A principled approach to conductivity uncertainty analysis in electric field calculations
A principled approach to conductivity uncertainty analysis in electric field calculations
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DOI：
10.1016/j.neuroimage.2018.12.053
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发表时间：
2019-03-01
期刊：
影响因子：
5.7
通讯作者：
Weise, Konstantin
中科院分区：
文献类型：
--
作者：
Saturnino, Guilherme B.;Thielscher, Axel;Weise, Konstantin
欧姆组织电导率的不确定性阻碍了对非侵入性脑刺激产生的电场的准确计算。我们提出了一个有效的和通用的技术不确定性和敏感性分析，量化的可靠性，现场估计，并确定最有影响力的参数。为此，我们采用了非侵入式的广义多项式混沌展开competencyapproximately的多维依赖的领域上的电导率。我们证明了所提出的管道产生详细的洞察力的经颅磁刺激（TMS）和经颅直流电刺激（tDCS）的场估计的不确定性，确定最相关的组织电导率，并强调刺激方法之间的特征差异。具体来说，我们测试的影响电导率变化（i）在每个灰质位置产生的电场的大小，（ii）其正常组成部分相对于皮质片，（iii）其整体幅度（索引的第98百分位数），（iv）其整体空间分布。我们表明，TMS领域一般受电导率的变化比tDCS领域。对于TMS和tDCS，电导率的不确定性导致的幅度更高的不确定性相比，电场的方向和整体空间分布。而TMS领域的主要影响灰色和白色物质的导电性，tDCS领域还依赖于头骨和头皮的导电性。通过所提出的技术实现的复杂系统的全面的不确定性分析是不可能的，与经典的方法，如蒙特卡洛采样，没有极端的计算工作。此外，我们的方法具有直接产生可解释和直观的输出指标，并易于适应新的问题的优点。
Uncertainty surrounding ohmic tissue conductivity impedes accurate calculation of the electric fields generated by non-invasive brain stimulation. We present an efficient and generic technique for uncertainty and sensitivity analyses, which quantifies the reliability of field estimates and identifies the most influential parameters. For this purpose, we employ a non-intrusive generalized polynomial chaos expansion to compactly approximate the multidimensional dependency of the field on the conductivities. We demonstrate that the proposed pipeline yields detailed insight into the uncertainty of field estimates for transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS), identifies the most relevant tissue conductivities, and highlights characteristic differences between stimulation methods. Specifically, we test the influence of conductivity variations on (i) the magnitude of the electric field generated at each gray matter location, (ii) its normal component relative to the cortical sheet, (iii) its overall magnitude (indexed by the 98th percentile), and (iv) its overall spatial distribution. We show that TMS fields are generally less affected by conductivity variations than tDCS fields. For both TMS and tDCS, conductivity uncertainty causes much higher uncertainty in the magnitude as compared to the direction and overall spatial distribution of the electric field. Whereas the TMS fields were predominantly influenced by gray and white matter conductivity, the tDCS fields were additionally dependent on skull and scalp conductivities. Comprehensive uncertainty analyses of complex systems achieved by the proposed technique are not possible with classical methods, such as Monte Carlo sampling, without extreme computational effort. In addition, our method has the advantages of directly yielding interpretable and intuitive output metrics and of being easily adaptable to new problems.