A neurotransmitter has been found essential to retrieving very specific memories, promising to improve the understanding and treatment of psychological conditions such as post-traumatic stress disorder and depression.

Researcher Stephen Thomas and colleagues at the University of Pennsylvania School of Medicine in Philadelphia have found that norepinephrine is critical for retrieving the memories but not for storing new ones.

Norepinephrine is a neurotransmitter—a chemical that communicates messages between neurons—that is similar to adrenaline.

Because it is released during emotional or exciting situations, it’s been thought to play a critical role in people’s ability to remember emotional events in general.

More here.