Sustained poststimulus elevation in cerebral oxygen utilization after vascular recovery

Hanzhang Lu, Xavier Golay, James J. Pekar, Peter C M Van Zijl

Research output: Contribution to journalArticlepeer-review

141 Scopus citations


The brain's response to functional activation is characterized by focal increases in cerebral blood flow. It is generally assumed that this hyperemia is a direct response to the energy demands of activation, the so-called flow-metabolism coupling. Here we report experimental evidence that increases in oxygen metabolism can occur after activation without increases in flow. When using multimodality functional MRI (fMRI) to study visual activation in human brain, we observed a postactivation period of about 30 seconds during which oxygen consumption remained elevated, while blood flow and volume had already returned to baseline levels. The finding of such a prolonged and complete dissociation of vascular response and energy metabolism during the poststimulus period indicates that increased metabolic demand needs not per se cause a concomitant increase in blood flow. The results also show that the postactivation undershoot after the positive blood-oxygen-level-dependent hemodynamic response in fMRI should be reinterpreted as a continued elevation of oxygen metabolism, rather than a delayed blood volume compliance.

Original languageEnglish (US)
Pages (from-to)764-770
Number of pages7
JournalJournal of Cerebral Blood Flow and Metabolism
Issue number7
StatePublished - Jul 2004


  • BOLD
  • Decoupling of Flow and Metabolism
  • Functional MRI
  • Oxygen utilization
  • VASO
  • Vascular recovery

ASJC Scopus subject areas

  • Neurology
  • Clinical Neurology
  • Cardiology and Cardiovascular Medicine


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