Predicting Vessel Diameter Changes to Up-Regulate Biphasic Blood Flow During Activation in Realistic Microvascular...

Area of Science:

• Neurovascular coupling
• Computational fluid dynamics
• Microcirculation physiology

Background:

• The brain's vasculature dynamically adjusts blood supply to match neuronal activity.
• The specific contribution of different vessel types to this regulation remains unclear.
• Understanding localized blood flow control is vital for brain function and disease.

Purpose of the Study:

• To develop a novel simulation method to quantify vessel diameter changes for targeted blood flow regulation.
• To systematically compare the roles of different vessel types (capillaries, arterioles) in achieving localized blood flow increases.
• To investigate the spatial and temporal characteristics of vascular diameter adjustments during neural activation.

Main Methods:

• Developed an inverse problem-solving simulation method to calculate required individual blood vessel diameter changes.
• Incorporated stochastic blood flow dynamics from red blood cell tracking.
• Applied a deterministic approach for time-averaged pressures and flow rates to enable analysis of large, realistic microvascular networks.

Main Results:

• Capillary diameter changes provide highly localized control over blood flow.
• Adaptation solely in larger vessels (arterioles) leads to widespread, non-specific flow changes.
• Minor dilations/constrictions across all vessel types significantly alter capillary blood flow distribution.

Conclusions:

• Precise, localized blood flow regulation relies on adjustments at the capillary level.
• Relying on larger vessels alone results in inefficient and diffuse blood flow redistribution.
• Microvascular diameter modulation is a key mechanism for targeted increases in brain perfusion.