Dimitrov G V, Lateva Z C, Dimitrova N A
CLBA, Centre of Biology, Bulgarian Academy of Sciences, Sofia.
Med Biol Eng Comput. 1990 Jan;28(1):24-30. doi: 10.1007/BF02441673.
The power spectra of the extracellular potentials (EPs) generated under activation of an infinite, homogeneous excitable fibre immersed into an infinite, resistive, isotropic and homogeneous volume conductor are theoretically analysed. The changes in the power spectrum related to the changes in the propagation velocity v, amplitudes Vm and duration Tin of the intracellular action potential (IAP) are analytically determined. It is found that in the ultra-low-frequency region the EP spectral power follows the course of alteration in the square of the modified Bessel function of the second kind and order zero multiplied by the fourth power of the frequency, and the Tin can be assessed by the deviation of the EP power spectrum from this function. It is shown why the sensitivity of the spectral characteristics depends substantially on the radial distance yo from the activated fibre to the point of observation; why the total spectral amplitude depends directly on the IAP wavelength but the total spectral power depends on the IAP wavelength as well as on its duration and propagation velocity; and why the EPs are not proportional to the IAP second spatial derivative even in close proximity to the fibre.
对浸入无限大、电阻性、各向同性且均匀的容积导体中的无限长、均匀可兴奋纤维激活时产生的细胞外电位（EPs）的功率谱进行了理论分析。分析确定了与细胞内动作电位（IAP）的传播速度v、幅度Vm和持续时间Tin的变化相关的功率谱变化。发现在超低频区域，EP谱功率遵循第二类零阶修正贝塞尔函数的平方乘以频率的四次方的变化过程，并且Tin可以通过EP功率谱与该函数的偏差来评估。说明了为什么谱特征的灵敏度在很大程度上取决于从激活纤维到观察点的径向距离yo；为什么总谱幅度直接取决于IAP波长，而总谱功率取决于IAP波长以及其持续时间和传播速度；以及为什么即使在纤维附近EPs也与IAP的二阶空间导数不成比例。
