Vartan Kurtcuoglu, Ph.D.

Assistant Professor of Computational and Experimental Physiology, Institute of Physiology, University of Zurich, Switzerland

Background: In vivo multi-photon excitation microscopy observations of tracer movement in the cerebral perivascular spaces have led to the conception of the ‘glymphatic system’ hypothesis. Since, in the meantime, the underlying assumption of directed bulk fluid flow through brain tissue has been questioned, the need for an analysis of how solutes move through the central nervous system has moved to center stage.

Methods: We have combined magnetic resonance imaging (MRI) and computational physiology to quantify and visualize the pulsatile motion of the cerebrospinal fluid flow (CSF) in humans. We have further quantified by computational modeling the transport of solutes through the mouse brain, testing the ‘glymphatic system’ hypothesis.

Results: Our investigations showed that the transient, pulsatile motion of CSF in the human brain is an order of magnitude more relevant for mixing of solutes than the net production of this fluid. In the mouse model, we found that directed net flow through the interstitial fluid space is not plausible.

Conclusion: Pulsation of the CSF may play an important role in the distribution of solutes throughout the central nervous system. The ‘glymphatic system’, on the other hand, is implausible.