Cited by 1,907Functional Brain Connectivity StudiesMedical Imaging Techniques and ApplicationsAdvanced MRI Techniques and Applications

Assessing the significance of focal activations using their spatial extent

Friston, K. J., Worsley, K. J., Frackowiak, R. S. J., Mazziotta, J. C., Evans, A. C.·1994·Human Brain Mapping

Abstract

Current approaches to detecting significantly activated regions of cerebral tissue use statistical parametric maps, which are thresholded to render the probability of one or more activated regions of one voxel, or larger, suitably small (e. g., 0.05). We present an approximate analysis giving the probability that one or more activated regions of a specified volume, or larger, could have occurred by chance. These results mean that detecting significant activations no longer depends on a fixed (and high) threshold, but can be effected at any (lower) threshold, in terms of the spatial extent of the activated region. The substantial improvement in sensitivity that ensues is illustrated using a power analysis and a simulated phantom activation study. © 1994 Wiley-Liss, Inc.

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Crossref · 10.1002/hbm.460010306

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  • Correction for multiple comparisons was performed at the cluster level with family-wise error correction p < .05, which restricts the likelihood of false positives.

    “Correction for multiple comparisons was performed at the cluster level (Friston, Worsley, Frackowiak, Mazziotta, & Evans, 1994), with clusters that survive correction for multiple corrections using a family-wise error correction ( p < .05;shown in bold font in Table 2A and B;see Results).This restricts the likelihood of false positives (Eklund et al., 2016).”

    From Functional Specificity and Sex Differences in the Neural Circuits Supporting the Inhibition of Automatic Imitation (2018) · cites this paper as Friston, Worsley, Frackowiak, Mazziotta, & Evans, 1994

  • The exact choice of the initial cluster-forming threshold can have a large impact on the results, particularly at lower cluster-forming thresholds (e.g., t,z < 4).

    “However, a limitation is the need to define the initial cluster-forming threshold. This threshold is arbitrary, and yet its exact choice can have a large impact on the results, particularly at the lower (e.g., t,z < 4) cluster- forming thresholds frequently used.”
  • The initial cluster-forming threshold in cluster-based thresholding is arbitrary.

    “However, a limitation is the need to define the initial cluster-forming threshold. This threshold is arbitrary, and yet its exact choice can have a large impact on the results, particularly at the lower (e.g., t,z < 4) cluster- forming thresholds frequently used.”
  • Multiple comparisons were corrected by controlling the family-wise error rate based on the theory of Gaussian random fields.

    “This approach corrects for the multiple comparisons by controlling the family-wise error rate, and is based on the theory of Gaussian random fields.”

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Authors
Friston, K. J., Worsley, K. J., Frackowiak, R. S. J., Mazziotta, J. C., & Evans, A. C.
Affiliations
  • Hammersmith Hospital (GB)
  • McGill University (CA)
  • University of California, Los Angeles (US)
Corresponding author
Friston, K. J.
Venue
Human Brain Mapping
Publisher
Wiley
Published
1994-01
Volume
1
Issue
3
Pages
210-220
ISSN
  • 1065-9471 (ISSN-L)
  • 1097-0193
OpenAlex
W2169428430
Cited by
1,907
References
11
Citations by year
2026: 18 · 2025: 31 · 2024: 27 · 2023: 31 · 2022: 41 · 2021: 51 · 2020: 54 · 2019: 35 · 2018: 81 · 2017: 62 · 2016: 57 · 2015: 64 · 2014: 46 · 2013: 56 · 2012: 61
FWCI
23.18
Type
journal article
Language
en
Open access
closed
Locations
  • Human Brain Mapping (publishedVersion)
  • PubMed (publishedVersion)
  • UCL Discovery (University College London) (submittedVersion)
Funders
Wellcome Trust
Topics
  • Life Sciences › Neuroscience › Cognitive Neuroscience › Functional Brain Connectivity Studies
  • Health Sciences › Medicine › Radiology, Nuclear Medicine and Imaging › Medical Imaging Techniques and Applications
  • Health Sciences › Medicine › Radiology, Nuclear Medicine and Imaging › Advanced MRI Techniques and Applications
Keywords
false positive probability, power analysis

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