The capillary bed offers the largest hemodynamic resistance to the cortical blood supply

The cortical angioarchitecture is a key factor in controlling cerebral blood flow and oxygen metabolism. Difficulties in imaging the microanatomy of the cortex have restricted insight about microcirculatory blood flow distribution. A new methodology combining microscopy data with large scale hemodynamic simulations enabled the quantification of the effect of the angioarchitecture on the cerebral microcirculation. High-resolution images of the mouse cortex were input into a comprehensive computational model of cerebral perfusion and oxygen supply ranging from pial vessels to individual brain cells. Simulations of blood flow, hematocrit and oxygen tension show that the wide variation of hemodynamic states in the tortuous, randomly organized capillary bed is responsible for relatively uniform cortical tissue perfusion and oxygenation. Computational analysis of microcirculatory blood flow and pressure drops further indicates that the capillary bed, including capillaries adjacent to feeding arterioles (d<10μm), are the largest contributors to hydraulic resistance. Simulations also suggest that the hydraulic resistance of the cortical blood supply does not behave as a series of resistors. Rather, parallel flow through a conductive plate network best describes the microcirculatory blood flow patterns in the cerebral cortex. This conductive plate network accurately predicted blood flow for a wide range of physiological pressure drops.