Exploring mechanisms of spontaneous functional connectivity in MEG: How delayed network interactions lead to structured amplitude envelopes of band-pass filtered oscillations

Joana Cabral, Henry Luckhoo, Mark W. Woolrich, Morten Joensson, Hamid Mohseni, Adam Baker, Morten L. Kringelbach, Gustavo Deco

Research output: Contribution to journalArticleResearchpeer-review

108 Citations (Scopus)

Abstract

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.

Original languageEnglish
Pages (from-to)423-435
Number of pages13
JournalNeuroImage
Volume90
DOIs
Publication statusPublished - 15 Apr 2014
Externally publishedYes

Keywords

  • Functional connectivity
  • Kuramoto
  • MEG
  • Modeling
  • Network
  • Oscillations
  • Resting state
  • Structural connectivity

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