Table of Contents
ISRN Neuroscience
Volume 2014 (2014), Article ID 756952, 10 pages
http://dx.doi.org/10.1155/2014/756952
Research Article

A Recurrent Increase of Synchronization in the EEG Continues from Waking throughout NREM and REM Sleep

1Klinik für Neurologie, Pfalzklinikum für Neurologie und Psychiatrie, Weinstraße 100, 76889 Klingenmünster, Germany
2Marienkrankenhaus St. Wendel, Stroke Unit, 66606 St. Wendel, Germany
3Klinik für Neurologie, Westpfalz Klinikum GmbH, Hellmut-Hartert-Straße 1, 67655 Kaiserslautern, Germany

Received 30 October 2013; Accepted 19 December 2013; Published 6 February 2014

Academic Editors: S. Bagnato and C. Kellinghaus

Copyright © 2014 Ralf Landwehr et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Pointwise transinformation (PTI) provides a quantitative nonlinear approach to spatiotemporal synchronization patterns of the rhythms of coupled cortical oscillators. We applied PTI to the waking and sleep EEGs of 21 healthy sleepers; we calculated the mean levels and distances of synchronized episodes and estimated the dominant frequency shift from unsynchronized to synchronized EEG segments by spectral analysis. Recurrent EEG synchronization appeared and ceased abruptly in the anterior, central, and temporal derivations; in the posterior derivations it appeared more fluctuating. This temporal dynamics of synchronization remained stable throughout all states of vigilance, while the dominant frequencies of synchronized phases changed markedly. Mean synchronization had high frontal and occipital levels and low central and midtemporal levels. Thus, a fundamental coupling pattern with recurrent increases of synchronization in the EEG (“RISE”) seems to exist during the brain’s resting state. The generators of RISE could be coupled corticocortical neuronal assemblies which might be modulated by subcortical structures. RISE designates the recurrence of transiently synchronized cortical microstates that are independent of specific EEG waves, the spectral content of the EEG, and especially the current state of vigilance. Therefore, it might be suited for EEG analysis in clinical situations without stable vigilance.