INVESTIGADORES
ROSSO Osvaldo Anibal
artículos
Título:
Characterization of time dynamical evolution of electroencephalographic epileptic records
Autor/es:
O. A. ROSSO; M. L. MAIRAL
Revista:
PHYSICA A - STATISTICAL AND THEORETICAL PHYSICS
Editorial:
Elsevier Science
Referencias:
Año: 2002 vol. 312 p. 469 - 504
ISSN:
0378-4371
Resumen:
Since traditional electrical brain signal analysis is mostly qualitative, the development of new quantitative methods is crucial for restricting the subjectivity in the study of brain signals. These methods are particularly fruitful when they are strongly correlated with intuitive physical concepts that allow a better understanding of the brain dynamics. The processing of information by the brain is re4ected in dynamical changes of the electrical activity in time, frequency, and space. Therefore, the concomitant studies require methods capable of describing the qualitative variation of the signal in both time and frequency. The entropy de5ned from the wavelet functions is a measure of the order=disorder degree present in a time series. In consequence, this entropy evaluates over EEG time series gives information about the underlying dynamical process in the brain, more speci5cally of the synchrony of the group cells involved in the di9erent neural responses. The total wavelet entropy results independent of the signal energy and becomes a good tool for detecting dynamical changes in the system behavior. In addition the total wavelet entropy has advantages over the Lyapunov exponents, because it is parameter free and independent of the stationarity of the time series. In this work we compared the results of the time evolution of the chaoticity (Lyapunov exponent as a function of time) with the corresponding time evolution of the total wavelet entropy in two di9erent EEG records, one provide by depth electrodes and other by scalp ones. c=disorder degree present in a time series. In consequence, this entropy evaluates over EEG time series gives information about the underlying dynamical process in the brain, more speci5cally of the synchrony of the group cells involved in the di9erent neural responses. The total wavelet entropy results independent of the signal energy and becomes a good tool for detecting dynamical changes in the system behavior. In addition the total wavelet entropy has advantages over the Lyapunov exponents, because it is parameter free and independent of the stationarity of the time series. In this work we compared the results of the time evolution of the chaoticity (Lyapunov exponent as a function of time) with the corresponding time evolution of the total wavelet entropy in two di9erent EEG records, one provide by depth electrodes and other by scalp ones.  =disorder degree present in a time series. In consequence, this entropy evaluates over EEG time series gives information about the underlying dynamical process in the brain, more speci5cally of the synchrony of the group cells involved in the di9erent neural responses. The total wavelet entropy results independent of the signal energy and becomes a good tool for detecting dynamical changes in the system behavior. In addition the total wavelet entropy has advantages over the Lyapunov exponents, because it is parameter free and independent of the stationarity of the time series. In this work we compared the results of the time evolution of the chaoticity (Lyapunov exponent as a function of time) with the corresponding time evolution of the total wavelet entropy in two di9erent EEG records, one provide by depth electrodes and other by scalp ones.