This work presents and evaluates a 12-electrode intracranial electroencephalography system developed at the National Institute of Mental Health (Klecany, Czech Republic) in terms of an electrical source imaging (ESI) technique in rats. The electrode system was originally designed for translational research purposes. This study demonstrates that it is also possible to use this well-established system for ESI, and estimates its precision, accuracy, and limitations. Furthermore, this paper sets a methodological basis for future implants. Source localization quality is evaluated using three approaches based on surrogate data, physical phantom measurements, and in vivo experiments. The forward model for source localization is obtained from the FieldTrip-SimBio pipeline using the finite-element method. Rat brain tissue extracted from a magnetic resonance imaging template is approximated by a single-compartment homogeneous tetrahedral head model. Four inverse solvers were tested: standardized low-resolution brain electromagnetic tomography, exact low-resolution brain electromagnetic tomography (eLORETA), linear constrained minimum variance (LCMV), and dynamic imaging of coherent sources. Based on surrogate data, this paper evaluates the accuracy and precision of all solvers within the brain volume using error distance and reliability maps. The mean error distance over the whole brain was found to be the lowest in the eLORETA solution through signal to noise ratios (SNRs) (0.2 mm for 25 dB SNR). The LCMV outperformed eLORETA under higher SNR conditions, and exhibiting higher spatial precision. Both of these inverse solvers provided accurate results in a phantom experiment (1.6 mm mean error distance across shallow and 2.6 mm across subcortical testing dipoles). Utilizing the developed technique in freely moving rats, an auditory steady-state response experiment provided results in line with previously reported findings. The obtained results support the idea of utilizing a 12-electrode system for ESI and using it as a solid basis for the development of future ESI dedicated implants.

中文翻译：

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自由移动大鼠的电源成像：12 电极皮层脑电图系统的评估

这项工作展示并评估了国家心理健康研究所（捷克共和国 Klecany）开发的 12 电极颅内脑电图系统的大鼠电源成像 (ESI) 技术。该电极系统最初是为转化研究目的而设计的。这项研究表明，也可以使用这个完善的 ESI 系统，并估计其精度、准确度和局限性。此外，本文为未来的植入物奠定了方法论基础。使用基于替代数据、物理体模测量和体内实验的三种方法来评估源定位质量。源定位的正向模型是使用有限元方法从 FieldTrip-SimBio 管道获得的。从磁共振成像模板中提取的大鼠脑组织通过单室均质四面体头部模型进行近似。测试了四种逆解算器：标准化低分辨率脑电磁断层扫描、精确低分辨率脑电磁断层扫描 (eLORETA)、线性约束最小方差 (LCMV) 和相干源动态成像。基于替代数据，本文使用误差距离和可靠性图评估大脑体积内所有求解器的准确度和精确度。通过信噪比 (SNR) 发现整个大脑的平均误差距离是 eLORETA 解决方案中最低的（25 dB SNR 为 0.2 毫米）。LCMV 在更高的 SNR 条件下优于 eLORETA，并表现出更高的空间精度。这两种逆求解器都在模型实验中提供了准确的结果（浅层平均误差距离为 1.6 毫米，皮层下测试偶极子平均误差距离为 2.6 毫米）。利用在自由活动的老鼠身上开发的技术，听觉稳态反应实验提供了与之前报道的结果一致的结果。获得的结果支持了利用 12 电极系统进行 ESI 的想法，并将其作为开发未来 ESI 专用植入物的坚实基础。