title: Spindles in Svarog: framework and software for parametrization of EEG transients.
abstract: We present a complete framework for time-frequency parametrization of EEG transients, based upon matching pursuit (MP) decomposition, applied to the detection of sleep spindles. Ranges of spindles duration (>0.5 s) and frequency (11-16 Hz) are taken directly from their standard definitions. Minimal amplitude is computed from the distribution of the root mean square (RMS) amplitude of the signal within the frequency band of sleep spindles. Detection algorithm depends on the choice of just one free parameter, which is a percentile of this distribution. Performance of detection is assessed on the first cohort/second subset of the Montreal Archive of Sleep Studies (MASS-C1/SS2). Cross-validation performed on the 19 available overnight recordings returned the optimal percentile of the RMS distribution close to 97 in most cases, and the following overall performance measures: sensitivity 0.63 ± 0.06, positive predictive value 0.47 ± 0.08, and Matthews coefficient of correlation 0.51 ± 0.04. These concordances are similar to the results achieved on this database by other automatic methods. Proposed detailed parametrization of sleep spindles within a universal framework, encompassing also other EEG transients, opens new possibilities of high resolution investigation of their relations and detailed characteristics. MP decomposition, selection of relevant structures, and simple creation of EEG profiles used previously for assessment of brain activity of patients in disorders of consciousness are implemented in a freely available software package Svarog (Signal Viewer, Analyzer and Recorder On GPL) with user-friendly, mouse-driven interface for review and analysis of EEG. Svarog can be downloaded from http://braintech.pl/svarog.
authors.affiliation: Faculty of Physics, University of Warsaw Warsaw, Poland.
authors.forename: Piotr J
authors.initials: PJ
authors.lastname: Durka
authors.affiliation: Department of Neurology, Epilepsy Center, Johns Hopkins University School of Medicine Baltimore, MD, USA.
authors.forename: Urszula
authors.initials: U
authors.lastname: Malinowska
authors.affiliation: Faculty of Physics, University of Warsaw Warsaw, Poland.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Zieleniewska
authors.affiliation: McConnell Brain Imaging Center, Montreal Neurological Institute, McGill University Montreal, QC, Canada ; Center for Advanced Research on Sleep Medicine, Centre de Recherche de l'Hôpital du Sacré-Cœur, Université de Montréal Montreal, QC, Canada.
authors.forename: Christian
authors.initials: C
authors.lastname: O'Reilly
authors.affiliation: College of Inter-Faculty Individual Studies in Mathematics and Natural Sciences, University of Warsaw Warsaw, Poland.
authors.forename: Piotr T
authors.initials: PT
authors.lastname: Różański
authors.affiliation: Faculty of Physics, University of Warsaw Warsaw, Poland.
authors.forename: Jarosław
authors.initials: J
authors.lastname: Żygierewicz
keywords: EEG transients; Svarog; free software; matching pursuit; open source; sleep; sleep spindles; time-frequency