斜方体内侧核与耳蜗背核神经元的动作电位特性比较

发布时间：2018-02-02 13:54

本文关键词： 动作电位斜方体内侧核耳蜗背核声源定位全细胞膜片钳　出处：《南方医科大学》2012年硕士论文　论文类型：学位论文

【摘要】：听觉系统的主要功能之一是确定声音来源的空间位置,这一信息对动物的生命活动有着重要的意义。历年来,声源定位研究都侧重于确定与定位有关的声音信号到达耳朵的物理参数特性上。目前,已知有三个主要的参数,每个参数都是由外来声波与头、外耳或者耳廓相互作用形成的,分别是：双耳时间差(interaural time difference, ITD),由内上橄榄核(medial superior olive, MSO)和外上橄榄核(lateral superior olive, LSO)共同编码；双耳强度差(interaural intensity difference, IID),由LSO编码；单耳频谱信号,由耳蜗背核(dorsal cochlear nucleus, DCN)处理。以前研究听觉神经元对声源空间信号的编码方式大都采用在体细胞外记录的实验手段,而对于单个神经元对听空间信息的膜反应特性是如何的呢?本实验选取共同参与处理水平方位ITD和IID信号的斜方体内侧核(Medial nucleus of trapezoid body, MNTB)主细胞和处理垂直方位单耳频谱信号的耳蜗背核(dorsal cochlear nucleus, DCN)梭形细胞,用全细胞膜片钳的技术研究单个神经元的膜反应特性,同时比较处理不同声空间信号的不同神经元的膜反应特性差异。本实验采用脑片膜片钳全细胞记录技术,通过给MNTB主细胞和DCN梭形细胞注入不同强度的电流刺激,记录两类细胞爆发的动作反应(即电压反应),然后在膜片钳数据分析软件Clamfit下统计并比较两类细胞的动作电位波形、峰值、去极化时程、复极化时程、阈值间隔、峰值间隔、动作电位发放个数、第一动作电位延时等,以揭示两类神经元处理不同听空间信号的电生理特性差异。实验共记录到36个神经元,MNTB主细胞25个,DCN梭形细胞11个。实验结果发现,MNTB主细胞发放两种动作电位波形,将其分为API (Action potential wareforml)型(n=6)和AP2(Action potential wareform2)型(n=19)。MNTB主细胞AP1型和AP2型的复极化时程、阈值间隔和峰值间隔有显著差异(P0.01)；而AP1型和AP2型的动作电位峰值和第一动作电位延时无显著差异(P0.05)。MNTB主细胞在很小刺激强度(30pA)就能产生动作电位,且动作电位的发放模式不随刺激强度的增加而发生变化。而DCN梭形细胞需要在200pA以上的刺激强度才能爆发动作电位,且随着刺激强度的增加发放模式分别呈建立型、休止型和梳状型。DCN梭形细胞与MNTB主细胞动作电位幅度、发放数、去极化时程、复极化时程、阈值间隔、峰值间隔、第一动作电位延时等经统计学分析发现都有显著差异(P0.05) 实验得出以下结论：1.MNTB主细胞表现出两种动作电位波形,且两种动作电位波形不同时存在于同一个神经元胞体上。经形态学和基本电生理学特性比较,除了复极化时程、阈值间隔和峰值间隔有统计学差异外,其他参数没有明显差别,说明这是同一类神经元的不同动作电位表征。而DCN梭形细胞只表现出一种经典的动作电位波形。2.DCN梭形细胞的动作电位发放模式随刺激强度的增加依次表现出三种放电模式：buildup、pause、chopper。而MNTB主细胞的动作电位发放模式不随刺激强度的变化而变化。3.DCN梭形细胞的动作电位幅度明显高于MNTB主细胞,DCN梭形细胞的去极化时程、复极化时程、阈值间隔、峰值间隔、第一动作电位延时都显著低于MNTB主细胞。两类细胞不同的电生理特性一定程度上反映了神经元对垂直方位的频谱信号和水平方位的IID和ITD信号的不同编码特性。
[Abstract]:One of the main functions of auditory system is to determine the spatial position of sound source . This information is of great significance to the life activities of animals . Three main parameters are known . Each parameter is formed by the interaction of external acoustic wave with head , outer ear or auricle . In this experiment , we used the technique of whole cell patch clamp to study the membrane reaction characteristics of individual neurons and to compare the difference of membrane reaction characteristics of different neurons in different acoustic spatial signals . In this experiment , the action response ( i.e . , voltage response ) of two types of cells was recorded by injecting different intensities of current stimulation to MNTB host cells and DCN spindle cells , then the action response ( i.e . , voltage response ) of two types of cells was recorded , then the action potentials waveform , peak value , depolarization time history , complex polarization duration , threshold interval , peak interval , action potential release number , first action potential delay and the like of the two types of cells were counted and compared under the Clamfit of the patch clamp data analysis software to reveal the differences in electrophysiological characteristics of the two types of neurons in the treatment of different auditory spatial signals . The results showed that the main cells of MNTB had two kinds of action potential waveforms , which were divided into API ( Action potential wareforml ) type ( n = 6 ) and ap2 ( Action potential wareform2 ) type ( P0.05 ) . The results showed that 1 . MNTB main cells showed two kinds of action potential waveforms , and the waveforms of two action potentials were not simultaneously present on the same neuron body . The action potential distribution pattern of DCN fusiform cells was significantly higher than that of MNTB main cells .

【学位授予单位】：南方医科大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：R764

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