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Origin of the Internal Noise in Insect Mechanoreceptor and Role of the Noise for Weak Signal Detection

昆虫机械感受器内部噪声的起源以及噪声在微弱信号检测中的作用

基本信息

批准号：
10640658
负责人：
SHIMOZAWA Tateo
金额：
$ 2.11万
依托单位：
HOKKAIDO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10640658/
关键词：
Mechanoireceptor Cricket Wind Receptor Hair Sensory Threshold Energy Threshold Thermal Noise Weak Signal Detection Fluctuation Analysis 感覚細胞閾値確率共鳴共分散符号化昆虫

项目摘要

Minimum amount of mechanical energy necessary to cause a neuronal spike in the wind receptor cell of cricket is determined to be at the order of kT (4×10ィイD1-21ィエD1 J at 300°K). The insect mechanoreceptors are therefore facing to the thermal noise of Brownian motion, when working near threshold. The evolution however has achieved a paradoxical solution for sensory signal transmission under the noise problem. Here we show the determination of mechanical energy and the information theoretic analysis on sensory spike trains of the insect mechanoreceptor.The estimation of the mechanical energy is based on three measurements, deflection sensitivity, sensory threshold, and mechanical resistance of hair support. The deflection sensitivity to air motion was measured by laser-Doppler velocimetry and Gaussian white noise analysis. The mechanical parameters, I.e. the moment of inertia of hair shaft, the spring stiffness of hair support, and the torsional resistance within the support were estimated by applying Stokes' theory for viscous force. Mechanical energy consumed by the resistance provides the maximum estimates of energy available to the receptor cell for stimulus transduction. The energy threshold of the mechanoreceptor is far below that of single photon quantum of visible light (ca. 3×10ィイD1-19ィエD1 J). The mechano-receptor is 100 times more sensitive than photoreceptors.Spike train of the wind receptor cell fluctuates in timing, when responding to weak stimuli near threshold. Simultaneous double recording from two cells revealed that the fluctuations are non-correlated between cells. The receptor array has utilized the cell-intrinsic noise for stochastic sampling of weak sub-threshold signals, and paradoxically improved the detection of signals under the inevitable thermal noise.

在板球的风感受器细胞中引起神经元放电所需的最小机械能被确定为KT的数量级(在300K时为4×10ィイd1-21ィエd1J)。因此，当昆虫机械感受器工作在阈值附近时，将面临布朗运动的热噪声。然而，这种进化为噪声问题下的感觉信号传输提供了一种矛盾的解决方案。在这里，我们给出了机械能的测定和对昆虫机械感受器感觉棘波序列的信息论分析，机械能的估计基于三个测量，即偏转敏感度、感觉阈值和毛发支架的机械阻力。利用激光多普勒测速仪和高斯白噪声分析测量了偏转对空气运动的敏感性。应用Stokes粘性力理论估算了毛轴的转动惯量、毛发支座的弹簧刚度和支座内的扭转阻力等力学参数。阻力所消耗的机械能提供了受体细胞可用于刺激转导的最大能量估计值。机械感受器的能量阈值远低于可见光的单光子量子阈值(约3×10ィイD_1-19ィエD_1J)。机械感受器的灵敏度是光感受器的100倍。当对接近阈值的弱刺激做出反应时，风感受器细胞的棘波序列会在时间上波动。来自两个细胞的同时双记录显示细胞之间的波动是不相关的。接收器阵列利用细胞固有噪声对弱亚阈值信号进行随机采样，并在不可避免的热噪声下提高了信号的检测能力。