This is how sleep helps memory form

We know that sleep helps the brain store memories and learning. If the mechanism behind this link remained quite mysterious until now, a team from the Charité University Hospital in Berlin has just made an interesting discovery.

Slow-wave sleep – one of two types of sleep – makes the neocortex, the location of long-term memory, particularly receptive to new information. The results were presented in the journal Nature CommunicationsDecember 12, 2024.

Sleep: slow waves strengthen synapses

To better understand how memories are formed during sleep, researchers obtained samples of intact human neocortical tissue taken from 45 patients while they were undergoing neurosurgery to treat epilepsy or a brain tumor. The team then simulated electrical voltage fluctuations similar to those observed during deep sleep. The response of the nerve cells was then measured using glass micropipettes.

The data obtained show that synaptic connections between neurons in the neocortex become much better after neuro-electrical activity increases from low to high. “During this brief window of time, the cortex can be said to have been placed in a state of high readiness. If the brain replays a memory at exactly that moment, it is transferred to long-term memory particularly efficiently Thus, slow-wave sleep obviously supports memory formation by making the neocortex particularly receptive for many short periods.“, explains Franz Xaver Mittermaier, researcher at the Charité Institute of Neurophysiology and first author of the study, in a press release.

Sleep and memory: the moment for the formation of memories identified

The researchers suggest that these results could help optimize treatment approaches aimed at treating memory disorders, such as transcranial electrical stimulation.

“Currently, these stimulation approaches are optimized through trial and error. Which is a laborious and time-consuming process,” explains Professor Jörg Geiger, director of the Charité Institute of Neurophysiology and leader of the study. “Our findings on perfect timing could contribute to this. Now, for the first time, they enable the targeted development of stimulation methods to contribute to memory formation.”