The coupling controversy

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15 Scopus citations


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 15O 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 %{increment} from fMRI. A first-person account of the PET "coupling" studies and their influence on the development of fMRI is provided.

Original languageEnglish (US)
Pages (from-to)594-601
Number of pages8
Issue number2
StatePublished - Aug 15 2012


  • CBF
  • CMRO
  • Cerebral blood flow
  • Cerebral metabolic rate
  • Coupling
  • FMRI
  • PET

ASJC Scopus subject areas

  • Neurology
  • Cognitive Neuroscience


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