The synchronized brain waves of non-REM sleep may play a key role in preventing toxins from accumulating in a person’s brain.
Laura Lewis and her team of researchers have been putting in late nights in their Boston University lab. Lewis ran tests until around 3:00 in the morning, then ended up sleeping in the next day. It was like she had jet lag, she says, without changing time zones. It’s not that Lewis doesn’t appreciate the merits of a good night’s sleep. She does. But when you’re trying to map what’s happening in a slumbering human’s brain, you end up making some sacrifices. “It’s this great irony of sleep research,” she says. “You’re constrained by when people sleep.”
Her results, published today in the journal Science, show how our bodies clear toxins out of our brains while we sleep and could open new avenues for treating and preventing neurodegenerative diseases like Alzheimer’s…..(See link for full article)
Coupled electrophysiological, hemodynamic, and cerebrospinal fluid oscillations in human sleep
Nina E. Fultz1,2Giorgio Bonmassar2,3,Kawin Setsompop2,3,Robert A. Stickgold4,5,Bruce R. Rosen2,3,Jonathan R. Polimeni2,3,Laura D. Lewis1,2,*
Science 01 Nov 2019:
Vol. 366, Issue 6465, pp. 628-631
DOI: 10.1126/science.aax5440
Fluid dynamics during sleep
During non–rapid eye movement sleep, low-frequency oscillations in neural activity support memory consolidation and neuronal computation. Sleep is also associated with increased interstitial fluid volume and clearance of metabolic waste products. It is unknown why these processes co-occur and how they are related. Fultz et al. simultaneously measured electrophysiological, hemodynamic, and flow signals in the human brain (see the Perspective by Grubb and Lauritzen). Large oscillations of fluid inflow to the brain appeared during sleep and were tightly coupled to functional magnetic resonance imaging signals and entrained to electroencephalogram slow waves. Slow oscillatory neuronal activity thus leads to oscillations in blood volume, drawing cerebrospinal fluid into and out of the brain.
Sleep is essential for both cognition and maintenance of healthy brain function. Slow waves in neural activity contribute to memory consolidation, whereas cerebrospinal fluid (CSF) clears metabolic waste products from the brain. Whether these two processes are related is not known. We used accelerated neuroimaging to measure physiological and neural dynamics in the human brain. We discovered a coherent pattern of oscillating electrophysiological, hemodynamic, and CSF dynamics that appears during non–rapid eye movement sleep. Neural slow waves are followed by hemodynamic oscillations, which in turn are coupled to CSF flow. These results demonstrate that the sleeping brain exhibits waves of CSF flow on a macroscopic scale, and these CSF dynamics are interlinked with neural and hemodynamic rhythms.
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