探索脑磁图中自发功能连接的机制：延迟的网络相互作用如何导致带通滤波振荡的结构化幅度包络。
Exploring mechanisms of spontaneous functional connectivity in MEG: how delayed network interactions lead to structured amplitude envelopes of band-pass filtered oscillations.
作者信息
Cabral Joana, Luckhoo Henry, Woolrich Mark, Joensson Morten, Mohseni Hamid, Baker Adam, Kringelbach Morten L, Deco Gustavo
机构信息
Theoretical and Computational Neuroscience Group, Center of Brain and Cognition, Universitat Pompeu Fabra, 08018 Barcelona, Spain; Department of Psychiatry, University of Oxford, OX3 7JX Oxford, UK.
Oxford Centre for Human Brain Activity, University of Oxford, OX3 7JX Oxford, UK; Centre for Doctoral Training in Healthcare Innovation, Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, OX1 3PJ Oxford, UK.
出版信息
Neuroimage. 2014 Apr 15;90:423-35. doi: 10.1016/j.neuroimage.2013.11.047. Epub 2013 Dec 7.
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.
在过去几十年中，自发（或静息态）脑活动吸引了越来越多的神经影像学研究。全脑网络模型已被证明有助于研究静息状态下功能磁共振成像（fMRI）中揭示的缓慢（<0.1 Hz）相关血流动力学波动的来源。然而，介导静息态长距离相关性的机制以及与更快神经活动的关系仍不清楚。来自脑磁图（MEG）研究的新见解表明，α和β频率振荡（~8 - 30 Hz）的振幅包络显示出与fMRI信号相似的相关模式。在这项工作中，我们结合实验和理论工作来研究自发MEG功能连接的机制。使用一个耦合振荡器的简单模型，该模型适用于纳入现实的全脑连接性和传导延迟，我们探索带通滤波信号的缓慢且有结构的振幅包络——相当程度上再现了从10名健康受试者静息状态下收集的MEG数据——是如何在脑网络的时空结构中自发产生的。我们的模拟结果表明，大规模神经解剖连接性提供了一个最佳网络结构来支持亚稳态同步状态。在这种状态下，不同子系统可能会在降低的集体频率（由于延迟而落在8 - 30 Hz范围内）下暂时同步，而全局系统从未完全同步。这种机制在缓慢的时间尺度（<0.1 Hz）上调节振荡器的频率，导致带通滤波信号有结构的振幅波动。总体而言，我们的结果表明，在静息态MEG数据中观察到的有结构的振幅包络波动可能源于大脑时空结构中自然发生的自发同步机制。
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