利用同步功能磁共振成像衍生的空间先验信息优化脑电图源重建
Optimizing EEG Source Reconstruction with Concurrent fMRI-Derived Spatial Priors.
作者信息
Abreu Rodolfo, Soares Júlia F, Lima Ana Cláudia, Sousa Lívia, Batista Sónia, Castelo-Branco Miguel, Duarte João Valente
机构信息
Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), Institute for Nuclear Sciences Applied To Health (ICNAS), University of Coimbra, Coimbra, Portugal.
Neurology Department, Centro Hospitalar e Universitário de Coimbra, Coimbra, Portugal.
出版信息
Brain Topogr. 2022 May;35(3):282-301. doi: 10.1007/s10548-022-00891-3. Epub 2022 Feb 10.
Reconstructing EEG sources involves a complex pipeline, with the inverse problem being the most challenging. Multiple inversion algorithms are being continuously developed, aiming to tackle the non-uniqueness of this problem, which has been shown to be partially circumvented by including prior information in the inverse models. Despite a few efforts, there are still current and persistent controversies regarding the inversion algorithm of choice and the optimal set of spatial priors to be included in the inversion models. The use of simultaneous EEG-fMRI data is one approach to tackle this problem. The spatial resolution of fMRI makes fMRI derived spatial priors very convenient for EEG reconstruction, however, only task activation maps and resting-state networks (RSNs) have been explored so far, overlooking the recent, but already accepted, notion that brain networks exhibit dynamic functional connectivity fluctuations. The lack of a systematic comparison between different source reconstruction algorithms, considering potentially more brain-informative priors such as fMRI, motivates the search for better reconstruction models. Using simultaneous EEG-fMRI data, here we compared four different inversion algorithms (minimum norm, MN; low resolution electromagnetic tomography, LORETA; empirical Bayes beamformer, EBB; and multiple sparse priors, MSP) under a Bayesian framework (as implemented in SPM), each with three different sets of priors consisting of: (1) those specific to the algorithm; (2) those specific to the algorithm plus fMRI task activation maps and RSNs; and (3) those specific to the algorithm plus fMRI task activation maps and RSNs and network modules of task-related dFC states estimated from the dFC fluctuations. The quality of the reconstructed EEG sources was quantified in terms of model-based metrics, namely the expectation of the posterior probability P(model|data) and variance explained of the inversion models, and the overlap/proportion of brain regions known to be involved in the visual perception tasks that the participants were submitted to, and RSN templates, with/within EEG source components. Model-based metrics suggested that model parsimony is preferred, with the combination MSP and priors specific to this algorithm exhibiting the best performance. However, optimal overlap/proportion values were found using EBB and priors specific to this algorithm and fMRI task activation maps and RSNs or MSP and considering all the priors (algorithm priors, fMRI task activation maps and RSNs and dFC state modules), respectively, indicating that fMRI spatial priors, including dFC state modules, might contain useful information to recover EEG source components reflecting neuronal activity of interest. Our main results show that providing fMRI spatial derived priors that reflect the dynamics of the brain might be useful to map neuronal activity more accurately from EEG-fMRI. Furthermore, this work paves the way towards a more informative selection of the optimal EEG source reconstruction approach, which may be critical in future studies.
重建脑电信号源涉及一个复杂的流程,其中逆问题是最具挑战性的。多种逆算法正在不断发展,旨在解决该问题的非唯一性,事实证明,通过在逆模型中纳入先验信息可以部分规避这一问题。尽管已经做出了一些努力,但对于选择何种逆算法以及在逆模型中应纳入的最佳空间先验集,目前仍存在争议。使用同步脑电-功能磁共振成像(EEG-fMRI)数据是解决此问题的一种方法。功能磁共振成像的空间分辨率使得从功能磁共振成像得出的空间先验对于脑电信号重建非常方便,然而,到目前为止,仅探索了任务激活图和静息态网络(RSN),却忽略了最近已被认可的一个观点,即脑网络表现出动态功能连接波动。考虑到可能包含更多脑信息先验(如功能磁共振成像)的情况下,缺乏对不同源重建算法之间的系统比较,这促使人们寻找更好的重建模型。在这里,我们使用同步脑电-功能磁共振成像数据,在贝叶斯框架下(如在统计参数映射软件(SPM)中实现)比较了四种不同的逆算法(最小范数,MN;低分辨率电磁断层成像,LORETA;经验贝叶斯波束形成器,EBB;以及多重稀疏先验,MSP),每种算法都有三组不同的先验,分别为:(1)特定于算法的先验;(2)特定于算法的先验加上功能磁共振成像任务激活图和静息态网络;(3)特定于算法的先验加上功能磁共振成像任务激活图和静息态网络以及从动态功能连接波动估计出的任务相关动态功能连接(dFC)状态的网络模块。根据基于模型的指标对重建的脑电信号源质量进行了量化,即后验概率P(模型|数据)的期望和逆模型解释的方差,以及已知参与参与者所接受的视觉感知任务的脑区与脑电信号源成分之间的重叠/比例,以及静息态网络模板。基于模型的指标表明,模型简约性更受青睐,MSP与该算法特定的先验相结合表现出最佳性能。然而,分别使用EBB和该算法特定的先验以及功能磁共振成像任务激活图和静息态网络,或者MSP并考虑所有先验(算法先验、功能磁共振成像任务激活图和静息态网络以及dFC状态模块)时,发现了最佳重叠/比例值,这表明包括dFC状态模块在内的功能磁共振成像空间先验可能包含有用信息,以恢复反映感兴趣神经元活动的脑电信号源成分。我们的主要结果表明,提供反映大脑动态的功能磁共振成像空间衍生先验可能有助于从脑电-功能磁共振成像中更准确地映射神经元活动。此外,这项工作为更明智地选择最佳脑电信号源重建方法铺平了道路,这在未来的研究中可能至关重要。