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The effects of single-trial averaging upon the spatial extent of fMRI activation.

Publication ,  Journal Article
Huettel, SA; McCarthy, G
Published in: Neuroreport
August 2001

We examined effects of trial averaging upon spatial extent, spatial topography, and temporal properties of fMRI activation. Two subjects participated in an event-related visual stimulation design. There was an exponential relation between number of trials and spatial extent, such that additional trials identified, on average, a constant proportion of the remaining voxels. At values typical of fMRI experimentation (e.g. 50 trials) only about 50% of eventually active voxels were significant; asymptotic values were approached by 150 trials. The variability of the estimated hemodynamic response decreased with signal averaging, becoming stable across samples of > or = 25 trials. Therefore, group or condition differences may result from differences in voxelwise noise exacerbated by averaging small numbers of trials.

Duke Scholars

Published In

Neuroreport

DOI

EISSN

1473-558X

ISSN

0959-4965

Publication Date

August 2001

Volume

12

Issue

11

Start / End Page

2411 / 2416

Related Subject Headings

  • Visual Cortex
  • Photic Stimulation
  • Neurology & Neurosurgery
  • Middle Aged
  • Male
  • Magnetic Resonance Imaging
  • Humans
  • Evoked Potentials, Visual
  • Artifacts
  • Adult
 

Citation

APA
Chicago
ICMJE
MLA
NLM
Huettel, S. A., & McCarthy, G. (2001). The effects of single-trial averaging upon the spatial extent of fMRI activation. Neuroreport, 12(11), 2411–2416. https://doi.org/10.1097/00001756-200108080-00025
Huettel, S. A., and G. McCarthy. “The effects of single-trial averaging upon the spatial extent of fMRI activation.Neuroreport 12, no. 11 (August 2001): 2411–16. https://doi.org/10.1097/00001756-200108080-00025.
Huettel SA, McCarthy G. The effects of single-trial averaging upon the spatial extent of fMRI activation. Neuroreport. 2001 Aug;12(11):2411–6.
Huettel, S. A., and G. McCarthy. “The effects of single-trial averaging upon the spatial extent of fMRI activation.Neuroreport, vol. 12, no. 11, Aug. 2001, pp. 2411–16. Epmc, doi:10.1097/00001756-200108080-00025.
Huettel SA, McCarthy G. The effects of single-trial averaging upon the spatial extent of fMRI activation. Neuroreport. 2001 Aug;12(11):2411–2416.

Published In

Neuroreport

DOI

EISSN

1473-558X

ISSN

0959-4965

Publication Date

August 2001

Volume

12

Issue

11

Start / End Page

2411 / 2416

Related Subject Headings

  • Visual Cortex
  • Photic Stimulation
  • Neurology & Neurosurgery
  • Middle Aged
  • Male
  • Magnetic Resonance Imaging
  • Humans
  • Evoked Potentials, Visual
  • Artifacts
  • Adult