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Updated: Dec 7, 2025
Microstate and Omega Complexity Analyses of the Resting-state Electroencephalography
Published on: June 15, 2018
EEG microstate periodicity explained by rotating phase patterns of resting-state alpha oscillations
F von Wegner1, S Bauer2, F Rosenow2
1School of Medical Sciences, University of New South Wales, Wallace Wurth Building, Kensington, NSW 2052, Australia; Epilepsy Center Frankfurt Rhine-Main, Center of Neurology and Neurosurgery, University Hospital Frankfurt and Center for Personalized Translational Epilepsy Research (CePTER), Goethe University Frankfurt, Frankfurt am Main, Germany.
Brain activity patterns, or electroencephalography (EEG) microstates, are driven by the phase, not amplitude, of alpha oscillations. This explains the periodic recurrence of microstates linked to alpha frequencies.
Area of Science:
- Neuroscience
- Computational Neuroscience
- Signal Processing
Background:
- Electroencephalography (EEG) microstates offer a discrete view of continuous cortical electric field patterns.
- Resting-state EEG microstates are primarily influenced by alpha frequencies (8-12 Hz).
- Previous research indicated microstate periodicity occurs at twice the alpha frequency.
Purpose of the Study:
- To investigate the origin of microstate periodicity by analyzing amplitude and phase of alpha oscillations independently.
- To determine the contribution of phase and amplitude to microstate sequence periodicity.
Main Methods:
- Analysis of analytic amplitude and phase of resting-state alpha oscillations in continuous EEG data.
- Time-lagged mutual information analysis of microstate sequences from amplitude and phase signals in 23 healthy adults.
- Validation using temporal principal component analysis (tPCA), autocorrelation analysis, and a computational model (Stuart-Landau oscillators).
Main Results:
- Rotating phase patterns with phase singularities were observed, spatially rotating at the alpha frequency.
- Phase sequences, not amplitude sequences, showed significant periodicity (peaks at multiples of 50 ms, main peak at 100 ms).
- Computational models demonstrated that phase-amplitude dynamics similar to EEG emerge near a supercritical Hopf bifurcation.
Conclusions:
- Microstate periodicity is driven solely by the phase dynamics of alpha oscillations, not their amplitude.
- The findings explain periodic microstate recurrence and its relationship to alpha oscillation timescales.
- Results support computational models of alpha rhythm and link experimental EEG patterns to critical oscillator network properties.
