Sleep-like cortical activity restores memory in awake mice

Scientists have demonstrated for the first time that artificially inducing a sleeplike state in a specific region of an awake mouse brain can replicate some of sleep’s restorative functions, including memory consolidation. The research, published in the journal Nature Neuroscience, suggests that the rhythmic silencing of neurons, not the global state of unconsciousness, may be a core mechanism behind sleep's benefits.

A team led by Chiara Cirelli at the University of Wisconsin–Madison used a combination of genetic engineering and light-based stimulation to create rhythmic "on-off" periods of neuronal activity in the cerebral cortex of mice that were kept awake. This pattern mimicked the slow-wave oscillations characteristic of non-rapid eye movement (NREM) sleep, which makes up about 80% of adult human sleep and is thought to be crucial for synaptic homeostasis—the process of pruning and strengthening neural connections formed during the day.

The researchers kept mice awake for five hours and then, for 30 minutes, used a light probe to induce the NREM-like state in one hemisphere of the brain. When the mice were later allowed to sleep normally, brain recordings showed the...