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Statistical modelling of blood flow and transport in brain micro-vascular networks

Goirand, Florian. Statistical modelling of blood flow and transport in brain micro-vascular networks. PhD, Dynamique Des fluides, Institut National Polytechnique de Toulouse, 2021

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Abstract

Micro-vascular networks play a key role in the blood supply to brain cells: they ensure an accurate delivery of oxygen and nutrients and the removal of toxic metabolic wastes. The joint alterations of these networks and of the cerebral micro-circulation have been recently highlighted as a critical mechanism in cognitive decline in (micro-)strokes or neuro-degenerative diseases like Alzheimer's. However, little is known about how the structure of brain micro-vascular networks influences the blood flow organization and its transport properties. In a first part, we demonstrate that the micro-vascular structure drives the blood flow organization similarly to dipole flows on random networks. This organization implies anomalous transport properties characterized by a broad distribution of Lagrangian particle travel times in the micro-vasculature. These transport properties are successfully captured by our Continuous Time Random Walk model which predicts notably the non-linear increase of the size of areas with abnormal concentrations of oxygen or metabolic wastes with global blood flow reduction. In a second part, we highlight the presence of local flow anti-correlations in homogeneous random networks. We demonstrate, thanks to the qmodel framework, that these anti-correlations result from the limitations of such networks to dissipate the pressure along their edges. In a final part, we highlight that the spatialized community structure of micro-vascular networks weakens their resilience to vessel occlusions compared to unstructured random networks. We quantify the role of these communities thanks to the design of a model inspired by percolation theory which allows to account for micro-vascular flow and structure heterogeneities. Furthermore, we show the existence of large flow perturbations induced by vessel occlusions. This work provides new theoretical tools to understand the onset and/or the progression of neuro-degenerative diseases

Item Type:PhD Thesis
Uncontrolled Keywords:
Institution:Université de Toulouse > Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE)
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Research Director:
Lorthois, Sylvie and Le Borgne, Tanguy
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Deposited On:05 Nov 2021 14:19

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