Clearing Fear From the Mind

Nov. 6, 2002 -- Banishing fears may be as simple as switching on the "all-clear" signal in the brain. Researchers say they've isolated a trigger in the brain that quells fear and could one day lead to new treatments for anxiety disorders.

A new study shows that stimulating a particular area in the front part of the brain silenced a normally fearful response among rats by mimicking the brain's own safety signal. The findings appear in the Nov. 7 issue of Nature.

Researchers say the study also reinforces the long-held notion that overcoming fear involves creating a new memory that inhibits the learned fear response.

Study author Gregory Quirk, PhD, of the Ponce School of Medicine in Puerto Rico, and colleagues say rats normally freeze with fear after they've been conditioned to associate a tone with an electric shock. But when a portion of the rats' brain known as the infralimbic area was simulated and paired with the fear-inducing sound, the rats showed little fear and didn't freeze up.

Researchers say this area of the brain produces the same activity as when a fear has been extinguished, like a built-in "all-clear" signal. The more activity in this area, the less the rats froze when they heard the tone. Later, the rats seemed to forget all about their fear of the tone and didn't require the stimulation, which suggests that this part of the brain plays a role in abolishing fears and creating feeling of safety.

The study authors say the frontal area of the brain studied is known to reach into areas deep in the brain for the memory of fear. They suggest that increasing activity in this frontal area strengthens the new, safe memories associated with a particular trigger and inhibits the memory of fear deep in these regions.

If additional studies confirm these results, researchers say antianxiety medications could be developed that boost activity in the infralimbic frontal area and help people with anxiety disorders overcome irrational fears faster and more easily.