Document Detail


Improving the use of principal component analysis to reduce physiological noise and motion artifacts to increase the sensitivity of task-based fMRI.
MedLine Citation:
PMID:  25481542     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
BACKGROUND: Functional magnetic resonance imaging (fMRI) time series are subject to corruption by many noise sources, especially physiological noise and motion. Researchers have developed many methods to reduce physiological noise, including RETROICOR, which retroactively removes cardiac and respiratory waveforms collected during the scan, and CompCor, which applies principal components analysis (PCA) to remove physiological noise components without any physiological monitoring during the scan.
NEW METHOD: We developed four variants of the CompCor method. The optimized CompCor method applies PCA to time series in a noise mask, but orthogonalizes each component to the BOLD response waveform and uses an algorithm to determine a favorable number of components to use as "nuisance regressors." Whole brain component correction (WCompCor) is similar, except that it applies PCA to time-series throughout the whole brain. Low-pass component correction (LCompCor) identifies low-pass filtered components throughout the brain, while high-pass component correction (HCompCor) identifies high-pass filtered components. Comparison with existing method: We compared the new methods with the original CompCor method by examining the resulting functional contrast-to-noise ratio (CNR), sensitivity, and specificity.
RESULTS: (1) The optimized CompCor method increased the CNR and sensitivity compared to the original CompCor method and (2) the application of WCompCor yielded the best improvement in the CNR and sensitivity.
CONCLUSIONS: The sensitivity of the optimized CompCor, WCompCor, and LCompCor methods exceeded that of the original CompCor method. However, regressing noise signals showed a paradoxical consequence of reducing specificity for all noise reduction methods attempted.
Authors:
David A Soltysik; David Thomasson; Sunder Rajan; Nadia Biassou
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2014-12-4
Journal Detail:
Title:  Journal of neuroscience methods     Volume:  -     ISSN:  1872-678X     ISO Abbreviation:  J. Neurosci. Methods     Publication Date:  2014 Dec 
Date Detail:
Created Date:  2014-12-8     Completed Date:  -     Revised Date:  2014-12-8    
Medline Journal Info:
Nlm Unique ID:  7905558     Medline TA:  J Neurosci Methods     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2014. Published by Elsevier B.V.
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