Neuroscientists at the Massachusetts Institute of Technology have found that they can manipulate the emotional connotation of the memories of mice. Is this, as the New York Times tweeted, “Eternal Sunshine of a Spotless (Mouse) Mind?”
Not exactly. Unlike in the film, the scientists weren’t erasing the negative memories—they were turning them into positive ones.
Here’s how it worked: After labeling neurons in the brains of mice with a light-sensitive protein, scientists identified patterns of neurons activated when mice created a negative or positive memory. The negative memory was created when mice received an electric shock to their feet. A positive one was formed when the male mice got to spend time with a female mouse. (Mice have a lot in common with students at an all-boys boarding school in this way.)
Next, the mice that had first received the electric shock got to spend time with the coveted female mice as scientists used light to activate the earlier negative memory. The result? The negative memory became less negative—the mice were less afraid in the place where they had been shocked. The reverse happened for the mice that first got to spend time around females—they then received a shock “while scientists activated the neurons associated with this positive memory.” And the positive memory became less positive. (The scientists concluded this as the mice “froze more and sniffed less.”)
There is indeed research into the full erasure of memories, but it’s highly ethically and morally contentious. This may be less so. The memories are still there—they’re just felt differently.
Scientists are excited by the potential impact these findings could have on, for example, treatment of post-traumatic stress disorder. For now, they only apply to mice, both because conclusions about the human brain cannot necessarily be drawn from experiments on rodents, and also because the techniques used on the mice cannot be performed on people, as they “involve inserting fiber optic wires and injecting a virus containing a protein into the brain.” But scientists are already exploring noninvasive techniques, that humans, too, may experience eternal sunshine of the spotted mind.