Brain health: Study finds why deep sleep is good for memory

• Adequate sleep is an important part of human health.
• Poor sleep is a risk factor for cognitive problems such as memory loss.
• Researchers at the Charité – Universitätsmedizin Berlin have clarified what happens during deep sleep – also known as slow wave sleep – to support the formation of memories in the brain.
• This study adds to the evidence showing the important role of sleep in memory consolidation, and may help scientists come up with preventive strategies against ‘dementia’.

“Depriving people of sleep causes all kinds of problems and can cause serious harm,” Franz Xaver Mittermaier, a member of the scientific staff of the Center for Neurophysiology at Charité – Universitätsmedizin Berlin in Germany, said. Medical News Today.

“It is reasonable to argue that the organ that needs the most sleep is the brain. Sleep isolates the brain from the outside world. The auditor’s agenda has been suspended. This allows the repetition of past experiences without the ‘external interference’ which is necessary to consolidate the memories of these experiences – that is, to transfer them to long-term memory,” he said.

Mittermaier is the first author of a new study published in the journal Nature Communication which explains how deep sleep – also known as slow-wave sleep – helps support the formation of memories in the brain.

For this study, Mittermaier and his team used intact tissue samples of neocortex – part of the brain of the brain – taken from 45 study participants.

“The neocortex is the outer part of the brain. Whenever we see a picture of the brain, the surface we are looking at is the neocortex – the spindle-shaped surface. It is a structure that contains 16 billion neurons (cells (electrical part of the brain) The neocortex is highly expanded in humans and plays a central role in the cognitive abilities that make us human: language, thinking, memory, etc.
– Franz Xaver Mittermaier

“In 2017, we started to create a platform, where we collect brain samples from neurosurgery that would otherwise be discarded,” said Mittermaier. “We were able to improve our methods to keep these cell samples alive for more than 24 hours in a physiological solution. This allows us to study the cells of the human brain and the relationships between them (synapses) with advanced, high-resolution recording techniques.”

“Once we had the ability to make these recordings, memory processes were an obvious topic to talk about. Prof. Geiger and Henrik Alle – co-author of the study the latest – they had published a Science in a journal paper in 2006, where they identified interesting synaptic mechanisms. These methods were where we started and the project developed from there,” he explained.

At the end of the study, the researchers found that the slow electrical waves created in the brain during deep sleep help to strengthen the synaptic connections between neurons in the neocortex, making it more “acceptable” to create memories.

“During deep slow-wave sleep, when the sensory flow from the outside world stops, the neocortex shows a very interesting activity with UP- and DOWN-states alternating so that bang once a second,” Mittermaier explained. “UP- and DOWN-states are caused by synchronous changes in the electrical activity of many thousands of neurons in the neocortex.”

“We can show through our experiments that this sequence of UP- and DOWN-states actually fixes the synapses (that is, the connections) between the brain cells and makes them (they) very strong when the neocortex changes from the DOWN-state to the UP-state ,” he continued.

“The neocortex is positioned to receive information during that window period. If the hippocampus – the area of ​​the brain that stores short-term memories – plays a memory during this window period, it leads to a more precise activation of the brain cells neocortical, leading to long-term storage.” he said MNT.

“We are just beginning to scratch the surface of the mechanisms that are actually at play when the brain is asleep. Furthermore, most of the research so far has been in laboratory animals and not in human tissue samples (as in our study). We have “There’s a lot of work to be done to better understand the sleeping brain. Our study is just the beginning. Understanding the sleeping brain will help us deal with problems like dementia in the elderly.”
– Franz Xaver Mittermaier

MNT spoke with Verna Porter, MD, a board-certified physician and director of Dementia, Alzheimer’s Disease and Neurocognitive Disorders at the Pacific Neuroscience Center at Providence Saint John’s Health Center in Santa Monica, CA, who suggested that this study it was fun and thought provoking. sheds light on the important role of slow-wave activity (SWA) during deep sleep in synaptic plasticity and memory consolidation.

“The ability of SWA to strengthen synapses and stabilize memories in a precise, cellular manner is very interesting,” Porter explained.

“For me, as a neurologist, this confirms the critical importance of healthy sleep patterns in maintaining cognitive function. Given that patients with dementia often have sleep disorders, these findings highlight the need to better understand and address sleep disorders as part of dementia care and prevention.
– Verna Porter, MD

“Next steps should focus on identifying how synaptic processes driven by SWA are altered in neurodegenerative diseases such as Alzheimer’s and other forms of dementia. Long-term studies are needed to assess whether promoting deep sleep can slow cognitive decline or improve memory retention in people at risk,” he continued.

MNT also spoke with Manisha Parulekar, MD, FACP, AGSF, CMD, director of the Division of Geriatrics at Hackensack University Medical Center and co-director of the Memory Loss and Brain Health Center at Hackensack University Medical Center in New Jersey, about and this lesson. .

“Deep sleep, especially slow-wave sleep, plays an important role in memory consolidation – a process for consolidating and consolidating newly acquired memories. This study highlights the potential pathways of sleep in memory and describes a method that can help improve memory.”
– Manisha Parulekar, MD, FACP, AGSF, CMD

“Dementia continues to be an important public health challenge. Studies suggest that the pathophysiology begins at an earlier time, 10 to 20 years before cognitive symptoms. Studies can help identify prevention strategies and evaluate treatment strategies aimed at supporting memory formation,” Parulekar said.

“One next step would be further studies that examine the effect of cognitive behavioral therapy for insomnia (CBT-I), mindfulness-based cognitive reduction, sleep hygiene education, light therapy, and techniques some unsustainable combination of thought and its psychological benefits,” he added.