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Anxiety disorders like post-traumatic stress disorder can develop after an overly stressful experience. Exposure therapy is a common treatment for those who suffer from an anxiety disorder because the patient tries to overcome their dear in a safe environment.

According to a new study, neuroscientists have determined how this form of therapy lessons fear in neurons. 

"Exposure therapy in humans does not work for every patient, and in patients that do respond to the treatment, it rarely leads to a complete and permanent suppression of fear," senior author, Leon Reijmers, Ph.D., assistant professor of neuroscience at Tufts University School of Medicine, said in a news release. "For this reason, there is a need for treatments that can make exposure therapy more effective."

For the study, mice experienced a traumatic experience by being placed in a box to instill fear. One group of mice did not receive exposure therapy while another group did receive it to help with their fear response. 

For the exposure therapy, researchers placed the mice receiving the therapy into a box without experience a fear-inducing event in order for their fear response to less, also known as a fear extinction method. 

Researchers found that the mice receiving exposure therapy had more perisomatic inhibitory synapses in the amygdala, a region in the brain, than the mice who were not receiving the therapy.  

According to Tufts, "Perisomatic inhibitory synapses are connections between neurons that enable one group of neurons to silence another group of neurons."  

Researchers said the increase in these synapses was found near fear neurons which after exposure therapy became silent. 

"We showed that the remodeling of perisomatic inhibitory synapses is closely linked to the activity state of fear neurons," said first author, Stéphanie Trouche, Ph.D., a former postdoctoral fellow in Reijmers' lab at Tufts. "Our findings shed new light on the precise location where mechanisms of fear regulation might act." 

Trouche added, "We hope that this will lead to new drug targets for improving exposure therapy." 

The findings are published in the journal Neuron.