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Alteration in pattern of rapid eye movements activity during REM sleep in depression

100%
Wichniak A., Antczak J., Wierzbicka A., Jernajczyk W.
Acta Neurobiologiae Experimentalis
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2002
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vol. 62
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issue 4
243-250
EN
The aim of the study was to evaluate REM sleep parameters, especially the temporal characteristics of rapid eye movement activity, in depressed patients, and to compare three different methods for scoring of REM density. The sleep of 15 nonmedicated depressed patients and 13 healthy controls was recorded during two consecutive nights. Sleep recordings were scored by raters blinded to the diagnosis. In comparison to healthy controls depressed patients showed an increased REM density and increased REM activity. Both groups differed also regarding the pattern of REM density changes between REM sleep periods (REMPs). Whereas in healthy controls REM density in the first REMP was significantly lower than in the successive REMPs, no such difference was found in depressed patients. On visual inspection we failed to find any significant differences in the time course of REM activity within the first REMP in depressed patients. All applied methods for scoring of REM density distinguished depressed patients from healthy controls with comparable accuracy.
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Quantitative measure of complexity of EEG signal dynamics

88%
Klonowski W., Jernajczyk W., Niedzielska K., Rydz A., Stepien R.
Acta Neurobiologiae Experimentalis
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1999
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vol. 59
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issue 4
315-321
EN
Since electroencephalographic (EEG) signal may be considered chaotic, Nonlinear Dynamics and Deterministic Chaos Theory may supply effective quantitative descriptors of EEG dynamics and of underlying chaos in the brain. We have used Karhunen-Loeve decomposition of the covariance matrix of the EEG signal to analyse EEG signals of 4 healthy subjects, under drug-free condition and under the influence of Diazepam. We found that what we call KL-complexity of the signal differs profoundly for the signals registered in different EEG channels, from about 5-8 for signals in frontal channels up to 40 and more in occipital ones. But no consistency in the influence of Diazepam administration on KL-complexity is observed. We also estimated the embedding dimension of the EEG signals of the same subjects, which turned to be between 7 and 11, so endorsing the presumption about existence of low-dimensional chaotic attractor. We are sure that nonlinear time series analysis can be used to investigate the dynamics underlying the generation of EEG signal. This approach does not seem practical yet, but deserves further study.
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