柞蚕幼虫在体胸神经节自发放电活动的观察

本文以百五龄幼虫为材料，运用微电极电生理技术，以胞外记录的方法，记录了柞蚕虫在体胸神经节的自发放电活动。结果，柞蚕幼虫胸神经节胞外自发放电有三种形式：慢节很单个放电、簇状放电及连续放电。     

Na~+、K~+、Ca~(2+)对柞蚕幼虫在体胸神经节自发放电活动的影响

以柞蚕五龄幼虫为材料 ,运用微电极电生理技术 ,以胞外记录的方法 ,记录了柞蚕幼虫在体胸神经节的自发放电活动 .并观察了胞外Na+、K+、Ca2 +的浓度变化对放电活动的影响 .结果表明 ,柞蚕幼虫胸神经节胞外自发放电有 3种形式 ,即慢节律单个放电、簇状放电及连续放电 ,其离子机制可能既有Na+动作电位 ,又有Ca2 +动作电位     

Na^＋,K^＋,Ca^2＋对杵柞蚕幼虫在体胸神经节自发放电活动的影响

以柞蚕五龄幼虫为材料,运用微电极电生理技术,以胞外记录的方法,记录了柞蚕幼虫在体胸神经节的自发放电活动,并观察了胞外Na^ ,K^ ,Ca^2 的浓度变化对放电活动的影响,结果表明,柞蚕幼虫胸神经节胞外自发放电有3种形式,即慢节律单个放电,簇状放电及连续放电,其离子机制可能既有Na^ 动作电位,又有Ca2 动作电位。     

γ-氨基丁酸对家鸽(

在25只家鸽的离体顶盖脑片上,用玻璃微电极胞外记录到顶盖Ⅲ层神经元自发放电单位55个,观察了γ-氨基丁酸(gamma-aminobutyric, GABA)及其拮抗剂以及电刺激Ⅱ     

东北小鲵松果体神经元自发电活动的胚后发育

探讨东北小鲵松果体神经元自发电活动的胚后发育变化。应用微电极电生理技术,对东北小鲵松果体神经元的自发放电活动进行在体胞外记录。结果表明,松果体神经元的自发放电有4种形式:单个放电、连续单个放电、簇状放电和连续簇状放电。后肢芽期有3种放电形式,没有记录到连续簇状放电。各发育时期都以单个放电和连续放电为主,但所占比例有所不同。单个放电和连续放电幅度随发育的进行呈下降的趋势,其均值变化更为明显。随着发育的进行,单个放电和连续簇状放电频率均随之增加,在变态期达最大。变态期和成体期簇状放电无明显变化,连续放电在成体期则降低。结论:神经元电活动形式随着松果体的发育逐渐多样化,放电幅度和频率随之发生变化。     

中华大蟾蜍胚后原始大脑皮层神经元自发电活动的发育变化

应用微电极电生理技术对中华大蟾蜍(Bufo bufo gargarizans)胚后端脑原始大脑皮层神经元的自发放电活动进行在体胞外记录,探讨其胚后端脑原始大脑皮层神经元自发电活的电生理学特性的发育变化。结果表明原始大脑皮层神经元的自发放电有5种形式。胚后发育的早期为4种放电类型,以簇状放电和连续放电为主;胚后发育的后期为5种放电类型,以簇状和连续簇状放电为主。随着原始大脑皮层的发育,单个放电的动作电位时程缩短,连续单个放电和连续簇状放电频率降低,连续放电、簇状放电和连续簇状放电的持续时间延长。随着端脑原始大脑皮层的发育,神经元的兴奋性逐步提高,神经元电活动形式逐渐呈现多样化。     

天冬氨酸对家鸽顶盖脑片Ⅱa—f层神经元电活动的影响

利用离体脑片技术，在５１例家鸽顶盖脑片上用玻璃微电极胞外记录了家鸽顶盖Ⅱａ－ｆ亚层神经元的自发放电活动。根据家鸽顶盖Ⅱａ－ｆ 层神经元自发放电活动的特征，将Ⅱａ－ｆ亚层神经元自发放电分为３种类型：慢而不规则型、快连续型和周期性簇状放电型。天冬氨酸（Ａｓｐ）对不同形式放电单位的作用均以兴奋为主，这种兴奋作用能被Ｎ－甲基－Ｄ－天冬氨酸（ＮＭＯＡ）增强，Ｄ－α－氨基－己二酸（Ｄ－α－ＡＡ）能阻断ＡＳＰ的     

腺苷及其阻断剂茶碱对大鼠尾状核脑薄片神经元自发放电的影响

本实验采用脑薄片电活动胞外记录法，研究腺苷及其非特异性阻断剂茶碱对大鼠尾状核脑薄片神经元自发放电的影响，在记录的３１个细胞中，对２１个细胞灌流了腺苷，其中３个细胞自发放电频率无明显变化，占３／２１＝１４２８％；在另外１８个对腺苷有反应的细胞中，有６个细胞自发放电频率增加，占６／２１＝２８５７％；有１２个细胞自发放电频率减少，占１２／２１＝５７２２％。腺苷的兴奋和抑制效应都有量效关系。茶碱对大鼠尾状核神经元自发放电的效应与腺苷相反。结果提示，大鼠尾状核内存在两种类型的腺苷受体：Ａ１和Ａ２；腺苷对大鼠尾状核脑片神经元自发放电的抑制效应是通过激活Ａ１受体实现的，而其兴奋效应是由于激活了Ａ２受体。     

谷氨酸对家鸽顶盖脑片Ⅱa？f亚层神经元自发电活动的影响

应用离体脑片技术,胞外记录观察了家鸽顶盖Ⅱa～f亚层神经元的自发放电特征,以及灌流和微电泳给予谷氨酸（glutamate,Glu）及其受体措抗剂谷氨酸二乙酯（glutamatediethylester,GDEE）对自发电活动的影响．在46例脑片上观察了80个Ⅱa～f亚层神经元的自发放电活动,其放电形式有3种：慢而不规则型（50个,占62．5％）;连续重复放电型（24,占30．0％）;周期性簇状放电型（6个,占7．5％）．分别用灌流和微电泳方式给予Glu后,受试神经元均出现明显的增频反应,且呈现剂量一效应关系．GDEE对自发放电有抑制作用,且能阻断Glu的兴奋作用一以上结果提示,家鸽顶盖Ⅱa～f亚层内存在Glu敏感神经元,外源性的Glu对这些神经元有兴奋作用,Glu可能作为神经递质参与了家鸽顶盖Ⅱa～f亚层神经元的活动．     

γ—氨基丁酸对家鸽（Columba livia）顶盖脑片Ⅲ层神经？…

在２５只家鸽的离体顶盖脑片上，用玻璃微电极胞外记录到顶盖Ⅲ层神经元自发放电单位５５个，观察了γ－氨基丁酸９ｇａｍｍａ－ａｍｉｎｏｂｕｔｙｒｉｃ，ＧＡＢＡ）及其拮抗剂以及电刺激Ⅲα￣ｆ亚层对Ⅲ岐神经元电活动的作用。作用显示：脑片灌流ＧＡＢＡ（１０＾－６ｍｏｌ／Ｌ，３ｍｉｎ）后，１６／２１个单位（占７６．２％）放电频率减少，１／２１个单位（占４．８％）放电频率增加，４／２１个单位（占１９．６％）放电频     

Firing patterns of long-term cultured neuronal network on multi-electrode array

Spontaneous neuronal activity plays an important role in the development and plasticity of brain. To explore the developmental changes in the firing pattern of the neuronal networks in vitro, the hippocampal neurons were cultured on the multi-microelectrode array dish for over 14 weeks and the spontaneous activity was recorded. The results showed that random firing was observed in the 1st week and transformed into synchronized activity after two weeks, then tightly synchronized activity appeared in week 2 to 7 and finally the activities transformed into the random firing pattern. These results suggested three stages in the long-term development of neuronal network in vitro: the stage for connection, the stage of synchronized activity and the mature stage. Synchronized firing shown by spontaneous activity was an important phenomenon in high density cultured neuronal network and transformed patterns during development.     

Effects of sleep and arousal on the processing of visual information in the cat

Single units in the cat lateral geniculate nucleus and primary visual cortex show changes in both spontaneous and visually evoked firing as a function of the state of wakefulness. On arousal spontaneous firing is smoother and often reduced, whereas evoked responses are usually enhanced; the result is an increase in the signal-to-noise ratio. Single- and double-label 2-deoxyglucose autoradiographs show further that slow-wave sleep differentially depresses visually evoked activity in the deeper layers of the visual cortex.     

Detection of bursts in neuronal spike trains by the mean inter-spike interval method

Bursts are electrical spikes firing with a high frequency, which are the most important property in synaptic plasticity and information processing in the central nervous system. However, bursts are difficult to identify because bursting activities or patterns vary with physiological conditions or external stimuli. In this paper, a simple method automatically to detect bursts in spike trains is described. This method auto-adaptively sets a parameter (mean inter-spike interval) according to intrinsic properties of the detected burst spike trains, without any arbitrary choices or any operator judgment. When the mean value of several successive inter-spike intervals is not larger than the parameter, a burst is identified. By this method, bursts can be automatically extracted from different bursting patterns of cultured neurons on multi-electrode arrays, as accurately as by visual inspection. Furthermore, significant changes of burst variables caused by electrical stimulus have been found in spontaneous activity of neuronal network. These suggest that the mean inter-spike interval method is robust for detecting changes in burst patterns and characteristics induced by environmental alterations.     

培养神经元网络自发活动规律性和复杂度分析

采用近似熵（approximate entropy,ApEn）的新统计方法衡量神经元不同自发放电活动时间序列数据的规律性和复杂度,对多电极阵列上培养的海马神经元网络自发活动的复杂度进行研究．结果表明不同自发放电活动的近似熵动态变化曲线有明显差别．静息期时近似熵值范围1．0-1．2;典型爆发活动时近似熵值呈现迅速下降而后上升再下降小幅振荡（0．2-0．6）;而伪爆发活动时近似熵值在0．2—0．7范围,沿平行时间轴的某一直线上下波动;连续发放锋电位时近似熵值在0．8-0．9范围;而随机单发锋电位时近似熵值0．6—0．8范围．以上分析结果说明近似熵动态变化曲线能够体现爆发活动和锋电位发放过程的规律性和复杂度变化,并可以有效地识别培养神经元网络自发的不同电生理信号,因而在神经元电信号分析中有着潜在的应用价值．     

A network of fast-spiking cells in the neocortex connected by electrical synapses

Encoding of information in the cortex is thought to depend on synchronous firing of cortical neurons. Inhibitory neurons are known to be critical in the coordination of cortical activity, but how interaction among inhibitory cells promotes synchrony is not well understood. To address this issue directly, we have recorded simultaneously from pairs of fast-spiking (FS) cells, a type of gamma-aminobutyric acid (GABA)-containing neocortical interneuron. Here we report a high occurrence of electrical coupling among FS cells. Electrical synapses were not found among pyramidal neurons or between FS cells and other cortical cells. Some FS cells were interconnected by both electrical and GABAergic synapses. We show that communication through electrical synapses allows excitatory signalling among inhibitory cells and promotes their synchronous spiking. These results indicate that electrical synapses establish a network of fast-spiking cells in the neocortex which may play a key role in coordinating cortical activity.     

Small modulation of ongoing cortical dynamics by sensory input during natural vision

During vision, it is believed that neural activity in the primary visual cortex is predominantly driven by sensory input from the environment. However, visual cortical neurons respond to repeated presentations of the same stimulus with a high degree of variability. Although this variability has been considered to be noise owing to random spontaneous activity within the cortex, recent studies show that spontaneous activity has a highly coherent spatio-temporal structure. This raises the possibility that the pattern of this spontaneous activity may shape neural responses during natural viewing conditions to a larger extent than previously thought. Here, we examine the relationship between spontaneous activity and the response of primary visual cortical neurons to dynamic natural-scene and random-noise film images in awake, freely viewing ferrets from the time of eye opening to maturity. The correspondence between evoked neural activity and the structure of the input signal was weak in young animals, but systematically improved with age. This improvement was linked to a shift in the dynamics of spontaneous activity. At all ages including the mature animal, correlations in spontaneous neural firing were only slightly modified by visual stimulation, irrespective of the sensory input. These results suggest that in both the developing and mature visual cortex, sensory evoked neural activity represents the modulation and triggering of ongoing circuit dynamics by input signals, rather than directly reflecting the structure of the input signal itself.     

Attractor dynamics of network UP states in the neocortex

The cerebral cortex receives input from lower brain regions, and its function is traditionally considered to be processing that input through successive stages to reach an appropriate output. However, the cortical circuit contains many interconnections, including those feeding back from higher centres, and is continuously active even in the absence of sensory inputs. Such spontaneous firing has a structure that reflects the coordinated activity of specific groups of neurons. Moreover, the membrane potential of cortical neurons fluctuates spontaneously between a resting (DOWN) and a depolarized (UP) state, which may also be coordinated. The elevated firing rate in the UP state follows sensory stimulation and provides a substrate for persistent activity, a network state that might mediate working memory. Using two-photon calcium imaging, we reconstructed the dynamics of spontaneous activity of up to 1,400 neurons in slices of mouse visual cortex. Here we report the occurrence of synchronized UP state transitions ('cortical flashes') that occur in spatially organized ensembles involving small numbers of neurons. Because of their stereotyped spatiotemporal dynamics, we conclude that network UP states are circuit attractors--emergent features of feedback neural networks that could implement memory states or solutions to computational problems.