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

1.通过调查以前观察到的生物信号的1/f波动，发现下列不同的生物信号表现出1/f的波动。在细胞水平，自发性神经元放电，轴突上的脉冲传播，快速眼动(REM)睡眠中的单个神经元活动，器官水平，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，拍手节奏。1/f谱线的功率谱密度从10^~(-5)~10 Hz不等。2.1/f谱线的下限频率是1/f谱线起伏最重要的特征之一。关于人的心率变异性，根据经验，1/f谱分布从10^lt；-1>1；扩展到10^lt；-4；或10^lt；-5hz，其中10^lt；-5hz大致对应于一天的时间尺度。在本研究中，长期记录猫的心率变量…3.采用记录电极直接贴在猫心脏的特殊制备方法，连续记录4天成功3次。这些实验证实，1/f的光谱分布可以精确到10^&lt；-4&gt；赫兹。此外，连续6天(144小时)的记录表明，在10^~(-4)~10^~(-5)~10^~(-5)赫兹之间，频率分布趋于平坦。在较低频率范围内这种减弱的功率可能来自于对笼中猫行为的有限程度的抑制。4.考虑到猫脑中单个神经元的活动，它们在REM睡眠期间的1/f波动在不同时期是一致的。全局抑制输入下的Hopfield型互联神经网络模型可以解释生理上真实的产生机制。另一方面，新提出了1/f涨落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。较少

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