The Brain May Forget, but It Doesn't Erase.

• Position: MEMORY

Forgetting is part of normal human function due to the limited capacity of the brain. Much research has gone into how memories form, but less has gone into the nature of forgetting or how it occurs in the brain. Some studies suggest that when a memory is forgotten, it simply is erased, and the learning is lost. Another possibility is that the memory and the learning just become harder to access during the forgetting process but remain in some form.

Forgetting can be a blessing and a curse. Some who have experienced a traumatic event cannot seem to forget, while others seem only to forget, and all too quickly.

Dilemmas like these have led neuroscientists to question how forgetting actually works in the brain and whether it can be sped up or slowed down. They still are a ways from understanding the process well enough to provide answers, but a group of Harvard University-led researchers are moving a small step closer.

In a study, the scientists, using C. elegans worms, a model organism for brain research, found that forgetting does not reverse changes in the brain resulting from learning or erase them, as some theories suggest. Instead, forgetting generates a novel brain state that is different from either the one before the learning occurred or the one that exists while the learned behavior is still remembered. In other words, what is forgotten...