Anatomy of Fear

How does your brain form its most significant memories? Studies of fear in rats have helped us learn much here. Although people and rats fear different things, the manner in which the rat and human brain and body respond to danger is similar. Because fear is at the core of many human pathologies, from panic attacks to posttraumatic stress disorder, breakthroughs in understanding the brain's fear system may lead to new ways to treat these disorders.

The core of the brain's fear system is found in a region called the "amygdala". This region receives information from all the senses and in turn controls the various networks that inspire the speeding heart, sweaty palms, wrenching stomach, muscle tension and hormonal floods that characterize being afraid.

A rat's amygdala responds to natural dangers (rats fear cats without having to learn to do so) and learns about new dangers (sounds, sights and smells that occur in anticipation of cats and other threats). It is through studies of the way the brain learns about stimuli, such as the sounds that precede danger, that our systems for learning about fear, and memory as a whole, have been elucidated through rat studies.