Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.07.02.183608v1?rss=1 Authors: Ladron-de-Guevara, A., Shang, J. K., Nedergaard, M., Kelley, D. H. Abstract: Cerebrospinal fluid (CSF) flows through the perivascular spaces surrounding cerebral arteries. Revealing the mechanisms driving its flow would bring improved understanding of brain waste transport and insights for disorders including Alzheimer's disease, stroke, and traumatic brain injury. In vivo CSF velocity measurements in mice have been used to argue that flow is driven primarily by the pulsatile motion of artery walls~--- perivascular pumping. However, fluid dynamics theory and simulation have predicted that perivascular pumping produces flows differing from in vivo observations starkly, particularly in the phase and relative amplitude of flow oscillation. Here we show that coupling theoretical and simulated flows to realistic end boundary conditions, using resistance and compliance values measured in mice, results in velocities that match observations closely in phase, relative amplitude of oscillation, and mean flow speed. This new, quantitative agreement among theory, simulation, and in vivo measurement further supports the idea that perivascular pumping is a primary CSF driver in physiological conditions. Copy rights belong to original authors. Visit the link for more info