Electrical fields induced inside the rat brain with skin, skull, and dural placements of the current injection electrode
Electrical fields induced inside the rat brain with skin, skull, and dural placements of the current injection electrode
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DOI：
10.1101/402578
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发表时间：
2018-08
期刊：
影响因子：
3.7
通讯作者：
A. Asan;Sinan Gok;M. Sahin
中科院分区：
文献类型：
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作者：
A. Asan;Sinan Gok;M. Sahin
经颅电刺激（tES）以其不同的形式迅速成为一种不可或缺的临床工具。为了更好地理解 tES 的潜在机制，迫切需要动物数据。为了动物实验结果的可重复性，需要准确预测注入电流引起的脑实质内的电场（E-Fields）。在这项研究中，当刺激电极通过开颅孔放置在皮肤、颅骨或硬脑膜上时，我们测量了大鼠大脑中垂直于大脑表面的电场，即垂直电场（VE场）。通过皮肤的电场衰减比颅骨的电场衰减大几倍，并且皮肤的存在大大降低了电极附近皮质表面的 VE 场峰值。软脑膜表面下方灰质的 VE 场下降速度比白质快得多，因此大的 VE 场主要包含在灰质中。灰质/白质边界处的转变导致 VE 场以及其他局部不均匀性出现显着峰值。通过将我们的 VE 场测量值与体积导体分析方程给出的场分布相匹配，将 0.57 S/m 的电导率值预测为整个大脑的全局值。最后，将电流返回电极插入肩部、颌下肌和后腿肌肉中，对硬膜外电极下方皮质中测量的电场幅度几乎没有影响。
Transcranial electrical stimulation (tES) is rapidly becoming an indispensable clinical tool with its different forms. Animal data are crucially needed for better understanding of the underlying mechanisms of tES. For reproducibility of results in animal experiments, the electric fields (E-Fields) inside the brain parenchyma induced by the injected currents need to be predicted accurately. In this study, we measured the electrical fields in the rat brain perpendicular to the brain surface, i.e. vertical electric field (VE-field), when the stimulation electrode was placed over the skin, skull, or dura mater through a craniotomy hole. The E-field attenuation through the skin was a few times larger than that of the skull and the presence of skin substantially reduced the VE-field peak at the cortical surface near the electrode. The VE-field declined much quicker in the gray matter underneath the pial surface than it did in the white matter, and thus the large VE-fields were contained mostly in the gray matter. The transition at the gray/white matter border caused a significant peak in the VE-field, as well as at other local inhomogeneties. A conductivity value of 0.57 S/m is predicted as a global value for the whole brain by matching our VE-field measurements to the field profile given by analytical equations for volume conductors. Finally, insertion of the current return electrode into the shoulder, submandibular, and hind leg muscles had virtually no effects on the measured E-field amplitudes in the cortex underneath the epidural electrodes.