Irnich Werner, Hebrank Franz X
Justus-Liebig-University, Giessen, Germany.
J Magn Reson Imaging. 2009 Jan;29(1):229-36. doi: 10.1002/jmri.21573.
To clarify whether sinusoidal pulses possess lower thresholds than rectangular ones at perception threshold, a statement often made that contradicts the theory of stimulation.
The results of a nerve stimulation study with 65 volunteers and with trapezoidal and sinusoidal gradient pulses were used to apply the combination of the electric field, induced in the tissue of the human body, with the "Fundamental Law of Electrostimulation." This law claims that the waveshape of a pulse is not essential as long as the amplitude of the pulse does not decrease below rheobase (rheobase condition).
If the rheobase condition is applied to sinusoidal waveforms and the pulse duration and amplitude is corrected accordingly, both trapezoidal and sinusoidal gradient pulses have identical threshold amplitudes as a function of pulse duration.
The "Fundamental Law of Electrostimulation," including the "rheobase condition," proved to be a good basis for describing magnetic field stimulation (magnetostimulation) and that application of it to magnetostimulation is suitable as the basis for describing magnetic field stimulation with various waveforms. For nonrectangular pulses, pulse durations and pulse amplitudes must be corrected according to the "rheobase condition." The exponential Blair Equation is less suited to be applied in magnetostimulation.
为了阐明在感知阈值方面，正弦脉冲的阈值是否低于矩形脉冲，这是一个常被提及的与刺激理论相矛盾的说法。
一项对65名志愿者进行的神经刺激研究结果，该研究使用了梯形和正弦梯度脉冲，将人体组织中感应的电场与“电刺激基本定律”相结合。该定律声称，只要脉冲幅度不降至基强度以下（基强度条件），脉冲的波形并不重要。
如果将基强度条件应用于正弦波形，并相应地校正脉冲持续时间和幅度，那么梯形和正弦梯度脉冲作为脉冲持续时间的函数，具有相同的阈值幅度。
“电刺激基本定律”，包括“基强度条件”，被证明是描述磁场刺激（磁刺激）的良好基础，并且将其应用于磁刺激适合作为描述各种波形磁场刺激的基础。对于非矩形脉冲，必须根据“基强度条件”校正脉冲持续时间和脉冲幅度。指数布莱尔方程不太适合应用于磁刺激。
