Linked Life Data

18723853

Source:http://linkedlifedata.com/resource/pubmed/id/18723853

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
2009-3-2
pubmed:abstractText
Functional magnetic resonance imaging (f MRI) is a noninvasive technique which is commonly used to quantify changes in blood oxygenation and flow coupled to neuronal activation. One of the primary goals of f MRI studies is to identify localized brain regions where neuronal activation levels vary between groups. Single voxel t-tests have been commonly used to determine whether activation related to the protocol differs across groups. Due to the generally limited number of subjects within each study, accurate estimation of variance at each voxel is difficult. Thus, combining information across voxels is desirable in order to improve efficiency. Here, we construct a hierarchical model and apply an empirical Bayesian framework for the analysis of group f MRI data, employing techniques used in high-throughput genomic studies. The key idea is to shrink residual variances by combining information across voxels and subsequently to construct an improved test statistic. This hierarchical model results in a shrinkage of voxel-wise residual sample variances toward a common value. The shrunken estimator for voxel-specific variance components on the group analyses outperforms the classical residual error estimator in terms of mean-squared error. Moreover, the shrunken test statistic decreases false-positive rates when testing differences in brain contrast maps across a wide range of simulation studies. This methodology was also applied to experimental data regarding a cognitive activation task.
pubmed:grant
pubmed:commentsCorrections
http://linkedlifedata.com/resource/pubmed/commentcorrection/18723853-11395427, http://linkedlifedata.com/resource/pubmed/commentcorrection/18723853-11747097, http://linkedlifedata.com/resource/pubmed/commentcorrection/18723853-12030832, http://linkedlifedata.com/resource/pubmed/commentcorrection/18723853-12210287, http://linkedlifedata.com/resource/pubmed/commentcorrection/18723853-13230290, http://linkedlifedata.com/resource/pubmed/commentcorrection/18723853-14511534, http://linkedlifedata.com/resource/pubmed/commentcorrection/18723853-14668230, http://linkedlifedata.com/resource/pubmed/commentcorrection/18723853-15618528, http://linkedlifedata.com/resource/pubmed/commentcorrection/18723853-15984011, http://linkedlifedata.com/resource/pubmed/commentcorrection/18723853-16627465, http://linkedlifedata.com/resource/pubmed/commentcorrection/18723853-8740983, http://linkedlifedata.com/resource/pubmed/commentcorrection/18723853-9040824, http://linkedlifedata.com/resource/pubmed/commentcorrection/18723853-9391144
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
1468-4357
pubmed:author
pubmed:issnType
Electronic
pubmed:volume
10
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
219-27
pubmed:dateRevised
2011-9-26
pubmed:meshHeading
pubmed:year
2009
pubmed:articleTitle
Modified test statistics by inter-voxel variance shrinkage with an application to f MRI.
pubmed:affiliation
Department of Biostatistics, Johns Hopkins Bloomberg School of Public Health, 615 North Wolfe Street, Baltimore, MD 21205-2179, USA. shsu@jhsph.edu
pubmed:publicationType
Journal Article, Comparative Study