Researchers have identified nerve cells and a region of the brain behind this innate fear response. With a new technique that uses specially-engineered viruses to uncover the nerve pathway involved and has pinpointed a tiny area of the mouse brain responsible for the scent-induced reaction.

It's known as the "amygdalo-piriform transition area," or AmPir for short; the researchers were surprised to find that the fear response was so concentrated in this one small region of the olfactory cortex, a part of the brain responsible for perceiving odors.

Although humans do not show innate fear to predator odors, studying how mice respond to predator cues can help us learn about our own innate emotions and responses, Noble Laurate, Linda Buck said. On a general level, the rodent stress response looks a lot like our own.

"Understanding the neural circuitry underlying fear and stress of various sorts is very important, not just to understand the basic biology and functions of the brain, but also for potentially finding evolutionarily conserved neural circuits and genes that play an important role in humans," said Buck.

http://www.fredhutch.org/en/news/center-news/2016/03/fear-response-brain-region-identified.html