© U.S. Air Force
Scientists have found the part of the brain that inhibits fear, a breakthrough that could help with the treatment of PTSD and other psychiatric issues.

A team from Texas A&M University identified a region of the thalamus, called the nucleus reuniens, which inhibited fear in rats. Their findings were published in Nature Communications.

Lead researcher Stephen Maren, a psychological and brain sciences at Texas A&M University, said the finding "points us to parts of the brain that are important for the inhibitory function of fear, which could be an avenue to new drugs, therapies, and interventions for psychiatric disorders."

Psychiatric disorders are currently treated with drugs that target all of the brain's neurons. A more targeted approach would be more beneficial.

Workings of the brain
© Nature Communications
Before now, the nucleus reuniens was understood to act as a transmitter for sensory information sent from the periphery of the brain to its cortex.

Post-Traumatic Stress Disorder (PTSD) can be treated with extinction therapy, where patients are repeatedly exposed to their trauma in a clinical setting. While effective, this form of treatment can see patients relapse.

© Nature Communications
Extinction therapy played a part in the Texas A&M research. Scientists exposed rats to noise paired with mild shocks in their feet so as to create fear. They then exposed the rats to the noise repeatedly to suppress their fear.

Next, they inactivated the nucleus reuniens, and found the rats were unable to suppress fear.

They then began to selectively silence neurons in the prefrontal cortex that were projecting to the reuniens. Inhibiting these also made it impossible for the rats to suppress fear.

Scientists now hope to translate the breakthrough from the research on rats into developing more targeted treatment for psychiatric disorders in humans.