title: Resting State fMRI Functional Connectivity Analysis Using Dynamic Time Warping.
abstract: Traditional resting-state network concept is based on calculating linear dependence of spontaneous low frequency fluctuations of the BOLD signals of different brain areas, which assumes temporally stable zero-lag synchrony across regions. However, growing amount of experimental findings suggest that functional connectivity exhibits dynamic changes and a complex time-lag structure, which cannot be captured by the static zero-lag correlation analysis. Here we propose a new approach applying Dynamic Time Warping (DTW) distance to evaluate functional connectivity strength that accounts for non-stationarity and phase-lags between the observed signals. Using simulated fMRI data we found that DTW captures dynamic interactions and it is less sensitive to linearly combined global noise in the data as compared to traditional correlation analysis. We tested our method using resting-state fMRI data from repeated measurements of an individual subject and showed that DTW analysis results in more stable connectivity patterns by reducing the within-subject variability and increasing robustness for preprocessing strategies. Classification results on a public dataset revealed a superior sensitivity of the DTW analysis to group differences by showing that DTW based classifiers outperform the zero-lag correlation and maximal lag cross-correlation based classifiers significantly. Our findings suggest that analysing resting-state functional connectivity using DTW provides an efficient new way for characterizing functional networks.
authors.affiliation: Department of Cognitive Science, Budapest University of Technology and EconomicsBudapest, Hungary; Brain Imaging Centre, Research Centre for Natural Sciences, Hungarian Academy of SciencesBudapest, Hungary.
authors.forename: Regina J
authors.initials: RJ
authors.lastname: Meszlényi
authors.affiliation: Brain Imaging Centre, Research Centre for Natural Sciences, Hungarian Academy of Sciences Budapest, Hungary.
authors.forename: Petra
authors.initials: P
authors.lastname: Hermann
authors.affiliation: Brain Imaging Centre, Research Centre for Natural Sciences, Hungarian Academy of Sciences Budapest, Hungary.
authors.forename: Krisztian
authors.initials: K
authors.lastname: Buza
authors.affiliation: Brain Imaging Centre, Research Centre for Natural Sciences, Hungarian Academy of Sciences Budapest, Hungary.
authors.forename: Viktor
authors.initials: V
authors.lastname: Gál
authors.affiliation: Department of Cognitive Science, Budapest University of Technology and EconomicsBudapest, Hungary; Brain Imaging Centre, Research Centre for Natural Sciences, Hungarian Academy of SciencesBudapest, Hungary.
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Vidnyánszky
keywords: Dynamic Time Warping; classification; connectome; functional magnetic resonance imaging; resting state connectivity