突触长时程增强形成机制的研究进展

高等动物脑内突触传递的可塑性是近30年来神经科学研究的热点,突触传递长时程增强（long-term potentiation,LTP)是神经元可塑性的反映,其形成主要与突触后机制有关。过去关于LTP机制的研究主要集中于N－甲基－D门冬氨酸（NMDA）受体的特征及该受体被激活后的细胞内级联反应,现认为脑内存在只具有NMDA受体而不具有α－氨基羟甲基恶唑丙酸（AMPA）受体的“静寂突触（silent synapse)”,这一概念的提出,使人们认识到AMPA受体在LTP表达的突触后机制中的重要作用。     

θ波与突触传递的长时程改变

长时程增强效应 (long -termpotentiation ,LTP)是一种突触强度的持续性增强 ,它通常由持续高频刺激引起 ,在海马和其他许多脑区均能产生。一般认为LTP与学习和记忆有密切关系。θ波是一种高幅、低频的脑电波 ,它通常在机体进行一些学习相关的行为时出现 ,而且在这种θ波存在的     

与长时程增强相关的基因表达的研究进展

长地程增强（long-term potentiation,LTP)现象在细胞水平和分子水平反映突触的可塑性,它被认为是记忆过程中神经元活动的客观电生理指标。对其机制的研究表明,伴随着LTP的产生,有基因表达和蛋白质成分的改变。揭开LTP形成过程中所伴随的基因表达的改变,也许是探讨LTP形成机制的关键。     

大鼠海马CA3区的习得性长时程突触增强

本实验应用慢性埋植电极技术以电生理学结合行为学的方法,观察大鼠条件性饮水反应的建立、消退和再建立过程中,其海马CA_3区突触效应的变化规律。以刺激内嗅区的穿通纤维(PP)诱发的单突触的群体锋电位(PS)及群体兴奋性突触后电位(EPSPs)为指标,经叠加处理分析,发现随着条件反应的建立,海马CA_3锥体细胞出现突触效应的长时程增强(LTP),它随行为反应的实验性消退而消退,而在随后再次建立条件反应时,又重新出现;且无论此LTP达最高水平还是它的完全消退均超前于条件性行为反应的水平。又在一个实验日训练作业结束时PS并未立即随之增大,在24h内它随时间而发展,但到第4小时已达最高水平,且条件反应率是与PS的水平相应的,对PS与EPSPs的斜率进行相关分析表明,PS的变化主要是突触传递功效的变化。上述结果表明,海马CA_3区随着行为训练有习得性LTP产生。从其发神变化特点及其与条件性行为的关系,提示此习得性LTP极其可能是本实验中学习和记忆的展经基础。     

海马突触传递长时程增强效应中的逆行信使

海马突触传递长时程增强现象的突触机制研究取得了许多重要进展,其中特别是发展了突触前膜与突触后膜功能双向调控的概念,即观察了逆行信使的存在和作用,这对于理解和阐明学习、记忆的机制具有重要的理论意义。本文结合笔者的工作,重点介绍一氧化氮等所谓的逆行信使在突触传递长时程增强中的功能。     

低频刺激诱发海马突触传递去长时程增强的特性研究

目的和方法：以频率为1、3或5Hz,脉冲数为300或900,与高频刺激（HFS）时间间隔是20min或100min的低频刺激（LFS）作用于大鼠海马脑片,分别观察其对CA1区突触传递去长时程增强（DP）形成的影响。结果：HFS（100Hz,100脉冲的串刺激两串,串间隔30s)可诱发突触传递效率的长时程增强（LTP）。HFS经20min给予3Hz900脉冲的LFS可翻转LTP,产生DP,该作用可为NMDA受体阻断剂AP5（50μmol/L)所阻断,1Hz、5Hz、低脉冲数或与HFS时间间隔长的LFS,其诱发DP的效率减弱。结论：诱发海马CA1区DP的产生,对LFS的参数有较强的依从性。该作用可能是通过激活NMDA受体而实现的。     

长时程突触可塑性中的突触标识

神经元长时程突触可塑性是学习和记忆的基础,神经元长时程突触可塑性的维持依赖于基因的转录和蛋白质合成.然而,这些转录产物和新合成的蛋白质是如何从胞体运输到突触点,还不甚清楚.近年来的研究显示,当长时程突触可塑性发生时,被激活的突触能通过建立突触标记(synaptic tag)来识别、捕捉和利用其所需要的基因产物,以维持突触可塑性的长时程变化.这一过程或现象被称为突触标识(synaptic tagging).本文就近年来突触标识的研究进展作一概述.     

伏衬蛋白与学习记忆的突触机制

伏衬蛋白是一种多肽聚合体,广泛存在于多种动物细胞内,在胞浆外层和质膜内侧形成一层“衬里”,并在神经元和突触后致密物质内高度浓集。80年代以来,人们对这种蛋白质的生化特性、种间分布、细胞分布以及功能作用进行了不少研究。本文对有关资料作一简要的评述,并重点介绍这种蛋白质在学习记忆突触机制中的可能作用。     

钙神经素与学习和记忆

钙神经素 (calcineurin ,CN)是一种钙依赖的蛋白磷酸酶 ,其催化亚基的基因编码具严格保守性。近年来研究证明其在学习和记忆中有重要作用 ,参与了大脑神经元突触效应的去增强、多种不同机制的长时程抑制 (LTD)、长时程增强 (LTP)、认知记忆、短期记忆向长期记忆的转换、脑老化等过程。深入研究CN参与学习和记忆的机制及其与记忆减退性疾病的关系 ,具有重要理论与实践意义     

The relationships between working memory and long-term memory

Recent studies have led to the proposal that working memory operates not as a gateway between sensory input and long-term memory but as a workspace. The core of argument is that access to acquired knowledge and prior learning occurs before information becomes available to working memory. This proposition is a way to accomodate Baddeley's multiple component working memory model and the view that considers that working memory is nothing other than temporary activations of representations and procedures in long-term memory. However, this ‘workspace’ conception of working memory raises the question of the relationships between the central executive system and long-term memory.     

Cyclin-dependent kinase 5 in synaptic plasticity, learning and memory

Cyclin-dependent kinase 5 (Cdk5) is a serine/threonine kinase with a multitude of functions. Although Cdk5 is widely expressed, it has been studied most extensively in neurons. Since its initial characterization, the fundamental contribution of Cdk5 to an impressive range of neuronal processes has become clear. These phenomena include neural development, dopaminergic function and neurodegeneration. Data from different fields have recently converged to provide evidence for the participation of Cdk5 in synaptic plasticity, learning and memory. In this review, we consider recent data implicating Cdk5 in molecular and cellular mechanisms underlying synaptic plasticity. We relate these findings to its emerging role in learning and memory. Particular attention is paid to the activation of Cdk5 by p25, which enhances hippocampal synaptic plasticity and memory, and suggests formation of p25 as a physiological process regulating synaptic plasticity and memory.     

Age-related changes in the relationship between learning progress and auditory working memory characteristics

In order to explore the relationship between learning progress and working memory characteristics, the psychoacoustic testing of 42 persons (20-65 years old) of medical staff taught a novel science (informatics) was carried out. The subjects were divided into three age groups: 20-35, 36-50, and 51-65-year-olds. Acoustical test consisted of a set of 12 target words (professional informatics terms) presented through headphones and subsequent presentation of a random succession of 12 target and 12 masking words (all of them being professional informatics terms). Listeners had to recognize the target words. The stepwise linear regression analysis revealed a link between the progress in acquisition of the new material and characteristics of acoustical working memory, whose role in learning progress increased with age. Because the memory efficiency reduction was found in subjects older than 35 years, it was supposed that age-related changes in characteristics of the acoustical working memory were responsible for the decline in ability to learn novel material.