While suffering from pathological anxiety is unbearable, a discovery could soon help sufferers.
- Anxiety disorders are twice as prevalent in women as in men.
- They affect approximately 15-20% of the population at some point in their lives.
Researchers from Inserm discovered the brain mechanism involved in the response to danger, a breakthrough for people suffering from morbid anxiety.
Avoidance study
In humans and animals, the defensive response is a mechanism in our brain that allows us to react effectively to danger. “One of the main defensive responses is avoidance. But excessive avoidance in the absence of real threat is a marker of anxiety-related pathologies, and the neural mechanisms that cause it were up to here still misunderstood”, explain the researchers in the preamble.
To overcome this lack of data, Cyril Herry’s team at the Neurocentre Magendie worked on mice, placing them in a maze made up of two compartments. In one of them, an unpleasant sound was emitted, associated with a threat. The mouse then had the opportunity to flee into the other compartment, thus stopping the sound associated with danger.
To understand the role of the amygdala and prefrontal cortex in this avoidance strategy, the researchers temporarily disabled these two regions in mice during the experiment. They then used optogenetic approaches coupled with recordings of the electrical activity of neurons, in order to manipulate and observe in real time at the neuronal level the behavioral changes that were occurring. The result is significant: when the mouse received the auditory stimulus, regardless of the deactivated region (amygdala or prefrontal cortex), the avoidance response was strongly disturbed. “This demonstrates the key role of these two brain regions, both in recognizing a threat, and in the avoidance response,” specifies Inserm.
Interdependence of two regions of the brain
Furthermore, the researchers discovered that the prefrontal cortex not only associates sound with a threat, but also controls the action to come. Indeed, one second before the decision to flee is made in mice, the researchers observed an activation of neurons in the prefrontal cortex.
Scientists have thus “revealed the interdependence of two brain regions, the basolateral amygdala and the dorsomedial prefrontal cortex, in the mechanism” avoidance, concludes Inserm in a press release. “These new data, published in the journal Nature, open up new avenues for treating patients with anxiety disorders, by directly targeting the regions of the brain that cause them.”
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