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    May 22

    脑神经随外界声音“打拍子”

    这是我记录的第三篇关于节律记忆的文章。看来这个问题很有理论研究的价值。
    这个月Prof. Y.C. Lai都在,他是非线性动力学和网路领域的专家,可以找他讨论讨论 :)
    The Journal of Neuroscience, May 6, 2009, 29(18):6013-6021;
    Entrainment of Slow Oscillations of Auditory Thalamic Neurons by Repetitive Sound Stimuli
    Slow oscillations at frequencies <1 Hz manifest in many brain regions as discrete transitions between a depolarized up state and a hyperpolarized down state of the neuronal membrane potential. Although up and down states are known to differentially affect sensory-evoked responses, 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 nonlemniscal auditory thalamic neurons exhibited spontaneous up/down transitions at random intervals in the range of 2–30 s, which could be entrained to a regular interval by repetitive sound stimuli. 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 unanesthetized guinea pigs also showed 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.
    作者:黄辛 来源:科学时报 发布时间:2009-5-21
    脑神经有时仿佛是一位聪明且敏感的音乐家,不仅能掌握自己的节奏和律动,而且还善于“倾听”外界的声音,甚至会随着外界声音“打拍子”。新近一期的国际学术期刊《神经科学杂志》(Journal of Neuroscience)发表了中国科学院上海生命科学研究院神经科学研究所研究员章晓辉课题组的研究结果:“节律的感觉输入调制大脑中神经网络活动的振荡频率”。
     
    他们在研究中发现了大脑神经网络活动中的有趣现象:以秒为时间间隔的外界声音刺激,可“吸引”丘脑中一种频率小于1赫兹的慢波振荡不由自主地跟上它的“拍子”。
     
    大脑中许多功能区呈现不同形式的神经网络振荡活动(oscillatory brain activity),它们反映群体神经元的同步活动以及大脑的不同功能状态。例如,在清醒工作状态下,振荡活动多表现为高频低幅;在睡眠状态下,振荡特征多为低频高幅。这些不同形式的振荡活动分别在大脑处理、传递和整合感觉信息,巩固记忆,以及一些高级认知活动(如注意行为)中发挥重要的作用。其中,调制神经网络活动的振荡特性是实现这些脑功能的可能机制之一。
     
    通过对整体动物的电生理研究,发现丘脑中一种频率小于1Hz的慢波振荡(slow oscillations)的活动节律,可以被声音刺激的节律所调制。时间间隔为秒的节律声音的短时间刺激可以促使丘脑慢波振荡活动的自发频率“跟随”外界声音刺激频率,并且在撤除刺激后,丘脑的自发振荡活动仍能保持声音刺激频率达数个振荡周期(约几十秒)。同时,这种慢波振荡的“跟随效应”也能特异地增强神经元对相同时间间隔的弱声音的反应,这一易化作用则可维持达十几分钟。这些研究发现揭示了一种与感觉输入特征相关的神经网络活动的可塑性,也提示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。

    Comments (3)

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    我印象中看过PRL中一篇文章,可以用类似fMNR的方法来记录大脑中各个区域在不同刺激时候的响应的同调,从而认为有连接.但应该没有到神经元连接的层次
    May 26
    jie renwrote:
    :), 实验上不知道。理论上倒是有些,印象中。要直接系统的测量大脑里神经元的物理连接,目前的实验技术还达不到。
    May 26
    Susan Shuaiwrote:
    Impressive. 有没有大脑不同区域之间oscillation的关联的文章阿?假如能和结构结合起来就更好了。
    May 22

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