Scientists stun world with groundbreaking proof on how memory consolidates during sleep!

New research led by scientists at UCLA Health and Tel Aviv University provides the first physiological evidence from inside the human brain that supports the mainstream scientific theory of how the brain consolidates memory during sleep. In addition, the researchers found that targeted deep brain stimulation during a critical time in the sleep cycle seemed to improve memory consolidation.

The research, published June 1 in neuroscience of nature, could offer new clues about how deep brain stimulation during sleep might one day help patients with memory disorders such as Alzheimer’s disease, said study co-author Itzhak Fried, MD, PhD. This was achieved using a novel “closed loop” system that delivered electrical pulses to one region of the brain precisely timed to recorded brain activity in another region.

According to the prevailing theory of how the brain converts new information into long-term memories during sleep, there is a nocturnal dialogue between the hippocampus, the brain’s memory center, and the cerebral cortex, which is associated with brain functions. superiors such as reasoning and planning. This occurs during a phase of deep sleep, when brain waves are especially slow and neurons in regions of the brain alternate between silent and synchronized rapid firing.

“This provides the first major evidence down to the level of individual neurons that there is indeed this mechanism of interaction between the memory center and the entire cortex,” said Fried, director of epilepsy surgery at UCLA Health and professor of neurosurgery, psychiatry and biobehavioral sciences at the UCLA David Geffen School of Medicine. “It has scientific value in terms of understanding how memory works in humans and using that knowledge to actually improve memory.”

The researchers had a unique opportunity to test this theory of memory consolidation via electrodes in the brains of 18 epilepsy patients at UCLA Health. The electrodes had been implanted in the brains of the patients to help pinpoint the source of their seizures during hospital stays that typically last around 10 days.

The study was carried out over two nights and two mornings. Just before bed, study participants were shown photo pairs of animals and 25 celebrities, including easily identifiable stars like Marilyn Monroe and Jack Nicholson. Their ability to remember which celebrity was paired with which animal was immediately tested, and tested again in the morning after a good night’s sleep.

On another night, they were shown 25 new animal and celebrity couples before bed. This time, they received targeted electrical stimulation overnight, and their ability to remember the pairings was tested in the morning. To deliver this electrical stimulation, the researchers created a real-time, closed-loop system that Fried likened to a music conductor: The system “listened” to electrical signals from the brain and when patients fell into the period of deep sleep associated with consolidation of the memory. , delivered gentle electrical pulses that instructed the rapidly firing neurons to “play” in sync.

Each individual tested performed better on memory tests after a night of electrically stimulated sleep compared to a night of quiet sleep. Key electrophysiological markers also indicated that information was flowing between the hippocampus and the cortex, providing physical evidence supporting memory consolidation.

“We found that we basically improved this pathway by which information flows to more permanent storage places in the brain,” Fried said.

Fried in 2012 wrote a New England Journal of Medicine study that first showed that electrical stimulation can strengthen memory, and his work has continued to explore how deep brain stimulation could improve memory, now moving on to the critical stage of sleep. She recently received a $7 million NIH grant to study whether artificial intelligence can help identify and strengthen specific memories in the brain.

“In our new study, we show that we can improve memory in general,” Fried said. “Our next challenge is whether we have the ability to modulate specific memories.”

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.