TY  - JOUR
A1  - Schaworonkow, Natalie
A1  - Nikulin, Vadim
T1  - Spatial neuronal synchronization and the waveform of oscillations : implications for EEG and MEG
T2  - PLoS Computational Biology
N2  - Neuronal oscillations are ubiquitous in the human brain and are implicated in virtually all brain functions. Although they can be described by a prominent peak in the power spectrum, their waveform is not necessarily sinusoidal and shows rather complex morphology. Both frequency and temporal descriptions of such non-sinusoidal neuronal oscillations can be utilized. However, in non-invasive EEG/MEG recordings the waveform of oscillations often takes a sinusoidal shape which in turn leads to a rather oversimplified view on oscillatory processes. In this study, we show in simulations how spatial synchronization can mask non-sinusoidal features of the underlying rhythmic neuronal processes. Consequently, the degree of non-sinusoidality can serve as a measure of spatial synchronization. To confirm this empirically, we show that a mixture of EEG components is indeed associated with more sinusoidal oscillations compared to the waveform of oscillations in each constituent component. Using simulations, we also show that the spatial mixing of the non-sinusoidal neuronal signals strongly affects the amplitude ratio of the spectral harmonics constituting the waveform. Finally, our simulations show how spatial mixing can affect the strength and even the direction of the amplitude coupling between constituent neuronal harmonics at different frequencies. Validating these simulations, we also demonstrate these effects in real EEG recordings. Our findings have far reaching implications for the neurophysiological interpretation of spectral profiles, cross-frequency interactions, as well as for the unequivocal determination of oscillatory phase.
KW  - Electroencephalography
KW  - Bandpass filters
KW  - Signal filtering
KW  - Butterworth filters
KW  - Fourier analysis
KW  - Eye movements
KW  - Sine waves
KW  - Neurophysiology
Y1  - 2019
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/50252
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-502528
SN  - 1553-7358
SN  - 1553-734X
N1  - Copyright: © 2019 Schaworonkow, Nikulin. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
VL  - 15
IS  - (5): e1007055
SP  - 1
EP  - 22
PB  - Public Library of Science
CY  - San Francisco, Calif.
ER  -