FROMLINE: Marta Wegorzewska

Newswise – There is a paradox in sleep. Its apparent calm contrasts with the busy activity of the brain. The night is quiet, but the brain is far from asleep. During sleep, brain cells generate electrical impulses that accumulate into rhythmic waves – a sign of increased brain cell function.

But why is the brain active when we rest?

Slow brain waves are associated with restful, refreshing sleep. And now scientists at Washington University School of Medicine in St. Louis have found that brain waves help flush waste from the brain during sleep. Individual nerve cells coordinate to produce rhythmic waves that propel fluid through dense brain tissue, washing the tissue in the process.

“These neurons are miniature pumps. “Synchronized neuronal activity promotes fluid flow and clearance of debris from the brain,” explained first author Li-Feng Jiang-Xie, PhD, a postdoctoral fellow in the Department of Pathology and Immunology. “If we can build on this process, there is the possibility of delaying or even preventing neurological diseases, including Alzheimer’s and Parkinson’s diseases, in which excess waste – such as metabolic waste and junk proteins – accumulates in the brain and lead to neurodegeneration.”

The results will be published on February 28th Nature.

Brain cells orchestrate thoughts, feelings, and body movements, forming dynamic networks that are essential for memory formation and problem solving. But to perform such energy-intensive tasks, brain cells need fuel. The absorption of nutrients from food creates metabolic waste.

“It is critical that the brain dispose of metabolic wastes that can accumulate and contribute to neurodegenerative diseases,” he said Jonathan Kipnis, PhDthe Alan A. and Edith L. Wolff Distinguished Professor of Pathology and Immunology and a BJC investigators. Kipnis is the senior author of the article. “We knew that sleep is a time when the brain initiates a cleansing process to flush out waste and toxins that accumulate while awake. But we didn’t know how this happened. These findings could give us clues about strategies and possible therapies to speed up the disposal of harmful waste and eliminate it before it can have dire consequences.”

But clearing the dense brain is not an easy task. The cerebrospinal fluid surrounding the brain invades and penetrates intricate networks of cells, collecting toxic wastes along the way. As contaminated fluid leaves the brain, it must pass through a barrier before entering the lymphatic vessels in the dura mater – the outer layer of tissue that covers the brain beneath the skull. But what drives the movement of fluid in, through, and out of the brain?

By studying the brains of sleeping mice, the researchers found that neurons drive the cleansing efforts by firing electrical signals in a coordinated manner to create rhythmic waves in the brain, Jiang-Xie explained. They found that such waves drive fluid movement.

The research team silenced certain regions of the brain so that the neurons in those regions did not produce rhythmic waves. Without these waves, fresh cerebrospinal fluid could not flow through the silenced brain regions and trapped waste could not leave the brain tissue.

“One of the reasons we sleep is to cleanse the brain,” Kipnis said. “And if we can improve this cleansing process, it may be possible to sleep less and stay healthy. Not everyone has the benefit of sleeping eight hours a night, and lack of sleep negatively impacts health. Other studies have shown that mice that are genetically predisposed to sleep less have healthy brains. Could it be because they remove waste from their brains more efficiently? “Could we help people with insomnia by improving their brain’s ability to cleanse so they can survive on less sleep?”

Brain wave patterns change throughout sleep cycles. Notably, higher brain waves with greater amplitude move fluid with more force. Researchers are now interested in understanding why neurons fire waves at different rhythms during sleep and which regions of the brain are most susceptible to waste accumulation.

“We think the brain cleaning process is similar to washing dishes,” explained neurobiologist Jiang-Xie. “For example, you start with a large, slow, rhythmic wiping motion to remove soluble waste that has spilled across the plate. Then reduce the range of motion and increase the speed of these motions to remove particularly sticky food particles from the plate. Despite the different amplitude and rhythms of your hand movements, the overall goal remains the same: to remove different types of waste from dishes. Perhaps the brain adjusts its cleaning method depending on the type and amount of waste.”

By admin

Leave a Reply

Your email address will not be published. Required fields are marked *