New study examines why there is typically a delayed response in the brain to a single stressful event. Chattarji Laboratory

BENGALURU, India, Dec. 28 (UPI) -- A team of scientists from India have studied how a single episode of severe stress can lead to delayed and long-term psychological trauma.

The research has shown that a single stressful incident can lead to increased electrical activity in the region of the brain known as the amygdala. The amygdala is a small, almond-shaped group of nerve cells located deep in the temporal lobe and plays a key role in emotional reactions, memory and decision making.


Changes in the amygdala have been linked to post-traumatic stress disorder, or PTSD.

The study, led by Sumantra Chattarji of the National Center for Biological Sciences and the Institute for Stem Cell Biology and Regenerative Medicine, inStem, found major changes in the structure of the nerve cells in the amygdala. Stress can cause the formation of new nerve connections, called synapses, in this part of the brain.

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The findings initially showed that a single instance of acute stress had no immediate effects on the amygdala in rats, but after 10 days, the rats began to show increased anxiety and delayed changes in the structures of the brain, including the amygdala. The increased anxiety is dependent on a molecule known as the N-Methyl-D-Aspartate Receptor or NMDA-R, an ion channel protein on nerve cells crucial for memory functions.

"We showed that our study system is applicable to PTSD," Chattarji said in a press release. "This delayed effect after a single episode of stress was reminiscent of what happens in PTSD patients. We know that the amygdala is hyperactive in PTSD patients. But no one knows as of now, what is going on in there."

Blocking the NMDA-R during stressful periods stopped the formation of new synapses and blocked the increase in electrical activity in the synapses.

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"So we have for the first time, a molecular mechanism that shows what is required for the culmination of events 10 days after a single stress," Chattarji said. "In this study, we have blocked the NMDA Receptor during stress. But we would like to know if blocking the molecule after stress can also block the delayed effects of the stress. And if so, how long after the stress can we block the receptor to define a window for therapy."

The study was published in Physiological Reports.