From Nature:
People can will themselves to forget traumatic or emotional scenes, researchers have found. When the brain conducts such deletions, brain regions that process vision and emotion go quiet.
Knowing that memories can be consciously suppressed, and the brain areas involved, could point to therapies for people who struggle to forget traumatic experiences, such as those with post-traumatic stress disorder or obsessive-compulsive disorder. Neuroscientist Brendan Depue, of the University of Colorado at Boulder, wanted to find out what goes wrong in the brains of sufferers of such conditions.Previous studies have shown that people can suppress memories of words. But to make the test relevant to traumatic memories, Depue’s team included an emotional component. They showed volunteers pairs of pictures: one of a face, and one to evoke an emotional response — a car crash, or a wounded person. Once the subjects had learned to associate the image pairs, they were shown the faces alone, and either told to think of the associated picture or to try not to think about it. The subjects’ brains were less active when they deliberately tried not to think of the associated picture, the team found.
More here.