Scientists found that two key regions of the brain - the amygdala and the hippocampus - become activated when a person is anticipating a difficult situation. The researchers studied the brain activity of 36 healthy volunteers using functional magnetic resonance imaging, which produces high-contrast images of human tissue.
They began by showing the volunteers two kinds of signals. One was neutral, but the other indicated that some type of gruesome picture was soon to follow, such as explicit photos of bloody, mutilated bodies. Thirty minutes after the researchers had shown dozens of violent images, they quizzed study participants on how well they remembered the pictures they had just seen.
"We found that the more activated the amygdala and hippocampus had been during the anticipation of the pictures, the more likely it was that a person would remember more of them right away," says Nitschke a UW-Madison assistant professor of psychiatry and psychology.
Two weeks after the experiment, scientists met with the study subjects again to measure how well they remembered the same disturbing images. This time, they found that people who best remembered them had shown the greatest amygdala and hippocampus activity during the picture-viewing exercise two weeks before. That suggested that those subjects' brains had already started converting short-term memories of the images into longer-lasting ones.
"Our study illustrates how the power of expectancy can extend to memory formation as well," says Nitschke. "Just the expectation of seeing something bad can enhance the memory of it after it happens."
The findings of the brain-imaging study, have important implications for the treatment of psychological conditions such as post-traumatic stress disorder (PTSD) and social anxiety, which are often characterized by flashbacks and intrusive memories of upsetting events.
MEDICA.de; Source: University of Wisconsin-Madison