Researchers in Spain think your memory might be one big take a penny, leave a penny system. Only in this case, one of those pennies gets erased completely.
The study, published in the journal Nature Communications, suggests while you're learning new things, your brain is also erasing other things. Cornelius Gross, who led the work at the European Molecular Biology Laboratory, looked at mouse brains, studying a region of the brain known to form memories called the hippocampus. He found that, as you cement memories in your brain, your neural connections become stronger — which is pretty much the impetus for saying the same phrases in Spanish class over and over.
Most of those connections occur on the same route in your brain, so when Gross's team blocked that route, the mice weren't able to learn to associate sounds with consequences — but they could still exhibit these Pavlovian responses if they learned them before the route was blocked.
However, according to Gross, when that route was blocked, connections to it were weakened, leading to the erasing of a memory.
"This is the first time that a pathway in the brain has been linked to forgetting, to actively erasing memories," Gross said in a press release.
For some reason, this only happens when you're trying to learn something. "One explanation for this is that there is limited space in the brain, so when you're learning, you have to weaken some connections to make room for others," Gross said, according to the release. "To learn new things, you have to forget things you've learned before."
The study means, essentially, that the more you learn new things, the more you're forgetting others. But what's tricky here is what's considered learning and that you don't realize you're doing it. For instance, if you take piano lessons, but lately you've spent a lot of energy learning the ins and outs of Minecraft instead, you're killing those neural connections that held your piano prowess. So, if you want to keep your brain from getting rid of things you care about, you need to revisit them and strengthen the connections.
There's another extremely cool implication. Maja Köhn's lab at the EMBL is working on a drug that could activate that erasing route in your brain. If the group is successful, they could create a drug to forget traumatic experiences. It's Eternal Sunshine of the Spotless Mind, only with fewer trips to Montauk.