Scientists implanted a false memory into a mouse's brain

Researchers at the Massachusetts Institute of Technology labeled a specific group of brain cells in mice while the animals explored a safe room, then found a way to switch those same cells back on later.

Using light-sensitive proteins inserted into neurons active during exploration of the first room, the team optically reactivated those memory cells while the mice were in a second, different room and received a mild foot shock. Afterward, mice froze in fear when returned to the original, safe room, even though nothing had ever happened to them there.

The experiment showed a false memory could be built from real neural components, by pairing an artificially reactivated memory trace with a new, unrelated event, rather than by altering what the mouse had actually experienced. It worked only in mice with genetically engineered, light-sensitive neurons, and years of further work were needed to show related effects in other memory systems.

A memory of a place never feared.