Journal
NEUROIMAGE
Volume 90, Issue -, Pages 423-435Publisher
ACADEMIC PRESS INC ELSEVIER SCIENCE
DOI: 10.1016/j.neuroimage.2013.11.047
Keywords
Resting state; MEG; Oscillations; Network; Kuramoto; Modeling; Structural connectivity; Functional connectivity
Funding
- ERC Advanced Grant: DYSTRUCTURE [295129]
- FET Flagship Human Brain Project
- Spanish Research Project [SAF2010-16085]
- BrainNRG through the James S. McDonnell Foundation
- FP7-ICT BrainScales
- RCUK Digital Economy Centre for Doctoral Training in Healthcare Innovation
- MINDLab Investment Capital for University Research Fund
- TrygFonden Charitable Foundation
- [CONSOLIDER-INGENIO 2010 CSD2007-00012]
- ICREA Funding Source: Custom
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Spontaneous (or resting-state) brain activity has attracted a growing body of neuroimaging research over the last decades. Whole-brain network models have proved helpful to investigate the source of slow (<0.1 Hz) correlated hemodynamic fluctuations revealed in fMRI during rest. However, the mechanisms mediating resting-state long-distance correlations and the relationship with the faster neural activity remain unclear. Novel insights coming from MEG studies have shown that the amplitude envelopes of alpha- and beta-frequency oscillations (-8-30 Hz) display similar correlation patterns as the fMRI signals. In this work, we combine experimental and theoretical work to investigate the mechanisms of spontaneous MEG functional connectivity. Using a simple model of coupled oscillators adapted to incorporate realistic whole-brain connectivity and conduction delays, we explore how slow and structured amplitude envelopes of band-pass filtered signals - fairly reproducing MEG data collected from 10 healthy subjects at rest - are generated spontaneously in the space-time structure of the brain network Our simulation results show that the large-scale neuroanatomical connectivity provides an optimal network structure to support a regime with metastable synchronization. In this regime, different subsystems may temporarily synchronize at reduced collective frequencies (falling in the 8-30 Hz range due to the delays) while the global system never fully synchronizes. This mechanism modulates the frequency of the oscillators on a slow time-scale (<0.1 Hz) leading to structured amplitude fluctuations of band-pass filtered signals. Taken overall, our results reveal that the structured amplitude envelope fluctuations observed in resting-state MEG data may originate from spontaneous synchronization mechanisms naturally occurring in the space-time structure of the brain. (C) 2013 The Authors. Published by Elsevier Inc. All rights reserved.
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