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Proceedings Paper

Unsupervised spatio-temporal detection of brain functional activation based on hidden Markov multiple event sequence models
Author(s): Sylvain Faisan; Laurent Thoraval; Jean-Paul Armspach; Fabrice Heitz; Jack Foucher
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Paper Abstract

This paper presents a novel, completely unsupervised fMRI brain mapping approach that addresses the three problems of hemodynamic response function (HRF) shape variability, neural event timing, and fMRI response linearity. To make it robust, the method takes into account spatial and temporal information directly into the core of the activation detection process. In practice, activation detection is formulated in terms of temporal alignment between the sequence of hemodynamic response onsets (HROs) detected in the fMRI signal at υ and in the spatial neighbourhood of υ, and the sequence of "off-on" transitions observed in the input blocked stimulation paradigm (when considering epoch-related fMRI data), or the sequence of stimuli of the event-based paradigm (when considering event-related fMRI data). This multiple event sequence alignment problem, which comes under multisensor data fusion, is solved within the probabilistic framework of hidden Markov multiple event sequence models (HMMESMs), a special class of hidden Markov models. Results obtained on real and synthetic data compete with those obtained with the popular statistical parametric mapping (SPM) approach, but without necessitating any prior definition of the expected activation patterns, the HMMESM mapping approach being completely unsupervised.

Paper Details

Date Published: 29 April 2005
PDF: 12 pages
Proc. SPIE 5747, Medical Imaging 2005: Image Processing, (29 April 2005); doi: 10.1117/12.592534
Show Author Affiliations
Sylvain Faisan, LSIIT/MIV, CNRS and Strasbourg I Univ. (France)
Laurent Thoraval, LSIIT/MIV, CNRS and Strasbourg I Univ. (France)
Jean-Paul Armspach, IPB, CNRS and Strasbourg Univ. (France)
Fabrice Heitz, LSIIT/MIV, CNRS and Strasbourg I Univ. (France)
Jack Foucher, INSERM (France)

Published in SPIE Proceedings Vol. 5747:
Medical Imaging 2005: Image Processing
J. Michael Fitzpatrick; Joseph M. Reinhardt, Editor(s)

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