Study Finds Underlying Mechanism That Consolidates Distant Fear Memories. Read On To Know

A remote terror memory is a recollection of traumatic events that occurred in the far past, which could be months or decades ago. Continue reading to learn more about the study's findings.

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Researchers have found the underlying mechanisms by which the brain consolidates distant fear memories, which may lead to the development of more effective interventions in the treatment of Post-traumatic stress disorder (PTSD), according to a study. 

A mouse study at the University of California, Riverside, found that distant fear memories established in the far past are permanently preserved in connections between memory neurons in the prefrontal cortex, or PFC.

A remote terror memory is a recollection of painful events that occurred in the far past, which might range from a few months to decades.

The findings were reported in the journal Nature Neuroscience.

What Impact Do Traumatic Events Have On The Functioning Of This Mechanism: 

"After traumatic events, prefrontal memory circuits are progressively strengthened, and this strengthening plays a vital role in how fear memories mature to stabilised forms in the cerebral cortex for permanent storage," lead researcher Jun-Hyeong Cho was quoted as saying by news agency PTI. 

"Other non-fear faraway memories could likewise be permanently retained in the PFC through a similar mechanism," Cho stated, PTI reported. 

According to the findings, the brain employs different processes to store recent vs distant fear memories. Previous research has revealed that while the hippocampus is involved in the creation of fear memory, it matures over time and becomes less reliant on it.

Much research has now demonstrated how recent fear memories are preserved, but how the brain consolidates distant fear memories remains unknown.

The researchers concentrated on the PFC, a region of the cerebral cortex previously linked to remote memory consolidation.

According to the PTI report, "we found a small set of nerve cells or neurons within the PFC, named memory neurons, were engaged during the initial traumatic event and were reactivated after the recall of remote fear memory," said Cho.

"When we selectively suppressed these memory neurons in the PFC, it prevented the mice from recalling far but not recent fear experiences, implying that PFC memory neurons play a vital role in the recall of remote fear memories," said Cho.

In the experiments, the mice were exposed to an unpleasant sensation in a setting known as a context. They become accustomed to associating the painful experience with the setting. When the mice were presented to the same setting a month later, they froze, demonstrating that they could recall distant fear memories.

The researchers discovered that connections, or synapses, between memory neurons in the PFC, known as prefrontal memory circuits, steadily strengthened with time following fear learning, allowing the PFC to store distant fear memories permanently.

The researchers then repeatedly exposed the mice to the identical fear-predictive context but without the unpleasant stimuli to erase the animals' remote fear memory. As a result, the terror response to the setting was lowered.

According to the report, "interestingly, the extinction of remote fear memory impaired the prefrontal memory circuits that had previously been reinforced to store the remote fear memory." Cho added. "Additionally, other interventions that hindered the strengthening of the PFC memory circuits also prevented the recall of remote fear memory," Cho explained.

Cho explained that dysregulation of fear memory consolidation in PTSD, which affects about 6% of the population at some time in their lives, can lead to chronic maladaptive fear.

"Because PTSD patients have fear memories from the far past, our work provides vital insight into creating therapeutic ways to reduce chronic fear in PTSD patients," he said, as per the report. 

Cho's team will then selectively damage prefrontal memory pathways to see if this reduces the recall of distant terror memories.

"We expect that the findings will contribute to the development of a more effective intervention in PTSD and other fear-related diseases," Cho added.

What Is Post-Traumatic Stress Disorder (PTSD): 

Post-traumatic stress disorder (PTSD) is defined by the National Institutes of Health (NIH), which is part of the U.S. Department of Health and Human Services, as a disorder that develops in some people who have witnessed a shocking, scary, or dangerous event. 

It is normal to feel scared during and after a terrible event. Fear causes several split-second changes in the body to assist defend against or avoid harm. This "fight-or-flight" response is a common reflex designed to keep a person safe. Almost everyone will have a variety of reactions to trauma, but the majority of people will heal spontaneously from the initial symptoms.

Those who continue to experience problems may be diagnosed with PTSD. People who have PTSD may feel stressed or frightened, even when they are not in danger.

Failure to recover after experiencing or witnessing a terrifying event characterises this disorder. The condition can last months or years, with triggers bringing back memories of the trauma and causing extreme emotional and physical reactions.

Nightmares or flashbacks, avoidance of circumstances that trigger the trauma, heightened responsiveness to stimuli, anxiety, or depression may be symptoms.

Treatment consists of many types of psychotherapy as well as symptom-management drugs.

(With Inputs From PTI)