What is the substrate of 1/f fluctuations in biological signals?

1.通过研究先前观察到的生物信号中的1/f波动，发现以下不同的生物信号表现出1/f波动。在细胞水平上，观察了猫脑神经元自发放电、轴突冲动传播、快动眼睡眠时单个神经元的活动;在器官水平上，观察了心率变异性、血压、呼吸节律、瞳孔直径和焦点控制、自主神经活动、α波频率的波动。在行为层面，身体摇摆，鼓掌节奏。1/f谱线的功率谱密度分布在10 <-5>~ 10 Hz的范围内。2. 1/f谱线的下限频率是1/f涨落的一个重要性质。关于人类心率变异性，经验上已知1/f频谱轮廓从10 μ Hz扩展<-1>到10 μ Hz<-4>或10 μ <-5>Hz，其中10 μ <-5>Hz大致对应于一天的时间尺度。在这项研究中，长期记录猫的心率变量， ...更多信息 3.在猫心脏上直接贴上记录电极的特殊准备下，成功地进行了三次连续四天的记录。这些实验证实，1/f光谱分布被观察到低至10^<-4>Hz。此外，连续6天（144小时）的记录表明，在10^-10^ Hz频率范围内存在平坦的分布<-4><-5>。这种低频范围内的减弱的功率预计来自于猫在笼子内有限范围内的行为抑制。4.关于猫脑中的单个神经元活动，它们在REM睡眠期间的1/f波动被证明是一致的。生理上真实的生成机制可以用全局抑制输入下的Hopfield型互联神经网络模型来解释。另一方面，首次提出了1/f涨落作为随机过程的数学解释，为1/f涨落的数值分析提供了理论基础。少

1.By surveying the previously observed 1/f fluctuations in biological signals, the following diverse biological signals had been found to exhibit 1/f fluctuations. At cell level, spontaneous neuronal discharge, impulse propagation on axon, single neuronal activity during rapid eye movement(REM)sleep in cat's brain.At level of organ, heart rate variability, blood pressure, respiration rhythm, pupil diameter and focus control, autonomic nerve activity, fluctuations in frequency of alpha wave. At behavior level, body sway, clapping ryhthm. Power spectral densities of 1/f profile were widely ranged from 10^<-5> to 10Hz.2.One of the most important properties of 1/f fluctuations is the lower limit frequency of 1/f spectral profile. Concerning human heart rate variability, 1/f spectral profile is empirically known to be extended from 10^<-1> to 10^<-4> or 10^<-5>Hz, where 10^<-5>Hz roughly corresponds to time scale of a day. In this study, the long-term recordings of cat's heart rate variabil … More ity was mainly performed.3.With special preparation in which the recording electrodes were directly attached to cat's heart, continuous recordings during four days were carried out three times successfully. These experiments confirmed that 1/f spectral profiles are observed down to 10^<-4>Hz. Besides, continuous recordings during 6days(144hr)showed the flat profile in the frequency tends to exist from 10^<-4> to 10^<-5>Hz. This weakened power in the lower frequency range is expected to come from the suppression of cat's behavior within the cage of limited extent.4.Concerning the single neuronal activities in cat's brain, their 1/f fluctuations during REM sleep were shown to be consistent through episodes. The physiologically realistic generation mechanism could be explained by the Hopfieldtype interconnected neural network model under global inhibitory input. On the other hand, the mathematical interpretation of 1/f fluctuation as a stochastic process was newly proposed, which could be a theoretical basis of numerical analyzes of 1/f fluctuations. Less