Why are we afraid? What brain mechanisms do we have fear and how does our primer work to overcome them?
Although in mice, researchers of the Sainsbury Wellcome Center (United Kingdom) have managed to reveal the precise mechanisms of the brain that allow animals to overcome instinctive fears.
Posted in ‘Science‘, the study in mice could have implications for the development of therapies for fear -related disorders, such as phobias, anxiety and post -traumatic stress disorder (PTSP).
The team, led by Sara Mederos and the teacher Hafer SonjaThey mapped how the brain learns to suppress responses to perceived threats that are harmless over time.
“Human beings are born with instinctive fear reactions, such as responses to strong noise or objects that quickly approach,” explains Mederos. However, we can cancel these instinctive responses through experience, such as children who learn to enjoy fireworks instead of fearing their strong noises. We wanted to understand the brain mechanisms that underlie these types of learning ».
Using an innovative experimental approach, the team studied mice exposed to a growing shadow that simulated an air predator approaching. Initially, the mice were sought to refuge by meeting this visual threat. However, with repeated exposure and without real danger, mice learned to stay calm instead of escaping, which provided researchers with a model to study the suppression of fear responses.
The study discovered that a part of the brain called VLGN helps control the fear of remembering past experiences. As the VLGN receives signs of the view, the researchers studied their role in learning to not be afraid of something we see. They found that the visual areas of the brain are important to learn not to fear, and that Vlgn keeps those memories. In addition, if they deactivated visual areas, animals did not learn to control fear, but once learned, they no longer need those active areas.
Coronal, 3D, sagittal and superior views of brain sections that show the projections of visual areas higher than the ventrolateral geniculate nucleus.
Sara Mederos, Sainsbury Wellcom Center
“Our results challenge traditional ideas about learning and memory,” says Professor Hofer, main author of the study. Although the cerebral cortex has been considered for a long time the main center of the brain for learning, memory and behavioral flexibility, we discover that the subcortical VLGN and not the visual cortex is the one who really stores these crucial memories. This neural route can provide a link between the neocortical cognitive processes and the ‘instinctive’ behaviors mediated by the brain trunk, allowing animals to adapt their instinctive behaviors ».
The implications of this discovery go beyond the laboratory. «Our findings could also help advance our understanding of what goes wrong in the brain when the regulation of fear responses is altered in conditions such as phobias, anxiety and PTSD. Although instinctive fear reactions to predators can be less relevant to modern humans, the brain path that we discover also exists in humans, ”says Hofer. “This could open new ways to treat fear disorders by stimulating VlGN circuits or localized endocannabinoid systems.”
The team now plans to collaborate with clinical researchers to study these brain circuits in humans, with the hope of one day developing new treatments and directed for poorly adaptive fear responses and anxiety disorders.
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