Artificial memories can be created during sleep, according to a study published online in Nature Neuroscience. The study demonstrates that associations between a particular place and a reward can be formed in mice while they sleep, and that these associations drive behavior once they wake up.
Place cells, found in a region of the brain called the hippocampus, are activated when an animal is in a specific location in its environment. Activity patterns generated in these cells during waking are replayed during sleep, which is thought to help consolidate a cognitive map of an animal’s environment.
Karim Benchenane and colleagues stimulated the brain’s reward pathways when place cells encoding a particular location were active in five sleeping mice. An additional two mice received non-rewarding stimulation. When they woke up, only the mice that received rewarding stimulation paired with activation of particular place cells spent more of their time in the location encoded by those cells, suggesting that an artificial memory had been formed in the mouse’s brain while it slept.
While previous studies have shown that memories can be artificially manipulated in mice, this is the first study to show this manipulation in sleeping animals. Whether such memory manipulation can occur in humans is currently unknown.