Think about your most vivid memories—a favorite relative, the first day at a new school, a triumph (or failure) in sports. Odds are that most of them are associated with strong emotion.

Previous research has proven what common sense dictates: that the events we remember best are the ones that evoked a strong emotional reaction. We also remember negative information better than positive information. Now neuroscientists are beginning to reveal the brain circuits responsible for these intense memories.

At the Massachusetts Institute of Technology's Department of Brain and Cognitive Sciences, HHMI predoctoral fellow Elizabeth A. Kensinger, working with professor Suzanne Corkin, took functional magnetic resonance imaging pictures of volunteers' brains as they were learning various kinds of words. Some words were designed to have negative connotations but not be emotionally arousing, such as "sorrow" and "mourning." Other words, such as "rape" and "slaughter," were both negative and emotionally charged.

Learning the two categories of words tended to trigger activity in different regions of the brain. The nonarousing words lit up regions in the front of the brain and in the hippocampus, a structure in the brain's interior that is often active when the brain is learning or remembering new information. The arousing words, in contrast, lit up the hippocampus and the amygdala, a separate region of the brain involved in fear and other emotional responses.

"What this study shows is the network of regions involved in these memory tasks," says Kensinger. "Other techniques are needed to tell you which part is sending and which is receiving."

Kensinger and Corkin are now looking at whether arousing and nonarousing words with positive connotations produce the same patterns. They are also beginning to investigate whether the brains of younger people and older people work differently when dealing with emotionally wrought memories.

—Steve Olson

Download this story in Acrobat PDF format.
(requires Acrobat Reader)

Reprinted from the HHMI Bulletin,
Fall 2004, pages 14-23.
©2004 Howard Hughes Medical Institute