Objectives

Functional connectivity (FC) is increasingly used as target for neuromodulation and enhancement of performance. A reliable assessment of FC with electroencephalography (EEG) currently requires a laboratory environment with high-density montages and a long preparation time. This study investigated the feasibility of reconstructing source FC with a low-density EEG montage towards a usage in real life applications.

Methods

Source FC was reconstructed with inverse solutions and quantified as node degree of absolute imaginary coherence in alpha frequencies. We used simulated coherent point sources as well as two real datasets to investigate the impact of electrode density (19 vs. 128 electrodes) and usage of template vs. individual MRI-based head models on localization accuracy. In addition, we checked whether low-density EEG is able to capture inter-individual variations in coherence strength.

Results

In numerical simulations as well as real data, a reduction of the number of electrodes led to less reliable reconstructions of coherent sources and of coupling strength. Yet, when comparing different approaches to reconstructing FC from 19 electrodes, source FC obtained with beamformers outperformed sensor FC, FC computed after independent component analysis, and source FC obtained with sLORETA. In particular, only source FC based on beamformers was able to capture neural correlates of motor behavior.

Conclusion

Reconstructions of FC from low-density EEG is challenging, but may be feasible when using source reconstructions with beamformers.

中文翻译：

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低密度脑电重构源功能连通性的可行性

目标

功能连接 (FC) 越来越多地用作神经调节和提高性能的目标。目前，使用脑电图 (EEG) 对 FC 进行可靠评估需要具有高密度蒙太奇和较长准备时间的实验室环境。本研究调查了用低密度脑电图蒙太奇重建源 FC 以用于现实生活应用的可行性。

方法

源 FC 用逆解重建并量化为 alpha 频率中绝对虚相干的节点度。我们使用模拟的相干点源以及两个真实数据集来研究电极密度（19 对 128 个电极）和模板使用与单个基于 MRI 的头部模型对定位精度的影响。此外，我们检查了低密度脑电图是否能够捕捉到相干强度的个体间变化。

结果

在数值模拟和实际数据中，电极数量的减少导致相干源和耦合强度的重建可靠性降低。然而，当比较从 19 个电极重建 FC 的不同方法时，使用波束形成器获得的源 FC 优于传感器 FC、在独立分量分析后计算的 FC，以及使用 sLORETA 获得的源 FC。特别是，只有基于波束形成器的源 FC 能够捕获运动行为的神经相关性。

结论

从低密度 EEG 重建 FC 具有挑战性，但在使用带有波束形成器的源重建时可能是可行的。