Spatiotemporal dynamics of the BOLD fMRI signals: Toward mapping submillimeter cortical columns using the early negative response

Timothy Q. Duong, Dae Shik Kim, Kâmil Uǧurbil, Seong Gi Kim

Research output: Contribution to journalArticlepeer-review

156 Scopus citations

Abstract

The existence of the early-negative blood-oxygenation-level-dependent (BOLD) response is controversial and its practical utility for mapping brain functions with columnar spatial specificity remains questionable. To address these issues, gradient-echo BOLD fMRI studies were performed at 4.7 T and 9.4 T using the well-established orientation column model in the cat visual cortex. A robust transient early-negative BOLD response was consistently observed in anesthetized cat (-0.35 ± 0.09%, mean ± SD, n = 8 at 2.9 ± 0.5 sec poststimulus onset for 4.7 T, TE = 31 ms; -0.29 ± 0.10%, n = 4 at 3.0 ± 0.8 sec poststimulus onset for 9.4 T, TE = 12 ms). In addition to its temporal evolution, the BOLD response also evolved dynamically in the spatial domain. The initially spatially localized early-negative signal appeared to dynamically drain from the active sites toward large vessels, followed by a wave of the delayed positive signal, which exhibited similar spatiotemporal dynamics. Only the early-negative BOLD response within 2 sec of the stimulus onset (not the entire dip) yielded columnar layouts without differential subtraction. The functional maps of two orthogonal orientations using the first 2-sec dip were indeed complementary. On the other hand, the delayed positive BOLD response appeared diffused and extended beyond the active sites. It was thus less suitable to resolve columnar layouts. These results have implications for the design and interpretation of the BOLD fMRI at columnar resolution. (C) 2000 Wiley-Liss, Inc.

Original languageEnglish (US)
Pages (from-to)231-242
Number of pages12
JournalMagnetic Resonance in Medicine
Volume44
Issue number2
DOIs
StatePublished - 2000

Keywords

  • Brain mapping
  • Cat visual cortex
  • Cerebral blood flow
  • Deoxyhemoglobin
  • Early dip
  • Hemodynamic response
  • High magnetic field
  • Ocular dominance columns
  • Optical imaging
  • Orientation columns
  • Oxygen consumption

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

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