共查询到20条相似文献，搜索用时 109 毫秒
1.
Signal-processing machines at the postsynaptic density 总被引：1，自引：0，他引：1
Kennedy MB 《Science (New York, N.Y.)》2000,290(5492):750-754
Dendrites of individual neurons in the vertebrate central nervous system are contacted by thousands of synaptic terminals relaying information about the environment. The postsynaptic membrane at each synaptic terminal is the first place where information is processed as it converges on the dendrite. At the postsynaptic membrane of excitatory synapses, neurotransmitter receptors are attached to large protein "signaling machines" that delicately regulate the strength of synaptic transmission. These machines are visible in the electron microscope and are called the postsynaptic density. By changing synaptic strength in response to neural activity, the postsynaptic density contributes to information processing and the formation of memories. 相似文献
2.
Biochemistry of information storage in the nervous system 总被引：11，自引：0，他引：11
I B Black J E Adler C F Dreyfus W F Friedman E F LaGamma A H Roach 《Science (New York, N.Y.)》1987,236(4806):1263-1268
The use of molecular biological approaches has defined new mechanisms that store information in the mammalian nervous system. Environmental stimuli alter steady-state levels of messenger RNA species encoding neurotransmitters, thereby altering synaptic, neuronal, and network function over time. External or internal stimuli alter impulse activity, which alters membrane depolarization and selectively changes the expression of specific transmitter genes. These processes occur in diverse peripheral and central neurons, suggesting that information storage is widespread in the neuraxis. The temporal profile of any particular molecular mnemonic process is determined by specific kinetics of turnover and by the geometry of the neuron resulting in axonal transport of molecules to different synaptic arrays at different times. Generally, transmitters, the agents of millisecond-to-millisecond communication, are subject to relatively long-lasting changes in expression, ensuring that ongoing physiological function is translated into information storage. 相似文献
3.
Control of synapse number by glia 总被引：1，自引：0，他引：1
Ullian EM Sapperstein SK Christopherson KS Barres BA 《Science (New York, N.Y.)》2001,291(5504):657-661
Although astrocytes constitute nearly half of the cells in our brain, their function is a long-standing neurobiological mystery. Here we show by quantal analyses, FM1-43 imaging, immunostaining, and electron microscopy that few synapses form in the absence of glial cells and that the few synapses that do form are functionally immature. Astrocytes increase the number of mature, functional synapses on central nervous system (CNS) neurons by sevenfold and are required for synaptic maintenance in vitro. We also show that most synapses are generated concurrently with the development of glia in vivo. These data demonstrate a previously unknown function for glia in inducing and stabilizing CNS synapses, show that CNS synapse number can be profoundly regulated by nonneuronal signals, and raise the possibility that glia may actively participate in synaptic plasticity. 相似文献
4.
Formation of myelin, the electrical insulation on axons produced by oligodendrocytes, is controlled by complex cell-cell signaling that regulates oligodendrocyte development and myelin formation on appropriate axons. If electrical activity could stimulate myelin induction, then neurodevelopment and the speed of information transmission through circuits could be modified by neural activity. We find that release of glutamate from synaptic vesicles along axons of mouse dorsal root ganglion neurons in culture promotes myelin induction by stimulating formation of cholesterol-rich signaling domains between oligodendrocytes and axons, and increasing local synthesis of the major protein in the myelin sheath, myelin basic protein, through Fyn kinase-dependent signaling. This axon-oligodendrocyte signaling would promote myelination of electrically active axons to regulate neural development and function according to environmental experience. 相似文献
5.
[目的]研究GABAergic神经元在VPM和"barrel"区的组织结构及形态特点;[方法]通过免疫组织化学的方法和激光共聚焦电子显微镜研究GABAergic神经元在VPM和"barrel"区分布状态;[结果]GABAergic神经元在VPM和"barrel"区分布状态不同,信息传递这2个区域编码程度也不一样;GABAergic在VPM区主要分布在列与列之间,且呈非对称分布,而GABAergic神经元的胞体、树突和轴突出现限定在"barrel"内,与周围"barrel"很少形成突触联系。[结论]提示VPM和"barrel"可能在信息传递及处理过程中具有不同的功能。 相似文献
6.
The normal function of neural networks depends on a delicate balance between excitatory and inhibitory synaptic inputs. Synapse formation is thought to be regulated by bidirectional signaling between pre- and postsynaptic cells. We demonstrate that members of the Neuroligin family promote postsynaptic differentiation in cultured rat hippocampal neurons. Down-regulation of neuroligin isoform expression by RNA interference results in a loss of excitatory and inhibitory synapses. Electrophysiological analysis revealed a predominant reduction of inhibitory synaptic function. Thus, neuroligins control the formation and functional balance of excitatory and inhibitory synapses in hippocampal neurons. 相似文献
7.
The mushroom bodies of the Drosophila brain are important for olfactory learning and memory. To investigate the requirement for mushroom body signaling during the different phases of memory processing, we transiently inactivated neurotransmission through this region of the brain by expressing a temperature-sensitive allele of the shibire dynamin guanosine triphosphatase, which is required for synaptic transmission. Inactivation of mushroom body signaling through alpha/beta neurons during different phases of memory processing revealed a requirement for mushroom body signaling during memory retrieval, but not during acquisition or consolidation. 相似文献
8.
FAN Zeng-jie CAO Zhi-heng WANG Zi-ren College of Biological Sciences Lanzhou University Lanzhou 《（《农业科学与技术》）编辑部》2008,(1)
To understand the structure of GABAergic neurons in the VMP and "barrel",the distribution of GABAergic neurons in the two areas were studied through immunohistochemistry and Laser Scanning Confocal Microscope.The results show that the distribution of GABAergic neurons in VMP and barrel are different,and the coding of information transmission in the two areas are also dissimilar;GABAergic neurons mainly distribute among the lines asymmetrically in VMP,the somata,dendrite and axon of GABAergic neurons are restricted in the "barrel",rarely having synaptic connections with other "barrel" around.Therefore,VMP and barrel may have different roles in transmission and on processing of informatiton. 相似文献
9.
DeFalco J Tomishima M Liu H Zhao C Cai X Marth JD Enquist L Friedman JM 《Science (New York, N.Y.)》2001,291(5513):2608-2613
We report the development of a pseudorabies virus that can be used for retrograde tracing from selected neurons. This virus encodes a green fluorescent protein marker and replicates only in neurons that express the Cre recombinase and in neurons in synaptic contact with the originally infected cells. The virus was injected into the arcuate nucleus of mice that express Cre only in those neurons that express neuropeptide Y or the leptin receptor. Sectioning of the brains revealed that these neurons receive inputs from neurons in other regions of the hypothalamus, as well as the amygdala, cortex, and other brain regions. These data suggest that higher cortical centers modulate leptin signaling in the hypothalamus. This method of neural tracing may prove useful in studies of other complex neural circuits. 相似文献
10.
Weijer CJ 《Science (New York, N.Y.)》2003,300(5616):96-100
Cells display a highly complex spatiotemporal organization, required to exert a wide variety of different functions, for example, detection, processing, and propagation of nerve impulses by neurons; contraction and relaxation by muscle cells; movement by leukocytes; and adsorption and secretion of nutrients and metabolites by epithelial cells lining the gut. Successful execution of these complex processes requires highly dynamic information transfer between different regions and compartments within cells. Through the development of fluorescent sensors for intracellular signaling molecules coupled with improved microscopic imaging techniques, it has now become possible to investigate signal propagation in cells with high spatial and temporal resolution. 相似文献
11.
Astrocytes play active roles in brain physiology. They respond to neurotransmitters and modulate neuronal excitability and synaptic function. However, the influence of astrocytes on synaptic transmission and plasticity at the single synapse level is unknown. Ca(2+) elevation in astrocytes transiently increased the probability of transmitter release at hippocampal area CA3-CA1 synapses, without affecting the amplitude of synaptic events. This form of short-term plasticity was due to the release of glutamate from astrocytes, a process that depended on Ca(2+) and soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) protein and that activated metabotropic glutamate receptors (mGluRs). The transient potentiation of transmitter release became persistent when the astrocytic signal was temporally coincident with postsynaptic depolarization. This persistent plasticity was mGluR-mediated but N-methyl-d-aspartate receptor-independent. These results indicate that astrocytes are actively involved in the transfer and storage of synaptic information. 相似文献
12.
Electrical activity in neurons is generally initiated in dendritic processes then propagated along axons to synapses, where it is passed to other neurons. Major structural features of neurons-their dendrites and axons-are thus related to their fundamental functions: the receipt and transmission of information. The acquisition of these distinct properties by dendrites and axons, called polarization, is a critical step in neuronal differentiation. We show here that SAD-A and SAD-B, mammalian orthologs of a kinase needed for presynaptic differentiation in Caenorhabditis elegans, are required for neuronal polarization. These kinases will provide entry points for unraveling signaling mechanisms that polarize neurons. 相似文献
13.
Ge WP Yang XJ Zhang Z Wang HK Shen W Deng QD Duan S 《Science (New York, N.Y.)》2006,312(5779):1533-1537
Interactions between neurons and glial cells in the brain may serve important functions in the development, maintenance, and plasticity of neural circuits. Fast neuron-glia synaptic transmission has been found between hippocampal neurons and NG2 cells, a distinct population of macroglia-like cells widely distributed in the brain. We report that these neuron-glia synapses undergo activity-dependent modifications analogous to long-term potentiation (LTP) at excitatory synapses, a hallmark of neuronal plasticity. However, unlike the induction of LTP at many neuron-neuron synapses, both induction and expression of LTP at neuron-NG2 synapses involve Ca2+-permeable AMPA receptors on NG2 cells. 相似文献
14.
Electrotonic transmission between spinal neurons is correlated with distinctive apposition of cell processes involving membrane fusion. In the same neurons, postsynaptic potentials appear to arise at typical synaptic knobs where there is an intercellular space. 相似文献
15.
SynCAM,a synaptic adhesion molecule that drives synapse assembly 总被引：1，自引：0，他引：1
Biederer T Sara Y Mozhayeva M Atasoy D Liu X Kavalali ET Südhof TC 《Science (New York, N.Y.)》2002,297(5586):1525-1531
Synapses, the junctions between nerve cells through which they communicate, are formed by the coordinated assembly and tight attachment of pre- and postsynaptic specializations. We now show that SynCAM is a brain-specific, immunoglobulin domain-containing protein that binds to intracellular PDZ-domain proteins and functions as a homophilic cell adhesion molecule at the synapse. Expression of the isolated cytoplasmic tail of SynCAM in neurons inhibited synapse assembly. Conversely, expression of full-length SynCAM in nonneuronal cells induced synapse formation by cocultured hippocampal neurons with normal release properties. Glutamatergic synaptic transmission was reconstituted in these nonneuronal cells by coexpressing glutamate receptors with SynCAM, which suggests that a single type of adhesion molecule and glutamate receptor are sufficient for a functional postsynaptic response. 相似文献
16.
Chemical messengers in development: a hypothesis 总被引：5，自引：0，他引：5
D McMahon 《Science (New York, N.Y.)》1974,185(156):1012-1021
The hypothesis that physiological and developmental regulatory mechanisms are similar has been presented. Well-known developmental systems chosen illustrate the capability of the model to suggest a simple mechanism underlying the effects on development of a diverse group of chemicals. This hypothesis might be applied to other systems including the induction of the lens, limb regeneration, and the induction of the head of hydra (124). I have proposed this hypothesis not only because it permits consideration of a complex and varied array of experimental observations as reflections of a simple basic biochemical mechanism, but because recent technical advances in instrumentation and methods allow it to be directly tested. The fluorescent antibody method for the cytochemical measurement of cyclic nucleotides provides a means for investigating changes in the concentrations of cyclic nucleotides in developing cells and could also be used to detect neurotransmitters in developing cells. Similarly, the scanning electron microscope in the emitted x-ray mode provides a method for measuring changes in the content and distribution of cations within developing cells. The hypothesis presented here suggests pleasing asceticism on the part of eukaryotes. It suggests that simple derivatives of metabolites, including neurotransmitters and cyclic nucleotides, are linked together as regulatory molecules throughout the eukaryotes. The neurotransmitters are suggested to have a more general role in information transmission in eukaryotes than is generally accepted. They are hypothesized to have progressed during evolution from being intracellular messengers to a role as intercellular messengers for the relatively slow communication of developmental informatbn; and, finally, this process has culminated with their participation in the rapid intercellular communication mediated by nerves. The thought that the complex pictures of physiological regulation and of the construction of a complex multicellular organism like man might be painted with so few colors is quite satisfying. 相似文献
17.
Electrical stimulation of the pigeon labyrinth evokes responses in many second-order vestibular neurons with a latency shorter than the monosynaptic delay. These early responses are probably due to electrically mediated synaptic transmission, or perhaps to antidromic invasion of cells supplying efferent fibers to the labyrinth. In either case the results demonstrate a difference between cat and pigeon with respect to connections between labyrinth and vestibular nuclei. 相似文献
18.
【目的】探究鸡肠Remak神经（intestinal nerve of Remak,INR）的神经元和过路节超微结构,为进一步阐明INR的生理功能提供理论基础。【方法】应用透射电镜技术观察鸡肠INR元与过路节的超微结构。【结果】INR有大量体积巨大的神经元和少量小强荧光细胞分布。神经元胞体周围有零散的卫星细胞围绕,但不能形成完整被囊,可见卫星细胞与神经元胞体之间形成突触样联系。神经元周围基膜不明显,神经元胞体表面常直接与周围细胞间质接触。细胞核圆而表面平滑,染色质松散清亮,核内可见棒状小体的特殊结构。核仁明显,结构和组成典型。胞质内分布着丰富的微管、发达的粗面内质网和高尔基复合体,粗面内质网池常有扩张膨大。可见中央有孔的致密颗粒分布于核周质,可能为肽类递质分泌颗粒。核糖体除了附着于粗面内质网表面外,还有大量游离核糖体分布于胞质中。线粒体形态多样,并有致密化现象。肠INR被膜下分布着少量成群的小强荧光细胞,其胞质和胞核的电子密度较高,细胞之间有不对称的突触联系。根据突触小泡的不同,INR内分布着4种过路节,它们与周围结构形成不同的突触联系。【结论】INR神经元具有旺盛合成和分泌功能的超微结构特征,而过路节的组成和联系显示出INR支配活动的多样化和复杂性。 相似文献
19.
Transmission between pairs of hippocampal slice neurons: quantal levels, oscillations, and LTP 总被引：3，自引：0，他引：3
R Malinow 《Science (New York, N.Y.)》1991,252(5006):722-724
Long-term potentiation (LTP) of synaptic transmission after coincident pre- and postsynaptic activity is considered a cellular model of changes underlying learning and memory. In intact tissue, LTP has been observed only between populations of neurons, making analysis of mechanisms difficult. Transmission between individual pre- and postsynaptic hippocampal cells was studied, suggesting quantal amplitude distributions with little variability in quantal size. LTP between such pairs is manifested by large, persistent, and synapse-specific potentiation with a shift in amplitude distribution that suggests presynaptic changes. Oscillations in amplitude of transmission, apparently of presynaptic origin, are common and can be triggered by LTP. 相似文献
20.
Communication between neurons in the brain occurs primarily through synapses made onto elaborate treelike structures called dendrites. New electrical and optical recording techniques have led to tremendous advances in our understanding of how dendrites contribute to neuronal computation in the mammalian brain. The varied morphology and electrical and chemical properties of dendrites enable a spectrum of local and long-range signaling, defining the input-output relationship of neurons and the rules for induction of synaptic plasticity. In this way, diversity in dendritic signaling allows individual neurons to carry out specialized functions within their respective networks. 相似文献