Scientists have known that newly acquired, short-term memories are often fleeting. But a new study in flies suggests that kind of forgetfulness doesn't just happen. Rather, an active process of erasing memories may in some ways be as important as the ability to lay down new memories, say researchers who report their findings in the February 19th issue of the journal Cell.
"Learning activates the biochemical formation of memory," says Yi Zhong of Tsinghua University and Cold Spring Harbor Laboratory. "But you need to remove memories for new information to come in. We've found that forgetting is an active process to remove memory."
The researchers have traced that process to a molecular pathway including a small protein known as Rac. When that mechanism is blocked, flies hold on to newly acquired memories for longer than they otherwise would.
At the psychological level, scientists have debated about the reasons we forget. One theory held that new memories are simply unstable and evaporate over time. On the other hand, some thought that interference caused earlier short-term memories to be overridden as new information comes in.
Now it appears that those competing notions are, at the molecular level at least, one and the same.