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Cited by 407Advanced MRI Techniques and ApplicationsFunctional Brain Connectivity StudiesAdvanced Neuroimaging Techniques and Applications

A method for removal of global effects from fMRI time series

Macey, Paul M, Macey, Katherine E, Kumar, Rajesh, Harper, Ronald M·2004·NeuroImage
DOI 10.1016/j.neuroimage.2003.12.042
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Abstract

We present a technique for removing global effects from functional magnetic resonance imaging (fMRI) images, using a voxel-level linear model of the global signal (LMGS). The procedure does not assume low-frequency global effects and is based on the assumption that the global signal (the time course of the average intensity per volume) is replicated in the same pattern throughout the brain, although not necessarily at the same magnitude. A second assumption is that all effects that match the global signal are of no interest and can be removed. The method involves modeling the time course of each voxel to the global signal and removing any such global component from the voxel's time course. A challenge that elicits a large change in the global blood oxygenation level-dependent (BOLD) signal, inspired hypercapnia (5% CO(2)/95% O(2)), was administered to 14 subjects during a 144-s, 24-scan fMRI procedure; baseline series were also collected. The method was applied to these data and compared to intensity normalization and low-frequency spline detrending. A large global BOLD signal increase emerged to the hypercapnic challenge. Intensity normalization failed to remove global components due to regional variability. Both LMGS and spline detrending effectively removed low-frequency components, but unlike spline detrending (which is designed to remove only low frequency trends), the LMGS removed higher-frequency global fluctuations throughout the challenge and baseline series. LMGS removes all effects correlated with the global signal, and may be especially useful for fMRI data that include large global effects and for generating detrended images to use with subsequent volume-of-interest (VOI) analyses.

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  • As controlled breathing is a key component of meditation, potential respiratory artifacts and confounds were accounted for by despiking the data and removing the run-specific global signal for each voxel.

    “As controlled breathing is a key component of meditation, we accounted for potential respiratory artifacts and confounds by despiking the data using the ArtRepair toolbox (version 4, http:// cibsr.stanford.edu/tools/human-brain-project/artrepair-software.html) and removing the run-specific global signal for each voxel (Macey et al., 2004) in line with previous work (e.g.Farb et al., 2013).”

    From Compassion-based emotion regulation up-regulates experienced positive affect and associated neural networks (2015) · cites this paper as Macey et al., 2004

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Authors
Macey, P. M., Macey, K. E., Kumar, R., & Harper, R. M.
Affiliations
University of California, Los Angeles (US)
Corresponding author
Harper, Ronald M
ORCID
Venue
NeuroImage
Publisher
Elsevier BV
Published
2004-05
Volume
22
Issue
1
Pages
360-366
ISSN
1053-8119 (ISSN-L)
DOI
10.1016/j.neuroimage.2003.12.042
OpenAlex
W2012237386
Cited by
407
References
22
Citations by year
2026: 9 · 2025: 19 · 2024: 13 · 2023: 8 · 2022: 14 · 2021: 23 · 2020: 19 · 2019: 24 · 2018: 18 · 2017: 15 · 2016: 25 · 2015: 28 · 2014: 18 · 2013: 27 · 2012: 34
FWCI
8.38
Type
journal article
Language
en
Open access
closed
Licence
www.elsevier.com/tdm/userlicense/1.0/ (tdm)
Locations
  • NeuroImage (publishedVersion)
  • PubMed (publishedVersion)
Funders
Eunice Kennedy Shriver National Institute of Child Health and Human Development (HD22695, R01HD022695)
Topics
  • Health Sciences › Medicine › Radiology, Nuclear Medicine and Imaging › Advanced MRI Techniques and Applications
  • Life Sciences › Neuroscience › Cognitive Neuroscience › Functional Brain Connectivity Studies
  • Health Sciences › Medicine › Radiology, Nuclear Medicine and Imaging › Advanced Neuroimaging Techniques and Applications
Keywords
fMRI time series, global signal, BOLD signal, intensity normalization, detrending
MeSH terms
Adolescent, Brain Mapping, Child, Female, Humans, Hypercapnia, Image Processing, Computer-Assisted, Magnetic Resonance Imaging, Male, Oxygen, Reference Values, Linear Models

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