Cited by 255Functional Brain Connectivity StudiesAdvanced MRI Techniques and ApplicationsAdvanced Neuroimaging Techniques and Applications

The perils of global signal regression for group comparisons: a case study of Autism Spectrum Disorders

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Gotts, Stephen J., Saad, Ziad S., Jo, Hang Joon, Wallace, Gregory L., Cox, Robert W., Martin, Alex·2013·Frontiers in Human Neuroscience

Abstract

We have previously argued from a theoretical basis that the standard practice of regression of the Global Signal from the fMRI time series in functional connectivity studies is ill advised, particularly when comparing groups of participants. Here, we demonstrate in resting-state data from participants with an Autism Spectrum Disorder and matched controls that these concerns are also well founded in real data. Using the prior theoretical work to formulate predictions, we show: (1) rather than simply altering the mean or range of correlation values amongst pairs of brain regions, Global Signal Regression systematically alters the rank ordering of values in addition to introducing negative values, (2) it leads to a reversal in the direction of group correlation differences relative to other preprocessing approaches, with a higher incidence of both long-range and local correlation differences that favor the Autism Spectrum Disorder group, (3) the strongest group differences under other preprocessing approaches are the ones most altered by Global Signal Regression, and (4) locations showing group differences no longer agree with those showing correlations with behavioral symptoms within the Autism Spectrum Disorder group. The correlation matrices of both participant groups under Global Signal Regression were well predicted by our previous mathematical analyses, demonstrating that there is nothing mysterious about these results. Finally, when independent physiological nuisance measures are lacking, we provide a simple alternative approach for assessing and lessening the influence of global correlations on group comparisons that replicates our previous findings. While this alternative performs less well for symptom correlations than our favored preprocessing approach that includes removal of independent physiological measures, it is preferable to the use of Global Signal Regression, which prevents unequivocal conclusions about the direction or location of group differences.

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Crossref · 10.3389/fnhum.2013.00356

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  • Hypnotic suggestibility was independent of age, educational level, handedness, trait anxiety, mental absorption, average movement during functional scans, and global correlation among all voxels.

    “HS was independent of age, educational level, handedness, trait anxiety, mental absorption, average movement during the functional scans, and global correlation among all voxels (“gcor” index [31]).”
  • There is the possibility that GSR altered connectivity patterns, which in turn may change the degree of similarity of individuals and thus the resulting community designations.

    “There is the possibility that GSR altered connectivity patterns [57], [58], which in turn may change the degree of similarity of individuals and thus the resulting community designations.”
  • Certain kinds of data scrubbing in resting-state fMRI artificially increase short-range connectivity and decrease long-range connectivity.

    “certain kinds of data scrubbing have been shown to artificially increase short-range connectivity and decrease long range connectivity (Gotts et al., 2013)”

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Authors
Gotts, S. J., Saad, Z. S., Jo, H. J., Wallace, G. L., Cox, R. W., & Martin, A.
Affiliations
National Institutes of Health (US)
Corresponding author
Gotts, Stephen J.
Venue
Frontiers in Human Neuroscience
Published
2013
Volume
7
Pages
356-356
ISSN
1662-5161 (ISSN-L)
OpenAlex
W2044820817
Cited by
255
References
70
Citations by year
2026: 6 · 2025: 12 · 2024: 5 · 2023: 7 · 2022: 15 · 2021: 10 · 2020: 28 · 2019: 25 · 2018: 30 · 2017: 29 · 2016: 32 · 2015: 28 · 2014: 23 · 2013: 5
FWCI
16.09
Type
journal article
Language
en
Open access
Licence
cc-by
Locations
  • Frontiers in Human Neuroscience (publishedVersion, cc-by)
  • Europe PMC (PubMed Central) (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
Funders
  • National Institutes of Health (NCT01031407)
  • National Institute of Mental Health (NCT01031407)
  • NHLBI Division of Intramural Research
Topics
  • Life Sciences › Neuroscience › Cognitive Neuroscience › Functional Brain Connectivity Studies
  • Health Sciences › Medicine › Radiology, Nuclear Medicine and Imaging › Advanced MRI Techniques and Applications
  • Health Sciences › Medicine › Radiology, Nuclear Medicine and Imaging › Advanced Neuroimaging Techniques and Applications
Keywords
global signal regression, resting-state functional connectivity, autism spectrum disorder, group comparison, rank reversal, long-range correlations, fMRI preprocessing

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