You know that scene in Eternal Sunshine of the Spotless Mind when they're scanning through Jim Carrey's playdoh-faced head, looking for bad memories to erase? A bunch of eggheads from MIT just figured out how to do that for real! Sort of. In all seriousness, though, the discovery is poised to do a lot of good for sufferers of post-traumatic stress disorder.
The gene in question is known as Tet1, and it controls memory by manipulating the levels of DNA methylation (read: altering access to genes). To test how Tet1 affects memories, the researchers conditioned mice that had been shocked by a particular cage to be fearful. After a while, they'd put the mice back in the same cage—without the shock—and record their reactions. Mice with normal Tet1 levels would eventually forget about the shock, letting new memories replace old ones. Mice with low Tet1 levels, however, had a hard time forgetting.
The low Tet1 levels could be key to understanding conditions like post-traumatic stress disorder, a condition that's continued to baffle medical researchers. If doctors could find a way to raise those levels in, say, soldiers returning from battle, they might be able to let positive memories erase the trauma. It would actually give the soldiers more agency.