Taylor dispersion refers to a process in which the combination of advection and diffusion leads to enhanced transport of a solute in a shear flow. Recent studies have suggested that a Taylor dispersion-like mechanism arising from an oscillatory flow (with zero net flow) may explain solute transport observed in perivascular spaces of the brain. We demonstrate that a steady flow component -- even in cases where it is much smaller than the oscillatory component -- leads to much greater solute transport. From Troyetsky et al 2021.
Following a stroke, a wave of intense neuronal activity, called spreading depolarization, propagates through the brain (green wave). This wave causes arteries to constrict which pulls an abnormally large amount of cerebrospinal fluid into the brain, causing swelling. From Mestre et al, Science 2020.
A model of perivascular spaces in the brain which we used to demonstrate that a moderately elongated shape permits greater fluid flow than a circular annulus. The “optimal” shape that we compute is very close to that of real perivascular spaces observed at the surface of the brain in mice and humans, which is perhaps a consequence of evolutionary optimization. Read more in Tithof et al, Fluids Barriers CNS 16 (2019): 19.
By injecting 1 µm spheres (green dots) and performing particle tracking velocimetry, we obtain quantitative measurements of cerebrospinal fluid flow through perivascular spaces in living mouse brains. Flow speeds are slower for high blood pressure (right panel) than normal blood pressure (left panel). Based on results reported in Mestre, Tithof, et al, Nature Commun. 9 (2018): 1-9.
The glymphatic system may offer a promising novel route for drug delivery to the brain. Here we inject a living mouse with hypertonic mannitol and image cerebrospinal fluid influx throughout the entire brain (left). Front tracking velocimetry (right) allows us to quantify the influx area and speed. From Plog et al. JCI Insight 3.20 (2018): e120922.