The coupling controversy.
Functional magnetic resonance imaging (fMRI) relies on the well-known phenomenon of coupling between neuronal activity and brain blood flow. For nearly a century, the presumption was that hemodynamics were coupled to neuronal activity via energy demand and oxidative metabolism. Early (15)O positron-emission tomographic (PET) studies challenged this theory, demonstrating a physiological "uncoupling" between brain blood flow and oxygen metabolism. These PET observations played a pivotal role in guiding the development of fMRI, by demonstrating which physiological parameters were most closely coupled to neuronal activity and by presaging the BOLD-contrast effect. Subsequent PET studies were crucial for constraining theories concerning the physiological mechanisms underlying hemodynamic/neuronal coupling and, thereby, guiding the development of models for quantification of oxygen metabolic rate %∆ from fMRI. A first-person account of the PET "coupling" studies and their influence on the development of fMRI is provided.
Department of Radiology, Research Imaging Institute, University of Texas Health Science Center at San Antonio, USA.
Peter T
PT
Fox
D000818:Animals; D001921:Brain / Q000098:blood supply* / Q000502:physiology; D001931:Brain Mapping / Q000266:history* / Q000379:methods; D002560:Cerebrovascular Circulation / Q000502:physiology*; D004734:Energy Metabolism / Q000502:physiology; D006439:Hemodynamics / Q000502:physiology; D049674:History, 21st Century; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000266:history* / Q000379:methods; D010100:Oxygen / Q000097:blood*; D010101:Oxygen Consumption / Q000502:physiology; D049268:Positron-Emission Tomography / Q000266:history / Q000379:methods
D010100:Oxygen