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Title: 声音重复刺激对听觉丘脑神经元慢波振荡活动的调制作用
Author: 高利霞
Degree Level: 博士
Issued Date: 2009-04-27
Degree Grantor: 中国科学院上海生命科学研究院
Place of Degree Grantor: 上海生命科学研究院
Supervisor: 蒲慕明
Keyword: 慢波振荡 ; 低电位期 ; 高电位期 ; 跟随效应 ; 时间间隔 ; 丘脑 ; 听觉系统
Alternative Title: Entrainment of slow oscillations of auditory thalamic neurons by repetitive sound stimuli
Major: 神经生物学
Abstract: 动物在慢波睡眠时期或麻醉状态下,大脑皮层及其它很多脑区的神经元存在频率小于1Hz的慢波振荡 (slow oscillation) 活动,这种慢波振荡的一个典型电生理特征是神经元膜电位在高电位期(UP state)和低电位期(DOWN state)之间交替转变 (transition)。已有研究表明,这种高、低电位期的交替也存在于清醒的动物,并能调制神经元对外界感觉刺激的编码机制。反之,外界的感觉刺激是否会影响神经元高、低电位期交替转变的节律 (rhythms),目前还不清楚。本课题以豚鼠为研究对象,主要采用细胞内记录,同时结合细胞外记录及形态学染色的方法,系统地研究了听觉刺激对听觉丘脑神经元慢波振荡活动的调制作用。实验结果表明:(1)在麻醉状态(戊巴比妥钠)下,胞内记录单个神经元电活动结果表明非外侧丘系听觉丘脑区(non-lemniscal auditory thalamus)神经元在慢波振荡时膜电位存在高、低电位期的交替转变。(2)外界声音刺激(白噪声,0.1-35 KHz)能调制神经元自发的高电、低电位期的传递节律:当声音刺激落在高电位期时,每一次声音刺激都会使细胞膜电位由高电位期向低电位期转变,并当声音刺激间隔在3-12秒范围内时,自发的高、低电位期的转变节律就同步于声音刺激的重复率,即跟随效应(entrainment)。(3)声音刺激诱发的低电位期主要由氯离子电流介导,可能主要来源于丘脑网状核团 (TRN)的抑制性突触输入。(4)更为重要的是,声音刺激结束后神经元膜电位自发的高、低电位期间的转变节律仍能保持与声音刺激的重复率相近,并能维持数个循环。(5)进一步实验发现,给予固定时间间隔的声音刺激5-10次能易化(增强)神经元对相对微弱声音刺激的反应幅度,这种易化效应(facilitation)具有刺激间隔特异性并可以持续二十分钟。(6)在非麻醉豚鼠上胞外记录的结果同样表明:在慢波睡眠时期,声音重复刺激可明显地引起听觉丘脑神经元的慢波振荡同步于声音刺激的跟随效应。 因此,我们的研究表明,听觉丘脑慢波振荡神经元活动的特性可被外界声音刺激特性所调制,这种节律刺激对慢波振荡发生频率的调制可能参与编码和短时记忆“秒级”时间间隔信息。
English Abstract: Slow oscillations at frequencies less than 1 Hz manifest in many brain regions as discrete transitions between a depolarized UP state and a hyperpolarized DOWN state of the membrane potential. These slow oscillations have been observed during slow wave sleep, under anesthesia or during quiet wakefulness. Even in awake and behaving animals, similar sub-threshold membrane potential dynamics were observed. The slow oscillations in many brain regions interact strongly with sensory-evoked responses. However, whether and how they are modulated by sensory stimuli are not well understood. In the present study, intracellular recording in anesthetized guinea pigs showed that membrane potentials of non-lemniscal auditory thalamic neurons exhibited spontaneous UP/DOWN transitions at random intervals in the range of 2-30 s. The frequency of spontaneous UP/DOWN transitions could be entrained to a regular interval by repetitive sound stimuli with intervals ranging 3-12 sec, in which each sound stimulus effectively induced a UP-to-DOWN transition. Further experiments suggested that those sound-induced DOWN-states were likely caused by the activation of GABAA receptor-medicated inhibitory synaptic inputs from TRN. Strikingly, after termination of the entraining stimulation (ES), regular UP/DOWN transitions persisted for several cycles at the ES interval. Furthermore, the efficacy of weak sound stimuli in triggering the UP-to-DOWN transition was potentiated specifically at the ES interval for at least 10 min. Extracellular recordings in the auditory thalamus of un-anesthetized guinea pigs also showed apparent entrainment of slow oscillations by rhythmic sound stimuli during slow wave sleep. These results demonstrate a novel form of network plasticity, which could help to retain the information of stimulus interval on the order of seconds.
Language: 中文
Content Type: 学位论文
URI: http://ir.sibs.ac.cn/handle/331001/2391
Appears in Collections:神经所(总)_学位论文

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Recommended Citation:
声音重复刺激对听觉丘脑神经元慢波振荡活动的调制作用.高利霞[d].中国科学院上海生命科学研究院,2009.20-25
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