电突触耦合Chay神经元同步振荡的研究

从微观解释异常神经元构建组织时癫痫样波形的相互制约关系对神经系统疾病的研究很有意义,而两神经元耦合特性的探索是重要的基础工作。采用Chay提供的Pacemaker神经元模型以电突触耦合来研究不同耦合强度对神经元动态时序的影响,并指出突触作用过程的混沌特征。给出并讨论了不同状态神经元相耦合时非线性振荡的数值计算结果,即：起搏神经元与处于冲动混沌状态神经元、处于冲动混沌和独态冲动状态的异常神经元、异常神经元与处于静息状态神经元的动态时序,还给出了部分相图以及Ca 离子浓度变化的特点。神经元这种负载特性的讨论有助于研究在活组织中癫痫发作的机理、传输和控制。     

基于初级视觉皮层的同步振荡目标检测模型

提出一种基于初级视觉皮层的目标检测模型,该模型只采用方位选择性细胞和皮层内水平连接等Ｖ１基本单元,它以链码表示的目标轮廓作为知识,允许该知识以时间脉冲的形式控制Ｖ１区内神经细胞的动态活动,使与知识轮廓形状相符合的轮廓内的细胞进入同步振荡状态,实现对视野中特定目标轮廓的识别。计算机仿真结果表明,在较高级皮层的“知识”控制之下,初级视觉皮层结构上实现简单的目标检测是可行的。     

金黄地鼠视皮层通过胼胝体顺行和逆行激活的神经元的电活动和分布

用细胞外记录技术研究了金黄地鼠一侧视皮层神经元对电刺激另一侧相应部位的反应及其对视觉刺激反应的特点。(1)在17—18a 交界区大多数(78%)细胞能被电刺激对侧相应点所驱动。在17区内部,被驱动细胞数随离开17—18a 交界距离增加而减少。(2)按对电刺激的反应形式,记录的细胞可分为四类:a.逆行驱动细胞,占17—18a 交界区记录细胞数的20%;b.顺行驱动细胞,占52%中;c.自发发放因电刺激而减少或完全停止的细胞,占6%,d.其余细胞(22%)对电刺激没有可察觉的反应。(3)在17—18a 交界,除了Ⅰ层以外的各层都可记录到顺行驱动细胞,而逆行驱动细胞则主要集中在Ⅲ及Ⅴ层。(4)17—18a 交界细胞感受野(RF)多位于垂直中线附近的对侧视野内,有些 RF 跨越中线,其边界延伸到同侧约10°处。(5)逆行驱动细胞包括刁和 Blakemore 以前在视皮层中记录到的所有细胞类型和各种程度的眼优势,但单眼细胞的比例增加,非对称式 RF 和中心对称式的给-撤型 RF 的比例有所减少。     

大鼠力竭运动中丘脑底核和皮层神经元电活动的变化

目的：探讨力竭过程中丘脑底核（SIN）对皮层兴奋性的调控作用。方法：采用皮层脑电（ECoG）及局部场电（LFPs）同步记录技术,对一次性力竭运动过程中大鼠SIN、皮层神经元电活动变化规律进行同步、动态观察。结果：运动开始阶段大鼠能够自主跟随跑台进行运动,运动持续约45min时（45±11．5min）,自我驱动下的运动能力明显降低;此时STN兴奋性显著增加（P〈0．01）,皮层兴奋性显著下降（P〈0．01）。如果给予大鼠一定的外部刺激后仍可继续运动一段时间直至力竭;力竭即刻皮层兴奋性降到最低值（P〈0．01）,而SIN兴奋性变化不显著（P〉0．05）。结论：大鼠在力竭运动过程中,皮层运动区神经元电活动随着运动疲劳的发生呈现广泛的抑制现象,而SIN神经元电活动在疲劳初期则明显增强,SIN通过负诱导作用参与了运动性中枢疲劳的调控,且STN神经元兴奋性增强可能是皮层实现保护性抑制机制的重要途径之一。     

猕猴F2及F4区皮层神经元在空间有序运动中的放电活动

用胞外单位放电记录的方法,研究了猕猴在执行记忆引导的空间有序运动（ＭＳＳ）时,大脑皮层弓形沟距背侧Ｆ２及腹侧Ｆ４区的放电活动。对于以绿色为暗示信号的ＭＳＳ－Ｇ任务,在暗示期,Ｆ２（７８．２％）比Ｆ４区（４１．５％）有更多的细胞发生放电变化（χ＾２＝１５．２,Ｐ＜０．００５）;在图形期,Ｆ４（６７．９％）比Ｆ２区（４５．４％）有更多的细胞发生放电变化（χ＾２＝５．５,Ｐ＜０．０５）;在触摸反应期,Ｆ     

金黄地鼠视皮层中乙酰胆碱(Ach)阳性神经元及纤维

本文通过色疫组织化学方法-PAP法,使用乙酰胆碱(Ach)抗体对金黄地鼠视皮层中的Ach进行定位Ach阳性神经元分布于视皮层的第Ⅱ—Ⅵ层,主要集中在Ⅱ、Ⅲ层.其细胞形态除大部分为非锥体神经元外,还发现有极少数锥体型神经元.这些神经元的数量和树突形态在视皮层17区和18区存在某些区域性差异.17区细胞比较密集,18区比较稀疏.17区第IA层细胞排列整齐,顶树突特别粗大,18区这种现象不太明显.皮层白质中也有少量的Ach阳性神经元.视皮层Ach阳性神经元的相对含量约为10%.视皮层中遍布外源性和内源性Ach阳性神经纤维,它们主要分布在第Ⅳ层.在视皮层微血管周围有大量Ach阳性神经元,说明对血管有舒张作用的Ach可能来源于血管内壁.     

金黄地鼠视皮层17、18区乙酰胆碱阳性神经元

利用乙酰胆碱( acetylcholine,Ach)自身抗体对金黄地鼠视皮层17、18区乙酰胆碱阳性神经元及其分布进行免疫学显示并进行量化分析.实验发现,Ach阳性细胞大部分为非锥体神经元,也有少量锥体神经元.Ach阳性神经元在视皮层的Ⅱ～Ⅵ层,主要分布在Ⅱ～Ⅳ层.在不同层次中其阳性神经元类型存在某些差异,Ⅱ～Ⅳ中双极细胞居多,其他层次中多极细胞占优势.17区的这类神经元数量较多且集中成垂直于皮层表面的细胞带,18区的神经元数量相对较少且多呈分散状态.     

神经酰胺诱导小鼠皮层神经元凋亡

本实验以原代培养的小鼠大脑皮层神经元为模型,观察了天然神经酰胺在神经元凋亡中的作用。从测定ＬＤＨ漏出率、ＭＴＴ代谢率、ＤＮＡ凝胶电泳,Ｇｉｅｍｓａ染色以及电镜观察等各个方面,探讨了神经酰胺对神经元的作用模式。研究发现,神经酰胺在５００～１０００ｎＭ浓度范围内,作用１２ｈ以上,即可诱导原代培养的皮层神经元凋亡,而且此作用具有时间依赖性和剂量依赖性。表明神经酰胺不仅对ＨＬ－６０细胞有促凋亡的作用,对大脑皮层神经元同样具有促凋亡的作用。     

屈光不正对儿童视觉皮层神经元活动影响的功能磁共振研究

目的：利用血氧水平依赖性功能性磁共振成像（BOLD-fMRI）技术及非金属MRI专用眼镜,分析探索屈光不正对儿童大脑皮层视觉功能区神经元活动的影响。方法：以1．5T磁共振成像系统采集8例屈光不正眼儿童屈光矫正前后枕叶视皮层兴趣区BOLD—fMRI数据,及8例正常眼凸透镜离焦前后枕叶视皮层兴趣区BOLD—fMRI数据,进行对比分析,比较屈光不正眼及其矫正后、正常眼及其离焦后皮层视觉功能区神经元活动的不同,分析其改变特点及原因。结果：屈光不正眼儿童矫正屈光后皮层视觉功能区神经元活动范围明显增加（P〈0．05）;正常眼离焦后皮层视觉功能区神经元活动范围明显减小（P〈0．05）。结论：屈光不正会明显降低儿童皮层视觉功能区的神经元活动。屈光不正患儿应尽早配镜矫正,以免影响视觉皮层功能发育。     

初级视皮层神经元集群对拓扑特征响应的可视化表征

神经元集群响应的高维特性是脑机制研究面临的主要困难之一.拓扑特征是图像的基本特征之一,为了有效表征高维的神经元集群响应的拓扑特征特性,提出了一种基于三维自组织映射网络采用RGB颜色特征表征神经元集群响应的动态可视化方法,分析多通道微电极阵列采集的大鼠初级视觉皮层(V1区)神经元集群信号,进而研究了V1区神经元集群对图形拓扑特征的响应特性.通过与主成分分析(PCA)方法进行对比发现:该方法能够有效表征V1区神经元集群对拓扑结构的时序动态响应特征,表征方式形象直观,具有一定的优越性.     

新生SD大鼠皮质神经元的体外培养和鉴定

目的：建立高纯度的新生SD大鼠皮质神经元原代培养方法。方法：取24h内的新生SD大鼠皮质,用木瓜酶和DNaseⅠ共同消化,5％胎牛血清终止消化,吹打分离组织获得单细胞悬液,进行细胞计数,用无血清DMEM／F12种植培养,4h后换成用无血清Neurobasal配制的维持培养液继续培养,尼氏小体染色和免疫荧光法鉴定神经元的纯度。结果：培养第10d,神经元胞体饱满,结构清晰完整,光晕明显,折光性强,可见粗长的树突和轴突,相邻细胞形成紧密网状联系,神经元纯度达到96％以上。结论：经改良和优化,无须添加阿糖胞苷抑制胶质细胞的生长即能够获得生长状态良好、高纯度的神经元。     

新生BALB/c小鼠大脑皮质神经元细胞培养方法的建立

目的:经改良和优化,建立高纯度BALB/c小鼠大脑皮质神经元培养的方法.方法:采用L-多聚赖氨酸包被细胞培养板,取新生BALB/c小鼠(出生24 h内)大脑皮质组织,经0.25%胰酶消化后吹打成单个细胞,按1×106/孔接种于35 mm的六孔板中,用神经元细胞培养种植液培养6 h后换神经元细胞培养饲养液,培养40 h时...     

Information in the Neuronal Representation of Individual Stimuli in the Primate Temporal Visual Cortex

To analyze the information provided about individual visual stimuliin the responses of single neurons in the primate temporal lobevisual cortex, neuronal responses to a set of 65 visual stimuli wererecorded in macaques performing a visual fixation task and analyzedusing information theoretical measures. The population of neuronsanalyzed responded primarily to faces. The stimuli included 23 facesand 42 nonface images of real-world scenes, so that the function ofthis brain region could be analyzed when it was processing relativelynatural scenes.It was found that for the majority of the neurons significantamounts of information were reflected about which of several of the23 faces had been seen. Thus the representation was not local, forin a local representation almost all the information available canbe obtained when the single stimulus to which the neuron respondsbest is shown. It is shown that the information available about anyone stimulus depended on how different (for example, how manystandard deviations) the response to that stimulus was from theaverage response to all stimuli. This was the case for responsesbelow the average response as well as above.It is shown that the fraction of information carried by the lowfiring rates of a cell was large—much larger than that carried bythe high firing rates. Part of the reason for this is that theprobability distribution of different firing rates is biased towardlow values (though with fewer very low values than would bepredicted by an exponential distribution). Another factor is thatthe variability of the response is large at intermediate and highfiring rates.Another finding is that at short sampling intervals (such as 20 ms)the neurons code information efficiently, by effectively acting asbinary variables and behaving less noisily than would be expectedof a Poisson process.     

Oxytocin Shapes Spontaneous Activity Patterns in the Developing Visual Cortex by Activating Somatostatin Interneurons

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Mouse Visual Cortex Is Modulated by Distance Traveled and by Theta Oscillations

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Functionally Distinct Gamma Range Activity Revealed by Stimulus Tuning in Human Visual Cortex

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Neuronal Activity Preceding Directional and Nondirectional Cues in the Premotor Cortex of Rhesus Monkeys

Pre-cue activity, the neuronal modulation that precedes a predictable stimulus, was studied in the premotor cortex of three rhesus monkeys. In one condition, a directional cue dictated the timing and target of a forelimb movement. In another condition, a non-directional cue provided identical timing information but did not indicate the target. Of 501 task-related neurons recorded in premotor cortex, 168 showed pre-cue activity. The onset time of pre-cue activity varied markedly from trial to trial and cell to cell, ranging from trial initiation to 4.8 sec later. No pre-cue activity reflected the direction of limb movement; thus, the data argue against the hypothesis that pre-cue activity reflects preparation for specific limb movements. A small number of cells showed greater pre-cue activity before directional than before nondirectional cues, and this difference may reflect anticipation of the cue's directional information. However, the vast majority (84%) of neurons lacked such differences. We therefore hypothesize that most pre-cue activity reflects or contributes to a facet of behavior common to the two conditions: anticipation of the time and/or nature of events.     

初级视皮层神经元非经典感受野研究的新进展

感觉皮层神经元的非经典感受野(简称"外周")对经典感受野(简称"中心")的调节作用广泛存在于哺乳动物中,被认为是感觉皮层神经元的基本特性.以初级视皮层神经元为例,刺激其外周能有效地调节刺激其中心引起的反应,这种作用主要是抑制性的.理解初级视皮层神经元的外周对中心的调节机制能够深入揭示哺乳动物的感觉皮层神经元信息处理的基本原则.本文综述了引起初级视皮层神经元非经典感受野对经典感受野调节作用的神经环路机制和计算模型研究的进展.     

Neuronal Mechanisms Encoding Global-to-Fine Information in Inferior-Temporal Cortex

Sugase et al. found that global information is represented at the initial transient firing of a single face-responsive neuron in inferior-temporal (IT) cortex, and that finer information is represented at the subsequent sustained firing. A feed-forward model and an attractor network are conceivable models to reproduce this dynamics. The attractor network, specifically an associative memory model, is employed to elucidate the neuronal mechanisms producing the dynamics. The results obtained by computer simulations show that a state of neuronal population initially approaches to a mean state of similar memory patterns, and that it finally converges to a memory pattern. This dynamics qualitatively coincides with that of face-responsive neurons. The dynamics of a single neuron in the model also coincides with that of a single face-responsive neuron. Furthermore, we propose two physiological experiments and predict the results from our model. Both predicted results are not explainable by the feed-forward model. Therefore, if the results obtained by actual physiological experiments coincide with our predicted results, the attractor network might be the neuronal mechanisms producing the dynamics of face-responsive neurons.