5月6日，《神经科学》（Journal of Neuroscience）发表了中科院上海生科院神经科学研究所章晓辉研究员课题组的研究发现——“节律的感觉输入调制大脑中神经网络活动的振荡频率”。博士研究生高丽霞、叶昌泉等通过对整体动物的电生理研究，发现丘脑中一种频率小于1 Hz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。
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。
该工作是在神经科学研究所蒲慕明教授和香港理工大学贺菊芳教授的课题组共同协作下完成，并受到中科院“创新项目”的资助。（生物谷Bioon.com）
生物谷推荐原始出处：
The Journal of Neuroscience, May 6, 2009, doi:10.1523/JNEUROSCI.5733-08.2009
Entrainment of Slow Oscillations of Auditory Thalamic Neurons by Repetitive Sound Stimuli
Lixia Gao,1 Xiankai Meng,2 Changquan Ye,1 Haitian Zhang,1 Chunhua Liu,1 Yang Dan,3,4 Mu-ming Poo,1,3 Jufang He,2 and Xiaohui Zhang1
1Institute of Neuroscience, State Key Laboratory of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China, 2Department of Rehabilitation Sciences, Hong Kong Polytechnic University, Hong Kong, China, and 3Division of Neurobiology, Department of Molecular and Cell Biology, Helen Wills Neuroscience Institute and 4Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, California 94720
Correspondence should be addressed to either of the following: Jufang He, Department of Rehabilitation Sciences, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China; or Xiaohui Zhang, Institute of Neuroscience, Chinese Academy of Sciences, 320 Yue-Yang Road, Shanghai 200031, China
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.
