The brain is a complex system made of billions of neurons (nerve cells) and thousands of connections that relate to every human feeling, including one of the strongest emotions, fear. Researchers have started using computer models of the brain to study the connections.

Most neurological fear studies have been rooted in fear-conditioning experiments. Now University of Missouri (U-M) researchers are using computational models to study the brain’s connections.

Guoshi Li, U-M electrical and computer engineering doctoral student, has discovered new evidence on how the brain reacts to fear, including important findings that could help victims of Post-Traumatic Stress Disorder (PTSD, an anxiety disorder associated with serious traumatic events).

“Computational models make it much easier to study the brain because they can effectively integrate different types of information related to a problem into a computational framework and analyse possible neural (bearing on nerve cells) mechanisms from a systems perspective,” Mr. Li said.

From previous experiments, scientists have found that fear can subside when overcome with fear extinction memory, but it is not permanently lost.

Fear extinction is a process in which a conditioned response to a stimulant that produces fear gradually diminishes over time as subjects, such as rats in auditory fear experiments, learn to disassociate a response from a stimulus.

One theory has concluded that fear extinction memory deletes fear memory, and another concluded that fear memory is not lost, but is inhibited by extinction memory as fear can recover with the passage of time after extinction, says an U-M release.

For PTSD victims, the fear circuit is disrupted and they cannot retrieve the fear extinction memory. However, the fear extinction memory exists, so the fear memory dominates every time when the victims get a fear cue.

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