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Here come the mice in black! Kyoto University experiment removes mouse memories with light

Katy Kelly Nov 19, 2021
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Scientists use flashes of light in the brain to really wipe away memories…in mice.

Ironically, few things stick in the memory of those who watched the 1997 blockbuster Men In Black like the Neuralyzer. It’s a fictional tool that, once directed at a hapless witness to supernatural or alien phenomena, emits a quick burst of light that wipes away the memory of whatever they saw.

▼ Since we’re a Japanese news website, please enjoy the Japanese dub of that very scene.

It feels…at least semi-plausible, right? Really good fiction can make you suspend your belief, and since it’s disorienting to get a light flash in your eye, it’s easy to make the leap that certain kinds of light flashes might affect your memory. But there’s no scientific basis for that fact, obviously. It’s just a movie. Isn’t it?

Well, a recent study from Kyoto University has made things a little more complicated with their recent research on mice. The findings were published on November 11, in a paper for Science titled “Stepwise synaptic plasticity events drive the early phase of memory consolidation” — the scientists managed to relax newly created synapses (the neural connections responsible for forming memories). The study involved mice learning that if they entered a dark chamber annexed to their bright habitat, they would receive an electric shock. Mice learned that they would be shocked upon entering, and thus became cautious and fearful around the dark chamber. Those that had their memories undone with the treatment would instead bound into the dark chamber happily as though they had never been exposed to it.

They achieved this result by using a protein derived from sea anenomes that produces destructive oxygen atoms in response to light exposure. This protein was introduced to the mice by way of a harmless virus, after editing the protein to reduce the damaging effects from the oxygen atoms. Rather than damaging neural pathways, now they just relax them, preventing recently formed memories from being recalled.

New memories are created from experience, like the experience of the mice entering the dark room and receiving a shock. These memories are transferred through the brain via sleep, where they enter the long-term memory. In the case of this experiment, a mouse was injected with the modified SuperNova protein and had an optic fibre inserted into its brain to stimulate it with light. After introducing it to the shock chamber with other control mice, this mouse had its brain stimulated with light right after it was shocked so that the newly learned information would be deleted. After sleeping and returning to the room, it didn’t demonstrate fear as the other mice did.

The scientists also tried erasing the memory another way by flashing light onto another part of the brain — one that summons more distant memories. Two days after the learning experience, they managed to erase what the mouse had learned. After 25 days, however, it had been too long and the memories had consolidated within the brain.

The field of studying light-sensitivities in neurons is called optogenetics. Previous studies by optogeneticists have concerned the whole brain, rather than specific areas where new memories might be formed. This study, though, concerns the specific time window where memories are created. Rather than existing as a single physical concept inside the brain, memories are actually thought to be recalled by cross-referencing various different neural highways—which might explain why certain memories are triggered by certain smells or sounds.

Using the knowledge derived from earlier experiments, the twelve authors of this study (Akihiro Goto, Ayaka Bota, Ken Miya, Jingbo Wang, Suzune Tsukamoto, Xinzhi Jiang, Daichi Hirai, Masanori Murayama, Tomoki Matsuda, Thomas J. McHugh, Takeharu Nagai, and Yasunori Hayashi) successfully showed that long-term memory formation can be stopped or even reverted in a localized window.

Online reactions have likened the procedure to something out of Doraemon or the SCP Foundation, joked “do me a favor and get rid of the last ten years,” and expressed concern about unsavory uses for the technology. Theoretically, as long as the synapses for specific memories can be determined and the technique performed in a timely manner, it could possibly be used in treating sufferers of PTSD and other forms of mental trauma. For the time being, though, this research is limited solely to mice. If you’d rather improve your memory than lose it, then you may want to read up on the benefits of coffee…or this gum from 2017, though we can’t remember if that one was especially successful or not.

Sources: Science – Stepwise synaptic plasticity events drive the early phase of memory consolidation, Nazology, Twitter/@NazologyInfo via My Game News Flash
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