Investigating the physiology of brain activation with MRI

Richard B. Buxton; Kamil Uludag; David J. Dubowitz

doi:10.1117/12.536820

30 April 2004 Investigating the physiology of brain activation with MRI

Richard B. Buxton, Kamil Uludag, David J. Dubowitz

Proceedings Volume 5369, Medical Imaging 2004: Physiology, Function, and Structure from Medical Images; (2004) https://doi.org/10.1117/12.536820
Event: Medical Imaging 2004, 2004, San Diego, California, United States

Abstract

Functional magnetic resonance imaging (fMRI) has become a powerful tool for investigating the working human brain based on the blood oxygenation level dependent (BOLD) effect on the MR signal. However, despite the widespread use of fMRI techniques for mapping brain activation, the basic physiological mechanisms underlying the observed signal changes are still poorly understood. Arterial spin labeling (ASL) techniques, which measure cerebral blood flow (CBF) and the BOLD effect simultaneously, provide a useful tool for investigating these physiological questions. In this paper, recent results of studies manipulating the baseline CBF both pharmacologically and physiologically will be discussed. These data are consistent with a feed-forward mechanism of neurovascular coupling, and suggest that the CBF change itself may be a more robust reflection of neural activity changes than the BOLD effect. Consistent with these data, a new thermodynamic hypothesis is proposed for the physiological function of CBF regulation: maintenance of the [O₂]/[CO₂] concentration ratio at the mitochondria in order to preserve the free energy available from oxidative metabolism. A kinetic model based on this hypothesis provides a reasonable quantitative description of the CBF changes associated with neural activity and altered blood gases (CO₂ and O₂).

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Richard B. Buxton, Kamil Uludag, and David J. Dubowitz "Investigating the physiology of brain activation with MRI", Proc. SPIE 5369, Medical Imaging 2004: Physiology, Function, and Structure from Medical Images, (30 April 2004); https://doi.org/10.1117/12.536820

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KEYWORDS

Blood

Oxygen

Mode conditioning cables

Acquisition tracking and pointing

Brain

Magnetic resonance imaging

Carbon dioxide

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