Neuroscientists are beginning to understand how the brain controls its memory center.
By reflexively rushing to pick up a hot frying pan that has fallen from the stove, you can pull your hand back at the last moment and avoid a burn. This is due to the ability of the brain's executive control center to intervene and break the chain of automatic commands. New evidence suggests the same is true for reflex memories - which means the brain can stop spontaneously recalling painful memories.
Memories reside in the brain as interconnected data. As a result, one memory can pull another with it, and eventually, without any conscious effort, the memories begin to bubble on the surface. “Having received a reminder, consciousness hastens to do us a favor by evoking the memory associated with it. But sometimes it turns out to be something we would rather not think about,”says Michael Anderson, a neuroscientist at the University of Cambridge.
But people are not powerless about this process. Previous imaging studies suggest that the frontal lobes of the brain can inhibit the activity of the hippocampus, an important memory organ, and thereby stop the retrieval of memories. To further explore this issue, Anderson and colleagues examined what happens when the hippocampus is suppressed. They asked 381 students to memorize pairs of loosely related words. Then they were shown one word and asked to remember the second or, conversely, asked to try not to think about the second word. From time to time in between these exercises, they were shown unusual pictures, such as a peacock in a parking lot.
According to Nature Communications, the study participants' ability to consistently recall peacocks and other strange pictures was 40% lower when they were asked to suppress the memory of words before or after the pictures they saw, compared to experiments when they were asked to recall words. The results support the existence of a memory control mechanism and suggest that trying to suppress a particular memory has a negative effect on memory as a whole. The researchers dubbed this phenomenon the "shadow of amnesia" because it supposedly blocks the memory of unrelated events that occurred while the hippocampus was inhibited. Experts not included in this study say the findings may explain why people who have experienced a traumatic event and try to forget about itdo not remember things in everyday life well.
If temporary amnesia is ruled out, memory suppression can be a useful skill, Anderson says. For this reason, he and his colleague Ana Catarino are studying whether people can be taught the art of suppressing memories. They are conducting an experiment in which they monitor participants' brain activity in real time and provide verbal feedback on how much the hippocampus has been suppressed. They hope to get a clue on how to learn to selectively forget the past. Such a skill could significantly ease the pain of people with PTSD.