While the brain region known as amygdala has long been associated with panic attacks or fear, researchers have now identified other areas of the brain that can also be linked with such sensations.
"This research says panic, or intense fear, is induced somewhere outside of the amygdala. This could be a fundamental part of explaining why people have panic attacks," said John Wemmie, senior study co-author and associate professor of psychiatry at Iowa University.
Other regions-such as the brainstem, diencephalon, or insular cortex, outside of the amygdala, an almond sized area-could sense the body's most primal inner signals of danger when basic survival is threatened, the journal Nature Neuroscience reports.
These pathways, discovered by Iowa medical scientists, could open the way to better treatments for panic attacks, post-traumatic stress syndrome, and anxiety-related conditions, according to an Iowa statement.
One of the patients, a woman in her 40s known as SM, involved in the tests, has an extremely rare condition called Urbach-Wiethe disease that damages the amygdala and kills all fear.
SM has not felt any terror since getting the disease in her adolescence, after being confronted with snakes, spiders, horror movies, haunted houses, and other external threats, even being held up at knife point.
But within minutes of being made to inhale a panic inducing dose of carbon dioxide CO2), by doctors at the Iowa University, SM cried for help, overwhelmed by the sensation of suffocation.
Researchers tested SM and other amygdala-damaged patients with a gas mix containing 35 percent carbon dioxide, one of the most commonly used lab experiments for inducing a brief bouts of panic attacks, to determine other brain areas linked with fear.