Linked Life Data

11305902

Source:http://linkedlifedata.com/resource/pubmed/id/11305902

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
2001-4-18
pubmed:abstractText
Local signals obtained from BOLD fMRI are generally confounded by global effects. In this paper, we make an essential distinction between global effects and the global signal. Global effects have a similar influence on local signals from a large proportion of cerebral voxels. They may reflect diffuse physiological processes or variations in scanner sensitivity and are difficult to measure directly. Global effects are often estimated from the global signal, which is the spatial average of local signals from all cerebral voxels. If the global signal is strongly correlated with experimental manipulations, meaningfully different results may be obtained whether or not global effects are modeled (G. K. Aguirre et al., 1998, NeuroImage, 8, 302-306). In particular, if local BOLD signals make a significant contribution to the global signal, analyses using ANCOVAor proportional scaling models may yield artifactual deactivations. In this paper, we present a modification to the proportional scaling model that accounts for the contribution of local BOLD signals to the global signal. An event-related oddball stimulus paradigm and a block design working memory task were used to illustrate the efficacy of our model.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
1053-8119
pubmed:author
pubmed:copyrightInfo
Copyright 2001 Academic Press.
pubmed:issnType
Print
pubmed:volume
13
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
751-8
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2001
pubmed:articleTitle
Removal of confounding effects of global signal in functional MRI analyses.
pubmed:affiliation
Neuroimaging Laboratory, Department of Psychiatry, University of British Columbia, Vancouver, British Columbia, V6T 2A1, Canada .
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't