Which part of the brain scares you?

Scientists have discovered where a primal emotion like fear is located in the mammalian brain.

Fear conditioning is a form of Pavlovian, or associative learning and is considered a model system for understanding human phobias, post-traumatic stress disorder and other anxiety disorders.

Using an imaging technique that enabled them to trace the process of neural activation in the brains of rats, University of Washington (UW) researchers have identified the region of the brain called the amygdala as the place where fear conditioning is encoded.

Neuroscientists previously suspected that both the amygdala and another brain region, the dorsal hippocampus, were where cues get associated when fear memories are formed.

But the new work indicates that the role of the hippocampus is to process and transmit information about conditioned stimuli to the amygdala, said Ilene Bernstein, study co-author.

Associative conditioning is a basic form of learning across the animal kingdom and is regularly used in studying how experience can change brain circuits.

The new work was designed to look for where information about conditioned and unconditioned stimuli converges in the brain as fear memories are formed, said a UW release.

The study was published in the Monday edition of PLoS One.