Onderzoekers van UCLA Health en Tel Aviv University hebben bewijs gevonden dat de theorie ondersteunt dat de hersenen het geheugen tijdens de slaap verbeteren. De studie maakte gebruik van gerichte diepe hersenstimulatie bij epilepsiepatiënten, wat resulteerde in verbeterde geheugenconsolidatie. Deze bevindingen kunnen mogelijk helpen bij de behandeling van geheugenstoornissen.
De onderzoekers rapporteren ook het eerste directe bewijs ter ondersteuning van de leidende theorie over hoe het menselijk geheugen tijdens de slaap wordt geconsolideerd.
Hoewel bekend is dat slaap een sleutelrol speelt bij het verbeteren van het geheugen, proberen wetenschappers nog steeds te ontcijferen hoe dit proces ‘s nachts in de hersenen plaatsvindt.
Nieuw onderzoek onder leiding van wetenschappers van de University of California, Los Angeles (UCLA) Health en Tel Aviv University biedt het eerste fysiologische bewijs van binnenuit het menselijk brein dat de heersende wetenschappelijke theorie ondersteunt over hoe de hersenen het geheugen consolideren tijdens de slaap. Bovendien ontdekten de onderzoekers dat gerichte diepe hersenstimulatie tijdens een kritieke periode in de slaapcyclus de geheugenconsolidatie leek te verbeteren.
Het onderzoek is op 1 juni gepubliceerd in het tijdschrift Natuur Neurowetenschappenzou nieuwe aanwijzingen kunnen geven over hoe diepe hersenstimulatie tijdens de slaap op een dag patiënten met geheugenstoornissen zou kunnen helpen, zoals[{” attribute=””>Alzheimer’s disease, said study co-author Itzhak Fried, MD, PhD. This was achieved by a novel “closed-loop” system that delivered electrical pulses in one brain region precisely synchronized to brain activity recorded from another region.
According to the dominant theory for how the brain converts new information into long-term memories during shuteye, there’s an overnight dialogue between the hippocampus – the brain’s memory hub – and the cerebral cortex, which is associated with higher brain functions like reasoning and planning. This occurs during a phase of deep sleep, when brain waves are especially slow and neurons across brain regions alternate between rapidly firing in sync and silence.
“This provides the first major evidence down to the level of single neurons that there is indeed this mechanism of interaction between the memory hub and the entire cortex,” said Fried, the director of epilepsy surgery at
On another night, they were shown 25 new animal and celebrity pairings before bedtime. This time, they received targeted electrical stimulation overnight, and their ability recall the pairings was tested in the morning. To deliver this electrical stimulation, the researchers had created a real-time closed-loop system that Fried likened to a musical conductor: The system “listened” to brain’s electrical signals, and when patients fell into the period of deep sleep associated with memory consolidation, it delivered gentle electrical pulses instructing the rapidly firing neurons to “play” in sync.
Each individual tested performed better on memory tests following a night of sleep with the electrical stimulation compared to a night of undisturbed sleep. Key electrophysiological markers also indicated that information was flowing between the hippocampus and throughout the cortex, providing physical evidence supporting of memory consolidation.
“We found we basically enhanced this highway by which information flows to more permanent storage places in the brain,” Fried said.
Fried in 2012 authored a New England Journal of Medicine study that for the first time showed that electrical stimulation can strengthen memory, and his work has continued to explore how deep brain stimulation could improve memory, now moving into the critical stage of sleep. He recently received a $7 million NIH grant to study whether artificial intelligence can help pinpoint and strengthen specific memories in the brain.
“In our new study, we showed we can enhance memory in general,” Fried said. “Our next challenge is whether we have the ability to modulate specific memories.”
Reference: “Deep brain stimulation during sleep enhances human brain synchrony and memory” 1 June 2023, Nature Neuroscience.
DOI: 10.1038/s41593-023-01342-3
Yuval Nir of Tel Aviv University co-supervised the study with Fried. Other authors include lead author Maya Geva-Sagiv, as well as Emily Mankin, Dawn Eliashiv, Natalie Cherry, Guldamla Kalender and Natalia Tchemodanov from UCLA, and Shdema Epstein from Tel-Aviv University.
Funding: National Science Foundation, U.S.-Israel Binational Science Foundation, NIH/National Institute of Neurological Disorders and Stroke, European Research Council
