A recent study published in Nature Communications has uncovered how our brains handle fear memories in two contradictory ways: making it hard to forget these memories, but also challenging to recall them precisely.
Researchers from Sony Computer Science Laboratories, Inc., ATR Computational Neuroscience Laboratories, and the University of Tokyo collaborated on this innovative research to reveal new insights into how fear memories are processed over time.
The researchers were interested in how the brain initially remembers fear-inducing experiences. They discovered that right after experiencing something scary, like a car accident, our brain creates broad, generalized memories.
These are not specific to the details or the sequence of the event. For example, after a car accident, someone might feel anxious or fearful around all cars, not just in situations similar to their accident.
This happens because the brain is using associative memory, where it connects fear to multiple triggers, regardless of when or how they happened.
To study this process, the researchers used functional Magnetic Resonance Imaging (fMRI) to observe brain activity in participants who were exposed to simulated scary events.
With the help of machine learning algorithms, they tracked changes in brain activity patterns. What they found was that, initially, the hippocampus—an area of the brain crucial for memory formation—was active in creating these broad fear associations.
However, something interesting happened over time. By the next day, the way the brain handled these fear memories began to change. A different part of the brain, the dorsolateral prefrontal cortex, took over from the hippocampus.
This brain region helped turn the broad, associative memories into more precise, timeline-based memories known as episodic memories. Essentially, the brain narrowed the scope of the fear, linking it more specifically to the original event sequence.
This change in how fear is stored could explain why fear memories are hard to forget, yet difficult to remember with specific details.
The brain’s gradual shift from broad, generalized memories to more specific, timeline-focused memories helps reduce unnecessary fear, refining the memory over time.
The study also explored why some people, particularly those with high anxiety or a higher risk of developing Post-Traumatic Stress Disorder (PTSD), have trouble with this transition. In people with high anxiety levels, the dorsolateral prefrontal cortex doesn’t seem to fully take over this integration role.
This means that their brains remain stuck in an early stage of fear memory, continuing to rely on broad, associative memories rather than transitioning to more specific ones.
As a result, these individuals may continue to feel strong, overwhelming fear linked to many different cues, which is a hallmark of PTSD.
Dr. Aurelio Cortese from ATR Computational Neuroscience Laboratories, one of the lead researchers, explained that the study highlights how the brain prioritizes and processes fear memories differently over time.
This dynamic balancing between brain regions could help explain why some individuals develop PTSD while others do not.
Dr. Ai Koizumi, from Sony Computer Science Laboratories, Inc., and one of the study’s senior authors, noted that these findings offer fresh perspectives on treating PTSD by focusing on how the brain integrates specific memories after a traumatic experience.
The research opens up new possibilities for developing PTSD interventions that aim to strengthen the brain’s ability to shift fear memories from broad associations to specific, episodic events.
This could potentially help individuals better manage their fear responses, making the memories less intrusive and less likely to interfere with daily life.
In summary, this study provides new insights into how fear memories are stored and recalled in the brain. By understanding how the brain gradually shifts from broad, generalized fear memories to more specific, time-based ones, researchers may be able to find better ways to treat disorders like PTSD.
If you care about mental health, please read studies about 6 foods you can eat to improve mental health, and B vitamins could help prevent depression and anxiety.
For more information about mental health, please see recent studies about how dairy foods may influence depression risk, and results showing Omega-3 fats may help reduce depression.
The research findings can be found in Nature Communications.
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