EEG functional connectivity metrics wPLI and wSMI account for distinct types of brain functional interactions
EEG functional connectivity metrics wPLI and wSMI account for distinct types of brain functional interactions
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DOI：
10.1038/s41598-019-45289-7
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发表时间：
2019-06-20
影响因子：
4.6
通讯作者：
Bernardi, Giulio
中科院分区：
文献类型：
--
作者：
Imperatori, Laura Sophie;Betta, Monica;Bernardi, Giulio
加权相位滞后指数（wPLI）和加权符号互信息（wSMI）是两种鲁棒且应用广泛的脑电信号功能连通性估计方法。有趣的是，这两种方法都被证明可以检测到与意识水平变化相关的大脑功能连接的相对改变，比如在严重脑损伤或麻醉状态下。尽管有这些有希望的发现，wPLI和wSMI是否可以解释不同或相似类型的功能相互作用尚不清楚。利用模拟的高密度（hd-）脑电图数据，我们证明，虽然wPLI对呈现线性和非线性相互依赖混合的耦合具有很高的灵敏度，但只有wSMI可以检测纯非线性相互作用动力学。此外，我们通过计算12名健康成人在清醒和深度（N3-）睡眠期间的高清脑电图记录中的wPLI和wSMI连通性，评估了这些差异对真实实验数据的潜在影响。与基于模拟的研究结果一致，该分析显示，两种方法对两种警惕状态下大脑连通性的变化具有不同的敏感性。我们的研究结果表明，联合使用wPLI和wSMI可能是研究生理和病理条件下意识功能基础的有力工具。
The weighted Phase Lag Index (wPLI) and the weighted Symbolic Mutual Information (wSMI) represent two robust and widely used methods for MEG/EEG functional connectivity estimation. Interestingly, both methods have been shown to detect relative alterations of brain functional connectivity in conditions associated with changes in the level of consciousness, such as following severe brain injury or under anaesthesia. Despite these promising findings, it was unclear whether wPLI and wSMI may account for distinct or similar types of functional interactions. Using simulated high-density (hd-) EEG data, we demonstrate that, while wPLI has high sensitivity for couplings presenting a mixture of linear and nonlinear interdependencies, only wSMI can detect purely nonlinear interaction dynamics. Moreover, we evaluated the potential impact of these differences on real experimental data by computing wPLI and wSMI connectivity in hd-EEG recordings of 12 healthy adults during wakefulness and deep (N3-)sleep, characterised by different levels of consciousness. In line with the simulation-based findings, this analysis revealed that both methods have different sensitivity for changes in brain connectivity across the two vigilance states. Our results indicate that the conjoint use of wPLI and wSMI may represent a powerful tool to study the functional bases of consciousness in physiological and pathological conditions.