Past theories about forgetting mostly emphasized relatively passive processes in which the loss of memories was a consequence of the physical traces of those memories (what some researchers refer to as “engrams”) naturally breaking down or becoming harder to access; those engrams may typically be interconnections between brain cells that prompt them to fire in a certain way. This forgetting process could involve the spontaneous decay of connections between neurons that encode a memory, the random death of those neurons, the failure of systems that would normally help to consolidate and stabilize new memories, or the loss of context cues or other factors that might make it hard to retrieve a memory.
Now, however, researchers are paying much more attention to mechanisms that actively erase or hide those memory engrams.
One form of active forgetting that scientists formally identified in 2017 is called intrinsic forgetting. It involves a certain subset of cells in the brain — which Ronald Davis and Yi Zhong, who wrote the paper that introduced the idea, casually call “forgetting cells” — that degrade the engrams in memory cells. [Continue reading…]