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Study Shows People Can Suppress Bad Thoughts

Research by neuroscientists shows that, with practice, people can suppress emotionally disturbing memories. Investigators say the finding could lead to therapies for individuals suffering from post-traumatic stress disorder. VOA's Jessica Berman reports.

Suppressed memory deals with a deliberate attempt to scrub a recurring, emotional memory from the mind. It is a controversial area. Investigators are routinely baffled when a person who witnessed a horrific crime cannot remember obvious details.

Now, researchers at the University of Colorado in Boulder have identified a brain mechanism that is activated when an individual attempts to suppress an unpleasant thought.

Researchers conducted a study of 16 participants in which they were asked to memorize 40 different pairs of pictures consisting of a neutral human face and a disturbing image, including a car crash, an electric chair or a wounded soldier.

The subjects were then placed in high-tech MRI brain scanner, and asked to think about, or not think about, the disturbing images. The MRI detected two brain regions that work together to suppress specific unpleasant memories. The regions are involved in visual recall, memory encoding and retrieval, and emotional response.

Researcher Brendan Depue is the study's lead author. Depue says the more the participants repeated the experiment, the more they suppressed memories of the unpleasant pictures. He and his colleagues have pinpointed the area of the brain where the suppression occurs.

"It looks like the prefrontal cortex, in which cognitive neuroscientists and psychologists basically consider the seat of effort to control of our behavior, basically is tuning-down or lessening the activity in brain areas that support memory representation," said Brendan Depue.

Depue says the findings may lead to treatments for those with post-traumatic stress disorder, in which people are haunted by memories of horrible events.

"Basically what we are trying to do is highlight the mechanisms or neural mechanisms in normal individuals that will actually lead to some insight possibly in that facet of the particular memory or thought disorder, in this case post-traumatic stress disorder," he said.

The results of the study on memory suppression are published in the current issue of the journal Science.