Summary of “To Remember, the Brain Must Actively Forget”

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 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.
Now researchers are paying much more attention to mechanisms that actively erase or hide those memory engrams.
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.
Previous studies have shown that neurogenesis can be important to the formation of new memories: In tests on lab animals, drugs that inhibit neurogenesis in the hippocampus can interfere with new memory formation, and drugs that enhance neurogenesis seem to help with learning new tasks if they are given before the learning process.
If the added neural wiring overlaps with the circuitry holding older memories, it may damage the older engrams or make it harder to isolate the old memories from newer ones.
Frankland’s explanation is that older memories are less sensitive to this effect because the brain gradually transfers important memories from the hippocampus to the cortex for long-term storage.
The pair, who have been studying how sea slugs form memories for a decade, recently switched their attention to the neurobiology of how the animals forget.
Even after a week – a significant part of a sea slug’s one-year lifespan – the brain is still not back to the way it was before it acquired the memory.

The orginal article.