The Creutzfeldt-Jakob disease in the hierarchy of chaotic attractors.
Agnessa Babloyantz and Alain Destexhe

In: From Chemical to Biological Organization, Edited by Markus, M., Muller, S. and Nicolis, G., Springer Series in Synergetics, Vol. 39, Springer-Verlag, Berlin, 1988, pp. 307-316.

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We report here the application of dimensional analysis to the human electroencephalogram (EEG) of a patient suffering from a neurological disorder known as the Creutzfeldt-Jakob (CJ) disease. The method of dimensional analysis show inherent difficulties which may induce errors of interpretation if the analysis is not carefully done. We show here that during CJ disease, the EEG is remarkably stable and coherent which allowed us to perform stationary recordings during long periods of time. The correlation dimension, calculated using four different methods, was stable and independent of the length of the time series, provided it was long enough. The dimension is compared with the previous studies of beta waves, alpha waves, sleep stages two, four, REM sleep and Petit-Mal type of epileptic seizures. We compare the values of the dimension to the coherence of the power spectrum and the amplitude variations of the EEG. By following the hierarchy of awake, REM sleep, light sleep, deep sleep, CJ disease and Petit-Mal epilepsy, there is a systematic increase of EEG amplitude, probably due to an increase of synchrony, and of the coherence of the power spectrum, which tends to be confined progressively in sharper peaks. The dimension follows very well this hierarchy and varies inversely proportional to the EEG amplitude. This suggests that more “synchronized” behavioral states are also more coherent temporally.