underlie the persistence and the extinction of fearful memories associated with trauma," said Koob.

Researchers examined clusters of neurons packed within the section of the brain of the mouse which regulates emotion and a foot shock method to create "traumatic memories" for the animals. 

Scientists say they observed the neuron clusters compete with one another through a process they call mutual synaptic inhibition which determines the strength of each memory prompting a unique level of defensive behavior to react to said memory. 

Andrew Holmes, Ph.D., chief of NIAAA’s Laboratory of Behavioral and Genomic Neuroscience said the persistence of disturbing memories is one of the hallmarks of mental illnesses like PTSD. 

"Our findings identify a neural circuit within the amygdala that orchestrates activity across a broad brain network to exert a powerful influence over the ability to switch between high and low fear states. This finding now raises interesting questions about whether dysfunction of this brain system could contribute to the marked individual differences in risk for trauma-related psychiatric disorders," Holmes said.