General strategy for hierarchical decomposition of multivariate time series: implications for temporal lobe seizures.

TitleGeneral strategy for hierarchical decomposition of multivariate time series: implications for temporal lobe seizures.
Publication TypeJournal Article
Year of Publication2001
AuthorsRepucci, M A., Schiff N D., and Victor J D.
JournalAnn Biomed Eng
Date Published2001 Dec
KeywordsAlgorithms, Computer Simulation, Electroencephalography, Epilepsy, Absence, Epilepsy, Temporal Lobe, Humans, Models, Neurological, Nonlinear Dynamics, Reproducibility of Results, Sensitivity and Specificity, Signal Processing, Computer-Assisted, Stochastic Processes

We describe a novel method for the analysis of multivariate time series that exploits the dynamic relationships among the multiple signals. The approach resolves the multivariate time series into hierarchically dependent underlying sources, each driven by noise input and influencing subordinate sources in the hierarchy. Implementation of this hierarchical decomposition (HD) combines principal components analysis (PCA), autoregressive modeling, and a novel search strategy among orthogonal rotations. For model systems conforming to this hierarchical structure, HD accurately extracts the underlying sources, whereas PCA or independent components analysis does not. The interdependencies of cortical, subcortical, and brainstem networks suggest application of HD to multivariate measures of brain activity. We show first that HD indeed resolves temporal lobe ictal electrocorticographic data into nearly hierarchical form. A previous analysis of these data identified characteristic nonlinearities in the PCA-derived temporal components that resembled those seen in absence (petit mal) seizure electroencephalographic traces. However, the components containing these characteristic nonlinearities accounted for only a small fraction of the power. Analysis of these data with HD reveals furthermore that components containing characteristic nonlinearities, though small, can be at the origin of the hierarchy. This finding supports the link between temporal lobe and absence epilepsy.

Alternate JournalAnn Biomed Eng
PubMed ID11853266
Grant ListEY7138 / EY / NEI NIH HHS / United States
EY7977 / EY / NEI NIH HHS / United States
EY9314 / EY / NEI NIH HHS / United States
NS02172 / NS / NINDS NIH HHS / United States

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