Pöpel B, Querfurth H
Biol Cybern. 1984;51(1):21-32. doi: 10.1007/BF00336184.
Nonlinear second order white-noise analysis has been applied to the isolated frog muscle spindle. Power (delta 2) of the Gaussian white noise (GWN) and the average prestretch level L were varied and the response of both the isolated receptor potential (transducer) and the action potential (encoder) level were analysed. The standard white-noise method is briefly presented. Particular emphasis, however, is put on the limitations in the range of validity of the method and, consequently, on the use and interpretation of the kernels as a Wiener model. Conclusions in the present paper are within this frame and are mainly of qualitative nature. The analysis reveals that the nonlinear contributions of the model are essential for approximating physiological results, thus ruling out purely linear modelling for this receptor organ. The dependence of the transducer kernels on delta are compatible with the behaviour of a rectifier. Rectification is represented by the lack of hyperpolarization within the isolated receptor potential and is enhanced by the substantial memory in the linear and nonlinear kernels as demonstrated by their extent in time. This is equivalent to low power in high frequencies of the response. Obviously, the hyperpolarizing potentials following each spike counteract the long transducer memory. At the encoder level the memory of the system is strongly reduced. This is achieved by using predominantly high frequency components of the receptor potential for triggering the process of impulse generation, and by the precise coupling and high frequency content of the impulses. This coupling precision is possible because of the sensitivity of the spike-generating mechanism to steep rising transients of the receptor potential and also owing to the reduction in transducer memory by the hyperpolarizing afterpotentials. The preference given to the high frequency components is also read from the structure of the second order transducer kernel and from both the linear and the second order encoder kernels, which allows the most effective input waveform for triggering action potentials to be determined. When the operating point is changed to higher prestretch values, kernel heights increase strongly implying higher response strength of the muscle spindle.(ABSTRACT TRUNCATED AT 400 WORDS)
非线性二阶白噪声分析已应用于离体青蛙肌梭。改变高斯白噪声（GWN）的功率（δ²）和平均预拉伸水平L，并分析离体感受器电位（换能器）和动作电位（编码器）水平的响应。简要介绍了标准白噪声方法。然而，特别强调的是该方法有效性范围的局限性，以及因此将核作为维纳模型的使用和解释。本文的结论在此框架内，主要是定性的。分析表明，模型的非线性贡献对于近似生理结果至关重要，因此排除了对该感受器器官进行纯线性建模的可能性。换能器核与δ的依赖性与整流器的行为相符。整流表现为离体感受器电位内缺乏超极化，并且线性和非线性核中的大量记忆增强了整流，这通过它们在时间上的范围得以证明。这相当于响应高频中的低功率。显然，每个尖峰后的超极化电位抵消了换能器的长时记忆。在编码器水平，系统的记忆大大减少。这是通过主要使用感受器电位的高频成分来触发冲动产生过程，以及通过冲动的精确耦合和高频含量来实现的。由于尖峰产生机制对感受器电位陡峭上升瞬变的敏感性，以及超极化后电位对换能器记忆的减少，这种耦合精度是可能的。对高频成分的偏好也从二阶换能器核的结构以及线性和二阶编码器核中看出，这使得能够确定触发动作电位的最有效输入波形。当工作点改变到更高的预拉伸值时，核高度强烈增加，这意味着肌梭的响应强度更高。（摘要截断于400字）
