Brain May Be Able to Suppress Memories

Experiment suggests humans can will themselves to forget.

By E.J. Mundell
HealthDay Reporter
Thursday, July 12, 2007; 12:00 AM

Copyright © 2007 ScoutNews, LLC. All rights reserved.

THURSDAY, July 12 (HealthDay News) -- Unwanted memories might be willfully banished from human consciousness, according to a new study that also outlines just how the brain might accomplish this feat.

The research, published in the July 13 issue of Science, may help end the debate as to how much control people have over their memories, scientists say.

It might also lead to treatments for individuals battling psychological ills tied to past traumatic events -- illnesses such as post-traumatic stress disorder (PTSD), chronic anxiety, depression, phobias and obsessive-compulsive disorder.

"These are people who have problems in clearing their consciousness -- at that moment in time -- of these reoccurring traumatic events," explained lead researcher Brendan Depue, a graduate student in the department of psychology at the University of Colorado, Boulder.

Depue stressed that the idea of suppressed memory does not include the controversial notion of "repressed memory," where the mind suddenly recalls a past trauma after a period of years or even decades.

Instead, his team looked at the ability of humans to consciously erase a memory they've only just made.

To do so, they presented healthy adults with 40 pairs of pictures. One picture in each pair depicted a person's face and was the "cue" photo. It was matched with a "target" image -- usually a picture of a disturbing, emotion-laden scene, such as a wounded soldier, an empty electric chair, or a grisly car crash.

Participants were shown these cue-target picture pairs until they appeared to know them all by heart.

In the second phase of the experiment, participants were hooked up to a functional MRI (fMRI) brain scanner and then presented with only the "cue" photos of people's faces. They were instructed that if the photo was contained within a green border, this meant that they should try and think of the matched target picture. However, if it was presented inside a red border, that meant they should try not to think of the matched picture.