Spatiotemporal independent component analysis of event-related fMRI data using skewed probability density functions.

Full Abstract

We introduce two independent component analysis (ICA) methods, spatiotemporal ICA (stICA) and skew-ICA, and demonstrate the utility of these methods in analyzing synthetic and event-related fMRI data. First, stICA simultaneously maximizes statistical independence over both time and space. This contrasts with conventional ICA methods, which maximize independence either over time only or over space only; these methods often yield physically improbable solutions. Second, skew-ICA is based on the assumption that images have skewed probability density functions (pdfs), an assumption consistent with spatially localized regions of activity. In contrast, conventional ICA is based on the physiologically unrealistic assumption that images have symmetric pdfs. We combine stICA and skew-ICA, to form skew-stICA, and use it to analyze synthetic data and data from an event-related, left-right visual hemifield fMRI experiment. Results obtained with skew-stICA are superior to those of principal component analysis, spatial ICA (sICA), temporal ICA, stICA, and skew-sICA. We argue that skew-stICA works because it is based on physically realistic assumptions and that the potential of ICA can only be realized if such prior knowledge is incorporated into ICA methods.

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Author information

Author/s: Stone, J V (JV); Porrill, J (J); Porter, N R (NR); Wilkinson, I D (ID);

Affiliation: Psychology Department, Sheffield University, Sheffield S10 2TP, England.

Journal and publication information

Publication Type: Journal Article; Research Support, Non-U.S. Gov't

Journal: NeuroImage (Neuroimage), published in United States. (Language: eng)

Reference: 2002-Feb; vol 15 (issue 2) : pp 407-21

Dates: Created 2002/01/18; Completed 2002/04/19; Revised 2006/11/15;

PMID: 11798275, status: MEDLINE (last retrieval date: 11/6/2008)

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Evoked Potentials - physiology
Fixation, Ocular
Functional Laterality
Humans
Magnetic Resonance Imaging - methods

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