Pupils dilated, blood rushing, heart pounding, adrenaline pumping; and it all happens in a matter of seconds.

The fight or flight reflex, a psychological and physical reaction to fear, is the cause of these symptoms. Fear is caused by anything that overactivates a part of the brain called called the amygdala.

Dr. James McGaugh, professor of neurobiology and behavior at the University of California, said, “The amygdala gets activated by emotional arousal, including that induced by pleasant as well as unpleasant experiences.” He explained that fear can be induced not only by unexpected negative experiences, but also by experiences that are associated with past frightening experiences.

When the amygdala encounters a stimuli, it “determines the significance of the stimulus and triggers emotional responses,” according to Serendip Studio, a website for student research papers from Bryn Mawr College.

The emotional response changes the way the body’s organs and glands work. The adrenal gland then releases adrenaline and cortisol to trigger the fight or flight reflex, McGaugh explained.

Fear is learned through “association of cues with fearful conditions,” McGaugh said. Every time the fight or flight reflex is triggered, the brain begins to associate the situation with fear, so the next time the situation comes up, the brain and body will be ready, McGaugh explained.

Being a learned emotion, it is possible to unlearn fear by “learning that something you thought to be dangerous is not,” McGaugh said.

Unlearning fears can take a long time, according to an article on Psychology Today.

The study showed that mice, when exposed to “short yet intense burst of stress-provoking stimuli,” eventually learned not to be afraid of the stimuli. However, unlearning their fear took 10 times as long as it took to learn the fear.

The human implications? A “similar model in human treatment might prove equally successful,” the article predicts.

In this method, a patient is exposed to multiple intense, short exposures to the conditions in which the fear was learned. This treatment is known as exposure therapy; however, traditional exposure therapy is not usually as prolonged as it should be.

Although this has been the best method of overcoming fear for decades, nearly half of all exposure therapy patients relapse, according to an article on the New Republic.

The article explains a new treatment for fear that Merel Kindt, a professor of clinical psychology at the University of Amsterdam, has found to be more effective than traditional exposure therapy.

In this treatment, Kindt pushes the patient to relive every detail of the experience that caused them fear, focusing in on the source of the fear, the article explained.

After a few minutes of reliving the fear, Kindt stops and has the patient take a single dose of propranolol, a drug usually prescribed for heart disease.

All of Kindt’s patients, so far, have had total neutralization of their fear; however, the long term effects of this treatment have not been studied as the treatment has been available for less than 10 years.

As science continues to find new ways to treat fear, Kindt “holds out the promise of a simple treatment—maybe even a permanent cure.”