Dimitrov G V, Dimitrova N A
Centre of Biomedical Engineering, Bulgarian Academy of Sciences, Sofia.
Med Eng Phys. 1998 Nov-Dec;20(9):702-7. doi: 10.1016/s1350-4533(98)00071-x.
The reasons for dependence of the power spectra of extracellular potentials (EPs) produced by a skeletal muscle fibre of finite length, on parameters altering with functional state was analysed. The sensitivity of the EP power spectra to alterations in the parameters depends on the distance of the observation point from the fibre. At large distances the sensitivity can change with longitudinal position as well. The differences in the sensitivity are due to the changes in the inter-relations between the power spectra of the input signal (the first temporal derivative of the intracellular action potential) and of the impulse response (IR) of the fibre of finite length as a linear system of EP generation. It was shown that not only the parameters affecting the IR (propagation velocity of the waves of depolarisation), but also the parameters determining the input signal (intracellular action potential duration and after-potential) can affect the characteristic frequencies of the EP power spectra.
分析了有限长度骨骼肌纤维产生的细胞外电位（EPs）功率谱依赖于随功能状态改变的参数的原因。EP功率谱对参数变化的敏感性取决于观察点与纤维的距离。在远距离时，敏感性也会随纵向位置而变化。敏感性的差异是由于作为EP产生线性系统的输入信号（细胞内动作电位的一阶时间导数）功率谱与有限长度纤维的脉冲响应（IR）之间相互关系的变化。结果表明，不仅影响IR的参数（去极化波的传播速度），而且决定输入信号的参数（细胞内动作电位持续时间和后电位）都会影响EP功率谱的特征频率。
