Cabral, JoanaLuckhoo, HenryWoolrich, Mark W.Joensson, MortenMohseni, HamidBaker, AdamKringelbach, Morten L.Deco, Gustavo2015-01-292015-01-292014Cabral J, Luckhoo H, Woolrich M, Joensson M, Mohseni H, Baker A, Kringelbach ML, Deco G. Exploring mechanisms of spontaneous functional connectivity in MEG: How delayed network interactions lead to structured amplitude envelopes of band-pass filtered oscillations. Neuroimage. 2014 Apr;90:423-35. DOI 10.1016/j.neuroimage.2013.11.0471053-8119http://hdl.handle.net/10230/23081Spontaneous (or resting-state) brain activity has attracted a growing body of neuroimaging research over the last/ndecades.Whole-brain networkmodels have proved helpful to investigate the source of slow(b0.1 Hz) correlated/nhemodynamic fluctuations revealed in fMRI during rest. However, the mechanisms mediating resting-state/nlong-distance correlations and the relationship with the faster neural activity remain unclear. Novel insights/ncoming from MEG studies have shown that the amplitude envelopes of alpha- and beta-frequency oscillations/n(8–30 Hz) display similar correlation patterns as the fMRI signals./nIn thiswork, we combine experimental and theoreticalwork to investigate the mechanisms of spontaneousMEG/nfunctional connectivity. Using a simple model of coupled oscillators adapted to incorporate realisticwhole-brain/nconnectivity and conduction delays, we explore how slow and structured amplitude envelopes of band-pass/nfiltered signals – fairly reproducing MEG data collected from 10 healthy subjects at rest – are generated spontaneously/nin the space-time structure of the brain network./nOur simulation results show that the large-scale neuroanatomical connectivity provides an optimal network/nstructure to support a regimewith metastable synchronization. In this regime, different subsystems may temporarily/nsynchronize at reduced collective frequencies (falling in the 8–30 Hz range due to the delays) while the/nglobal system never fully synchronizes. This mechanism modulates the frequency of the oscillators on a slow/ntime-scale (b0.1 Hz) leading to structured amplitude fluctuations of band-pass filtered signals. Taken overall,/nour results reveal that the structured amplitude envelope fluctuations observed in resting-state MEG data may/noriginate from spontaneous synchronization mechanisms naturally occurring in the space-time structure of/nthe brain.13 p.application/pdfeng© 2013 The Authors. Published by Elsevier Inc. Open access under CC-BY-NC-ND Licenseinfo:eu-repo/semantics/articlehttp://dx.doi.org/10.1016/j.neuroimage.2013.11.047Resting stateMEGOscillationsNetworkKuramotoModelingStructural connectivityFunctional connectivityinfo:eu-repo/semantics/openAccess