Modeling of brain efflux: Constraints of brain surfaces
A simplified advection–diffusion-based model is proposed which highlights the critical role of surface membranes and indicates that advection contributes to steady-state waste clearance through a surface membrane bottleneck.
Abstract
Significance Fluid flows into and out of the brain have been studied for decades, but due to the technical challenges of imaging under the skull, classical empirical reports contain apparent contradictions and are inconclusive about whether the brain tissue itself has bulk flow through it. We here propose a simplified advection–diffusion-based model which highlights the critical role of surface membranes and resolve the apparent contradictions in the classical empirical reports. We then perform histological analyses to determine surface membrane parameters and record magnetic resonance images to test the model. The model is able to represent the data and indicates that advection contributes to steady-state waste clearance through a surface membrane bottleneck.