Initial Pattern of Brain Activity Recreated at Memory Recall
Researchers find they can predict what object study subjects are thinking about
THURSDAY, Dec. 22 (HealthDay News) -- People who are asked to recall a specific memory recreate the same pattern of brain activity as when the memory initially occurred, according to a report in the Dec. 23 issue of Science. Indeed, researchers found they were able to predict what object a person was thinking about roughly five seconds before they talked about it.
Sean M. Polyn, Ph.D., of the University of Pennsylvania in Philadelphia, and colleagues presented nine subjects with photographs of famous faces, locations or objects. Each category contained a list of 30 items. Subjects were asked to study the list to create a distinctive mental context for each category, and the researchers later asked them to recall as many of the photos as possible. Brain activity was measured during the study and recall periods using functional magnetic resonance imaging.
The investigators found a distinctive pattern of brain activity associated with each photo, which was recreated when the subjects were asked to recall the photo. The brain pattern of activity even preceded the subjects talking about them by about five seconds, and the researchers found that they could predict what the subjects were going to recall.
"As subjects search for memories from a particular event, their brain state progressively comes to resemble their brain state during the sought-after event, and the degree of match predicts what kinds of information the subject will retrieve," Polyn and colleagues conclude. "By providing a direct view of how subjects are cueing memory, the methods presented here constitute a powerful new tool that researchers can use to test and refine theories of how people mine the recesses of the past."