July 14, 2007	Saturday	Jamadi-us-Sani 28, 1428

LONDON: Brain scans showing how the mind buries painful memories could lead to revolutionary therapies for emotional problems such as anxiety, depression and post-traumatic stress disorder, psychologists said on Thursday.

The ability to suppress memories has long been a controversial issue in psychology, but researchers at the University of Colorado found that with practice, volunteers could learn to forget, a skill they used to block out images that were chosen to cause them distress.

Scans of the volunteers’ brains revealed that key neural circuits switched on when their minds were trying to banish painful memories, giving scientists a new level of understanding into how the brain works, and raising hopes that it may be possible to design drugs to help troublesome memories fade away. “We think we now have a grasp of the neural mechanisms at work, and hope the new findings and future research will lead to new therapeutic and pharmacological approaches to treating a variety of emotional disorders,” said Brendan Depue, lead scientist on the study at the University of Colorado at Boulder.

Volunteers were asked to memorise 40 different pairs of pictures. Each pair consisted of an emotionally neutral human face linked to a disturbing image, such as a car crash, an injured person or an electric chair. The participants were then placed in a magnetic resonance imaging brain scanner and shown only the facial images. While being scanned, half were asked to try to remember the distressing image linked to each face, while the other half were asked to do their utmost not to remember the associated image.

In a memory test afterwards, the psychologists found that 71.1% of participants asked to remember the painful images could still do so, compared with just 53.2 % of those told to banish the memory from their minds.

When the team checked the brain scans, they found that memories were suppressed in two stages. First, an area of the prefrontal cortex dampened down activity in a part of the brain linked to visual aspects of memory. Then, activity in a part of the brain linked to the emotional content of a memory was suppressed. None of the participants were advised on the best way to avoid thinking about the distressing images.

“By essentially shutting down specific portions of the brain, they were able to stop the retrieval process of particular memories,” said Mr Depue, whose work appears in the US journal Science. —Dawn/Guardian News Service