False Memory Successfully Implanted in Mouse Brain

Researchers have successfully planted a false memory in the brain of a mouse, a feat they hope will aid in better understanding how human memory can, at times, be remarkably unreliable.

In a laboratory at the Riken - M.I.T. Center for Neural Circuit Genetics at the Massachusetts Institute of Technology, researchers attempted a sort of mind control experiment on mice that planted false memories in the mice by triggering certain brain cells with light. The scientists were able to convince a mouse that it was about to receive an electric shock based on a prior memory it did not actually have.

The experiment took place over three stages. First, a mouse was placed into a chamber with a black cardboard floor. The odor of vinegar was introduced to the chamber, as was a reddish light. The mouse was allowed to look around. A compound injected into the part of the mouse's brain that involves memory tagged active cells, and fiber optic cables wired to the mouse's brain recorded activity.

On the next day, the mouse was placed in a markedly different chamber with a metal floor, an almond scent and a blue light. The researchers delivered three electric shocks to the mouse's feet with in two-second intervals while also stimulating the cells in the brain that were triggered during the first stage of the experiment.

Later, when the mouse was put back into the first chamber, where it never received an electric shock, it froze. It is a typical and well-documented that mice freeze in their tracks when they fear something. By freezing after being reintroduced to the first chamber, the mice exhibited that they had something to be afraid of, even though they were never shocked in the first chamber.

The researchers ran several versions of the experiment to confirm that they were indeed seeing the mouse act on a false memory.

Susumu Tonegawa, a Nobel laureate and MIT neuroscientist who led the research, said that the finding in the mice may lead to better understanding of how humans create false memories of their own. Be it a witness in a courtroom misremembering what they saw on the night of a crime, or a friend insisting you were at a party that you were in fact not invited to, humans are apt to have false memories. What's more, we are also inclined to truly believe those false memories are real, an unfortunate reality that has, for instance, sent the wrong people to prison.

"We suspect and hypothesize this way of implanting false memories that was carried out with a mouse is actually something very similar [to what] is taking place during the formation of false human memory," said Tonegawa, according to the Boston Globe.

"Our study showed that the false memory and the genuine memory are based on very similar, almost identical, brain mechanisms," Tonegawa said, according to The Guardian. "It is difficult for the false memory bearer to distinguish between them. We hope our future findings along this line will further alert legislatures and legal experts how unreliable memory can be."

MIT neuroscientist Ann Graybiel told the Boston Globe that Tonegawa's research presents "stunning evidence for the exquisite specificity of microcircuits that produce memory."

"This work is a landmark piece of science and has broad implications for understanding how we create memories and how we can recall them," she said.

Tonegawa and his colleagues' research is published in the journal Science.