Researchers reveal brain mechanisms that help you overcome instinctive fear

Researchers at UCL's Sainsbury Wellcome Center (SWC) have published precise brain mechanisms that allow animals to overcome instinctive fear. It's been released today Sciencestudies in mice may have an effect on developing medications for fear-related disorders such as phobias, anxiety, and post-traumatic stress disorder (PTSD).

A research team led by Dr. Sarah Medelos and Professor Sonya Hofer mapped how the brain learns to suppress responses to perceived threats that prove harmless over time.

“Humans are born from instinctive fear responses such as loud, loud noise responses and rapid approach objects,” explains Dr. Mederos, a researcher at SWC's Hofer Lab. “But we can negate these instinctive responses through experience. It seems that children are learning to enjoy fireworks rather than fearing loud bangs. I wanted to understand the brain mechanisms underlying shape learning.”

Using an innovative approach, the team studied mice and presented an overhead enlarged shadow that mimics approaching aviation predators. Initially, mice searched for shelter when they encountered this visual threat. However, due to repeated exposure and no actual danger, mice learned to remain calm rather than escape, providing researchers with a model to study inhibition of fear responses.

Based on previous research in Hofer Lab, the team states that a brain region called the ventrolateral geniculate nucleus (VLGN) can suppress fear responses when active and track knowledge of previous experiences of threats. I knew it. The VLGN also receives strong input from visual regions of the cerebral cortex, so researchers investigated whether this neural pathway played a role in learning not to fear visual threats.

This study uncovered two important components in this learning process. (1) Certain regions of the visual cortex have proven essential for the learning process, and (2) brain structures called the ventrolateral geniculate nucleus (VLGN) store these learning-induced memories.

“We found that animals were unable to learn to suppress fear responses when the visual regions of certain inactivated cortex became inactive. However, animals already flee. After learning to stop, the cerebral cortex was no longer necessary,” explained Dr. Medelos.

Our results challenge traditional views on learning and memory. Although the cerebral cortex has long been considered a major center for brain learning, memory and behavioral flexibility, we have discovered that the visual cortex does not actually store these important memories . This neural pathway provides a link between cognitive neocortical processes and brainstem-mediated behaviors “wired to hardlines” allowing animals to adapt their instinctive behavior. ”

Professor Sonja Hofer, Senior Author of the Study

The researchers also revealed the cellular and molecular mechanisms behind this process. Learning occurs due to increased neural activity in specific VLGN neurons and is triggered by the release of endocannabinoids. It is a brain messenger molecule known to regulate mood and memory. This release reduces inhibitory input to VLGN neurons, increasing activity in this brain region when encountering visual threat stimuli and suppresses fear responses.

The implications of this discovery are extended beyond the laboratory. “Our findings can also help us to better understand what is wrong in our brain when conditions like phobia, anxiety, PTSD and other impaired regulation of our fear response. We are We discovered that it exists in humans too,” explains Professor Hofer. “This could open new avenues for treating fear disorders by targeting the VLGN circuit or local endocannabinoid system.”

The research team is currently planning to work with clinical researchers to study these brain circuits in humans, one day developing new targeted therapies for unfortunate fear responses and anxiety disorders. I'm hoping for this.

This study was funded by the Sainsbury Welcome Centre Core Grant from the Gatsby Charity Foundation and Welcome (090843/f/09/z). Wellcome Investigator Award (219561/z/19/z); EMBO Post-Doctoral Fellowship (EMBO ALTF 327-2021) and Wellcome Early Career Award (225708/Z/22/Z).