Memories do indeed light up the corners of our mind, just as the songwriter said.
Scientific evidence for this notion comes from studies using magnetic resonance imaging to examine the living human brain. These studies show that certain brain areas "light up" as an individual is learning information.
Scientists had previously established that people remember emotionally charged events and facts better than neutral ones. Now researchers at MIT have discovered that memories with an element of arousal or excitement are remembered by a different area of the brain--the amygdala--from memories of a calmer nature, which are remembered by the prefrontal cortex. These findings, published in the journal PNAS Online on Feb. 23, are an important step in understanding how the brain makes memories. Scientists hope this information will one day lead to a treatment for memory loss and learning impairments.
For the study, Elizabeth Kensinger, a researcher in MIT's Department of Brain and Cognitive Sciences, and Suzanne Corkin, professor of behavioral neuroscience in the same department, asked 14 men and 14 women to "learn" 150 words related to events, while the participants brains were being scanned in an fMRI (functional magnetic resonance imaging) procedure. Some of the words represented arousing events, such as "rape" or "slaughter." Others were nonarousing, such as "sorrow" and "mourning."
They then tested the participants to see which of the words they remembered having been shown. Kensinger and Corkin found that on average, people remembered more of the arousing words than the others. They also discovered that the hippocampus was active while all the words were learned, but the amygdala and prefrontal cortex were active only for learning the arousing and nonarousing words, respectively.
"This result suggests that stress hormones, which are released as part of the response to emotionally arousing events, are responsible for enhancing memories of those events," said the researchers. "We think that detailed cognitive processing may underlie the enhanced memory for the nonarousing events."
The next steps in this research will be a similar study using words denoting positive events, both arousing and nonarousing, and a study to examine the fate of emotional memory in aging.
The researchers used the brain scanning facilities at the Athinoula A. Martinos Center for Biomedical Imaging, a collaborative research center founded by MIT, Massachusetts General Hospital and Harvard Medical School. The National Science Foundation and the National Institute on Aging funded the Kensinger and Corkin study.
A version of this article appeared in MIT Tech Talk on March 3, 2004.
