Annu Int Conf IEEE Eng Med Biol Soc. 2022 Jul;2022:4826-4829. doi: 10.1109/EMBC48229.2022.9872004.
Inaccurate estimation of skull conductivity is the largest impediment to high-resolution EEG source imaging because of its strong influence and wide variability across individuals. Nonetheless, there is yet no widely applied method for noninvasively measuring individual skull conductivity. We presented a skull conductivity and source location estimation algorithm (SCALE) for simultaneously estimating skull conductivity and the cortical distributions of 18-20 effective sources derived from the EEG data by independent component analysis (ICA). SCALE combines a realistic Finite Element Method (FEM) head model built from a magnetic resonance (MR) head image with the effective source scalp maps to estimate brain-to-skull conductivity ratio (BSCR) and to map the effective sources on the cortical surface. To estimate the robustness of SCALE BSCR estimates, we applied SCALE to MR image and high-density EEG data from ten participants, five having data from 2-3 different tasks and sessions. As expected, across participants SCALE BSCR estimates differed widely (mean 32.8, range 18-78). Within-participant SCALE BSCR estimates were far more consistent than between participants. By incorporating SCALE-optimized distributed EEG source localization, stable functional imaging of cortical EEG effective sources can become routine, giving relatively low-cost EEG imaging a spatial resolution compatible with other brain imaging results and uniquely capable for studying brain dynamics supporting thought and action in laboratory, virtual, and natural environments.
不准确的颅骨电导率估计是高分辨率 EEG 源成像的最大障碍，因为它对个体的影响很大且变化范围很广。尽管如此，目前还没有广泛应用的无创测量个体颅骨电导率的方法。我们提出了一种颅骨电导率和源定位估计算法（SCALE），用于通过独立成分分析（ICA）同时估计颅骨电导率和从 EEG 数据中得出的 18-20 个有效源的皮质分布。SCALE 将基于磁共振（MR）头部图像构建的真实有限元方法（FEM）头部模型与有效源头皮图相结合，以估计脑颅骨电导率比（BSCR）并在皮质表面映射有效源。为了估计 SCALE BSCR 估计的稳健性，我们将 SCALE 应用于来自十个参与者的 MR 图像和高密度 EEG 数据，其中五个参与者的数据来自 2-3 个不同的任务和会话。如预期的那样，跨参与者的 SCALE BSCR 估计差异很大（平均值为 32.8，范围为 18-78）。参与者内的 SCALE BSCR 估计比参与者间的更一致。通过纳入 SCALE 优化的分布式 EEG 源定位，皮质 EEG 有效源的稳定功能成像可以成为常规，为相对低成本的 EEG 成像提供与其他脑成像结果兼容的空间分辨率，并能够独特地研究支持实验室、虚拟和自然环境中的思维和行动的大脑动力学。
