Kohl Alexandra S, Conforto Adriana Bastos, Z'Graggen Werner J, Kaelin-Lang Alain
Neurology Department, Inselspital, University of Berne, CH-3010 Berne, Switzerland.
J Neurosci Methods. 2006 Oct 30;157(2):278-84. doi: 10.1016/j.jneumeth.2006.04.018. Epub 2006 Jun 5.
The aim of this study is to develop a new simple method for analyzing one-dimensional transcranial magnetic stimulation (TMS) mapping studies in humans. Motor evoked potentials (MEP) were recorded from the abductor pollicis brevis (APB) muscle during stimulation at nine different positions on the scalp along a line passing through the APB hot spot and the vertex. Non-linear curve fitting according to the Levenberg-Marquardt algorithm was performed on the averaged amplitude values obtained at all points to find the best-fitting symmetrical and asymmetrical peak functions. Several peak functions could be fitted to the experimental data. Across all subjects, a symmetric, bell-shaped curve, the complementary error function (erfc) gave the best results. This function is characterized by three parameters giving its amplitude, position, and width. None of the mathematical functions tested with less or more than three parameters fitted better. The amplitude and position parameters of the erfc were highly correlated with the amplitude at the hot spot and with the location of the center of gravity of the TMS curve. In conclusion, non-linear curve fitting is an accurate method for the mathematical characterization of one-dimensional TMS curves. This is the first method that provides information on amplitude, position and width simultaneously.
本研究的目的是开发一种新的简单方法，用于分析人类的一维经颅磁刺激（TMS）映射研究。在沿着穿过拇短展肌（APB）热点和头顶的一条线的头皮上的九个不同位置进行刺激期间，从拇短展肌（APB）记录运动诱发电位（MEP）。对在所有点获得的平均幅度值进行根据Levenberg-Marquardt算法的非线性曲线拟合，以找到最佳拟合的对称和非对称峰值函数。几个峰值函数可以拟合到实验数据。在所有受试者中，一条对称的钟形曲线，即互补误差函数（erfc）给出了最佳结果。该函数由给出其幅度、位置和宽度的三个参数表征。测试的具有少于或多于三个参数的数学函数均没有拟合得更好。erfc的幅度和位置参数与热点处的幅度以及TMS曲线的重心位置高度相关。总之，非线性曲线拟合是对一维TMS曲线进行数学表征的一种准确方法。这是第一种同时提供幅度、位置和宽度信息的方法。
