Scientists know that cerebrospinal fluid (CSF) is produced within the ventricles of the brain and then flows down into the spine, but there is debate about what happens in between those two phases.
Some, including Maiken Nedergaard from the University of Rochester, have suggested that CSF powers a “glymphatic” waste clearance system that operates primarily during sleep; however, there is little experimental evidence to support this.
Now, Nedergaard’s group has provided some evidence supporting the idea that CSF flows rhythmically during NREM sleep, but experts in vascular biology and neuroscience are divided on the validity of the results and the interpretation.
Alan Verkman says some aspects of the theory are physically implausible, while others suggest the work is complex but lacks sufficient data to back up the hypothesis.
“Nobody has the truth,” says Steven Proulx from the University of Bern. “Some people think they know. But I think we don’t know.
