© LAURA LEWIS



N.E. Fultz et al., "Coupled electrophysiological, hemodynamic, and cerebrospinal fluid oscillations in human sleep," Science, doi:10.1126/science.aax5440, 2019.



Abby Olena is a freelance journalist based in North Carolina. Find her on Twitter @abbyolena.

, according to a new study published today (October 31) in Science . The authors show thatThe work "is exciting because it's linking neural activity to blood flow and cleaning the brain. Most neuroscientists would not say those are linked," Maiken Nedergaard , a neuroscientist at the University of Rochester Medical Center, tells The Scientist. She did not participate in the study, but work from her group has indicated that CSF helps take out the brain's garbage.It was this idea of CSF as a brain wash — combined with recent evidence showing that— that led Boston University's Laura Lewis and colleagues to investigate what CSF does during sleep. For the current study, they designed a new approach combining simultaneous electroencephalograms (EEGs) to measure the brain's electrical activity and blood oxygen level dependent functional magnetic resonance imaging (BOLD fMRI) to collect blood oxygen levels and the flow of CSF in the brain.The team recorded neuronal activity, blood levels, and CSF flow in two men and 11 women while they wore caps with EEG electrodes and slept in an fMRI scanner for up to two and a half hours. The researchers knew from— a finding they also confirmed in this study. ButPlus, the CSF dynamics were coupled to the brain's electrical activity. Specifically, an electrical slow wave and corresponding increase in blood flow was followed a few seconds later by a decrease in blood oxygenation and volume and then a surge of CSF."This team has found this wonderful way of measuring these interrelated signals that are implicated heavily in just about every brain disease we know," says Christopher Moore , a neuroscientist at Brown University who did not participate in the study. It's possible the relationship between, he explains. "The clinical potential of this as both a research tool [and] maybe diagnostically is tremendous."says Lewis, adding that all of the subjects in the current study are young adults."We're working now on trying to understand how these CSF waves are affected across the lifespan and in patient populations."Right now, the paper draws a correlation between neural activity, blood flow, and CSF rhythms, Moore adds, so another extension of the work will be to use animal models to manipulate each oscillation and see what happens downstream. An additional question, he says, is "how do all these vascular and CSF dynamics impact neurons? They could be for taking out the garbage, but