Simultaneous assessment of flow and BOLD signals in resting-state functional connectivity maps

Bharat B. Biswal, Joel Van Kylen, James S. Hyde

Research output: Contribution to journalArticlepeer-review

516 Scopus citations


We have recently demonstrated using functional magnetic resonance imaging the presence of synchronous low-frequently fluctuations of signal intensities from the resting human brain that have a high degree of temporal correlations (p <0.0001) beth within and across the sensorimotor cortex. A statistically significant overlap between the resting-state functional connectivity map and the task-activation map due to bilateral finger tapping was obtained. Similar results have been obtained in the auditory and visual cortex. Because the pulse sequence used for collecting data was sensitive to blood flow and blood oxygenation, these low-frequency fluctuations of signal intensity may have arisen from variations of both. The objective of this study was simultaneously to determine the contribution of the blood oxygenation level signal and the flow signal to physiological fluctuations in the resting brain using the flow-sensitive alternating inversion recovery pulse sequence. In all subjects, the functional connectivity maps obtained from BOLD had a greater coincidence with task-activation maps than the corresponding functional connectivity maps obtained from blood-flow signals at the same level of statistical significance. Results of this study suggest that while variations in blood flow might contribute to functional connectivity maps, BOLD signals play a dominant role in the mechanism that gives rise to functional connectivity in the resting human brain.

Original languageEnglish (US)
Pages (from-to)165-170
Number of pages6
JournalNMR in Biomedicine
Issue number4-5
StatePublished - 1997
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Molecular Medicine
  • Radiology Nuclear Medicine and imaging
  • Spectroscopy


  • Blood flow
  • Blood oxygenation
  • Functional connectivity
  • Resting brain


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