Journal Article

A Multicompartment Vascular Model for Inferring Baseline and Functional Changes in Cerebral Oxygen Metabolism and Arterial Dilation

Boas, David A, Benav, Heval, Allen, Monica S, Huppert, Theodore J, Jones, Phill B

2007

Overview

Functional hemodynamic responses are the composite results of underlying variations in cerebral oxygen consumption and the dilation of arterial vessels after neuronal activity. The development of biophysically based models of the cerebral vasculature allows the separation of the neuro-metabolic and neuro-vascular influences on measurable hemodynamic signals such as functional magnetic resonance imaging or optical imaging. We describe a multicompartment model of the vascular and oxygen transport dynamics associated with stimulus-driven neuronal activation. Our model offers several unique features compared with previous formulations such as the ability to estimate baseline blood flow, volume, and oxygen consumption from functional data. In addition, we introduce a capillary compliance model, arterial and venous oxygen permeability, and model the dynamics of extravascular tissue oxygenation. We apply this model to multimodal optical spectroscopic and laser speckle imaging of the rat somato-sensory cortex during nine conditions of whisker stimulation. By fitting the model using a psuedo-Bayesian framework to incorporate multimodal observations, we estimate baseline blood flow to be 94 (±15) mL/100 g min and baseline oxygen consumption to be 6.7 (±1.3) mL O2/100 gmin. We calculate parametric, linear increases in arterial dilation (R2 = 0.96) and CMRo2 (R2 = 0.87) responses over the nine conditions. Other parameters estimated by the model include vascular transit time and volume reserve, oxygen content, saturation, diffusivity rate constants, and partial pressure of oxygen in the vascular compartments and in the extravascular tissue. Finally, we compare this model to earlier work and find that the multicompartment model more accurately describes the observed oxygenation changes when compared with a single compartment version.

• Publisher: SAGE Publications,Lippincott Williams & Wilkins,Sage Publications Ltd
• Subject: Arteries / Bayes Theorem / Biological and medical sciences / Brain - blood supply / Brain Chemistry / Headache. Facial pains. Syncopes. Epilepsia. Intracranial hypertension. Brain oedema. Cerebral palsy / Humans / Medical sciences / Models, Cardiovascular / Nervous system (semeiology, syndromes) / Neurology / Neuropharmacology / Neuroprotective agent / Oxygen - metabolism / Pharmacology. Drug treatments / Vascular diseases and vascular malformations of the nervous system / Vasodilation