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Sample records for central synapse formation

  1. Dynamic Aspects of Synapse Formation

    OpenAIRE

    McAllister, A. Kimberley

    2007-01-01

    The mammalian central nervous system (CNS) requires the proper formation of exquisitely precise circuits to function correctly. These neuronal circuits are assembled during development by the formation of synaptic connections between thousands of differentiating neurons. Proper synapse formation during childhood provides the substrate for cognition while improper formation or function of these synapses leads to neurodevelopmental disorders, including mental retardation and autism. Recent work...

  2. Synapse formation and remodeling

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Synapses are specialized structures that mediate information flow between neurons and target cells,and thus are the basis for neuronal system to execute various functions,including learning and memory.There are around 1011 neurons in the human brain,with each neuron receiving thousands of synaptic inputs,either excitatory or inhibitory.A synapse is an asymmetric structure that is composed of pre-synaptic axon terminals,synaptic cleft,and postsynaptic compartments.Synapse formation involves a number of cell adhesion molecules,extracellular factors,and intracellular signaling or structural proteins.After the establishment of synaptic connections,synapses undergo structural or functional changes,known as synaptic plasticity which is believed to be regulated by neuronal activity and a variety of secreted factors.This review summarizes recent progress in the field of synapse development,with particular emphasis on the work carried out in China during the past 10 years(1999-2009).

  3. Astrocytic role in synapse formation after injury.

    Science.gov (United States)

    Li, Ying; Li, Daqing; Raisman, Geoffrey

    2016-08-15

    In 1969 a paper entitled Neuronal plasticity in the septal nuclei of the adult rat proposed that new synapses are formed in the adult brain after injury (Raisman, 1969). The quantitative electron microscopic study of the timed responses to selective partial denervation of the neuropil of the adult rat septal nuclei after distant transection of the hippocampal efferent axons in the fimbria showed that the new synapses arise by sprouting of surviving adjacent synapses which selectively take over the previously denervated sites and thus restore the number of synapses to normal. This article presents the evidence for the role of perisynaptic astrocytic processes in the removal and formation of synapses and considers its significance as one of the three major divisions of the astrocytic surface in terms of the axonal responses to injury and regeneration. This article is part of a Special Issue entitled SI:50th Anniversary Issue. PMID:26746338

  4. Synapse formation is regulated by the signaling adaptor GIT1

    OpenAIRE

    Zhang, Huaye; Webb, Donna J.; Asmussen, Hannelore; Horwitz, Alan F.

    2003-01-01

    Dendritic spines in the central nervous system undergo rapid actin-based shape changes, making actin regulators potential modulators of spine morphology and synapse formation. Although several potential regulators and effectors for actin organization have been identified, the mechanisms by which these molecules assemble and localize are not understood. Here we show that the G protein–coupled receptor kinase–interacting protein (GIT)1 serves such a function by targeting actin regulators and lo...

  5. Flotillin-1 Promotes Formation of Glutamatergic Synapses in Hippocampal Neurons

    OpenAIRE

    Swanwick, Catherine Croft; Shapiro, Marietta E.; Vicini, Stefano; Wenthold, Robert J.

    2010-01-01

    Synapse malformation underlies numerous neurodevelopmental illnesses, including autism spectrum disorders. Here we identify the lipid raft protein flotillin-1 as a promoter of glutamatergic synapse formation. We cultured neurons from the hippocampus, a brain region important for learning and memory, and examined them at two weeks in vitro, a time period rich with synapse formation. Double-label immunocytochemistry of native flot-1 with glutamatergic and GABAergic synapse markers showed that f...

  6. A Nutrient Combination that Can Affect Synapse Formation

    OpenAIRE

    Wurtman, Richard J.

    2014-01-01

    Brain neurons form synapses throughout the life span. This process is initiated by neuronal depolarization, however the numbers of synapses thus formed depend on brain levels of three key nutrients—uridine, the omega-3 fatty acid DHA, and choline. Given together, these nutrients accelerate formation of synaptic membrane, the major component of synapses. In infants, when synaptogenesis is maximal, relatively large amounts of all three nutrients are provided in bioavailable forms (e.g., uridine...

  7. Functions of axon guidance molecules in synapse formation

    OpenAIRE

    Chen, Shih-Yu; Cheng, Hwai-Jong

    2009-01-01

    Axon guidance and synapse formation are important developmental events for establishing a functional neuronal circuitry. These two related cellular processes occur in a coordinated fashion but previous studies from multiple model organisms seemed to suggest that axon guidance and synapse formation are mediated by distinct molecular cues. Thus, axon guidance molecules are responsible for guiding the navigating axon toward its target area, while other adhesion or ligand-receptor molecules speci...

  8. Cooperative synapse formation in the neocortex

    OpenAIRE

    Stepanyants Armen; Fares Tarec

    2009-01-01

    Neuron morphology plays an important role in defining synaptic connectivity. Clearly, only pairs of neurons with closely positioned axonal and dendritic branches can be synaptically coupled. For excitatory neurons in the cerebral cortex, such axo-dendritic oppositions, termed potential synapses, must be bridged by dendritic spines to form synaptic connections. To explore the rules by which synaptic connections are formed within the constraints imposed by neuron morphology, we compared the dis...

  9. Transmembrane Agrin Regulates Dendritic Filopodia and Synapse Formation in Mature Hippocampal Neuron Cultures

    OpenAIRE

    McCroskery, Seumas; Bailey, Allison; Lin, Lin; Daniels, Mathew P.

    2009-01-01

    The transmembrane isoform of agrin (Tm-agrin) is the predominant form expressed in the brain but its putative roles in brain development are not well understood. Recent reports have implicated Tm-agrin in the formation and stabilization of filopodia on neurites of immature central and peripheral neurons in culture. In maturing central neurons, dendritic filopodia are believed to facilitate synapse formation. In the present study we have investigated the role of Tm-agrin in regulation of dendr...

  10. Activity-dependent acceleration of endocytosis at a central synapse.

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    Wu, Wei; Xu, Jianhua; Wu, Xin-Sheng; Wu, Ling-Gang

    2005-12-14

    Accumulated evidence indicates the existence of rapid and slow endocytosis at many synapses. It has been proposed that rapid endocytosis is activated by intense stimulation when vesicle recycling needs to be speeded up to supply vesicles at hippocampal synapses. However, the evidence, as obtained with imaging techniques, which are somewhat indirect in indicating rapid endocytosis, is controversial. Furthermore, a slower time course of endocytosis is often found after more intense nerve activity, casting doubt on the role of rapid endocytosis at synapses. Here, we addressed this issue at a mammalian central synapse, the calyx of Held, using a capacitance measurement technique that provides a higher time resolution than imaging techniques. We found that rapid endocytosis with a time constant of approximately 1-2 s was activated during intense nerve activity. Reducing the presynaptic calcium current or buffering the intracellular calcium with EGTA significantly inhibited rapid endocytosis, suggesting that calcium triggers rapid endocytosis. During intense stimulation, rapid endocytosis retrieved up to approximately eight vesicles per second per active zone, approximately eightfold larger than reported in the hippocampus, and thus played a dominant role during and within 3 s after intense stimulation. Slow endocytosis became dominant 3 s after intense stimulation likely because of the fall of the intracellular calcium level that deactivated rapid endocytosis. These results underscore the importance of calcium-triggered rapid endocytosis, which offers the nerve terminal the plasticity to speed up vesicle cycling during intense nerve activity. PMID:16354926

  11. A Nutrient Combination that Can Affect Synapse Formation

    Directory of Open Access Journals (Sweden)

    Richard J. Wurtman

    2014-04-01

    Full Text Available Brain neurons form synapses throughout the life span. This process is initiated by neuronal depolarization, however the numbers of synapses thus formed depend on brain levels of three key nutrients—uridine, the omega-3 fatty acid DHA, and choline. Given together, these nutrients accelerate formation of synaptic membrane, the major component of synapses. In infants, when synaptogenesis is maximal, relatively large amounts of all three nutrients are provided in bioavailable forms (e.g., uridine in the UMP of mothers’ milk and infant formulas. However, in adults the uridine in foods, mostly present at RNA, is not bioavailable, and no food has ever been compelling demonstrated to elevate plasma uridine levels. Moreover, the quantities of DHA and choline in regular foods can be insufficient for raising their blood levels enough to promote optimal synaptogenesis. In Alzheimer’s disease (AD the need for extra quantities of the three nutrients is enhanced, both because their basal plasma levels may be subnormal (reflecting impaired hepatic synthesis, and because especially high brain levels are needed for correcting the disease-related deficiencies in synaptic membrane and synapses.

  12. Tau and spectraplakins promote synapse formation and maintenance through Jun kinase and neuronal trafficking

    Science.gov (United States)

    Voelzmann, Andre; Okenve-Ramos, Pilar; Qu, Yue; Chojnowska-Monga, Monika; del Caño-Espinel, Manuela; Prokop, Andreas; Sanchez-Soriano, Natalia

    2016-01-01

    The mechanisms regulating synapse numbers during development and ageing are essential for normal brain function and closely linked to brain disorders including dementias. Using Drosophila, we demonstrate roles of the microtubule-associated protein Tau in regulating synapse numbers, thus unravelling an important cellular requirement of normal Tau. In this context, we find that Tau displays a strong functional overlap with microtubule-binding spectraplakins, establishing new links between two different neurodegenerative factors. Tau and the spectraplakin Short Stop act upstream of a three-step regulatory cascade ensuring adequate delivery of synaptic proteins. This cascade involves microtubule stability as the initial trigger, JNK signalling as the central mediator, and kinesin-3 mediated axonal transport as the key effector. This cascade acts during development (synapse formation) and ageing (synapse maintenance) alike. Therefore, our findings suggest novel explanations for intellectual disability in Tau deficient individuals, as well as early synapse loss in dementias including Alzheimer’s disease. DOI: http://dx.doi.org/10.7554/eLife.14694.001 PMID:27501441

  13. Steps in the formation of neurites and synapses studied in cultured leech neurons

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    De-Miguel F.F.

    2000-01-01

    Full Text Available Leech neurons in culture have provided novel insights into the steps in the formation of neurite outgrowth patterns, target recognition and synapse formation. Identified adult neurons from the central nervous system of the leech can be removed individually and plated in culture under well-controlled conditions, where they retain their characteristic physiological properties, grow neurites and form specific chemical or electrical synapses. Different identified neurons develop distinctive outgrowth patterns that depend on their identities and on the molecular composition of the substrate. On native substrates, the patterns displayed by these neurons reproduce characteristics from the adult or the developing neurons. In addition, the substrate may induce selective directed growth between pairs of neurons that normally make contact in the ganglion. Upon contact, pairs of cultured leech neurons form chemical or electrical synapses, or both types depending on the neuronal identities. Anterograde and retrograde signals during membrane contact and synapse formation modify the distribution of synaptic terminals, calcium currents, and responses to 5-hydroxytryptamine.

  14. Slitrks control excitatory and inhibitory synapse formation with LAR receptor protein tyrosine phosphatases

    OpenAIRE

    Yim, Yeong Shin; Kwon, Younghee; Nam, Jungyong; Yoon, Hong In; Lee, Kangduk; Kim, Dong Goo; Kim, Eunjoon; Kim, Chul Hoon; Ko, Jaewon

    2013-01-01

    The balance between excitatory and inhibitory synaptic inputs, which is governed by multiple synapse organizers, controls neural circuit functions and behaviors. Slit- and Trk-like proteins (Slitrks) are a family of synapse organizers, whose emerging synaptic roles are incompletely understood. Here, we report that Slitrks are enriched in postsynaptic densities in rat brains. Overexpression of Slitrks promoted synapse formation, whereas RNAi-mediated knockdown of Slitrks decreased synapse dens...

  15. Antibody to a molecular marker of cell position inhibits synapse formation in retina.

    OpenAIRE

    Trisler, D.; Bekenstein, J; Daniels, M P

    1986-01-01

    A topographic gradient of TOP molecules in retina can be used to identify neuron position. Antibody to TOP from hybridoma cells that were injected into in vivo embryo eyes diffused into the retina and bound in a topographic gradient of [antibody.TOP] ([Ab.TOP]) complexes. Synapse formation in retina was inhibited in the presence of anti-TOP antibody. This suggests that TOP is involved in synapse formation and that recognition of position by neurons is necessary for normal synapse formation.

  16. ZAP-70 kinase regulates HIV cell-to-cell spread and virological synapse formation

    OpenAIRE

    Sol-Foulon, Nathalie; Sourisseau, Marion; Porrot, Françoise; Thoulouze, Maria-Isabel; Trouillet, Céline; Nobile, Cinzia; Blanchet, Fabien; Di Bartolo, Vincenzo; Noraz, Nelly; Taylor, Naomi; Alcover, Andres; Hivroz, Claire; Schwartz, Olivier

    2007-01-01

    HIV efficiently spreads in lymphocytes, likely through virological synapses (VSs). These cell–cell junctions share some characteristics with immunological synapses, but cellular proteins required for their constitution remain poorly characterized. We have examined here the role of ZAP-70, a key kinase regulating T-cell activation and immunological synapse formation, in HIV replication. In lymphocytes deficient for ZAP-70, or expressing a kinase-dead mutant of the protein, HIV replication was ...

  17. GA-Binding Protein Is Dispensable for Neuromuscular Synapse Formation and Synapse-Specific Gene Expression▿

    OpenAIRE

    Jaworski, Alexander; Smith, Cynthia L.; Burden, Steven J.

    2007-01-01

    The mRNAs encoding postsynaptic components at the neuromuscular junction are concentrated in the synaptic region of muscle fibers. Accumulation of these RNAs in the synaptic region is mediated, at least in part, by selective transcription of the corresponding genes in synaptic myofiber nuclei. The transcriptional mechanisms that are responsible for synapse-specific gene expression are largely unknown, but an Ets site in the promoter regions of acetylcholine receptor (AChR) subunit genes and o...

  18. The Role of MuSK in Synapse Formation and Neuromuscular Disease

    OpenAIRE

    Burden, Steven J.; Yumoto, Norihiro; Zhang, Wei

    2013-01-01

    Muscle-specific kinase (MuSK) is essential for each step in neuromuscular synapse formation. Before innervation, MuSK initiates postsynaptic differentiation, priming the muscle for synapse formation. Approaching motor axons recognize the primed, or prepatterned, region of muscle, causing motor axons to stop growing and differentiate into specialized nerve terminals. MuSK controls presynaptic differentiation by causing the clustering of Lrp4, which functions as a direct retrograde signal for p...

  19. [Synapse elimination and functional neural circuit formation in the cerebellum].

    Science.gov (United States)

    Kano, Masanobu

    2013-06-01

    Neuronal connections are initially redundant, but unnecessary connections are eliminated subsequently during postnatal development. This process, known as 'synapse elimination', is thought to be crucial for establishing functionally mature neural circuits. The climbing fiber (CF) to the Purkinje cell (PC) synapse in the cerebellum is a representative model of synapse elimination. We disclose that one-to-one connection from CF to PC is established through four distinct phases: (1) strengthening of a single CF among multiple CFs in each PC at P3-P7, (2) translocation of a single strengthened CF to PC dendrites from around P9, and (3) early phase (P7 to around P11) and (4) late phase (around P12 to P17) of elimination of weak CF synapses from PC somata. Mice with PC-selective deletion of P/Q-type voltage-dependent Ca2+ channel (VDCC) exhibit severe defects in strengthening of single CFs, dendritic translocation of single CFs and CF elimination from P7. In contrast, mice with a mutation of a single allele for the GABA-synthesizing enzyme GAD67 have a selective impairment of CF elimination from P10 due to reduced inhibition and elevated Ca2+ influx to PC somata. Thus, regulation of Ca2+ influx to PCs is crucial for the four phases of CF synapse elimination. PMID:25069248

  20. The Wnt/Planar Cell Polarity Pathway Component Vangl2 Induces Synapse Formation through Direct Control of N-Cadherin

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    Tadahiro Nagaoka

    2014-03-01

    Full Text Available Although regulators of the Wnt/planar cell polarity (PCP pathway are widely expressed in vertebrate nervous systems, their roles at synapses are unknown. Here, we show that Vangl2 is a postsynaptic factor crucial for synaptogenesis and that it coprecipitates with N-cadherin and PSD-95 from synapse-rich brain extracts. Vangl2 directly binds N-cadherin and enhances its internalization in a Rab5-dependent manner. This physical and functional interaction is suppressed by β-catenin, which binds the same intracellular region of N-cadherin as Vangl2. In hippocampal neurons expressing reduced Vangl2 levels, dendritic spine formation as well as synaptic marker clustering is significantly impaired. Furthermore, Prickle2, another postsynaptic PCP component, inhibits the N-cadherin-Vangl2 interaction and is required for normal spine formation. These results demonstrate direct control of classic cadherin by PCP factors; this control may play a central role in the precise formation and maturation of cell-cell adhesions at the synapse.

  1. IQ Motif and SEC7 Domain-containing Protein 3 (IQSEC3) Interacts with Gephyrin to Promote Inhibitory Synapse Formation.

    Science.gov (United States)

    Um, Ji Won; Choii, Gayoung; Park, Dongseok; Kim, Dongwook; Jeon, Sangmin; Kang, Hyeyeon; Mori, Takuma; Papadopoulos, Theofilos; Yoo, Taesun; Lee, Yeunkum; Kim, Eunjoon; Tabuchi, Katsuhiko; Ko, Jaewon

    2016-05-01

    Gephyrin is a central scaffold protein that mediates development, function, and plasticity of mammalian inhibitory synapses by interacting with various inhibitory synaptic proteins. Here, we show that IQSEC3, a guanine nucleotide exchange factor for ARF6, directly interacts with gephyrin, an interaction that is critical for the inhibitory synapse localization of IQSEC3. Overexpression of IQSEC3 increases inhibitory, but not excitatory, synapse density in a guanine nucleotide exchange factor activity-dependent manner. Conversely, knockdown of IQSEC3 decreases size of gephyrin cluster without altering gephyrin puncta density. Collectively, these data reveal that IQSEC3 acts together with gephyrin to regulate inhibitory synapse development. PMID:27002143

  2. GABAA receptors can initiate the formation of functional inhibitory GABAergic synapses

    OpenAIRE

    Fuchs, C.; Abitbol, K.; Burden, J. J.; A. Mercer; Brown, L.; Iball, J.; Anne Stephenson, F.; Thomson, A. M.; Jovanovic, J N

    2013-01-01

    The mechanisms that underlie the selection of an inhibitory GABAergic axon's postsynaptic targets and the formation of the first contacts are currently unknown. To determine whether expression of GABAA receptors (GABAA Rs) themselves - the essential functional postsynaptic components of GABAergic synapses - can be sufficient to initiate formation of synaptic contacts, a novel co-culture system was devised. In this system, the presynaptic GABAergic axons originated from embryonic rat basal gan...

  3. Coordinated trafficking of synaptic vesicle and active zone proteins prior to synapse formation

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    Sabo Shasta L

    2011-05-01

    Full Text Available Abstract Background The proteins required for synaptic transmission are rapidly assembled at nascent synapses, but the mechanisms through which these proteins are delivered to developing presynaptic terminals are not understood. Prior to synapse formation, active zone proteins and synaptic vesicle proteins are transported along axons in distinct organelles referred to as piccolo-bassoon transport vesicles (PTVs and synaptic vesicle protein transport vesicles (STVs, respectively. Although both PTVs and STVs are recruited to the same site in the axon, often within minutes of axo-dendritic contact, it is not known whether or how PTV and STV trafficking is coordinated before synapse formation. Results Here, using time-lapse confocal imaging of the dynamics of PTVs and STVs in the same axon, we show that vesicle trafficking is coordinated through at least two mechanisms. First, a significant proportion of STVs and PTVs are transported together before forming a stable terminal. Second, individual PTVs and STVs share pause sites within the axon. Importantly, for both STVs and PTVs, encountering the other type of vesicle increases their propensity to pause. To determine if PTV-STV interactions are important for pausing, PTV density was reduced in axons by expression of a dominant negative construct corresponding to the syntaxin binding domain of syntabulin, which links PTVs with their KIF5B motor. This reduction in PTVs had a minimal effect on STV pausing and movement, suggesting that an interaction between STVs and PTVs is not responsible for enhancing STV pausing. Conclusions Our results indicate that trafficking of STVs and PTVs is coordinated even prior to synapse development. This novel coordination of transport and pausing might provide mechanisms through which all of the components of a presynaptic terminal can be rapidly accumulated at sites of synapse formation.

  4. Presynaptic GABAB receptors reduce transmission at parabrachial synapses in the lateral central amygdala by inhibiting N-type calcium channels.

    Science.gov (United States)

    Delaney, A J; Crane, J W

    2016-01-01

    The nocioceptive information carried by neurons of the pontine parabrachial nucleus to neurons of the lateral division of the central amydala (CeA-L) is thought to contribute to the affective components of pain and is required for the formation of conditioned-fear memories. Importantly, excitatory transmission between parabrachial axon terminals and CeA-L neurons can be inhibited by a number of presynaptic receptors linked to Gi/o-type G-proteins, including α2-adrenoceptors and GABAB receptors. While the intracellular signalling pathway responsible for α2-adrenoceptor inhibition of synaptic transmission at this synapse is known, the mechanism by which GABAB receptors inhibits transmission has not been determined. The present study demonstrates that activation of presynaptic GABAB receptors reduces excitatory transmission between parabrachial axon terminals and CeA-L neurons by inhibiting N-type calcium channels. While the involvement of Gβγ subunits in mediating the inhibitory effects of GABAB receptors on N-type calcium channels is unclear, this inhibition does not involve Gβγ-independent activation of pp60C-src tyrosine kinase. The results of this study further enhance our understanding of the modulation of the excitatory input from parabrachial axon terminals to CeA-L neurons and indicate that presynaptic GABAB receptors at this synapse could be valuable therapeutic targets for the treatment of fear- and pain-related disorders. PMID:26755335

  5. Microglia promote learning-dependent synapse formation through BDNF

    OpenAIRE

    Parkhurst, Christopher N; Yang, Guang; Ninan, Ipe; Savas, Jeffrey N; Yates, John R.; Lafaille, Juan J.; Hempstead, Barbara L.; Littman, Dan R.; Gan, Wen-Biao

    2013-01-01

    Microglia are the resident macrophages of the central nervous system and their functions have been extensively studied in various brain pathologies. The physiological roles of microglia in brain plasticity and function, however, remain unclear. To address this question, we generated CX3CR1CreER mice expressing tamoxifen-inducible Cre recombinase that allow for specific manipulation of gene function in microglia. Using CX3CR1CreER to drive diphtheria toxin receptor expression in microglia, we ...

  6. The human language-associated gene SRPX2 regulates synapse formation and vocalization in mice.

    Science.gov (United States)

    Sia, G M; Clem, R L; Huganir, R L

    2013-11-22

    Synapse formation in the developing brain depends on the coordinated activity of synaptogenic proteins, some of which have been implicated in a number of neurodevelopmental disorders. Here, we show that the sushi repeat-containing protein X-linked 2 (SRPX2) gene encodes a protein that promotes synaptogenesis in the cerebral cortex. In humans, SRPX2 is an epilepsy- and language-associated gene that is a target of the foxhead box protein P2 (FoxP2) transcription factor. We also show that FoxP2 modulates synapse formation through regulating SRPX2 levels and that SRPX2 reduction impairs development of ultrasonic vocalization in mice. Our results suggest FoxP2 modulates the development of neural circuits through regulating synaptogenesis and that SRPX2 is a synaptogenic factor that plays a role in the pathogenesis of language disorders. PMID:24179158

  7. Nonneuronal cells regulate synapse formation in the vestibular sensory epithelium via erbB-dependent BDNF expression

    OpenAIRE

    Gómez-Casati, Maria E; MURTIE, JOSHUA C.; Rio, Carlos; Stankovic, Konstantina; Liberman, M. Charles; Corfas, Gabriel

    2010-01-01

    Recent studies indicate that molecules released by glia can induce synapse formation. However, what induces glia to produce such signals, their identity, and their in vivo relevance remain poorly understood. Here we demonstrate that supporting cells of the vestibular organ—cells that have many characteristics of glia—promote synapse formation only when induced by neuron-derived signals. Furthermore, we identify BDNF as the synaptogenic signal produced by these nonneuronal cells. Mice in which...

  8. The role of MuSK in synapse formation and neuromuscular disease.

    Science.gov (United States)

    Burden, Steven J; Yumoto, Norihiro; Zhang, Wei

    2013-05-01

    Muscle-specific kinase (MuSK) is essential for each step in neuromuscular synapse formation. Before innervation, MuSK initiates postsynaptic differentiation, priming the muscle for synapse formation. Approaching motor axons recognize the primed, or prepatterned, region of muscle, causing motor axons to stop growing and differentiate into specialized nerve terminals. MuSK controls presynaptic differentiation by causing the clustering of Lrp4, which functions as a direct retrograde signal for presynaptic differentiation. Developing synapses are stabilized by neuronal Agrin, which is released by motor nerve terminals and binds to Lrp4, a member of the low-density lipoprotein receptor family, stimulating further association between Lrp4 and MuSK and increasing MuSK kinase activity. In addition, MuSK phosphorylation is stimulated by an inside-out ligand, docking protein-7 (Dok-7), which is recruited to tyrosine-phosphorylated MuSK and increases MuSK kinase activity. Mutations in MuSK and in genes that function in the MuSK signaling pathway, including Dok-7, cause congenital myasthenia, and autoantibodies to MuSK, Lrp4, and acetylcholine receptors are responsible for myasthenia gravis. PMID:23637281

  9. Spike-timing dependence of structural plasticity explains cooperative synapse formation in the neocortex.

    Directory of Open Access Journals (Sweden)

    Moritz Deger

    Full Text Available Structural plasticity governs the long-term development of synaptic connections in the neocortex. While the underlying processes at the synapses are not fully understood, there is strong evidence that a process of random, independent formation and pruning of excitatory synapses can be ruled out. Instead, there must be some cooperation between the synaptic contacts connecting a single pre- and postsynaptic neuron pair. So far, the mechanism of cooperation is not known. Here we demonstrate that local correlation detection at the postsynaptic dendritic spine suffices to explain the synaptic cooperation effect, without assuming any hypothetical direct interaction pathway between the synaptic contacts. Candidate biomolecular mechanisms for dendritic correlation detection have been identified previously, as well as for structural plasticity based thereon. By analyzing and fitting of a simple model, we show that spike-timing correlation dependent structural plasticity, without additional mechanisms of cross-synapse interaction, can reproduce the experimentally observed distributions of numbers of synaptic contacts between pairs of neurons in the neocortex. Furthermore, the model yields a first explanation for the existence of both transient and persistent dendritic spines and allows to make predictions for future experiments.

  10. EphB-mediated degradation of the RhoA GEF Ephexin5 relieves a developmental brake on excitatory synapse formation

    OpenAIRE

    Margolis, Seth S.; Salogiannis, John; Lipton, David M.; Mandel-Brehm, Caleigh; Wills, Zachary P.; Mardinly, Alan R.; Hu, Linda; Greer, Paul L.; Bikoff, Jay B.; Ho, Hsin-Yi Henry; Soskis, Michael J.; Sahin, Mustafa; Greenberg, Michael E.

    2010-01-01

    The mechanisms that promote excitatory synapse formation and maturation have been extensively studied. However, the molecular events that limit excitatory synapse development so that synapses form at the right time and place and in the correct numbers are less well understood. We have identified a RhoA guanine nucleotide exchange factor, Ephexin5, which negatively regulates excitatory synapse development until EphrinB binding to the EphB receptor tyrosine kinase triggers Ephexin5 phosphorylat...

  11. Quantifying Signaling-Induced Reorientation of TCR's During Immunological Synapse Formation

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    Moss, W C; Irvine, D J; Davis, M M; Krummel, M F

    2002-10-17

    Productive T cell recognition of antigen-presenting cells (APCs) is normally accompanied by the formation of a cell-cell contact called the 'immunological synapse.' Our understanding of the steps leading up to this formation has been limited by the absence of tools for analyzing 3D surfaces and surface distributions as they change over time. Here we use a 3D fluorescence quantitation method to show that T cell receptors are recruited in bulk within the first minute after the onset of activation and with velocities ranging from 0.04 to 0.1 {micro}m/s; a speed significantly greater than unrestricted diffusion. Our method reveals a second feature of this reorientation: a conformational change as the T cell pushes more total membrane into the interface creating a larger contact area for additional receptors. Analysis of individual T cell receptor velocities using a single-particle tracking method confirms our velocity measurement. This method should permit the quantitation of other dynamic membrane events and the associated movement of cell-surface molecules.

  12. Aplysia cell adhesion molecule and a novel protein kinase C activity in the postsynaptic neuron are required for presynaptic growth and initial formation of specific synapses

    OpenAIRE

    Hu, Jiang-Yuan; Chen, Yang; Bougie, Joanna K; Sossin, Wayne S.; Schacher, Samuel

    2010-01-01

    To explore the role of both Aplysia cell adhesion molecule (ApCAM) and activity of specific protein kinase C (PKC) isoforms in the initial formation of sensory neuron synapses with specific postsynaptic targets (L7 but not L11), we examined presynaptic growth, initial synapse formation, and the expression of the presynaptic neuropeptide sensorin following cell-specific reduction of ApCAM or of a novel PKC activity. Synapse formation between sensory neurons and L7 begins by 3 h after plating a...

  13. Spatial Regulation of Gene Expression in Neurons During Synapse Formation and Synaptic Plasticity

    OpenAIRE

    Kim, Sangmok

    2013-01-01

    mRNA localization and regulated translation allow individual neurons to locally regulate the proteome of each of their many subcellular compartments. To investigate the spatial regulation of gene expression during synaptic plasticity, we used a translational reporter system to demonstrate synapse- and stimulus-specific translation during long-term facilitation of Aplysia sensory-motor synapse. These studies revealed a role for a retrograde signal from the postsynaptic motor neuron in regulati...

  14. Paracrine intercellular communication by a Ca2+- and SNARE-independent release of GABA and glutamate prior to synapse formation.

    OpenAIRE

    Demarque, Michael; Represa, Alfonso; Becq, Hélène; Khalilov, Ilgam; Ben-Ari, Yehezkel; Aniksztejn, Laurent

    2002-01-01

    International audience GABA and glutamate receptors are expressed in immature "silent" CA1 pyramidal neurons prior to synapse formation, but their function is unknown. We now report the presence of tonic, spontaneous, and evoked currents in embryonic and neonatal CA1 neurons mediated primarily by the activation of GABA(A) receptors. These currents are mediated by a nonconventional release of transmitters, as they persist in the presence of calcium channel blockers or botulinium toxin and a...

  15. Forskolin induces NMDA receptor-dependent potentiation at a central synapse in the leech.

    Science.gov (United States)

    Grey, Kathryn B; Burrell, Brian D

    2008-05-01

    In vertebrate hippocampal neurons, application of forskolin (an adenylyl cyclase activator) and rolipram (a phosphodiesterase inhibitor) is an effective technique for inducing chemical long-term potentiation (cLTP) that is N-methyl-d-aspartate (NMDA) receptor (NMDAR)-dependent. However, it is not known whether forskolin induces a similar potentiation in invertebrate synapses. Therefore, we examined whether forskolin plus rolipram treatment could induce potentiation at a known glutamatergic synapse in the leech (Hirudo sp.), specifically between the pressure (P) mechanosensory and anterior pagoda (AP) neurons. Perfusion of isolated ganglia with forskolin (50 muM) in conjunction with rolipram (0.1 muM) in Mg(2+)-free saline significantly potentiated the P-to-AP excitatory postsynaptic potential. Application of 2-amino-5-phosphonovaleric acid (APV, 100 muM), a competitive NMDAR antagonist, blocked the potentiation, indicating P-to-AP potentiation is NMDAR-dependent. Potentiation was blocked by injection of bis-(o-aminophenoxy)-N,N,N',N'-tetraacetic acid (BAPTA, 1 mM) into the postsynaptic cell, but not by BAPTA injection into the presynaptic neuron, indicating a requirement for postsynaptic elevation of intracellular Ca(2+). Application of db-cAMP mimicked the potentiating effects of forskolin, and Rp-cAMP, an inhibitor of protein kinase A, blocked forskolin-induced potentiation. Potentiation was also blocked by autocamtide-2-related inhibitory peptide (AIP), indicating a requirement for activation of Ca(2+)/calmodulin-dependent kinase II (CaMKII). Finally, potentiation was blocked by botulinum toxin, suggesting that trafficking of glutamate receptors also plays a role in this form of synaptic plasticity. These experiments demonstrate that techniques used to induce cLTP in vertebrate synapses also induce NMDAR-dependent potentiation in the leech CNS and that many of the cellular processes that mediate LTP are conserved between vertebrate and invertebrate phyla. PMID

  16. Rescuing Z+ agrin splicing in Nova null mice restores synapse formation and unmasks a physiologic defect in motor neuron firing

    OpenAIRE

    Ruggiu, Matteo; Herbst, Ruth; Kim, Natalie; Jevsek, Marko; Fak, John J.; Mann, Mary Anne; Fischbach, Gerald; Burden, Steven J.; Darnell, Robert B.

    2009-01-01

    Synapse formation at the neuromuscular junction (NMJ) requires an alternatively spliced variant of agrin (Z+ agrin) that is produced only by neurons. Here, we show that Nova1 and Nova2, neuron-specific splicing factors identified as targets in autoimmune motor disease, are essential regulators of Z+ agrin. Nova1/Nova2 double knockout mice are paralyzed and fail to cluster AChRs at the NMJ, and breeding them with transgenic mice constitutively expressing Z+ agrin in motor neurons rescued AChR ...

  17. The Tail-Elicited Tail Withdrawal Reflex of "Aplysia" Is Mediated Centrally at Tail Sensory-Motor Synapses and Exhibits Sensitization across Multiple Temporal Domains

    Science.gov (United States)

    Philips, Gary T.; Sherff, Carolyn M.; Menges, Steven A.; Carew, Thomas J.

    2011-01-01

    The defensive withdrawal reflexes of "Aplysia californica" have provided powerful behavioral systems for studying the cellular and molecular basis of memory formation. Among these reflexes the (T-TWR) has been especially useful. In vitro studies examining the monosynaptic circuit for the T-TWR, the tail sensory-motor (SN-MN) synapses, have…

  18. The therapeutic effect of memantine through the stimulation of synapse formation and dendritic spine maturation in autism and fragile X syndrome.

    Directory of Open Access Journals (Sweden)

    Hongen Wei

    Full Text Available Although the pathogenic mechanisms that underlie autism are not well understood, there is evidence showing that metabotropic and ionotropic glutamate receptors are hyper-stimulated and the GABAergic system is hypo-stimulated in autism. Memantine is an uncompetitive antagonist of NMDA receptors and is widely prescribed for treatment of Alzheimer's disease treatment. Recently, it has been shown to improve language function, social behavior, and self-stimulatory behaviors of some autistic subjects. However the mechanism by which memantine exerts its effect remains to be elucidated. In this study, we used cultured cerebellar granule cells (CGCs from Fmr1 knockout (KO mice, a mouse model for fragile X syndrome (FXS and syndromic autism, to examine the effects of memantine on dendritic spine development and synapse formation. Our results show that the maturation of dendritic spines is delayed in Fmr1-KO CGCs. We also detected reduced excitatory synapse formation in Fmr1-KO CGCs. Memantine treatment of Fmr1-KO CGCs promoted cell adhesion properties. Memantine also stimulated the development of mushroom-shaped mature dendritic spines and restored dendritic spine to normal levels in Fmr1-KO CGCs. Furthermore, we demonstrated that memantine treatment promoted synapse formation and restored the excitatory synapses to a normal range in Fmr1-KO CGCs. These findings suggest that memantine may exert its therapeutic capacity through a stimulatory effect on dendritic spine maturation and excitatory synapse formation, as well as promoting adhesion of CGCs.

  19. IL1RAPL1 Associated with Mental Retardation and Autism Regulates the Formation and Stabilization of Glutamatergic Synapses of Cortical Neurons through RhoA Signaling Pathway

    OpenAIRE

    Hayashi, Takashi; Yoshida, Tomoyuki; Ra, Moonjin; Taguchi, Ryo; Mishina, Masayoshi

    2013-01-01

    Interleukin-1 receptor accessory protein-like 1 (IL1RAPL1) is associated with X-linked mental retardation and autism spectrum disorder. We found that IL1RAPL1 regulates synapse formation of cortical neurons. To investigate how IL1RAPL1 controls synapse formation, we here screened IL1RAPL1-interacting proteins by affinity chromatography and mass spectroscopy. IL1RAPL1 interacted with Mcf2-like (Mcf2l), a Rho guanine nucleotide exchange factor, through the cytoplasmic Toll/IL-1 receptor domain....

  20. IL1RAPL1 associated with mental retardation and autism regulates the formation and stabilization of glutamatergic synapses of cortical neurons through RhoA signaling pathway.

    Directory of Open Access Journals (Sweden)

    Takashi Hayashi

    Full Text Available Interleukin-1 receptor accessory protein-like 1 (IL1RAPL1 is associated with X-linked mental retardation and autism spectrum disorder. We found that IL1RAPL1 regulates synapse formation of cortical neurons. To investigate how IL1RAPL1 controls synapse formation, we here screened IL1RAPL1-interacting proteins by affinity chromatography and mass spectroscopy. IL1RAPL1 interacted with Mcf2-like (Mcf2l, a Rho guanine nucleotide exchange factor, through the cytoplasmic Toll/IL-1 receptor domain. Knockdown of endogenous Mcf2l and treatment with an inhibitor of Rho-associated protein kinase (ROCK, the downstream kinase of RhoA, suppressed IL1RAPL1-induced excitatory synapse formation of cortical neurons. Furthermore, we found that the expression of IL1RAPL1 affected the turnover of AMPA receptor subunits. Insertion of GluA1-containing AMPA receptors to the cell surface was decreased, whereas that of AMPA receptors composed of GluA2/3 was enhanced. Mcf2l knockdown and ROCK inhibitor treatment diminished the IL1RAPL1-induced changes of AMPA receptor subunit insertions. Our results suggest that Mcf2l-RhoA-ROCK signaling pathway mediates IL1RAPL1-dependent formation and stabilization of glutamatergic synapses of cortical neurons.

  1. A multi nutrient concept to enhance synapse formation and function: science behind a medical food for Alzheimer’s disease

    Directory of Open Access Journals (Sweden)

    Sijben John W.C.

    2011-09-01

    Full Text Available Alzheimer’s Disease (AD is the leading cause of dementia. Epidemiological studies suggest that AD is linked with poor status of nutrients including DHA, B-vitamins and the vitamins E and C. Ongoing neurodegeneration, particularly synaptic loss, leads to the classical clinical features of AD namely, memory impairment, language deterioration, and executive and visuospatial dysfunction. The main constituents of neural and synaptic membranes are phospholipids. Supplemenation of animals with three dietary precursors of phospholipids namely, DHA, uridine monophosphate and choline, results in increased levels of brain phospholipids, synaptic proteins, neurite outgrowth, dendritic spines formation (i.e. the anatomical precursors of new synapses and an improvement in learning and memory. Other nutrients act as co-factors in the synthesis pathway of neuronal membranes. For example B-vitamins are involved in methylation processes, thereby enhancing the availability of choline as a synaptic membrane precursor. A multi-nutrient concept that includes these nutrients may improve membrane integrity, thereby influencing membrane-dependent processes such as receptor function and amyloid precursor protein (APP processing, as shown by reduced amyloid production and amyloid β plaque burden, as well as toxicity. Together, these insights provided the basis for the development of a medical food for patients with AD, Souvenaid®, containing a specific combination of nutrients (Fortasyn™ Connect and designed to enhance synapse formation in AD. The effect of Souvenaid on memory and cognitive performance was recently assessed in a proof-of-concept study, SOUVENIR I, with 212 drug-naïve mild AD patients (MMSE 20-26. This proof-of-concept study demonstrated that oral nutritional supplementation with Souvenaid® for 12 weeks improves memory in patients with mild AD. To confirm and extend these findings, we have designed and initiated three additional studies. Two of

  2. A chemical-genetic strategy reveals distinct temporal requirements for SAD-1 kinase in neuronal polarization and synapse formation

    Directory of Open Access Journals (Sweden)

    Shokat Kevan M

    2008-09-01

    Full Text Available Abstract Background Neurons assemble into a functional network through a sequence of developmental processes including neuronal polarization and synapse formation. In Caenorhabditis elegans, the serine/threonine SAD-1 kinase is essential for proper neuronal polarity and synaptic organization. To determine if SAD-1 activity regulates the establishment or maintenance of these neuronal structures, we examined its temporal requirements using a chemical-genetic method that allows for selective and reversible inactivation of its kinase activity in vivo. Results We generated a PP1 analog-sensitive variant of SAD-1. Through temporal inhibition of SAD-1 kinase activity we show that its activity is required for the establishment of both neuronal polarity and synaptic organization. However, while SAD-1 activity is needed strictly when neurons are polarizing, the temporal requirement for SAD-1 is less stringent in synaptic organization, which can also be re-established during maintenance. Conclusion This study reports the first temporal analysis of a neural kinase activity using the chemical-genetic system. It reveals that neuronal polarity and synaptic organization have distinct temporal requirements for SAD-1.

  3. Dscam Mediates Trans-Synaptic Interactions for Remodeling of Glutamate Receptors in Aplysia During De Novo and Learning-Related Synapse Formation

    OpenAIRE

    Li, Hsiu-Ling; Huang, Ben S.; Vishwasrao, Harshad; Sutedja, Nadia; Chen, Wei; Jin, Iksung; Hawkins, Robert D.; Bailey, Craig H.; Kandel, Eric R.

    2009-01-01

    Trans-synaptic interactions between neurons are essential during both developmental and learning-related synaptic growth. We have used Aplysia neuronal cultures to examine the contribution of trans-synaptic signals in both types of synapse formation. We find that during de novo synaptogenesis, specific presynaptic innervation is required for the clustering of postsynaptic AMPA-like but not NMDA-like receptors. We further find that the cell adhesion molecule Dscam is involved in these trans-sy...

  4. Distinct target cell-dependent forms of short-term plasticity of the central visceral afferent synapses of the rat

    Directory of Open Access Journals (Sweden)

    Watabe Ayako M

    2010-10-01

    Full Text Available Abstract Background The visceral afferents from various cervico-abdominal sensory receptors project to the dorsal vagal complex (DVC, which is composed of the nucleus of the solitary tract (NTS, the area postrema and the dorsal motor nucleus of the vagus nerve (DMX, via the vagus and glossopharyngeal nerves and then the solitary tract (TS in the brainstem. While the excitatory transmission at the TS-NTS synapses shows strong frequency-dependent suppression in response to repeated stimulation of the afferents, the frequency dependence and short-term plasticity at the TS-DMX synapses, which also transmit monosynaptic information from the visceral afferents to the DVC neurons, remain largely unknown. Results Recording of the EPSCs activated by paired or repeated TS stimulation in the brainstem slices of rats revealed that, unlike NTS neurons whose paired-pulse ratio (PPR is consistently below 0.6, the distribution of the PPR of DMX neurons shows bimodal peaks that are composed of type I (PPR, 0.6-1.5; 53% of 120 neurons recorded and type II (PPR, Conclusions These two general types of short-term plasticity might contribute to the differential activation of distinct vago-vagal reflex circuits, depending on the firing frequency and type of visceral afferents.

  5. MHCI promotes developmental synapse elimination and aging-related synapse loss at the vertebrate neuromuscular junction.

    Science.gov (United States)

    Tetruashvily, Mazell M; McDonald, Marin A; Frietze, Karla K; Boulanger, Lisa M

    2016-08-01

    Synapse elimination at the developing neuromuscular junction (NMJ) sculpts motor circuits, and synapse loss at the aging NMJ drives motor impairments that are a major cause of loss of independence in the elderly. Here we provide evidence that at the NMJ, both developmental synapse elimination and aging-related synapse loss are promoted by specific immune proteins, members of the major histocompatibility complex class I (MHCI). MHCI is expressed at the developing NMJ, and three different methods of reducing MHCI function all disrupt synapse elimination during the second postnatal week, leaving some muscle fibers multiply-innervated, despite otherwise outwardly normal synapse formation and maturation. Conversely, overexpressing MHCI modestly accelerates developmental synapse elimination. MHCI levels at the NMJ rise with aging, and reducing MHCI levels ameliorates muscle denervation in aged mice. These findings identify an unexpected role for MHCI in the elimination of neuromuscular synapses during development, and indicate that reducing MHCI levels can preserve youthful innervation of aging muscle. PMID:26802986

  6. Mfn2 is Required for Mitochondrial Development and Synapse Formation in Human Induced Pluripotent Stem Cells/hiPSC Derived Cortical Neurons

    Science.gov (United States)

    Fang, Du; Yan, Shijun; Yu, Qing; Chen, Doris; Yan, Shirley ShiDu

    2016-01-01

    Mitochondria are essential dynamic organelles for energy production. Mitochondria dynamically change their shapes tightly coupled to fission and fusion. Imbalance of fission and fusion can cause deficits in mitochondrial respiration, morphology and motility. Mfn2 (mitofusin 2), a mitochondrial membrane protein that participates in mitochondrial fusion in mammalian cells, contributes to the maintenance and operation of the mitochondrial network. Due to lack of applicable model systems, the mechanisms and involvement of mitochondria in neurogenesis in human brain cells have not been well explored. Here, by employing the human induced pluripotent stem cells (hiPSCs) differentiation system, we fully characterized mitochondrial development, neurogenesis and synapse formation in hiPSCs-derived cortical neurons. Differentiation of hiPSCs to cortical neurons with extended period demonstrates mature neurophysiology characterization and functional synaptic network formation. Mitochondrial respiration, morphology and motility in the differentiated neurons also exhibit pronounced development during differentiation. Mfn2 knock-down results in deficits in mitochondrial metabolism and network, neurogenesis and synapse formation, while Mfn2 overexpression enhances mitochondrial bioenergetics and functions, and promotes the differentiation and maturation of neurons. Together, our data indicate that Mfn2 is essential for human mitochondrial development in neuronal maturation and differentiation, which will enhance our understanding of the role of Mfn2 in neurogenesis. PMID:27535796

  7. Mfn2 is Required for Mitochondrial Development and Synapse Formation in Human Induced Pluripotent Stem Cells/hiPSC Derived Cortical Neurons.

    Science.gov (United States)

    Fang, Du; Yan, Shijun; Yu, Qing; Chen, Doris; Yan, Shirley ShiDu

    2016-01-01

    Mitochondria are essential dynamic organelles for energy production. Mitochondria dynamically change their shapes tightly coupled to fission and fusion. Imbalance of fission and fusion can cause deficits in mitochondrial respiration, morphology and motility. Mfn2 (mitofusin 2), a mitochondrial membrane protein that participates in mitochondrial fusion in mammalian cells, contributes to the maintenance and operation of the mitochondrial network. Due to lack of applicable model systems, the mechanisms and involvement of mitochondria in neurogenesis in human brain cells have not been well explored. Here, by employing the human induced pluripotent stem cells (hiPSCs) differentiation system, we fully characterized mitochondrial development, neurogenesis and synapse formation in hiPSCs-derived cortical neurons. Differentiation of hiPSCs to cortical neurons with extended period demonstrates mature neurophysiology characterization and functional synaptic network formation. Mitochondrial respiration, morphology and motility in the differentiated neurons also exhibit pronounced development during differentiation. Mfn2 knock-down results in deficits in mitochondrial metabolism and network, neurogenesis and synapse formation, while Mfn2 overexpression enhances mitochondrial bioenergetics and functions, and promotes the differentiation and maturation of neurons. Together, our data indicate that Mfn2 is essential for human mitochondrial development in neuronal maturation and differentiation, which will enhance our understanding of the role of Mfn2 in neurogenesis. PMID:27535796

  8. Proteomic studies of a single CNS synapse type: the parallel fiber/purkinje cell synapse.

    Directory of Open Access Journals (Sweden)

    Fekrije Selimi

    2009-04-01

    Full Text Available Precise neuronal networks underlie normal brain function and require distinct classes of synaptic connections. Although it has been shown that certain individual proteins can localize to different classes of synapses, the biochemical composition of specific synapse types is not known. Here, we have used a combination of genetically engineered mice, affinity purification, and mass spectrometry to profile proteins at parallel fiber/Purkinje cell synapses. We identify approximately 60 candidate postsynaptic proteins that can be classified into 11 functional categories. Proteins involved in phospholipid metabolism and signaling, such as the protein kinase MRCKgamma, are major unrecognized components of this synapse type. We demonstrate that MRCKgamma can modulate maturation of dendritic spines in cultured cortical neurons, and that it is localized specifically to parallel fiber/Purkinje cell synapses in vivo. Our data identify a novel synapse-specific signaling pathway, and provide an approach for detailed investigations of the biochemical complexity of central nervous system synapse types.

  9. Up-regulation of Ras/Raf/ERK1/2 signaling in the spinal cord impairs neural cell migration, neurogenesis, synapse formation, and dendritic spine development

    Institute of Scientific and Technical Information of China (English)

    CAO Fu-jiang; ZHANG Xu; LIU Tao; LI Xia-wen; Mazar Malik; FENG Shi-qing

    2013-01-01

    Background The Ras/Raf/ERK1/2 signaling pathway controls many cellular responses such as cell proliferation,migration,differentiation,and death.In the nervous system,emerging evidence also points to a death-promoting role for ERK1/2 in both in vitro and in vivo models of neuronal death.To further investigate how Ras/Raf/ERK1/2 up-regulation may lead to the development of spinal cord injury,we developed a cellular model of Raf/ERK up-regulation by overexpressing c-Raf in cultured spinal cord neurons (SCNs) and dorsal root ganglions (DRGs).Methods DRGs and SCNs were prepared from C57BL/6J mouse pups.DRGs or SCNs were infected with Ad-Raf-1 or Ad-Null adenovirus alone.Cell adhesion assay and cell migration assay were investigated,Dil labeling was employed to examine the effect of the up-regulation of Ras/Raf/ERK1/2 signaling on the dendritic formation of spinal neurons.We used the TO-PRO-3 staining to examine the apoptotic effect of c-Raf on DRGs or SCNs.The effect on the synapse formation of neurons was measured by using immunofluorescence.Results We found that Raf/ERK up-regulation stimulates the migration of both SCNs and DRGs,and impairs the formation of excitatory synapses in SCNs.In addition,we found that Raf/ERK up-regulation inhibits the development of mature dendritic spines in SCNs.Investigating the possible mechanisms through which Raf/ERK up-regulation affects the excitatory synapse formation and dendritic spine development,we discovered that Raf/ERK up-regulation suppresses the development and maturation of SCNs.Conclusion The up-regulation of the Raf/ERK signaling pathway may contribute to the pathogenesis of spinal cord injury through both its impairment of the SCN development and causing neural circuit imbalances.

  10. The sticky synapse

    DEFF Research Database (Denmark)

    Owczarek, Sylwia Elzbieta; Kristiansen, Lars Villiam; Walmod, Peter Schledermann

    NCAM-type proteins modulate multiple neuronal functions, including the outgrowth and guidance of neurites, the formation, maturation, and plasticity of synapses, and the induction of both long-term potentiation and long-term depression. The ectodomains of NCAM proteins have a basic structure...... cleavage of their ectodomains. Although specific aspects of NCAM proteins have changed through evolution, core structural and functional features are conserved between NCAM-type proteins in vertebrates and invertebrates, demonstrating that the functions of this class of adhesive proteins are of general...

  11. Emerging Roles of BAI Adhesion-GPCRs in Synapse Development and Plasticity.

    Science.gov (United States)

    Duman, Joseph G; Tu, Yen-Kuei; Tolias, Kimberley F

    2016-01-01

    Synapses mediate communication between neurons and enable the brain to change in response to experience, which is essential for learning and memory. The sites of most excitatory synapses in the brain, dendritic spines, undergo rapid remodeling that is important for neural circuit formation and synaptic plasticity. Abnormalities in synapse and spine formation and plasticity are associated with a broad range of brain disorders, including intellectual disabilities, autism spectrum disorders (ASD), and schizophrenia. Thus, elucidating the mechanisms that regulate these neuronal processes is critical for understanding brain function and disease. The brain-specific angiogenesis inhibitor (BAI) subfamily of adhesion G-protein-coupled receptors (adhesion-GPCRs) has recently emerged as central regulators of synapse development and plasticity. In this review, we will summarize the current knowledge regarding the roles of BAIs at synapses, highlighting their regulation, downstream signaling, and physiological functions, while noting the roles of other adhesion-GPCRs at synapses. We will also discuss the relevance of BAIs in various neurological and psychiatric disorders and consider their potential importance as pharmacological targets in the treatment of these diseases. PMID:26881134

  12. Emerging Roles of BAI Adhesion-GPCRs in Synapse Development and Plasticity

    Directory of Open Access Journals (Sweden)

    Joseph G. Duman

    2016-01-01

    Full Text Available Synapses mediate communication between neurons and enable the brain to change in response to experience, which is essential for learning and memory. The sites of most excitatory synapses in the brain, dendritic spines, undergo rapid remodeling that is important for neural circuit formation and synaptic plasticity. Abnormalities in synapse and spine formation and plasticity are associated with a broad range of brain disorders, including intellectual disabilities, autism spectrum disorders (ASD, and schizophrenia. Thus, elucidating the mechanisms that regulate these neuronal processes is critical for understanding brain function and disease. The brain-specific angiogenesis inhibitor (BAI subfamily of adhesion G-protein-coupled receptors (adhesion-GPCRs has recently emerged as central regulators of synapse development and plasticity. In this review, we will summarize the current knowledge regarding the roles of BAIs at synapses, highlighting their regulation, downstream signaling, and physiological functions, while noting the roles of other adhesion-GPCRs at synapses. We will also discuss the relevance of BAIs in various neurological and psychiatric disorders and consider their potential importance as pharmacological targets in the treatment of these diseases.

  13. The ultrastructural properties of CGRP-like immunoreactive synapses in the central nucleus of amygdala%中央杏仁核内 CGRP 能阳性突触的超微结构研究

    Institute of Scientific and Technical Information of China (English)

    鲁亚成; 田菲; 李云庆; 董玉琳

    2012-01-01

    Objective: To observe synaptic ultrastructure of calcitonin-gene-related peptide (CGRP)-like immunoreactive (LI) axonal terminals in the central nucleus of amygdala ( CeA). Methods; Immunofluorescence and pre-embedding electronic microscopy were employed to detect the classification and structural features of synapses made by CGRP-LI axonal terminals in the CeA. Results: CGRP-LI terminals were observed to make synapses on the soma of neurons, dendritic shafts and spines. Almost all the axo-soma synapses were symmetrical; However, most of the axo-dendritic shaft and axo-spine synapses were asymmetrical. In all asymmetrical synapses, the ratio of axo-dendritic shaft synapses were 84.9% , and axo-spine synapses 15. 1%. The average length of postsynaptic density (PSD) of axo-dendritic shaft synapses was 790.77 ±313. 55 nm, whereas of axo-spine synapses 723. 34 ±357. 20 nm. There was no significant difference of PSD length between two types of synapses. Conclusion: The CGRP-LI axo-dendritic shaft synapses play important roles in the transmission of nociception and pain-related abnormal emotional responses.%目的:观察降钙素基因相关肽(calcitonin-gene-related peptide,CGRP)样阳性终末在中央杏仁核(central nucleus of amygdala,CeA)内形成的突触的超微结构.方法:应用免疫荧光组织化学和包埋前免疫电镜等方法,观察CGRP样阳性终末在CeA内所形成的突触分布形式及结构特点.结果:CGRP样阳性终末在中央杏仁核内可以与细胞体、树突干和树突棘等结构形成突触;轴-体突触几乎全为对称性突触,而轴-树突触和轴-棘突触则多为非对称性突触.在所有的非对称性突触里,轴-树突触占84.9%,而轴-棘突触占15.1%.CGRP样阳性轴-树的突触后致密带的平均长度为(790.77±313.55)nm,而轴-棘突触的突触后致密带的平均长度为(723.34±357.20)nm,两者之间没有显著性差异.结论:CGPR样阳性的兴奋性突触尤其是轴-树

  14. Type I bHLH Proteins Daughterless and Tcf4 Restrict Neurite Branching and Synapse Formation by Repressing Neurexin in Postmitotic Neurons

    Directory of Open Access Journals (Sweden)

    Mitchell D’Rozario

    2016-04-01

    Full Text Available Proneural proteins of the class I/II basic-helix-loop-helix (bHLH family are highly conserved transcription factors. Class I bHLH proteins are expressed in a broad number of tissues during development, whereas class II bHLH protein expression is more tissue restricted. Our understanding of the function of class I/II bHLH transcription factors in both invertebrate and vertebrate neurobiology is largely focused on their function as regulators of neurogenesis. Here, we show that the class I bHLH proteins Daughterless and Tcf4 are expressed in postmitotic neurons in Drosophila melanogaster and mice, respectively, where they function to restrict neurite branching and synapse formation. Our data indicate that Daughterless performs this function in part by restricting the expression of the cell adhesion molecule Neurexin. This suggests a role for these proteins outside of their established roles in neurogenesis.

  15. The Nesprin family member ANC-1 regulates synapse formation and axon termination by functioning in a pathway with RPM-1 and β-Catenin.

    Directory of Open Access Journals (Sweden)

    Erik D Tulgren

    2014-07-01

    Full Text Available Mutations in Nesprin-1 and 2 (also called Syne-1 and 2 are associated with numerous diseases including autism, cerebellar ataxia, cancer, and Emery-Dreifuss muscular dystrophy. Nesprin-1 and 2 have conserved orthologs in flies and worms called MSP-300 and abnormal nuclear Anchorage 1 (ANC-1, respectively. The Nesprin protein family mediates nuclear and organelle anchorage and positioning. In the nervous system, the only known function of Nesprin-1 and 2 is in regulation of neurogenesis and neural migration. It remains unclear if Nesprin-1 and 2 regulate other functions in neurons. Using a proteomic approach in C. elegans, we have found that ANC-1 binds to the Regulator of Presynaptic Morphology 1 (RPM-1. RPM-1 is part of a conserved family of signaling molecules called Pam/Highwire/RPM-1 (PHR proteins that are important regulators of neuronal development. We have found that ANC-1, like RPM-1, regulates axon termination and synapse formation. Our genetic analysis indicates that ANC-1 functions via the β-catenin BAR-1, and the ANC-1/BAR-1 pathway functions cell autonomously, downstream of RPM-1 to regulate neuronal development. Further, ANC-1 binding to the nucleus is required for its function in axon termination and synapse formation. We identify variable roles for four different Wnts (LIN-44, EGL-20, CWN-1 and CWN-2 that function through BAR-1 to regulate axon termination. Our study highlights an emerging, broad role for ANC-1 in neuronal development, and unveils a new and unexpected mechanism by which RPM-1 functions.

  16. Regulation of excitatory synapse development by the RhoGEF Ephexin5

    OpenAIRE

    Salogiannis, John

    2013-01-01

    The neuronal synapse is a specialized cell-cell junction that mediates communication between neurons. The formation of a synapse requires the coordinated activity of signaling molecules that can either promote or restrict synapse number and function. Tight regulation of these signaling molecules are critical to ensure that synapses form in the correct number, time and place during brain development. A number of molecular mechanisms that promote synapse formation have been elucidated, but s...

  17. Syntaxin 1B, but not syntaxin 1A, is necessary for the regulation of synaptic vesicle exocytosis and of the readily releasable pool at central synapses.

    Directory of Open Access Journals (Sweden)

    Tatsuya Mishima

    Full Text Available Two syntaxin 1 (STX1 isoforms, HPC-1/STX1A and STX1B, are coexpressed in neurons and function as neuronal target membrane (t-SNAREs. However, little is known about their functional differences in synaptic transmission. STX1A null mutant mice develop normally and do not show abnormalities in fast synaptic transmission, but monoaminergic transmissions are impaired. In the present study, we found that STX1B null mutant mice died within 2 weeks of birth. To examine functional differences between STX1A and 1B, we analyzed the presynaptic properties of glutamatergic and GABAergic synapses in STX1B null mutant and STX1A/1B double null mutant mice. We found that the frequency of spontaneous quantal release was lower and the paired-pulse ratio of evoked postsynaptic currents was significantly greater in glutamatergic and GABAergic synapses of STX1B null neurons. Deletion of STX1B also accelerated synaptic vesicle turnover in glutamatergic synapses and decreased the size of the readily releasable pool in glutamatergic and GABAergic synapses. Moreover, STX1A/1B double null neurons showed reduced and asynchronous evoked synaptic vesicle release in glutamatergic and GABAergic synapses. Our results suggest that although STX1A and 1B share a basic function as neuronal t-SNAREs, STX1B but not STX1A is necessary for the regulation of spontaneous and evoked synaptic vesicle exocytosis in fast transmission.

  18. The Central Asian Armies Facing the Challenge of Formation

    Directory of Open Access Journals (Sweden)

    Sébastien Peyrouse

    2011-03-01

    Full Text Available This article focuses on one of the main challenges that Central Asian armies face, that is, the problem of training and formation. Having rapidly increased since 2007, Central Asian military budgets have been able to multiply the purchases of equipment and weapons from foreign partners (Russia, western countries, Israel, China, South Korea, etc.. Money is not enough, however, to get the military institution back on its feet in its most human aspect, that of formation. In fact, the teaching institutions and the training possibilities provided to conscripts and professional soldiers on contract are generally of inadequate quality and impede the overall military capacities of the Central Asian states. This article will examine the main problems of the Central Asian military institutions and will discuss the means that have been implemented by Central Asian governments to reduce the negative impact of difficulties in promoting human capital.

  19. Astrocytes mediate synapse elimination through MEGF10 and MERTK pathways

    Science.gov (United States)

    Chung, Won-Suk; Clarke, Laura E.; Wang, Gordon X.; Stafford, Benjamin K.; Sher, Alexander; Chakraborty, Chandrani; Joung, Julia; Foo, Lynette C.; Thompson, Andrew; Chen, Chinfei; Smith, Stephen J.; Barres, Ben A.

    2013-12-01

    To achieve its precise neural connectivity, the developing mammalian nervous system undergoes extensive activity-dependent synapse remodelling. Recently, microglial cells have been shown to be responsible for a portion of synaptic pruning, but the remaining mechanisms remain unknown. Here we report a new role for astrocytes in actively engulfing central nervous system synapses. This process helps to mediate synapse elimination, requires the MEGF10 and MERTK phagocytic pathways, and is strongly dependent on neuronal activity. Developing mice deficient in both astrocyte pathways fail to refine their retinogeniculate connections normally and retain excess functional synapses. Finally, we show that in the adult mouse brain, astrocytes continuously engulf both excitatory and inhibitory synapses. These studies reveal a novel role for astrocytes in mediating synapse elimination in the developing and adult brain, identify MEGF10 and MERTK as critical proteins in the synapse remodelling underlying neural circuit refinement, and have important implications for understanding learning and memory as well as neurological disease processes.

  20. Effects of influenza A virus infections and interferon-gamma on synapse formation and function in hippocampal neurons in culture

    OpenAIRE

    Brask, Johan

    2004-01-01

    The central nervous system (CNS) can be the target for several infections that include those with RNA viruses. The parenchyma of the CNS is considered an immuneprivileged site since it is protected behind the blood-brain barrier, expresses no or only low levels of major histocompatibility complex (MHC) molecules and contains a paucity of antigenpresenting cells that prime an immune response. Nevertheless, viral infections in the brain can be controlled to be cleared or becom...

  1. Peculiar early-type galaxies with central star formation

    Institute of Scientific and Technical Information of China (English)

    Chong Ge; Qiu-Sheng Gu

    2012-01-01

    Early-type galaxies (ETGs) are very important for understanding the formation and evolution of galaxies.Recent observations suggest that ETGs are not simply old stellar spheroids as we previously thought.Widespread recent star formation,cool gas and dust have been detected in a substantial fraction of ETGs.We make use of the radial profiles of g - r color and the concentration index from the Sloan Digital Sky Survey database to pick out 31 peculiar ETGs with central blue cores.By analyzing the photometric and spectroscopic data,we suggest that the blue cores are caused by star formation activities rather than the central weak active galactic nucleus.From the results of stellar population synthesis,we find that the stellar population of the blue cores is relatively young,spreading from several Myr to less than one Gyr.In 14 galaxies with H I observations,we find that the average gas fraction of these galaxies is about 0.55.The bluer galaxies show a higher gas fraction,and the total star formation rate (SFR) correlates very well with the H l gas mass.The star formation history of these ETGs is affected by the environment,e.g.in the denser environment the H 1 gas is less and the total SFR is lower.We also discuss the origin of the central star formation of these early-type galaxies.

  2. The immunological synapse

    DEFF Research Database (Denmark)

    Klemmensen, Thomas; Pedersen, Lars Ostergaard; Geisler, Carsten

    2003-01-01

    distinct 3-dimensional supramolecular structure at the T cell/APC interface has been suggested to be involved in the information transfer. Due to its functional analogy to the neuronal synapse, the structure has been termed the "immunological synapse" (IS). Here, we review molecular aspects concerning IS...

  3. Neuroligin-1 loss is associated with reduced tenacity of excitatory synapses.

    Directory of Open Access Journals (Sweden)

    Adel Zeidan

    Full Text Available Neuroligins (Nlgns are postsynaptic, integral membrane cell adhesion molecules that play important roles in the formation, validation, and maturation of synapses in the mammalian central nervous system. Given their prominent roles in the life cycle of synapses, it might be expected that the loss of neuroligin family members would affect the stability of synaptic organization, and ultimately, affect the tenacity and persistence of individual synaptic junctions. Here we examined whether and to what extent the loss of Nlgn-1 affects the dynamics of several key synaptic molecules and the constancy of their contents at individual synapses over time. Fluorescently tagged versions of the postsynaptic scaffold molecule PSD-95, the AMPA-type glutamate receptor subunit GluA2 and the presynaptic vesicle molecule SV2A were expressed in primary cortical cultures from Nlgn-1 KO mice and wild-type (WT littermates, and live imaging was used to follow the constancy of their contents at individual synapses over periods of 8-12 hours. We found that the loss of Nlgn-1 was associated with larger fluctuations in the synaptic contents of these molecules and a poorer preservation of their contents at individual synapses. Furthermore, rates of synaptic turnover were somewhat greater in neurons from Nlgn-1 knockout mice. Finally, the increased GluA2 redistribution rates observed in neurons from Nlgn-1 knockout mice were negated by suppressing spontaneous network activity. These findings suggest that the loss of Nlgn-1 is associated with some use-dependent destabilization of excitatory synapse organization, and indicate that in the absence of Nlgn-1, the tenacity of excitatory synapses might be somewhat impaired.

  4. The function of RNA-binding proteins at the synapse: implications for neurodegeneration.

    Science.gov (United States)

    Sephton, Chantelle F; Yu, Gang

    2015-10-01

    The loss of synapses is a central event in neurodegenerative diseases. Synaptic proteins are often associated with disease neuropathology, but their role in synaptic loss is not fully understood. Of the many processes involved in sustaining the integrity of synapses, local protein translation can directly impact synaptic formation, communication, and maintenance. RNA-binding proteins and their association with RNA granules serve to regulate mRNA transportation and translation at synapses and in turn regulate the synapse. Genetic mutations in RNA-binding proteins FUS and TDP-43 have been linked with causing neurodegenerative diseases: amyotrophic lateral sclerosis and frontotemporal dementia. The observation that mutations in FUS and TDP-43 coincide with changes in RNA granules provides evidence that dysfunction of RNA metabolism may underlie the mechanism of synaptic loss in these diseases. However, we do not know how mutations in RNA-binding proteins would affect RNA granule dynamics and local translation, or if these alterations would cause neurodegeneration. Further investigation into this area will lead to important insights into how disruption of RNA metabolism and local translation at synapses can cause neurodegenerative diseases. PMID:26047658

  5. Star Formation in the Central Kiloparsec of Nearby Active Galaxies

    International Nuclear Information System (INIS)

    We investigate star formation (SF) activity in the central kpc of a sample of nearby Active Galactic Nuclei (AGNs). AGN activities are expected to either trigger SF via accreting ISM to the central regions of the host galaxies or quench the SF via the energy feedback of the AGNs. To study the AGN-SF relation we select 113 nearby galaxies that host 8 GHz central radio sources. We use 8 GHz radio emission to represent the AGN activity and 8 micron dust emission in the central kpc regions of these galaxies to estimate the SF rate (SFR). The SFR is found to be correlated with the stellar mass for stellar mass greater than 1010 solar mass and looks scattered for stellar mass less than 1010 solar mass. There is no correlation between the specific SFR (SSFR) and the AGN activity for all sources. However, if we exclude the sources with the central stellar mass greater than 1010 solar mass, we find that the 8 GHz radio emission is well correlated with the SSFR. These results suggest that the AGN activity is significant in triggering SF activity only for small galaxies. Besides, we also select about 20 nearby AGN galaxies to investigate the radial variation of their surface specific star formation rate.

  6. Neuron network activity scales exponentially with synapse density

    OpenAIRE

    Brewer, G. J.; Boehler, M D; Pearson, R. A.; DeMaris, A A; Ide, A. N.; Wheeler, B C

    2008-01-01

    Neuronal network output in the cortex as a function of synapse density during development has not been explicitly determined. Synaptic scaling in cortical brain networks seems to alter excitatory and inhibitory synaptic inputs to produce a representative rate of synaptic output. Here, we cultured rat hippocampal neurons over a three-week period to correlate synapse density with the increase in spontaneous spiking activity. We followed the network development as synapse formation and spike rat...

  7. Recruitment of dynein to the Jurkat immunological synapse

    OpenAIRE

    Combs, Jeffrey; Kim, Soo Jin; Tan, Sarah; Ligon, Lee A.; Holzbaur, Erika L.F.; Kuhn, Jeffrey; Poenie, Martin

    2006-01-01

    Binding of T cells to antigen-presenting cells leads to the formation of the immunological synapse, translocation of the microtubule-organizing center (MTOC) to the synapse, and focused secretion of effector molecules. Here, we show that upon activation of Jurkat cells microtubules project from the MTOC to a ring of the scaffolding protein ADAP, localized at the synapse. Loss of ADAP, but not lymphocyte function-associated antigen 1, leads to a severe defect in MTOC polarization at the immuno...

  8. Cell Adhesion, the Backbone of the Synapse: “Vertebrate” and “Invertebrate” Perspectives

    OpenAIRE

    Giagtzoglou, Nikolaos; Ly, Cindy V.; Bellen, Hugo J.

    2009-01-01

    Synapses are asymmetric intercellular junctions that mediate neuronal communication. The number, type, and connectivity patterns of synapses determine the formation, maintenance, and function of neural circuitries. The complexity and specificity of synaptogenesis relies upon modulation of adhesive properties, which regulate contact initiation, synapse formation, maturation, and functional plasticity. Disruption of adhesion may result in structural and functional imbalance that may lead to neu...

  9. Cadherin-9 Regulates Synapse-Specific Differentiation in the Developing Hippocampus

    OpenAIRE

    Williams, Megan E.; Wilke, Scott A.; Daggett, Anthony; Davis, Elizabeth; Otto, Stefanie; Ravi, Deepak; Ripley, Beth; Bushong, Eric A.; Ellisman, Mark H.; Klein, Gerd; Ghosh, Anirvan

    2011-01-01

    Our understanding of mechanisms that regulate the differentiation of specific classes of synapses is limited. Here, we investigate the formation of synapses between hippocampal dentate gyrus (DG) neurons and their target CA3 neurons and find that DG neurons preferentially form synapses with CA3 rather than DG or CA1 neurons in culture, suggesting that specific interactions between DG and CA3 neurons drive synapse formation. Cadherin-9 is expressed selectively in DG and CA3 neurons, and downre...

  10. Synapses and Memory Storage

    OpenAIRE

    Mayford, Mark; Siegelbaum, Steven A.; Kandel, Eric R.

    2012-01-01

    The synapse is the functional unit of the brain. During the last several decades we have acquired a great deal of information on its structure, molecular components, and physiological function. It is clear that synapses are morphologically and molecularly diverse and that this diversity is recruited to different functions. One of the most intriguing findings is that the size of the synaptic response in not invariant, but can be altered by a variety of homo- and heterosynaptic factors such as ...

  11. Resolving the Formation of Protogalaxies. II.Central Gravitational Collapse

    Energy Technology Data Exchange (ETDEWEB)

    Wise, John H.; Turk, Matthew J.; Abel, Tom

    2007-10-15

    Numerous cosmological hydrodynamic studies have addressed the formation of galaxies. Here we choose to study the first stages of galaxy formation, including non-equilibrium atomic primordial gas cooling, gravity and hydrodynamics. Using initial conditions appropriate for the concordance cosmological model of structure formation, we perform two adaptive mesh refinement simulations of {approx} 10{sup 8} M{sub {circle_dot}} galaxies at high redshift. The calculations resolve the Jeans length at all times with more than 16 cells and capture over 14 orders of magnitude in length scales. In both cases, the dense, 10{sup 5} solar mass, one parsec central regions are found to contract rapidly and have turbulent Mach numbers up to 4. Despite the ever decreasing Jeans length of the isothermal gas, we only find one site of fragmentation during the collapse. However, rotational secular bar instabilities transport angular momentum outwards in the central parsec as the gas continues to collapse and lead to multiple nested unstable fragments with decreasing masses down to sub-Jupiter mass scales. Although these numerical experiments neglect star formation and feedback, they clearly highlight the physics of turbulence in gravitationally collapsing gas. The angular momentum segregation seen in our calculations plays an important role in theories that form supermassive black holes from gaseous collapse.

  12. LRIT3 is essential to localize TRPM1 to the dendritic tips of depolarizing bipolar cells and may play a role in cone synapse formation.

    Science.gov (United States)

    Neuillé, Marion; Morgans, Catherine W; Cao, Yan; Orhan, Elise; Michiels, Christelle; Sahel, José-Alain; Audo, Isabelle; Duvoisin, Robert M; Martemyanov, Kirill A; Zeitz, Christina

    2015-08-01

    Mutations in LRIT3 lead to complete congenital stationary night blindness (cCSNB). The exact role of LRIT3 in ON-bipolar cell signaling cascade remains to be elucidated. Recently, we have characterized a novel mouse model lacking Lrit3 [no b-wave 6, (Lrit3(nob6/nob6) )], which displays similar abnormalities to patients with cCSNB with LRIT3 mutations. Here we compare the localization of components of the ON-bipolar cell signaling cascade in wild-type and Lrit3(nob6/nob6) retinal sections by immunofluorescence confocal microscopy. An anti-LRIT3 antibody was generated. Immunofluorescent staining of LRIT3 in wild-type mice revealed a specific punctate labeling in the outer plexiform layer (OPL), which was absent in Lrit3(nob6/nob6) mice. LRIT3 did not co-localize with ribeye or calbindin but co-localized with mGluR6. TRPM1 staining was severely decreased at the dendritic tips of all depolarizing bipolar cells in Lrit3(nob6/nob6) mice. mGluR6, GPR179, RGS7, RGS11 and Gβ5 immunofluorescence was absent at the dendritic tips of cone ON-bipolar cells in Lrit3(nob6/nob6) mice, while it was present at the dendritic tips of rod bipolar cells. Furthermore, peanut agglutinin (PNA) labeling was severely reduced in the OPL in Lrit3(nob6/nob6) mice. This study confirmed the localization of LRIT3 at the dendritic tips of depolarizing bipolar cells in mouse retina and demonstrated the dependence of TRPM1 localization on the presence of LRIT3. As tested components of the ON-bipolar cell signaling cascade and PNA revealed disrupted localization, an additional function of LRIT3 in cone synapse formation is suggested. These results point to a possibly different regulation of the mGluR6 signaling cascade between rod and cone ON-bipolar cells. PMID:25997951

  13. Star Formation in the Central Regions of Galaxies

    Science.gov (United States)

    Tsai, Mengchun

    2015-08-01

    The galactic central region connects the galactic nucleus to the host galaxy. If the central black hole co-evolved with the host galaxies, there should be some evidence left in the central region. We use the environmental properties in the central regions such as star-forming activity, stellar population and molecular abundance to figure out a possible scenario of the evolution of galaxies. In this thesis at first we investigated the properties of the central regions in the host galaxies of active and normal galaxies. We used radio emission around the nuclei of the host galaxies to represent activity of active galactic nuclei (AGNs), and used infrared ray (IR) emission to represent the star-forming activity and stellar population of the host galaxies. We determined that active galaxies have higher stellar masses (SMs) within the central kiloparsec radius than normal galaxies do independent of the Hubble types of the host galaxies; but both active and normal galaxies exhibit similar specific star formation rates (SSFRs). We also discovered that certain AGNs exhibit substantial inner stellar structures in the IR images; most of the AGNs with inner structures are Seyferts, whereas only a few LINERs exhibit inner structures. We note that the AGNs with inner structures show a positive correlation between the radio activity of the AGNs and the SFRs of the host galaxies, but the sources without inner structures show a negative correlation between the radio power and the SFRs. These results might be explained with a scenario of starburst-AGN evolution. In this scenario, AGN activities are triggered following a nuclear starburst; during the evolution, AGN activities are accompanied by SF activity in the inner regions of the host galaxies; at the final stage of the evolution, the AGNs might transform into LINERs, exhibiting weak SF activity in the central regions of the host galaxies. For further investigation about the inner structure, we choose the most nearby and luminous

  14. Astrocyte scar formation aids central nervous system axon regeneration.

    Science.gov (United States)

    Anderson, Mark A; Burda, Joshua E; Ren, Yilong; Ao, Yan; O'Shea, Timothy M; Kawaguchi, Riki; Coppola, Giovanni; Khakh, Baljit S; Deming, Timothy J; Sofroniew, Michael V

    2016-04-14

    Transected axons fail to regrow in the mature central nervous system. Astrocytic scars are widely regarded as causal in this failure. Here, using three genetically targeted loss-of-function manipulations in adult mice, we show that preventing astrocyte scar formation, attenuating scar-forming astrocytes, or ablating chronic astrocytic scars all failed to result in spontaneous regrowth of transected corticospinal, sensory or serotonergic axons through severe spinal cord injury (SCI) lesions. By contrast, sustained local delivery via hydrogel depots of required axon-specific growth factors not present in SCI lesions, plus growth-activating priming injuries, stimulated robust, laminin-dependent sensory axon regrowth past scar-forming astrocytes and inhibitory molecules in SCI lesions. Preventing astrocytic scar formation significantly reduced this stimulated axon regrowth. RNA sequencing revealed that astrocytes and non-astrocyte cells in SCI lesions express multiple axon-growth-supporting molecules. Our findings show that contrary to the prevailing dogma, astrocyte scar formation aids rather than prevents central nervous system axon regeneration. PMID:27027288

  15. Rare de novo variants associated with autism implicate a large functional network of genes involved in formation and function of synapses

    OpenAIRE

    Gilman, Sarah R; Iossifov, Ivan; Levy, Dan; Ronemus, Michael; Wigler, Michael; Vitkup, Dennis

    2011-01-01

    Identification of complex molecular networks underlying common human phenotypes is a major challenge of modern genetics. In this study we develop a method for NETwork-Based Analysis of Genetic associations (NETBAG). We use NETBAG to identify a large biological network of genes affected by rare de novo CNVs in autism. The genes forming the network are primarily related to synapse development, axon targeting and neuron motility. The identified network is strongly related to genes previously imp...

  16. The X-linked intellectual disability protein IL1RAPL1 regulates excitatory synapse formation by binding PTPδ and RhoGAP2

    OpenAIRE

    Valnegri, Pamela; Montrasio, Chiara; Brambilla, Dario; Ko, Jaewon; Passafaro, Maria; Sala, Carlo

    2011-01-01

    Mutations of the Interleukin-1-receptor accessory protein like 1 (IL1RAPL1) gene are associated with cognitive impairment ranging from non-syndromic X-linked mental retardation to autism. IL1RAPL1 belongs to a novel family of IL1/Toll receptors, which is localized at excitatory synapses and interacts with PSD-95. We previously showed that IL1RAPL1 regulates the synaptic localization of PSD-95 by controlling c-Jun N-terminal kinase activity and PSD-95 phosphorylation. Here, we show that the Ig...

  17. Fragment Formation in Central Heavy Ion Collisions at Relativistic Energies

    CERN Document Server

    Santini, E; Colonna, M; Di Toro, M

    2005-01-01

    We perform a systematic study of the fragmentation path of excited nuclear matter in central heavy ion collisions at the intermediate energy of $0.4 AGeV$. The theoretical calculations are based on a Relativistic Boltzmann-Uehling-Uhlenbeck ($RBUU$) transport equation including stochastic effects. A Relativistic Mean Field ($RMF$) approach is used, based on a non-linear Lagrangian, with coupling constants tuned to reproduce the high density results of calculations with correlations. At variance with the case at Fermi energies, a new fast clusterization mechanism is revealed in the early compression stage of the reaction dynamics. Fragments appear directly produced from phase-space fluctuations due to two-body correlations. In-medium effects of the elastic nucleon-nucleon cross sections on the fragmentation dynamics are particularly discussed. The subsequent evolution of the primordial clusters is treated using a simple phenomenological phase space coalescence algorithm. The reliability of the approach, format...

  18. Dopamine synapse is a neuroligin-2-mediated contact between dopaminergic presynaptic and GABAergic postsynaptic structures.

    Science.gov (United States)

    Uchigashima, Motokazu; Ohtsuka, Toshihisa; Kobayashi, Kazuto; Watanabe, Masahiko

    2016-04-12

    Midbrain dopamine neurons project densely to the striatum and form so-called dopamine synapses on medium spiny neurons (MSNs), principal neurons in the striatum. Because dopamine receptors are widely expressed away from dopamine synapses, it remains unclear how dopamine synapses are involved in dopaminergic transmission. Here we demonstrate that dopamine synapses are contacts formed between dopaminergic presynaptic and GABAergic postsynaptic structures. The presynaptic structure expressed tyrosine hydroxylase, vesicular monoamine transporter-2, and plasmalemmal dopamine transporter, which are essential for dopamine synthesis, vesicular filling, and recycling, but was below the detection threshold for molecules involving GABA synthesis and vesicular filling or for GABA itself. In contrast, the postsynaptic structure of dopamine synapses expressed GABAergic molecules, including postsynaptic adhesion molecule neuroligin-2, postsynaptic scaffolding molecule gephyrin, and GABAA receptor α1, without any specific clustering of dopamine receptors. Of these, neuroligin-2 promoted presynaptic differentiation in axons of midbrain dopamine neurons and striatal GABAergic neurons in culture. After neuroligin-2 knockdown in the striatum, a significant decrease of dopamine synapses coupled with a reciprocal increase of GABAergic synapses was observed on MSN dendrites. This finding suggests that neuroligin-2 controls striatal synapse formation by giving competitive advantage to heterologous dopamine synapses over conventional GABAergic synapses. Considering that MSN dendrites are preferential targets of dopamine synapses and express high levels of dopamine receptors, dopamine synapse formation may serve to increase the specificity and potency of dopaminergic modulation of striatal outputs by anchoring dopamine release sites to dopamine-sensing targets. PMID:27035941

  19. Rhythmic changes in synapse numbers in Drosophila melanogaster motor terminals.

    Directory of Open Access Journals (Sweden)

    Santiago Ruiz

    Full Text Available Previous studies have shown that the morphology of the neuromuscular junction of the flight motor neuron MN5 in Drosophila melanogaster undergoes daily rhythmical changes, with smaller synaptic boutons during the night, when the fly is resting, than during the day, when the fly is active. With electron microscopy and laser confocal microscopy, we searched for a rhythmic change in synapse numbers in this neuron, both under light:darkness (LD cycles and constant darkness (DD. We expected the number of synapses to increase during the morning, when the fly has an intense phase of locomotion activity under LD and DD. Surprisingly, only our DD data were consistent with this hypothesis. In LD, we found more synapses at midnight than at midday. We propose that under LD conditions, there is a daily rhythm of formation of new synapses in the dark phase, when the fly is resting, and disassembly over the light phase, when the fly is active. Several parameters appeared to be light dependent, since they were affected differently under LD or DD. The great majority of boutons containing synapses had only one and very few had either two or more, with a 70∶25∶5 ratio (one, two and three or more synapses in LD and 75∶20∶5 in DD. Given the maintenance of this proportion even when both bouton and synapse numbers changed with time, we suggest that there is a homeostatic mechanism regulating synapse distribution among MN5 boutons.

  20. Synapses, synaptic activity and intraneuronal Aβ in Alzheimer's disease

    Directory of Open Access Journals (Sweden)

    Davide Tampellini

    2010-05-01

    Full Text Available β-amyloid peptide accumulation plays a central role in the pathogenesis of Alzheimer’s disease. Aberrant β-amyloid buildup in the brain has been shown to be present both in the extracellular space and within neurons. Synapses are important targets of β-amyloid, and alterations in synapses better correlate with cognitive impairment than amyloid plaques or neurofibrillary tangles. The link between β-amyloid and synapses became even tighter when it was discovered that β-amyloid accumulates within synapses and that synaptic activity modulates β-amyloid secretion. Currently, a central question in Alzheimer’s disease research is what role synaptic activity plays in the disease process, and how specifically β-amyloid is involved in the synaptic dysfunction that characterizes the disease.

  1. Hair cell ribbon synapses

    OpenAIRE

    Moser, Tobias; Brandt, Andreas; Lysakowski, Anna

    2006-01-01

    Hearing and balance rely on the faithful synaptic coding of mechanical input by the auditory and vestibular hair cells of the inner ear. Mechanical deflection of their stereocilia causes the opening of mechanosensitive channels, resulting in hair cell depolarization, which controls the release of glutamate at ribbon-type synapses. Hair cells have a compact shape with strong polarity. Mechanoelectrical transduction and active membrane turnover associated with stereociliar renewal dominate the ...

  2. Menin: A Tumor Suppressor That Mediates Postsynaptic Receptor Expression and Synaptogenesis between Central Neurons of Lymnaea stagnalis

    OpenAIRE

    Nichole Flynn; Angela Getz; Frank Visser; Tara A Janes; Syed, Naweed I.

    2014-01-01

    Neurotrophic factors (NTFs) support neuronal survival, differentiation, and even synaptic plasticity both during development and throughout the life of an organism. However, their precise roles in central synapse formation remain unknown. Previously, we demonstrated that excitatory synapse formation in Lymnaea stagnalis requires a source of extrinsic NTFs and receptor tyrosine kinase (RTK) activation. Here we show that NTFs such as Lymnaea epidermal growth factor (L-EGF) act through RTKs to t...

  3. Imaging Structural Plasticity Of Synapses In The Brain

    OpenAIRE

    Yu, Xinzhu

    2012-01-01

    Synapses are the sites where neurons contact each other and exchange information in the brain. Experience-dependent changes in synaptic connections are fundamental for numerous neurological processes, ranging from the development of neuronal circuitry to learning and memory. Dendritic spines are the postsynaptic sites of the majority of excitatory synapses in the mammalian central nervous system. The morphology and dynamics of dendritic spines change throughout the lifespan of animals, espe...

  4. RNA-binding protein Hermes/RBPMS inversely affects synapse density and axon arbor formation in retinal ganglion cells in vivo.

    Science.gov (United States)

    Hörnberg, Hanna; Wollerton-van Horck, Francis; Maurus, Daniel; Zwart, Maarten; Svoboda, Hanno; Harris, William A; Holt, Christine E

    2013-06-19

    The RNA-binding protein Hermes [RNA-binding protein with multiple splicing (RBPMS)] is expressed exclusively in retinal ganglion cells (RGCs) in the CNS, but its function in these cells is not known. Here we show that Hermes protein translocates in granules from RGC bodies down the growing axons. Hermes loss of function in both Xenopus laevis and zebrafish embryos leads to a significant reduction in retinal axon arbor complexity in the optic tectum, and expression of a dominant acting mutant Hermes protein, defective in RNA-granule localization, causes similar defects in arborization. Time-lapse analysis of branch dynamics reveals that the decrease in arbor complexity is caused by a reduction in new branches rather than a decrease in branch stability. Surprisingly, Hermes depletion also leads to enhanced early visual behavior and an increase in the density of presynaptic puncta, suggesting that reduced arborization is accompanied by increased synaptogenesis to maintain synapse number. PMID:23785151

  5. Rare de novo variants associated with autism implicate a large functional network of genes involved in formation and function of synapses.

    Science.gov (United States)

    Gilman SR; Iossifov I; Levy D; Ronemus M; Wigler M; Vitkup D

    2011-06-09

    Identification of complex molecular networks underlying common human phenotypes is a major challenge of modern genetics. In this study, we develop a method for network-based analysis of genetic associations (NETBAG). We use NETBAG to identify a large biological network of genes affected by rare de novo CNVs in autism. The genes forming the network are primarily related to synapse development, axon targeting, and neuron motility. The identified network is strongly related to genes previously implicated in autism and intellectual disability phenotypes. Our results are also consistent with the hypothesis that significantly stronger functional perturbations are required to trigger the autistic phenotype in females compared to males. Overall, the presented analysis of de novo variants supports the hypothesis that perturbed synaptogenesis is at the heart of autism. More generally, our study provides proof of the principle that networks underlying complex human phenotypes can be identified by a network-based functional analysis of rare genetic variants.

  6. Emerging Roles of BAI Adhesion-GPCRs in Synapse Development and Plasticity

    OpenAIRE

    Duman, Joseph G.; Yen-Kuei Tu; Tolias, Kimberley F.

    2016-01-01

    Synapses mediate communication between neurons and enable the brain to change in response to experience, which is essential for learning and memory. The sites of most excitatory synapses in the brain, dendritic spines, undergo rapid remodeling that is important for neural circuit formation and synaptic plasticity. Abnormalities in synapse and spine formation and plasticity are associated with a broad range of brain disorders, including intellectual disabilities, autism spectrum disorders (ASD...

  7. Advanced Fluorescence Protein-Based Synapse-Detectors.

    Science.gov (United States)

    Lee, Hojin; Oh, Won Chan; Seong, Jihye; Kim, Jinhyun

    2016-01-01

    The complex information-processing capabilities of the central nervous system emerge from intricate patterns of synaptic input-output relationships among various neuronal circuit components. Understanding these capabilities thus requires a precise description of the individual synapses that comprise neural networks. Recent advances in fluorescent protein engineering, along with developments in light-favoring tissue clearing and optical imaging techniques, have rendered light microscopy (LM) a potent candidate for large-scale analyses of synapses, their properties, and their connectivity. Optically imaging newly engineered fluorescent proteins (FPs) tagged to synaptic proteins or microstructures enables the efficient, fine-resolution illumination of synaptic anatomy and function in large neural circuits. Here we review the latest progress in fluorescent protein-based molecular tools for imaging individual synapses and synaptic connectivity. We also identify associated technologies in gene delivery, tissue processing, and computational image analysis that will play a crucial role in bridging the gap between synapse- and system-level neuroscience. PMID:27445785

  8. Functional inactivation of a fraction of excitatory synapses in mice deficient for the active zone protein bassoon

    DEFF Research Database (Denmark)

    Altrock, Wilko D; tom Dieck, Susanne; Sokolov, Maxim;

    2003-01-01

    normal synaptic transmission, which can be attributed to the inactivation of a significant fraction of glutamatergic synapses. At these synapses, vesicles are clustered and docked in normal numbers but are unable to fuse. Phenotypically, the loss of Bassoon causes spontaneous epileptic seizures. These...... data show that Bassoon is not essential for synapse formation but plays an essential role in the regulated neurotransmitter release from a subset of glutamatergic synapses....

  9. Get Ready to Wnt: Prepatterning in Neuromuscular Junction Formation

    OpenAIRE

    Zhang, Bin; Xiong, Wen C.; Mei, Lin

    2009-01-01

    Clustering of acetylcholine receptors (AChR) in muscle fibers prior to innervation by motor neurons is thought to be involved in neuromuscular junction formation. Jing et al. now report in Neuron that this prepatterning of AChRs, via a novel MuSK-dependent Wnt pathway, may guide motor axons to the central region of muscle fibers for synapse formation in zebrafish.

  10. Phospholipase D-mediated hypersensitivity at central synapses is associated with abnormal behaviours and pain sensitivity in rats exposed to prenatal stress.

    Science.gov (United States)

    Sun, Liting; Gooding, Hayley L; Brunton, Paula J; Russell, John A; Mitchell, Rory; Fleetwood-Walker, Sue

    2013-11-01

    Adverse events at critical stages of development can lead to lasting dysfunction in the central nervous system (CNS). To seek potential underlying changes in synaptic function, we used a newly developed protocol to measure alterations in receptor-mediated Ca(2+) fluorescence responses of synaptoneurosomes, freshly isolated from selected regions of the CNS concerned with emotionality and pain processing. We compared adult male controls and offspring of rats exposed to social stress in late pregnancy (prenatal stress, PS), which showed programmed behavioural changes indicating anxiety, anhedonia and pain hypersensitivity. We found corresponding increases, in PS rats compared with normal controls, in responsiveness of synaptoneurosomes from frontal cortex to a glutamate receptor (GluR) agonist, and from spinal cord to activators of nociceptive afferents. Through a combined pharmacological and biochemical strategy, we found evidence for a role of phospholipase D1 (PLD1)-mediated signalling, that may involve 5-HT2A receptor (5-HT2AR) activation, at both levels of the nervous system. These changes might participate in underpinning the enduring alterations in behaviour induced by PS. PMID:23932932

  11. Synapse-to-neuron ratio is inversely related to neuronal density in mature neuronal cultures

    OpenAIRE

    Cullen, D. Kacy; Gilroy, Meghan; Irons, Hillary R.; LaPlaca, Michelle C.

    2010-01-01

    Synapse formation is a fundamental process in neurons that occurs throughout development, maturity, and aging. Although these stages contain disparate and fluctuating numbers of mature neurons, tactics employed by neuronal networks to modulate synapse number as a function of neuronal density are not well understood. The goal of this study was to utilize an in vitro model to assess the influence of cell density and neuronal maturity on synapse number and distribution. Specifically, cerebral co...

  12. NK cell survival mediated through the regulatory synapse with human DCs requires IL-15Rα

    OpenAIRE

    Brilot, Fabienne; Strowig, Till; Roberts, Susanne M.; Arrey, Frida; Münz, Christian

    2007-01-01

    DCs activate NK cells during innate immune responses to viral infections. However, the composition and kinetics of the immunological synapse mediating this interaction are largely unknown. Here, we report the rapid formation of an immunological synapse between human resting NK cells and mature DCs. Although inhibitory NK cell receptors were polarized to this synapse, where they are known to protect mature DCs from NK cell lysis, the NK cell also received activation signals that induced mobili...

  13. Cortical synaptogenesis and excitatory synapse number are determined via a Neuroligin-1-dependent intercellular competition

    OpenAIRE

    Kwon, Hyung-Bae; Kozorovitskiy, Yevgenia; Oh, Won-Jong; Peixoto, Rui T.; Akhtar, Nazia; Saulnier, Jessica L.; Gu, Chenghua; Sabatini, Bernardo L.

    2012-01-01

    Members of the neuroligin (NL) family of cell-adhesion proteins are found at excitatory and inhibitory synapses and are mutated in some familial forms of autism spectrum disorders. Although they display synaptogenic properties in heterologous systems, a function of NLs in vivo in regulating synapse formation and synapse number has been difficult to establish. Here we show that neuroligin-1 (NL1), which is located at excitatory post-synaptic densities, does regulate activity-dependent synaptog...

  14. Calcium channel-dependent molecular maturation of photoreceptor synapses.

    Directory of Open Access Journals (Sweden)

    Nawal Zabouri

    Full Text Available Several studies have shown the importance of calcium channels in the development and/or maturation of synapses. The Ca(V1.4(α(1F knockout mouse is a unique model to study the role of calcium channels in photoreceptor synapse formation. It features abnormal ribbon synapses and aberrant cone morphology. We investigated the expression and targeting of several key elements of ribbon synapses and analyzed the cone morphology in the Ca(V1.4(α(1F knockout retina. Our data demonstrate that most abnormalities occur after eye opening. Indeed, scaffolding proteins such as Bassoon and RIM2 are properly targeted at first, but their expression and localization are not maintained in adulthood. This indicates that either calcium or the Ca(V1.4 channel, or both are necessary for the maintenance of their normal expression and distribution in photoreceptors. Other proteins, such as Veli3 and PSD-95, also display abnormal expression in rods prior to eye opening. Conversely, vesicle related proteins appear normal. Our data demonstrate that the Ca(V1.4 channel is important for maintaining scaffolding proteins in the ribbon synapse but less vital for proteins related to vesicular release. This study also confirms that in adult retinae, cones show developmental features such as sprouting and synaptogenesis. Overall we present evidence that in the absence of the Ca(V1.4 channel, photoreceptor synapses remain immature and are unable to stabilize.

  15. Neurotrophin-3 regulates ribbon synapse density in the cochlea and induces synapse regeneration after acoustic trauma

    OpenAIRE

    Wan, Guoqiang; Gómez-Casati, Maria E; Gigliello, Angelica R.; Liberman, M. Charles; Corfas, Gabriel

    2014-01-01

    Neurotrophin-3 (Ntf3) and brain derived neurotrophic factor (Bdnf) are critical for sensory neuron survival and establishment of neuronal projections to sensory epithelia in the embryonic inner ear, but their postnatal functions remain poorly understood. Using cell-specific inducible gene recombination in mice we found that, in the postnatal inner ear, Bbnf and Ntf3 are required for the formation and maintenance of hair cell ribbon synapses in the vestibular and cochlear epithelia, respective...

  16. Chanco formation, a potential Cretaceous reservoir, central Chile

    Energy Technology Data Exchange (ETDEWEB)

    Cecione, G.

    1983-07-01

    The Chanco embayment lies 300 km SSW of Santiago, Chile. The sequence within this basin above the metamorphic basement is: Chanco Formation (very clean sandstone), Quiriquina Formation (glauconitic sandstone, rich in organic matter), and Navidad Group (a very good caprock). This section thus contains reservoir, source and caprocks, and is therefore very promising for petroleum investigations. The offshore C-1 well yielded salt-water with gas shows, and two wells drilled onshore yielded shows of gas. The C-1 well lies on a gently-dipping EW-striking anticlinal structure, the presence of which makes the area very prospective.

  17. Menin: a tumor suppressor that mediates postsynaptic receptor expression and synaptogenesis between central neurons of Lymnaea stagnalis.

    Directory of Open Access Journals (Sweden)

    Nichole Flynn

    Full Text Available Neurotrophic factors (NTFs support neuronal survival, differentiation, and even synaptic plasticity both during development and throughout the life of an organism. However, their precise roles in central synapse formation remain unknown. Previously, we demonstrated that excitatory synapse formation in Lymnaea stagnalis requires a source of extrinsic NTFs and receptor tyrosine kinase (RTK activation. Here we show that NTFs such as Lymnaea epidermal growth factor (L-EGF act through RTKs to trigger a specific subset of intracellular signalling events in the postsynaptic neuron, which lead to the activation of the tumor suppressor menin, encoded by Lymnaea MEN1 (L-MEN1 and the expression of excitatory nicotinic acetylcholine receptors (nAChRs. We provide direct evidence that the activation of the MAPK/ERK cascade is required for the expression of nAChRs, and subsequent synapse formation between pairs of neurons in vitro. Furthermore, we show that L-menin activation is sufficient for the expression of postsynaptic excitatory nAChRs and subsequent synapse formation in media devoid of NTFs. By extending our findings in situ, we reveal the necessity of EGFRs in mediating synapse formation between a single transplanted neuron and its intact presynaptic partner. Moreover, deficits in excitatory synapse formation following EGFR knock-down can be rescued by injecting synthetic L-MEN1 mRNA in the intact central nervous system. Taken together, this study provides the first direct evidence that NTFs functioning via RTKs activate the MEN1 gene, which appears sufficient to regulate synapse formation between central neurons. Our study also offers a novel developmental role for menin beyond tumour suppression in adult humans.

  18. Biofilm formation in long-term central venous catheters in children with cancer

    DEFF Research Database (Denmark)

    Handrup, Mette Møller; Fuursted, Kurt; Funch, Peter;

    2012-01-01

    Taurolidine has demonstrated inhibition of biofilm formation in vitro. The aim of this study was to compare the effect of catheter locking with taurolidine vs heparin in biofilm formation in central venous catheters. Forty-eight children with cancer were randomized to catheter locking by heparin ...

  19. Central role of pyrophosphate in acellular cementum formation.

    Directory of Open Access Journals (Sweden)

    Brian L Foster

    Full Text Available BACKGROUND: Inorganic pyrophosphate (PP(i is a physiologic inhibitor of hydroxyapatite mineral precipitation involved in regulating mineralized tissue development and pathologic calcification. Local levels of PP(i are controlled by antagonistic functions of factors that decrease PP(i and promote mineralization (tissue-nonspecific alkaline phosphatase, Alpl/TNAP, and those that increase local PP(i and restrict mineralization (progressive ankylosis protein, ANK; ectonucleotide pyrophosphatase phosphodiesterase-1, NPP1. The cementum enveloping the tooth root is essential for tooth function by providing attachment to the surrounding bone via the nonmineralized periodontal ligament. At present, the developmental regulation of cementum remains poorly understood, hampering efforts for regeneration. To elucidate the role of PP(i in cementum formation, we analyzed root development in knock-out ((-/- mice featuring PP(i dysregulation. RESULTS: Excess PP(i in the Alpl(-/- mouse inhibited cementum formation, causing root detachment consistent with premature tooth loss in the human condition hypophosphatasia, though cementoblast phenotype was unperturbed. Deficient PP(i in both Ank and Enpp1(-/- mice significantly increased cementum apposition and overall thickness more than 12-fold vs. controls, while dentin and cellular cementum were unaltered. Though PP(i regulators are widely expressed, cementoblasts selectively expressed greater ANK and NPP1 along the root surface, and dramatically increased ANK or NPP1 in models of reduced PP(i output, in compensatory fashion. In vitro mechanistic studies confirmed that under low PP(i mineralizing conditions, cementoblasts increased Ank (5-fold and Enpp1 (20-fold, while increasing PP(i inhibited mineralization and associated increases in Ank and Enpp1 mRNA. CONCLUSIONS: Results from these studies demonstrate a novel developmental regulation of acellular cementum, wherein cementoblasts tune cementogenesis by modulating

  20. Feedforward lateral inhibition in retinal bipolar cells: input-output relation of the horizontal cell-depolarizing bipolar cell synapse.

    OpenAIRE

    Yang, X. L.; S. M. Wu

    1991-01-01

    Lateral inhibition is the ubiquitous strategy used by visual neurons for spatial resolution throughout the animal kingdom. It has been a puzzle whether lateral inputs in retinal bipolar cells are mediated by the horizontal cell (HC)-cone feedback synapse, by the HC-bipolar cell feedforward synapse, or by both. By blocking the central inputs of the depolarizing bipolar cells (DBCs) with L-2-amino-4-phosphonobutyrate, we were able to eliminate the contribution of the feedback synapse and to dem...

  1. Going Mobile: AMPA Receptors Move Synapse to Synapse In Vivo

    OpenAIRE

    Rongo, Christopher

    2013-01-01

    Plasticity models invoke the synaptic delivery of AMPARs, yet we know little about how receptors move in vivo. In this issue of Neuron, Hoerndli et al. show that lateral diffusion and kinesin-mediated transport move AMPARs between synapses in vivo.

  2. Synapse Pathology in Psychiatric and Neurologic Disease

    NARCIS (Netherlands)

    M. van Spronsen (Myrrhe); C.C. Hoogenraad (Casper)

    2010-01-01

    textabstractInhibitory and excitatory synapses play a fundamental role in information processing in the brain. Excitatory synapses usually are situated on dendritic spines, small membrane protrusions that harbor glutamate receptors and postsynaptic density components and help transmit electrical sig

  3. Synapse Pathology in Psychiatric and Neurologic Disease

    OpenAIRE

    Spronsen, Myrrhe; Hoogenraad, Casper

    2010-01-01

    textabstractInhibitory and excitatory synapses play a fundamental role in information processing in the brain. Excitatory synapses usually are situated on dendritic spines, small membrane protrusions that harbor glutamate receptors and postsynaptic density components and help transmit electrical signals. In recent years, it has become evident that spine morphology is intimately linked to synapse function-smaller spines have smaller synapses and support reduced synaptic transmission. The relat...

  4. NKp46 clusters at the immune synapse and regulates NK cell polarization

    Directory of Open Access Journals (Sweden)

    Uzi eHadad

    2015-09-01

    Full Text Available Natural killer cells play an important role in first-line defense against tumor and virus-infected cells. The activity of NK cells is tightly regulated by a repertoire of cell-surface expressed inhibitory and activating receptors. NKp46 is a major NK cell activating receptor that is involved in the elimination of target cells. NK cells form different types of synapses that result in distinct functional outcomes: cytotoxic, inhibitory, and regulatory. Recent studies revealed that complex integration of NK receptor signaling controls cytoskeletal rearrangement and other immune synapse-related events. However the distinct nature by which NKp46 participates in NK immunological synapse formation and function remains unknown. In this study we determined that NKp46 forms microclusters structures at the immune synapse between NK cells and target cells. Over-expression of human NKp46 is correlated with increased accumulation of F-actin mesh at the immune synapse. Concordantly, knock-down of NKp46 in primary human NK cells decreased recruitment of F-actin to the synapse. Live cell imaging experiments showed a linear correlation between NKp46 expression and lytic granules polarization to the immune synapse. Taken together, our data suggest that NKp46 signaling directly regulates the NK lytic immune synapse from early formation to late function.

  5. ALPINE MAGMATIC-METALLOGENIC FORMATIONS OF THE NORTHWESTERN AND CENTRAL DINARIDES

    Directory of Open Access Journals (Sweden)

    Jakob Pamić

    1997-12-01

    Full Text Available In the paper are presented basic geological, petrologieca1, geochemi-cal and mineral deposit data for five main magmatic-metallogenic formations of the northwestern and central Dinarides: (lThe Permo Triassic rifting related andesite-diorite formations; (2 The Jurassic-Lower Cretaceous accretionary (ophiolite formations; (3 The Upper Cretaceous-Paleogene subduction related basalt-rhyohite formations; (4 The Paleogene collisional granite formations, and (5 The Oligo-cene-Neogene postsubduction andesite formations. All these magmatic-metallogenic formations originated in different geotectonic settings during the Alpine evolution of the Dinaridic parts of thc Tethys and the postorogenic evolution of the Paratethys and the Pannonian Basin, respectively.

  6. Galaxy Bulge Formation: Interplay with Dark Matter Halo and Central Supermassive Black Hole

    CERN Document Server

    Xu, B X; Zhao, H S; Xu, Bing-Xiao; Wu, Xue-Bing; Zhao, HongSheng

    2007-01-01

    We present a simple scenario where the formation of galactic bulges was regulated by the dark halo gravity and regulated the growth of the central supermassive black hole. Assuming the angular momentum is low, we suggest that bulges form in a runaway collapse due to the "gravothermal" instability once the central gas density or pressure exceeds certain threshold (Xu & Zhao 2007). We emphasize that the threshold is nearly universal, set by the background NFW dark matter gravity $g_{DM} \\sim 1.2 \\times 10^{-8}{\\rm cm} {\\rm sec}^{-2}$ in the central cusps of halos. Unlike known thresholds for gradual formation of galaxy disks, we show that the universal "halo-regulated" star formation threshold for spheroids matches the very high star formation rate and star formation efficiency shown in high-redshift observations of central starburst regions. The starburst feedback also builds up a pressure shortly after the collapse. This large pressure could both act outward to halt further infall of gas from larger scale...

  7. A compound memristive synapse model for statistical learning through STDP in spiking neural networks

    Directory of Open Access Journals (Sweden)

    Johannes eBill

    2014-12-01

    Full Text Available Memristors have recently emerged as promising circuit elements to mimic the function of biological synapses in neuromorphic computing. The fabrication of reliable nanoscale memristive synapses, that feature continuous conductance changes based on the timing of pre- and postsynaptic spikes, has however turned out to be challenging. In this article, we propose an alternative approach, the compound memristive synapse, that circumvents this problem by the use of memristors with binary memristive states. A compound memristive synapse employs multiple bistable memristors in parallel to jointly form one synapse, thereby providing a spectrum of synaptic efficacies. We investigate the computational implications of synaptic plasticity in the compound synapse by integrating the recently observed phenomenon of stochastic filament formation into an abstract model of stochastic switching. Using this abstract model, we first show how standard pulsing schemes give rise to spike-timing dependent plasticity (STDP with a stabilizing weight dependence in compound synapses. In a next step, we study unsupervised learning with compound synapses in networks of spiking neurons organized in a winner-take-all architecture. Our theoretical analysis reveals that compound-synapse STDP implements generalized Expectation-Maximization in the spiking network. Specifically, the emergent synapse configuration represents the most salient features of the input distribution in a Mixture-of-Gaussians generative model. Furthermore, the network’s spike response to spiking input streams approximates a well-defined Bayesian posterior distribution. We show in computer simulations how such networks learn to represent high-dimensional distributions over images of handwritten digits with high fidelity even in presence of substantial device variations and under severe noise conditions. Therefore, the compound memristive synapse may provide a synaptic design principle for future neuromorphic

  8. Live cell linear dichroism imaging reveals extensive membrane ruffling within the docking structure of natural killer cell immune synapses

    DEFF Research Database (Denmark)

    Benninger, Richard K P; Vanherberghen, Bruno; Young, Stephen;

    2009-01-01

    We have applied fluorescence imaging of two-photon linear dichroism to measure the subresolution organization of the cell membrane during formation of the activating (cytolytic) natural killer (NK) cell immune synapse (IS). This approach revealed that the NK cell plasma membrane is convoluted into...... absent from the center of the mature synapse. Understanding the role of such extensive membrane ruffling in the assembly of cytolytic synapses is an intriguing new goal....

  9. Shaping inhibition: activity dependent structural plasticity of GABAergic synapses

    Directory of Open Access Journals (Sweden)

    Pablo Mendez

    2014-10-01

    Full Text Available Inhibitory transmission through the neurotransmitter Ɣ-aminobutyric acid (GABA shapes network activity in the mammalian cerebral cortex by filtering synaptic incoming information and dictating the activity of principal cells. The incredibly diverse population of cortical neurons that use GABA as neurotransmitter shows an equally diverse range of mechanisms that regulate changes in the strength of GABAergic synaptic transmission and allow them to dynamically follow and command the activity of neuronal ensembles. Similarly to glutamatergic synaptic transmission, activity-dependent functional changes in inhibitory neurotransmission are accompanied by alterations in GABAergic synapse structure that range from morphological reorganization of postsynaptic density to de novo formation and elimination of inhibitory contacts. Here we review several aspects of structural plasticity of inhibitory synapses, including its induction by different forms of neuronal activity, behavioral and sensory experience and the molecular mechanisms and signaling pathways involved. We discuss the functional consequences of GABAergic synapse structural plasticity for information processing and memory formation in view of the heterogenous nature of the structural plasticity phenomena affecting inhibitory synapses impinging on somatic and dendritic compartments of cortical and hippocampal neurons.

  10. 'Then give him to the crocodiles': violence, State formation, and cultural discontinuity in west central Zambia, 1600-2000

    OpenAIRE

    Binsbergen, van, W.M.J.

    2003-01-01

    The purpose of this chapter is to explore the extent to which violence can be said to underlie any form of Stae formation in precolonial Africa. This is done by examining the role of violence in State formation in west central Zambia from the 17th century onwards. The chapter shows that State formation in west central Zambia entailed the imposition upon local village communities of a more or less centralized sociopolitical structure, representing a departure from the social organization and i...

  11. FORMATION 2005 Pour L'Afrique SURLA TECHNIQUE DES PETITES CENTRALES HYDRO-ELECTRIQUES

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    “Le stage de formation 2005 por l'Afrique sur la technique de petites centrales hydro-electrique”est subventionnte par le Gouvernement Chinois specialement pour les pays en voie de developpement,dans le cadre de l'aide aux pays en voie de developpement.Charge par le Ministere chinois du Commerce,

  12. Long-Term Depression at Parallel Fiber to Golgi Cell Synapses

    OpenAIRE

    Robberechts, Quinten; Wijnants, Mike; Giugliano, Michele; De Schutter, Erik

    2010-01-01

    Golgi cells (GoCs) are the primary inhibitory interneurons of the granular layer of the cerebellum. Their inhibition of granule cells is central to operate the relay of excitatory inputs to the cerebellar cortex. Parallel fibers (PFs) establish synapses to the GoCs in the molecular layer; these synapses contain AMPA, N-methyl-d-aspartate (NMDA), and mostly group II metabotropic glutamate receptors. Long-term changes in the efficacy of synaptic transmission at the PF-GoC synapse have not been ...

  13. Astrocytes Assemble Thalamocortical Synapses by Bridging NRX1α and NL1 via Hevin.

    Science.gov (United States)

    Singh, Sandeep K; Stogsdill, Jeff A; Pulimood, Nisha S; Dingsdale, Hayley; Kim, Yong Ho; Pilaz, Louis-Jan; Kim, Il Hwan; Manhaes, Alex C; Rodrigues, Wandilson S; Pamukcu, Arin; Enustun, Eray; Ertuz, Zeynep; Scheiffele, Peter; Soderling, Scott H; Silver, Debra L; Ji, Ru-Rong; Medina, Alexandre E; Eroglu, Cagla

    2016-01-14

    Proper establishment of synapses is critical for constructing functional circuits. Interactions between presynaptic neurexins and postsynaptic neuroligins coordinate the formation of synaptic adhesions. An isoform code determines the direct interactions of neurexins and neuroligins across the synapse. However, whether extracellular linker proteins can expand such a code is unknown. Using a combination of in vitro and in vivo approaches, we found that hevin, an astrocyte-secreted synaptogenic protein, assembles glutamatergic synapses by bridging neurexin-1alpha and neuroligin-1B, two isoforms that do not interact with each other. Bridging of neurexin-1alpha and neuroligin-1B via hevin is critical for the formation and plasticity of thalamocortical connections in the developing visual cortex. These results show that astrocytes promote the formation of synapses by modulating neurexin/neuroligin adhesions through hevin secretion. Our findings also provide an important mechanistic insight into how mutations in these genes may lead to circuit dysfunction in diseases such as autism. PMID:26771491

  14. Age, Stratigraphy, and Correlations of the Late Neogene Purisima Formation, Central California Coast Ranges

    Science.gov (United States)

    Powell, Charles L.; Barron, John A.; Sarna-Wojcicki, Andrei M.; Clark, Joseph C.; Perry, Frank A.; Brabb, Earl E.; Fleck, Robert J.

    2007-01-01

    The Purisima Formation is an important upper Miocene and Pliocene stratigraphic unit in central California, cropping out from the coast at Point Reyes north of San Francisco to more extensive exposures in the Santa Cruz Mountains to the south. The fine-grained rocks in the lower parts of the Purisima Formation record a latest Miocene transgressive event, whereas the middle and upper parts of the formation consist of increasingly clastic-rich siltstones and sandstones resulting from uplift of adjacent coastal regions and the Sierra Nevada during Pliocene transgressive and regressive sea-level events. Exposures of the Purisima occur in three different, fault-bounded, structural blocks - the Santa Cruz, Pigeon Point, and Point Reyes tectonic blocks - that complicate correlations and regional age assignments. We summarize and compare published and new biostratigraphic and geochronologic data for various exposures of the Purisima Formation on the basis of mollusks, diatoms, radiometric dating, magnetostratigraphy, tephrochronology, and strontium isotope dating. On the basis of these data, we conclude that the Purisima Formation ranges in age from the latest Miocene (about 7 Ma) to the late Pliocene (about 2.6 Ma). The Purisima Formation of Santa Cruz County, exposed in the sea cliffs from Santa Cruz to Rio del Mar, is here designated a supplementary reference section because it is the most complete and well studied Purisima section in central California.

  15. CHAMBERED HEXACTINELLID SPONGES FROM UPPER TRIASSIC(NORIAN-RHAETIAN? REEFS OF NAYBAND FORMATION IN CENTRAL IRAN

    Directory of Open Access Journals (Sweden)

    B. SENOWBARI-DARYAN

    2012-07-01

    Full Text Available This paper describes several chambered hexactinellid sponges, including Casearia iranica n.sp., C. vezvanensis n. sp., C. delijanensis n. sp., Esfahanella magna gen. n. n. sp., and E. parva gen. n. n. sp. from reefs of the Upper Triassic (Norian-Rhaetian Nayband Formation exposed south of the town of Delijan in central Iran. The relative abundance of chambered and non-chambered hexactinellid sponges at this locality - as compared to hypercalcified representatives - highlight the importance of this group of sponges in reef and reefal limestones in central and east Tethys (China, Caucasia, Iran. 

  16. Learning Spike Time Codes Through Morphological Learning With Binary Synapses.

    Science.gov (United States)

    Roy, Subhrajit; San, Phyo Phyo; Hussain, Shaista; Wei, Lee Wang; Basu, Arindam

    2016-07-01

    In this brief, a neuron with nonlinear dendrites (NNLDs) and binary synapses that is able to learn temporal features of spike input patterns is considered. Since binary synapses are considered, learning happens through formation and elimination of connections between the inputs and the dendritic branches to modify the structure or morphology of the NNLD. A morphological learning algorithm inspired by the tempotron, i.e., a recently proposed temporal learning algorithm is presented in this brief. Unlike tempotron, the proposed learning rule uses a technique to automatically adapt the NNLD threshold during training. Experimental results indicate that our NNLD with 1-bit synapses can obtain accuracy similar to that of a traditional tempotron with 4-bit synapses in classifying single spike random latency and pairwise synchrony patterns. Hence, the proposed method is better suited for robust hardware implementation in the presence of statistical variations. We also present results of applying this rule to real-life spike classification problems from the field of tactile sensing. PMID:26173221

  17. Synapse: Synthetic Application Profiler and Emulator

    OpenAIRE

    Merzky, Andre; Jha, Shantenu

    2015-01-01

    We introduce Synapse motivated by the needs to estimate and emulate workload execution characteristics on high-performance and distributed heterogeneous resources. Synapse has a platform independent application profiler, and the ability to emulate profiled workloads on a variety of heterogeneous resources. Synapse is used as a proxy application (or "representative application") for real workloads, with the added advantage that it can be tuned at arbitrary levels of granularity in ways that ar...

  18. Analyzing the exhaustiveness of the synapse protocol

    OpenAIRE

    Marinkovic, Bojan; Ciancaglini, Vincenzo; Ognjanovic, Zoran; Glavan, Paola; Liquori, Luigi; Maksimovic, Petar

    2015-01-01

    International audience The Synapse protocol is a scalable protocol designed for information retrieval over inter-connected heterogeneous overlay networks. In this paper, we give a formal description of Synapse using the Abstract State Machines framework. The formal description pertains to Synapse actions that manipulate distributed keys. Based on this formal description, we present results concerning the expected exhaustiveness for a number of scenarios and systems maintained by the Synaps...

  19. The Biochemical Anatomy of Cortical Inhibitory Synapses

    OpenAIRE

    Heller, E.A.; Zhang, W.; Selimi, F.; Earnheart, J.C.; Slimak, M.A.; Santos-Torres, J.; Ibanez-Tallon, I.; Aoki, C; Chait, B. T.; Heintz, N

    2012-01-01

    Classical electron microscopic studies of the mammalian brain revealed two major classes of synapses, distinguished by the presence of a large postsynaptic density (PSD) exclusively at type 1, excitatory synapses. Biochemical studies of the PSD have established the paradigm of the synapse as a complex signal-processing machine that controls synaptic plasticity. We report here the results of a proteomic analysis of type 2, inhibitory synaptic complexes isolated by affinity purification from th...

  20. FORMATION MECHANISM AND SPATIAL PATTERN OF URBAN AGGLOMERATION IN CENTRAL JILIN OF CHINA

    Institute of Scientific and Technical Information of China (English)

    QIN Gan; ZHANG Ping-yu; JIAO Bin

    2006-01-01

    Urban agglomeration is made up of cities with different sizes to be linked by traffic network in a given area, and it is an inevitable result when urbanization reaches a certain level. Taking urban agglomerationin central Jilin(UACJ) as an example, this article analyzes the formation mechanism and spatial pattern of urban agglomeration in the less-developed area. First, the dynamics of UACJ has been analyzed from the aspects of geographical condition, economic foundation, policy background, and traffic condition. Then the development process is divided into three stages-single city, city group and city cluster. Secondly, the central cities are identified from the aspects of city centrality, and the development axes are classified based on economic communication capacity. Finally, the urban agglomeration is divided into five urban economic regions in order to establish the reasonable distribution of industries.

  1. QUENCHING OF STAR FORMATION IN SLOAN DIGITAL SKY SURVEY GROUPS: CENTRALS, SATELLITES, AND GALACTIC CONFORMITY

    International Nuclear Information System (INIS)

    We re-examine the fraction of low-redshift Sloan Digital Sky Survey satellites and centrals in which star formation has been quenched, using the environment quenching efficiency formalism that separates out the dependence of stellar mass. We show that the centrals of the groups containing the satellites are responding to the environment in the same way as their satellites (at least for stellar masses above 1010.3 M ☉), and that the well-known differences between satellites and the general set of centrals arise because the latter are overwhelmingly dominated by isolated galaxies. The widespread concept of ''satellite quenching'' as the cause of environmental effects in the galaxy population can therefore be generalized to ''group quenching''. We then explore the dependence of the quenching efficiency of satellites on overdensity, group-centric distance, halo mass, the stellar mass of the satellite, and the stellar mass and specific star formation rate (sSFR) of its central, trying to isolate the effect of these often interdependent variables. We emphasize the importance of the central sSFR in the quenching efficiency of the associated satellites, and develop the meaning of this ''galactic conformity'' effect in a probabilistic description of the quenching of galaxies. We show that conformity is strong, and that it varies strongly across parameter space. Several arguments then suggest that environmental quenching and mass quenching may be different manifestations of the same underlying process. The marked difference in the apparent mass dependencies of environment quenching and mass quenching which produces distinctive signatures in the mass functions of centrals and satellites will arise naturally, since, for satellites at least, the distributions of the environmental variables that we investigate in this work are essentially independent of the stellar mass of the satellite

  2. Subcellular dynamics of T cell immunological synapses and kinapses in lymph nodes

    OpenAIRE

    Azar, Georges A.; Lemaître, Fabrice; Robey, Ellen A.; Bousso, Philippe

    2010-01-01

    In vitro studies have revealed that T cell activation occurs during the formation of either dynamic or stable interactions with antigen-presenting cells (APC), and the respective cell junctions have been referred to as immunological kinapses and synapses. However, the relevance and molecular dynamics of kinapses and synapses remain to be established in vivo. Using two-photon imaging, we tracked the distribution of LAT-EGFP molecules during antigen recognition by activated CD4+ T cells in lymp...

  3. The Dendritic Cell Synapse: A Life Dedicated to T Cell Activation.

    Science.gov (United States)

    Benvenuti, Federica

    2016-01-01

    T-cell activation within immunological synapses is a complex process whereby different types of signals are transmitted from antigen-presenting cells to T cells. The molecular strategies developed by T cells to interpret and integrate these signals have been systematically dissected in recent years and are now in large part understood. On the other side of the immune synapse, dendritic cells (DCs) participate actively in synapse formation and maintenance by remodeling of membrane receptors and intracellular content. However, the details of such changes have been only partially characterized. The DCs actin cytoskeleton has been one of the first systems to be identified as playing an important role in T-cell priming and some of the underlying mechanisms have been elucidated. Similarly, the DCs microtubule cytoskeleton undergoes major spatial changes during synapse formation that favor polarization of the DCs subcellular space toward the interacting T cell. Recently, we have begun to investigate the trafficking machinery that controls polarized delivery of endosomal vesicles at the DC-T immune synapse with the aim of understanding the functional relevance of polarized secretion of soluble factors during T-cell priming. Here, we will review the current knowledge of events occurring in DCs during synapse formation and discuss the open questions that still remain unanswered. PMID:27014259

  4. What controls star formation in the central 500 pc of the Galaxy?

    CERN Document Server

    Kruijssen, J M Diederik; Elmegreen, Bruce G; Murray, Norman; Bally, John; Testi, Leonardo; Kennicutt, Robert C

    2013-01-01

    The star formation rate (SFR) in the Central Molecular Zone (CMZ, i.e. the central 500 pc) of the Milky Way is lower by a factor of >10 than expected for the substantial amount of dense gas it contains, which challenges current star formation theories. In this paper, we quantify which physical mechanisms could be causing this observation. On scales larger than the disc scale height, the low SFR is found to be consistent with episodic star formation due to secular instabilities or variations of the gas inflow along the Galactic bar. The CMZ is marginally Toomre-stable when including gas and stars, but highly Toomre-stable when only accounting for the gas, indicating that the condensation of self-gravitating clouds may be limited. On small scales, we find that the SFR in the CMZ is consistent with an elevated critical density for star formation due to the high turbulent pressure - potentially aided by weak magnetic effects and an underproduction of massive stars due to a bottom-heavy IMF. The existence of a uni...

  5. Stratigraphy and depositional environments of Catahoula Formation sandstones and associated facies in south-central Mississippi

    Energy Technology Data Exchange (ETDEWEB)

    Cameron, C.P. (Univ. of Southern Mississippi, Hattiesburg (USA)); Day, L.A. (Geraghty and Miller, Baton Rouge, LA (USA))

    1990-09-01

    Surface and subsurface studies of the Catahoula Formation in a seven county area of south-central Mississippi have revealed major problems and misconceptions regarding Neogene stratigraphy and geological mapping in this part of the Gulf basin. The results of these investigations show that the traditional stratigraphic subdivisions of the up-dip Neogene section in Mississippi are invalid, and that the fundamental criteria for defining rock stratigraphic units at the formation rank are nonexistent. Although the base of the Neogene section is reasonably well defined by virtue of its relatively continuous contact with the Bucatunna Formation (Oligocene Vicksburg Group), a mappable bounding sequence above the Catahoula-Bucatunna Formation contact does not exist in the study area. An overall fine-grained interval above the Catahoula Formation appears to wedge out before reaching outcrop. Hence, differentiation between up-dip sandy gravels of the Catahoula and similar facies of the Citronelle Formation is difficult. Further complicating the problem of stratigraphic unit discrimination is the discovery of sandy gravels within the Hattiesburg Formation interval. A subsurface analysis in this study area revealed that the Catahoula Formation, as defined by Day, attains a thickness of 625 ft and has a rough three-tiered stratigraphy: (a) a basal unit composed of sands and subordinate fine-grained facies; (b) a relatively fine-grained middle unit composed of silts and clays with recurrent, discontinuous, sand bodies; and (c) an upper unit composed largely of sand and gravels. This study confirmed that most of these sediments are the product of fluvial channel and associated floodplain deposition. However, in the basal unit deltaic facies appear to be preserved on outcrop in Smith County and perhaps in a mild structural depression in the southwest portion of the study area.

  6. CHARACTERIZATION AND FORMATION MECHANISM OF THE CENTRAL UPLIFT OF THE QIANGTANG BASIN

    Institute of Scientific and Technical Information of China (English)

    YIN Fuguang

    2004-01-01

    The Qiangtang basin is located between Kekexili-Jingshajiang suture belt and Bangong-Lujiang suture belt, and is divided into the north part and south part by the central uplift that has no crop out of Mesozoic strata. When the Jinshajiang Ocean was closed, the subducting plate was subducted southward. In the central part of the Qiangtang basin, the cushioning effect of the asthenosphere resulted in the thermal doming of the mantle and subsequent large-scale anatexis. Mantle source materials and antectic materials were upwelled and extruded into the middle crust, leading to the thickening of the middle crust and the heating and weakening of the middle to upper crust, and resulting in the rapid deformation (detachment) and tectonic erosion, and in the isostatic uplifting and the formation of metamorphic core complex. The upwelling of anatectic materials would further enhance the buoyant repercussion, which would combine with the side stress due from extrusion in resulting in the formation of an extensional stress field. The extensional structure and detachment fault are formed under the influence of the losing stabilized gravitation. In the deformation area in both the upper part and the lower part, an extensional deposition area would be formed, and this is the generation of a new basin.The metamorphic core complex of the central uplift is comprised of gneiss, which is itself overlain by non-metamorphic to weakly metamorphic covering strata intersected by faults.

  7. Molecular Gas and Star Formation Properties in the Central and Bar Regions of NGC 6946

    CERN Document Server

    Pan, Hsi-An; Koda, Jin; Hirota, Akihiko; Sorai, Kazuo; Kaneko, Hiroyuki

    2015-01-01

    In this work, we investigate the molecular gas and star formation properties in the barred spiral galaxy NGC 6946 using multiple molecular lines and star formation tracers. High-resolution image (100 pc) of $^{13}$CO (1-0) is created by single dish NRO45 and interferometer CARMA for the inner 2 kpc disk, which includes the central region (nuclear ring and bar) and the offset ridges of the primary bar. Single dish HCN (1-0) observations were also made to constrain the amount of dense gas. Physical properties of molecular gas are inferred by (1) the Large Velocity Gradient (LVG) calculations using our observations and archival $^{12}$CO (1-0), $^{12}$CO(2-1) data, (2) dense gas fraction suggested by HCN to $^{12}$CO (1-0) luminosity ratio, and (3) infrared color. The results show that the molecular gas in the central region is warmer and denser than that of the offset ridges. Dense gas fraction of the central region is similar with that of LIRGs/ULIRGs, while the offset ridges are close to the global average of...

  8. Paleotectonic controls on deposition of upper Upper Jurassic La Casita Formation, east-central Chihuahua, Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, D.C.

    1989-03-01

    Surface mapping of the basal Mesozoic La Casita Formation (upper Upper Jurassic) in east-central Chihuahua, Mexico, indicates initial Mesozoic sedimentation occurred in a segmented, interconnected subbasin of the Chihuahua trough. La Casite Formation (1200 m thick) is a tectonostratigraphic unit resting with angular unconformity on the Lower Permian Plomosas Formation. It consists primarily of siliciclastic material with sporadic interbedded limestones. The dominant lithofacies, approximately 1000 m thick, consists of turbiditic sandstone units (10-20 m) alternating with thicker, monotonous shale sequences. In the mapped area (approximately 30 km/sup 2/), flute cast measurements indicate flows from both the northeast (N20/degree/E) and southwest (S58/degree/W). Turbiditic sandstone units appear to pinch out and/or interfinger as they extend from the north and south into the central portion of the area. The initial opening of the Chihuahua trough is often associated with Late Jurassic block faulting, related to development of the ancestral Gulf of Mexico. Synrift depositional sequences of a similar age have been described in southern Coahuila, northern Zacatecas, and western Chiapas, Mexico. The subbasin (graben ) examined here may be ascribed a paleoposition near the western edge of the early Chihuahua trough. The western boundary of the early trough may have comprised a series of these subbasins, forming a cuspate or serrated coastline. Late Jurassic ammonites recovered from this and other localities along the length of the Chihuahua trough suggest that the subbasins were interconnected by means of an eastern continuous seaway.

  9. The adhesion protein IgSF9b is coupled to neuroligin 2 via S-SCAM to promote inhibitory synapse development

    OpenAIRE

    Woo, Jooyeon; Kwon, Seok-Kyu; Nam, Jungyong; Choi, Seungwon; Takahashi, Hideto; Krueger, Dilja; Park, Joohyun; Lee, Yeunkum; Bae, Jin Young; Lee, Dongmin; Ko, Jaewon; Kim, Hyun; Kim, Myoung-Hwan; Bae, Yong Chul; Chang, Sunghoe

    2013-01-01

    Synaptic adhesion molecules regulate diverse aspects of synapse formation and maintenance. Many known synaptic adhesion molecules localize at excitatory synapses, whereas relatively little is known about inhibitory synaptic adhesion molecules. Here we report that IgSF9b is a novel, brain-specific, homophilic adhesion molecule that is strongly expressed in GABAergic interneurons. IgSF9b was preferentially localized at inhibitory synapses in cultured rat hippocampal and cortical interneurons an...

  10. Efficient Associative Computation with Discrete Synapses.

    Science.gov (United States)

    Knoblauch, Andreas

    2016-01-01

    Neural associative networks are a promising computational paradigm for both modeling neural circuits of the brain and implementing associative memory and Hebbian cell assemblies in parallel VLSI or nanoscale hardware. Previous work has extensively investigated synaptic learning in linear models of the Hopfield type and simple nonlinear models of the Steinbuch/Willshaw type. Optimized Hopfield networks of size n can store a large number of about n(2)/k memories of size k (or associations between them) but require real-valued synapses, which are expensive to implement and can store at most C = 0.72 bits per synapse. Willshaw networks can store a much smaller number of about n(2)/k(2) memories but get along with much cheaper binary synapses. Here I present a learning model employing synapses with discrete synaptic weights. For optimal discretization parameters, this model can store, up to a factor ζ close to one, the same number of memories as for optimized Hopfield-type learning--for example, ζ = 0.64 for binary synapses, ζ = 0.88 for 2 bit (four-state) synapses, ζ = 0.96 for 3 bit (8-state) synapses, and ζ > 0.99 for 4 bit (16-state) synapses. The model also provides the theoretical framework to determine optimal discretization parameters for computer implementations or brainlike parallel hardware including structural plasticity. In particular, as recently shown for the Willshaw network, it is possible to store C(I) = 1 bit per computer bit and up to C(S) = log n bits per nonsilent synapse, whereas the absolute number of stored memories can be much larger than for the Willshaw model. PMID:26599711

  11. Stratigraphy, sedimentology and paleontology of lower Eocene San Jose formation, central San Juan basin, New Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Lucas, S.G.; Smith, L.N. (New Mexico Museum of Natural History, Albuquerque (USA))

    1989-09-01

    The lower Eocene San Jose Formation in the central portion of the San Juan basin (Gobernador-Vigas Canyon area) consists of the Cuba Mesa, Regina, Llaves, and Tapicitos Members. Well log data indicate that, from its 100-m thickness, the Cuba Mesa Member thins toward the basin center and pinches out to the northeast by lat. 36{degree}40'N, long. 107{degree}19'W. The Regina Member has the most extensive outcrops in the central basin, and it decreases in sandstone/mud rock ratio to the north. The Llaves and Tapicitos Members occur only at the highest elevations, are thin due to erosion, and are not mappable as separate units. Well log data and 1,275 m of measured stratigraphic section in the Regina, Llaves, and Tapicitos Members indicate these strata are composed of approximately 35% medium to coarse-grained sandstone and 65% fine-grained sandstone and mud rock. Sedimentology and sediment-dispersal patterns indicate deposition by generally south-flowing streams that had sources to the northwest, northeast, and east. Low-sinuosity, sand-bedded, braided( ) streams shifted laterally across about 1 km-wide channel belts to produce sheet sandstones that are prominent throughout the San Jose Formation. Subtle levees separated channel environments from floodplain and local lacustrine areas. Avulsion relocated channels periodically to areas on the floodplain, resulting in the typically disconnected sheet sandstones within muddy overbank deposits of the Regina Member.

  12. Understanding the Structure and Function of the Immunological Synapse

    OpenAIRE

    Dustin, Michael L.; Chakraborty, Arup K.; Shaw, Andrey S

    2010-01-01

    The immunological synapse has been an area of very active scientific interest over the last decade. Surprisingly, much about the synapse remains unknown or is controversial.  Here we review some of these current issues in the field:  how the synapse is defined, its potential role in T-cell function, and our current understanding about how the synapse is formed.

  13. SynDB: a Synapse protein DataBase based on synapse ontology

    OpenAIRE

    Zhang, Wuxue; Zhang, Yong; Zheng, Hui; Zhang, Chen; Xiong, Wei; Olyarchuk, John G.; Walker, Michael; Xu, Weifeng; Zhao, Min; Zhao, Shuqi; Zhou, Zhuan; Wei, Liping

    2006-01-01

    A synapse is the junction across which a nerve impulse passes from an axon terminal to a neuron, muscle cell or gland cell. The functions and building molecules of the synapse are essential to almost all neurobiological processes. To describe synaptic structures and functions, we have developed Synapse Ontology (SynO), a hierarchical representation that includes 177 terms with hundreds of synonyms and branches up to eight levels deep. associated 125 additional protein keywords and 109 InterPr...

  14. The chemical component of the mixed GF-TTMn synapse in Drosophila melanogaster uses acetylcholine as its neurotransmitter

    OpenAIRE

    Allen, Marcus J.; Murphey, R K

    2007-01-01

    The largest central synapse in adult Drosophila is a mixed electro-chemical synapse whose gap junctions require the product of the shaking-B (shak-B) gene. Shak-B 2 mutant flies lack gap junctions at this synapse, which is between the giant fibre (GF) and the tergotrochanteral motor neuron (TTMn), but it still exhibits a long latency response upon GF stimulation. We have targeted the expression of the light chain of tetanus toxin to the GF, to block chemical transmission, in shak-B 2 flies. T...

  15. A Gata3-Mafb transcriptional network directs post-synaptic differentiation in synapses specialized for hearing.

    Science.gov (United States)

    Yu, Wei-Ming; Appler, Jessica M; Kim, Ye-Hyun; Nishitani, Allison M; Holt, Jeffrey R; Goodrich, Lisa V

    2013-01-01

    Information flow through neural circuits is determined by the nature of the synapses linking the subtypes of neurons. How neurons acquire features distinct to each synapse remains unknown. We show that the transcription factor Mafb drives the formation of auditory ribbon synapses, which are specialized for rapid transmission from hair cells to spiral ganglion neurons (SGNs). Mafb acts in SGNs to drive differentiation of the large postsynaptic density (PSD) characteristic of the ribbon synapse. In Mafb mutant mice, SGNs fail to develop normal PSDs, leading to reduced synapse number and impaired auditory responses. Conversely, increased Mafb accelerates synaptogenesis. Moreover, Mafb is responsible for executing one branch of the SGN differentiation program orchestrated by the Gata3 transcriptional network. Remarkably, restoration of Mafb rescues the synapse defect in Gata3 mutants. Hence, Mafb is a powerful regulator of cell-type specific features of auditory synaptogenesis that offers a new entry point for treating hearing loss. DOI: http://dx.doi.org/10.7554/eLife.01341.001. PMID:24327562

  16. A new measure for the strength of electrical synapses

    Directory of Open Access Journals (Sweden)

    Julie S Haas

    2015-09-01

    Full Text Available Electrical synapses, like chemical synapses, mediate intraneuronal communication. Electrical synapses are typically quantified by subthreshold measurements of coupling, which fall short in describing their impact on spiking activity in coupled neighbors. Here we describe a novel measurement for electrical synapse strength that directly evaluates the effect of synaptically transmitted activity on spike timing. This method, also applicable to neurotransmitter-based synapses, communicates the considerable strength of electrical synapses. For electrical synapses measured in rodent slices of the thalamic reticular nucleus, spike timing is modulated by tens of ms by activity in a coupled neighbor.

  17. Presenilin/γ-secretase regulates neurexin processing at synapses.

    Directory of Open Access Journals (Sweden)

    Carlos A Saura

    Full Text Available Neurexins are a large family of neuronal plasma membrane proteins, which function as trans-synaptic receptors during synaptic differentiation. The binding of presynaptic neurexins to postsynaptic partners, such as neuroligins, has been proposed to participate in a signaling pathway that regulates synapse formation/stabilization. The identification of mutations in neurexin genes associated with autism and mental retardation suggests that dysfunction of neurexins may underlie synaptic defects associated with brain disorders. However, the mechanisms that regulate neurexin function at synapses are still unclear. Here, we show that neurexins are proteolytically processed by presenilins (PS, the catalytic components of the γ-secretase complex that mediates the intramembraneous cleavage of several type I membrane proteins. Inhibition of PS/γ-secretase by using pharmacological and genetic approaches induces a drastic accumulation of neurexin C-terminal fragments (CTFs in cultured rat hippocampal neurons and mouse brain. Neurexin-CTFs accumulate mainly at the presynaptic terminals of PS conditional double knockout (PS cDKO mice lacking both PS genes in glutamatergic neurons of the forebrain. The fact that loss of PS function enhances neurexin accumulation at glutamatergic terminals mediated by neuroligin-1 suggests that PS regulate the processing of neurexins at glutamatergic synapses. Interestingly, presenilin 1 (PS1 is recruited to glutamatergic terminals mediated by neuroligin-1, thus concentrating PS1 at terminals containing β-neurexins. Furthermore, familial Alzheimer's disease (FAD-linked PS1 mutations differentially affect β-neurexin-1 processing. Expression of PS1 M146L and PS1 H163R mutants in PS-/- cells rescues the processing of β-neurexin-1, whereas PS1 C410Y and PS1 ΔE9 fail to rescue the processing defect. These results suggest that PS regulate the synaptic function and processing of neurexins at glutamatergic synapses, and that

  18. The Diversity of Cortical Inhibitory Synapses

    Directory of Open Access Journals (Sweden)

    Yoshiyuki eKubota

    2016-04-01

    Full Text Available The most typical and well known inhibitory action in the cortical microcircuit is a strong inhibition on the target neuron by axo-somatic synapses. However, it has become clear that synaptic inhibition in the cortex is much more diverse and complicated. Firstly, at least ten or more inhibitory non-pyramidal cell subtypes engage in diverse inhibitory functions to produce the elaborate activity characteristic of the different cortical states. Each distinct non-pyramidal cell subtype has its own independent inhibitory function. Secondly, the inhibitory synapses innervate different neuronal domains, such as axons, spines, dendrites and soma, and their IPSP size is not uniform. Thus cortical inhibition is highly complex, with a wide variety of anatomical and physiological modes. Moreover, the functional significance of the various inhibitory synapse innervation styles and their unique structural dynamic behaviors differ from those of excitatory synapses. In this review, we summarize our current understanding of the inhibitory mechanisms of the cortical microcircuit.

  19. Aging of cholinergic synapses: fiction or reality?

    International Nuclear Information System (INIS)

    The authors make use of the ciliary ganglion iris preparation of the aging chicken as a model of senescent peripheral cholinergic synapses. Based on the studies performed on the iris, an hypothesis of aging of the cholinergic synapse has been suggested. In order to establish the nature of a deficit, the authors examine the ability of chloinergic synapses in the iris at various ages to take up the precursor tritium-choline and release the formed tritium-ACh in response to high K+ (115 mM) depolarization. A summary of preliminary results of morphometric analysis of nerve endings and synaptic components in the iris of young adult and aged chickens is shown. The experiments suggest that severe changes may occur at later stages of life. A specific functional defect in the cholinergic synapse during aging is found

  20. Sedimentary characteristics of tide-dominated estuary in Donghetang Formation(Upper Devonian), central Tarim Basin

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The Donghetang Formation (Upper Devonian) in central Tarim Basin has been thought an important oil and gas reservoir since the abundant oil and gas resources were found in the wells W16, W20, W34, and other fields. However, the sedimentary environment of the Donghetang Formation has been disputed because it suffered from both tidal and fluvial actions and there were not rich fossils in the sandstone. After the authors analyzed sedimentary features by means of drill cores, well logging data, paleosols, and with SEM obseruations, three kinds of sedimentary environments were distinguished: alluvial fan, tide-dominated estuary, and shelf. Particularly, the sedimentary features of tide-dominated estuary were studied in detail. Besides, the authors discussed sedimentary characteristics of the Donghetang Formation which was divided into two fourth-order sequences and five system tracts. At the same time, according to the forming process of five system tracts, the whole vertical evolution and lateral transition of tide-dominated estuary were illustrated clearly. Finally, the reservoir quality was evaluated based on porosity and permeability.

  1. A single-transistor silicon synapse

    OpenAIRE

    Diorio, Chris; Hasler, Paul; Minch, Bradley A.; Mead, Carver A.

    1996-01-01

    We have developed a new floating-gate silicon MOS transistor for analog learning applications. The memory storage is nonvolatile; hot-electron injection and electron tunneling permit bidirectional memory updates. Because these updates depend on both the stored memory value and the transistor terminal voltages, the synapse can implement a learning function. We have derived a memory-update rule from the physics of the tunneling and injection processes, and have investigated synapse learning in ...

  2. A new measure for the strength of electrical synapses

    OpenAIRE

    Haas, Julie S.

    2015-01-01

    Electrical synapses, like chemical synapses, mediate intraneuronal communication. Electrical synapses are typically quantified by subthreshold measurements of coupling, which fall short in describing their impact on spiking activity in coupled neighbors. Here, we describe a novel measurement for electrical synapse strength that directly evaluates the effect of synaptically transmitted activity on spike timing. This method, also applicable to neurotransmitter-based synapses, communicates the c...

  3. Biofilm Formation by Gram-Negative Bacteria on Central Venous Catheter Connectors: Effect of Conditioning Films in a Laboratory Model

    OpenAIRE

    Murga, R.; Miller, J.M.; Donlan, R. M.

    2001-01-01

    Human blood components have been shown to enhance biofilm formation by gram-positive bacteria. We investigated the effect of human blood on biofilm formation on the inner lumen of needleless central venous catheter connectors by several gram-negative bacteria, specifically Enterobacter cloacae, Pseudomonas aeruginosa, and Pantoea agglomerans. Results suggest that a conditioning film of blood components promotes biofilm formation by these organisms in an in vitro system.

  4. Oceanic crust formation in the Egeria Fracture Zone Complex (Central Indian Ocean)

    Science.gov (United States)

    Le Minor, Marine; Gaina, Carmen; Sigloch, Karin; Minakov, Alexander

    2016-04-01

    This study aims to analyse in detail the oceanic crust fabric and volcanic features (seamounts) formed for the last 10 million years at the Central Indian Ridge between 19 and 21 latitude south. Multibeam bathymetry and magnetic data has been collected in 2013 as part of the French-German expedition RHUM-RUM (Reunion hotspot and upper mantle - Reunion's unterer mantel). Three long profiles perpendicular on the Central Indian Ridge (CIR), south of the Egeria fracture zone, document the formation of oceanic crust since 10 million years, along with changes in plate kinematics and variations in the magmatic input. We have inspected the abyssal hill geometry and orientation along conjugate oceanic flanks and within one fracture zone segment where we could identify J-shaped features that are indicators of changes in plate kinematics. The magnetic anomaly data shows a slight asymmetry in seafloor spreading rates on conjugate flanks: while a steady increase in spreading rate from 10 Ma to the present is shown by the western flank, the eastern part displays a slowing down from 5 Ma onwards. The deflection of the anti J-shaped abyssal hill lineations suggest that the left-stepping Egeria fracture zone complex (including the Egeria, Flinders and an un-named fracture zone to the southeast) was under transpression from 9 to 6 Ma and under transtension since 3 Ma. The transpressional event was triggered by a clockwise mid-ocean ridge reorientation and a decrease of its offset, whereas the transtensional regime was probably due to a counter-clockwise change in the spreading direction and an increase of the ridge offset. The new multibeam data along the three profiles reveal that crust on the eastern side is smoother (as shown by the abyssal hill number and structure) and hosts several seamounts (with age estimations of 7.67, 6.10 and 0.79 Ma), in contrast to the rougher conjugate western flank. Considering that the western flank was closer to the Reunion plume, and therefore

  5. Artificial Synapses: Organometal Halide Perovskite Artificial Synapses (Adv. Mater. 28/2016).

    Science.gov (United States)

    Xu, Wentao; Cho, Himchan; Kim, Young-Hoon; Kim, Young-Tae; Wolf, Christoph; Park, Chan-Gyung; Lee, Tae-Woo

    2016-07-01

    A synapse-emulating electronic device based on organometal halide perovskite thin films is described by T.-W. Lee and co-workers on page 5916. The device successfully emulates important characteristics of a biological synapse. This work extends the application of organometal halide perovskites to bioinspired electronic devices, and contributes to the development of neuromorphic electronics. PMID:27442971

  6. Central Role of Maladapted Astrocytic Plasticity in Ischemic Brain Edema Formation.

    Science.gov (United States)

    Wang, Yu-Feng; Parpura, Vladimir

    2016-01-01

    Brain edema formation and the ensuing brain damages are the major cause of high mortality and long term disability following the occurrence of ischemic stroke. In this process, oxygen and glucose deprivation and the resulting reperfusion injury play primary roles. In response to the ischemic insult, the neurovascular unit experiences both intracellular and extracellular edemas, associated with maladapted astrocytic plasticity. The astrocytic plasticity includes both morphological and functional plasticity. The former involves a reactive gliosis and the subsequent glial retraction. It relates to the capacity of astrocytes to buffer changes in extracellular chemical levels, particularly K(+) and glutamate, as well as the integrity of the blood-brain barrier (BBB). The latter involves the expression and activity of a series of ion and water transport proteins. These molecules are grouped together around glial fibrillary acidic protein (GFAP) and water channel protein aquaporin 4 (AQP4) to form functional networks, regulate hydromineral balance across cell membranes and maintain the integrity of the BBB. Intense ischemic challenges can disrupt these capacities of astrocytes and result in their maladaptation. The maladapted astrocytic plasticity in ischemic stroke cannot only disrupt the hydromineral homeostasis across astrocyte membrane and the BBB, but also leads to disorders of the whole neurovascular unit. This review focuses on how the maladapted astrocytic plasticity in ischemic stroke plays the central role in the brain edema formation. PMID:27242440

  7. Central role of maladapted astrocytic plasticity in ischemic brain edema formation

    Directory of Open Access Journals (Sweden)

    Yu-Feng eWang

    2016-05-01

    Full Text Available Brain edema formation and the ensuing brain damages are the major cause of high mortality and long term disability following the occurrence of ischemic stroke. In this process, oxygen and glucose deprivation and the ensuing reperfusion injury play primary roles. In response to the ischemic insult, the neurovascular unit experiences both intracellular and extracellular edemas; the two processes are interactive closely under the driving of maladapted astrocytic plasticity. The astrocytic plasticity includes both morphologic and functional plasticity. The former involves a reactive gliosis and the ensuing glial retraction. It relates to the capacity of astrocytes to buffer changes in extracellular chemical levels, particularly K+ and glutamate, as well as the integrity of the blood-brain barrier. The latter involves the expression and activity of a series of ion and water transport proteins. These molecules are grouped together around glial fibrillary acidic protein and water channel protein aquaporin 4 to form functional networks, regulate hydromineral balance across cell membranes and maintain the integrity of the blood-brain barrier. Intense ischemic challenges can disrupt these capacities of astrocytes and result in their maladaptation. The maladapted astrocytic plasticity in ischemic stroke cannot only disrupt the hydromineral homeostasis across astrocyte membrane and the blood-brain barrier, but also lead to disorders of the whole neurovascular unit. This review focuses on how the maladapted astrocytic plasticity in ischemic stroke plays the central role in the brain edema formation.

  8. Extracellular proteolysis in structural and functional plasticity of mossy fiber synapses in hippocampus

    Directory of Open Access Journals (Sweden)

    Grzegorz eWiera

    2015-11-01

    Full Text Available Brain is continuously altered in response to experience and environmental changes. One of the underlying mechanisms is synaptic plasticity, which is manifested by modification of synapse structure and function. It is becoming clear that regulated extracellular proteolysis plays a pivotal role in the structural and functional remodeling of synapses during brain development, learning and memory formation. Clearly, plasticity mechanisms may substantially differ between projections. Mossy fiber synapses onto CA3 pyramidal cells display several unique functional features, including pronounced short-term facilitation, a presynaptically expressed LTP that is independent of NMDAR activation, and NMDA-dependent metaplasticity. Moreover, structural plasticity at mossy fiber synapses ranges from the reorganization of projection topology after hippocampus-dependent learning, through intrinsically different dynamic properties of synaptic boutons to pre- and postsynaptic structural changes accompanying LTP induction. Although concomitant functional and structural plasticity in this pathway strongly suggests a role of extracellular proteolysis, its impact only starts to be investigated in this projection. In the present report, we review the role of extracellular proteolysis in various aspects of synaptic plasticity in hippocampal mossy fiber synapses. A growing body of evidence demonstrates that among perisynaptic proteases, tPA/plasmin system, β-site amyloid precursor protein-cleaving enzyme 1 (BACE1 and metalloproteinases play a crucial role in shaping plastic changes in this projection. We discuss recent advances and emerging hypotheses on the roles of proteases in mechanisms underlying mossy fiber target specific synaptic plasticity and memory formation.

  9. Effects of Trace Metal Profiles Characteristic for Autism on Synapses in Cultured Neurons

    Directory of Open Access Journals (Sweden)

    Simone Hagmeyer

    2015-01-01

    Full Text Available Various recent studies revealed that biometal dyshomeostasis plays a crucial role in the pathogenesis of neurological disorders such as autism spectrum disorders (ASD. Substantial evidence indicates that disrupted neuronal homeostasis of different metal ions such as Fe, Cu, Pb, Hg, Se, and Zn may mediate synaptic dysfunction and impair synapse formation and maturation. Here, we performed in vitro studies investigating the consequences of an imbalance of transition metals on glutamatergic synapses of hippocampal neurons. We analyzed whether an imbalance of any one metal ion alters cell health and synapse numbers. Moreover, we evaluated whether a biometal profile characteristic for ASD patients influences synapse formation, maturation, and composition regarding NMDA receptor subunits and Shank proteins. Our results show that an ASD like biometal profile leads to a reduction of NMDAR (NR/Grin/GluN subunit 1 and 2a, as well as Shank gene expression along with a reduction of synapse density. Additionally, synaptic protein levels of GluN2a and Shanks are reduced. Although Zn supplementation is able to rescue the aforementioned alterations, Zn deficiency is not solely responsible as causative factor. Thus, we conclude that balancing Zn levels in ASD might be a prime target to normalize synaptic alterations caused by biometal dyshomeostasis.

  10. Effects of the Geometry of the Immunological Synapse on the Delivery of Effector Molecules

    OpenAIRE

    Coombs, Daniel; Goldstein, Byron

    2004-01-01

    Recent experiments focusing on the function of the immunological synapse formed between a T cell and an antigen-presenting cell raise many questions about its purpose. We examine the proposal that the close apposition of the cell membranes in the central region of the synapse acts to focus T-cell secretions on the target cell, thus reducing the effect on nearby cells. We show that the efficiency of targeted T-cell responses to closely apposed cells is only weakly dependent on the distance bet...

  11. Modeling synaptic transmission of the tripartite synapse

    Science.gov (United States)

    Nadkarni, Suhita; Jung, Peter

    2007-03-01

    The tripartite synapse denotes the junction of a pre- and postsynaptic neuron modulated by a synaptic astrocyte. Enhanced transmission probability and frequency of the postsynaptic current-events are among the significant effects of the astrocyte on the synapse as experimentally characterized by several groups. In this paper we provide a mathematical framework for the relevant synaptic interactions between neurons and astrocytes that can account quantitatively for both the astrocytic effects on the synaptic transmission and the spontaneous postsynaptic events. Inferred from experiments, the model assumes that glutamate released by the astrocytes in response to synaptic activity regulates store-operated calcium in the presynaptic terminal. This source of calcium is distinct from voltage-gated calcium influx and accounts for the long timescale of facilitation at the synapse seen in correlation with calcium activity in the astrocytes. Our model predicts the inter-event interval distribution of spontaneous current activity mediated by a synaptic astrocyte and provides an additional insight into a novel mechanism for plasticity in which a low fidelity synapse gets transformed into a high fidelity synapse via astrocytic coupling.

  12. Graben formation during the Bárðarbunga rifting event in central Iceland

    KAUST Repository

    Ruch, Joel

    2015-04-01

    On the 16th of August 2014, an intense seismic swarm was detected at the Bárðarbunga caldera (central Iceland), which migrated to the east and then to the northeast during the following days. The swarm, highlighting magma propagation pathway from the caldera, migrated laterally during the following two weeks over 40 km. By the end of August, a volcanic eruption had started along a north-south oriented fissure located ~45 km from the caldera. Here we focus on the near-field deformation related to the dike emplacement in the shallow crust, which generated in few days an 8 km long by 0.8 km wide graben (depression) structure. The new graben extends from the northern edge of the Vatnajökull glacier and to the north to the eruptive fissure. We analyze the temporal evolution of the graben by integrating structural mapping using multiple acquisitions of TerraSAR-X amplitude radar images, InSAR and ground-truth data with GPS and structural measurements. Pixel-offset tracking of radar amplitude images shows clearly the graben subsidence, directly above the intrusion pathway, of up to 6 meters in the satellite line-of-sight direction. We installed a GPS profile of 15 points across the graben in October 2014 and measured its depth up to 8 meters, relative to the flanks of the graben. Field structural observations show graben collapse structures that typically accompany dike intrusions, with two tilted blocks dipping toward the graben axis, bordered by two normal faults. Extensive fractures at the center of the graben and at the graben edges show a cumulative extension of ~8 meters. The formation of the graben was also accompanied by strong seismic activity locally, constraining the time frame period of the main graben formation subsidence. Our results show a rare case of a graben formation captured from space and from ground observations. Such structures are the dominant features along rift zones, however, their formation remain poorly understood. The results also provide

  13. The Nogo Receptor Family Restricts Synapse Number in the Developing Hippocampus

    OpenAIRE

    Wills, Zachary P.; Mandel-Brehm, Caleigh; Mardinly, Alan R.; McCord, Alejandra E.; Giger, Roman J.; Greenberg, Michael E.

    2012-01-01

    Neuronal development is characterized by a period of exuberant synaptic growth that is well studied. However, the mechanisms that restrict this process are less clear. Here we demonstrate that glycosyl-phosphatidylinositol-anchored cell-surface receptors of the Nogo Receptor family (NgR1, NgR2, and NgR3) restrict excitatory synapse formation. Loss of any one of the NgRs results in an increase in synapse number in vitro, whereas loss of all three is necessary for abnormally elevated synaptogen...

  14. Palynostratigraphy of the Nayband Formation, Tabas, Central Iran Basin: Paleogeographical and paleoecological implications

    Science.gov (United States)

    Sajjadi, F.; Hashemi, H.; Borzuee, E.

    2015-11-01

    Reasonably diverse and moderately preserved palynofloras of exclusively terrestrial derivation occur in surface samples of the Nayband Formation, Kamar Macheh Kuh, southeastern Tabas, east-central Iran. No marine palynomorphs encountered in the samples examined. The palynofloras comprise 62 species including radially symmetrical and monolete spores (37 species allocated to 27 genera) and pollen (25 species designated to 19 genera). Of the latter, such bisaccate taxa as Ovalipollis ovalis, Alisporites spp., Falcisporites nuthallensis, the inaperturate Araucariacites australis, and the monosulcate Chasmatosporites major dominate the assemblages. Representatives of such trilete spores as Dictyophyllidites mortonii, Kyrtomisporis laevigatus, and Gleicheiniidites senonicus are essentially abundant in the palynofloras examined. Vertical distribution of miospores allows erection within the Nayband Formation of three informal distinctive stratigraphically successive interval biozones, viz., A. australis-Annulispora folliculosa biozone, Conbaculatisporites sp.-Ricciisporites tuberculatus biozone, and R. tuberculatus-Polypodiisporites polymicroforatus biozone based on the First Observed Occurrence (FOO) and Last Observed Occurrence (LOO) of selected taxa. These are compared with palynozones from ±coeval strata in Iran and elsewhere. Additionally, two non-palyniferous intervals, one at the base (188 m thick) and another (18 m in thickness) at uppermost part of the section studied are identified. Based on the association of such key misopore species as Lunatisporites rhaeticus, O. ovalis (alias pseudoalatus), A. folliculosa, Polycingulatisporites mooniensis, Limbosporites lundbladii, Quadraeculina anellaeformis, R. tuberculatus, Conbaculatisporites sp., P. polymicroforatus, and Striatisaccus novimundi within the Nayband palynofloras, the host strata are assigned to Late Triassic (Norian-Rhaetian). This dating while corroborating previous attempts made with reference to mostly

  15. Stratigraphy, geochronology, geochemistry and tectonic setting of the Mesozoic Nazas Formation, north-central Mexico

    Science.gov (United States)

    Bartolini, Claudio

    Late Triassic to Middle Jurassic volcanic-sedimentary sequences that were part of the Mesozoic continental-margin of western North America are exposed in northern and central Mexico. These sequences have been grouped into the Nazas Formation and crop out in the states of Durango, Coahuila, Zacatecas, and San Luis Potosi. The Nazas Formation consists of 2,500 m or more of volcanic and pyroclastic rocks and interbedded clastic sedimentary rocks that were deposited in alluvial fan and fluvial depositional systems that developed in intra-arc basins, mainly fault-bound grabens and topographic depressions within an extending Mesozoic volcanic arc. Major and trace element geochemistry of volcanic rocks suggests that the volcanic suite is calc-alkaline and includes rhyolite, dacite, rhyodacite, andesite, trachyandesite and rare basalt. Pyroclastic rocks are basically air-fall tuffs and volcanic breccias. The sedimentary strata include conglomerate, sandstone, shale, and siltstone, locally red in color. Geochronology (Ar-Ar, K-Ar and Rb-Sr) and field evidence indicate that the age of the Nazas Formation ranges from Late Triassic to Middle Jurassic, but the peak of arc volcanism appears to be Early and Middle Jurassic. The Mesozoic magmatic arc in Mexico has a northwest trend and extends from Sonora to Chiapas. The arc structure is more than 2,000 km long, and possibly up to 150 km wide. The width of the arc is uncertain due to the limited number of surface outcrops, however, it did not extend east into the Gulf of Mexico. Arc-related magmatism began in latest Triassic time, but the peak of arc evolution occurred during the Early and Middle Jurassic. By Oxfordian time, the arc was deeply dissected and eroded, and magmatic activity had ceased. A marine transgression from the Gulf of Mexico covered most of the Nazas arc, depositing the initial sediments of the Oxfordian Zuloaga Limestone in the Mexican Geosyncline. Jurassic crustal extension in the Gulf of Mexico was

  16. Calcium influx through CRAC channels controls actin organization and dynamics at the immune synapse

    Science.gov (United States)

    Hartzell, Catherine A; Jankowska, Katarzyna I; Burkhardt, Janis K; Lewis, Richard S

    2016-01-01

    T cell receptor (TCR) engagement opens Ca2+ release-activated Ca2+ (CRAC) channels and triggers formation of an immune synapse between T cells and antigen-presenting cells. At the synapse, actin reorganizes into a concentric lamellipod and lamella with retrograde actin flow that helps regulate the intensity and duration of TCR signaling. We find that Ca2+ influx is required to drive actin organization and dynamics at the synapse. Calcium acts by promoting actin depolymerization and localizing actin polymerization and the actin nucleation promotion factor WAVE2 to the periphery of the lamellipod while suppressing polymerization elsewhere. Ca2+-dependent retrograde actin flow corrals ER tubule extensions and STIM1/Orai1 complexes to the synapse center, creating a self-organizing process for CRAC channel localization. Our results demonstrate a new role for Ca2+ as a critical regulator of actin organization and dynamics at the synapse, and reveal potential feedback loops through which Ca2+ influx may modulate TCR signaling. DOI: http://dx.doi.org/10.7554/eLife.14850.001 PMID:27440222

  17. Calcium influx through CRAC channels controls actin organization and dynamics at the immune synapse.

    Science.gov (United States)

    Hartzell, Catherine A; Jankowska, Katarzyna I; Burkhardt, Janis K; Lewis, Richard S

    2016-01-01

    T cell receptor (TCR) engagement opens Ca(2+) release-activated Ca(2+) (CRAC) channels and triggers formation of an immune synapse between T cells and antigen-presenting cells. At the synapse, actin reorganizes into a concentric lamellipod and lamella with retrograde actin flow that helps regulate the intensity and duration of TCR signaling. We find that Ca(2+) influx is required to drive actin organization and dynamics at the synapse. Calcium acts by promoting actin depolymerization and localizing actin polymerization and the actin nucleation promotion factor WAVE2 to the periphery of the lamellipod while suppressing polymerization elsewhere. Ca(2+)-dependent retrograde actin flow corrals ER tubule extensions and STIM1/Orai1 complexes to the synapse center, creating a self-organizing process for CRAC channel localization. Our results demonstrate a new role for Ca(2+) as a critical regulator of actin organization and dynamics at the synapse, and reveal potential feedback loops through which Ca(2+) influx may modulate TCR signaling. PMID:27440222

  18. Synapse: a Scalable Protocol for Interconnecting Heterogeneous Overlay Networks

    OpenAIRE

    Liquori, Luigi; Tedeschi, Cédric; Vanni, Laurent; Ciancaglini, Vincenzo; Bongiovanni, Francesco; Marinkovic, Bojan

    2010-01-01

    International audience This paper presents Synapse, a scalable protocol for information retrieval over the inter-connection of heterogeneous overlay networks. Applications on top of Synapse see those intra-overlay networks as a unique inter-overlay network. Scalability in Synapse is achieved via co-located nodes, i.e. nodes that are part of multiple overlay networks at the same time. Co-located nodes, playing the role of neural synapses and connected to several overlay networks, give a lar...

  19. Ancient and recent clay formation on Mars as revealed from a global survey of hydrous minerals in crater central peaks

    Science.gov (United States)

    Sun, Vivian Z.; Milliken, Ralph E.

    2015-12-01

    Clay minerals on Mars have commonly been interpreted as the remnants of pervasive water-rock interaction during the Noachian period (>3.7 Ga). This history has been partly inferred by observations of clays in central peaks of impact craters, which often are presumed uplifted from depth. However, combined mineralogical and morphological analyses of individual craters have shown that some central peak clays may represent post-impact, possibly authigenic processes. Here we present a global survey of 633 central peaks to assess their hydrous minerals and the prevalence of uplifted, detrital, and authigenic clays. Central peak regions are examined using high-resolution Compact Reconnaissance Imaging Spectrometer for Mars and High Resolution Imaging Science Experiment data to identify hydrous minerals and place their detections in a stratigraphic and geologic context. We find that many occurrences of Fe/Mg clays and hydrated silica are associated with potential impact melt deposits. Over 35% of central peak clays are not associated with uplifted rocks; thus, caution must be used when inferring deeper crustal compositions from surface mineralogy of central peaks. Uplifted clay-bearing rocks suggest the Martian crust hosts clays to depths of at least 7 km. We also observe evidence for increasing chloritization with depth, implying the presence of fluids in the upper portions of the crust. Our observations are consistent with widespread Noachian/Early Hesperian clay formation, but a number of central peak clays are also suggestive of clay formation during the Amazonian. These results broadly support current paradigms of Mars' aqueous history while adding insight to global crustal and diagenetic processes associated with clay mineral formation and stability.

  20. Copper at synapse: Release, binding and modulation of neurotransmission.

    Science.gov (United States)

    D'Ambrosi, Nadia; Rossi, Luisa

    2015-11-01

    Over the last decade, a piece of the research studying copper role in biological systems was devoted to unravelling a still elusive, but extremely intriguing, aspect that is the involvement of copper in synaptic function. These studies were prompted to provide a rationale to the finding that copper is released in the synaptic cleft upon depolarization. The copper pump ATP7A, which mutations are responsible for diseases with a prominent neurodegenerative component, seems to play a pivotal role in the release of copper at synapses. Furthermore, it was found that, when in the synaptic cleft, copper can control, directly or indirectly, the activity of the neurotransmitter receptors (NMDA, AMPA, GABA, P2X receptors), thus affecting excitability. In turn, neurotransmission can affect copper trafficking and delivery in neuronal cells. Furthermore, it was reported that copper can also modulate synaptic vesicles trafficking and the interaction between proteins of the secretory pathways. Interestingly, proteins with a still unclear role in neuronal system though associated with the pathogenesis of neurodegenerative diseases (the amyloid precursor protein, APP, the prion protein, PrP, α-synuclein, α-syn) show copper-binding domains. They may act as copper buffer at synapses and participate in the interplay between copper and the neurotransmitters receptors. Given that copper dysmetabolism occurs in several diseases affecting central and peripheral nervous system, the findings on the contribution of copper in synaptic transmission, beside its more consolidate role as a neuronal enzymes cofactor, may open new insights for therapy interventions. PMID:26187063

  1. Astrocytes, Synapses and Brain Function: A Computational Approach

    Science.gov (United States)

    Nadkarni, Suhita

    2006-03-01

    Modulation of synaptic reliability is one of the leading mechanisms involved in long- term potentiation (LTP) and long-term depression (LTD) and therefore has implications in information processing in the brain. A recently discovered mechanism for modulating synaptic reliability critically involves recruitments of astrocytes - star- shaped cells that outnumber the neurons in most parts of the central nervous system. Astrocytes until recently were thought to be subordinate cells merely participating in supporting neuronal functions. New evidence, however, made available by advances in imaging technology has changed the way we envision the role of these cells in synaptic transmission and as modulator of neuronal excitability. We put forward a novel mathematical framework based on the biophysics of the bidirectional neuron-astrocyte interactions that quantitatively accounts for two distinct experimental manifestation of recruitment of astrocytes in synaptic transmission: a) transformation of a low fidelity synapse transforms into a high fidelity synapse and b) enhanced postsynaptic spontaneous currents when astrocytes are activated. Such a framework is not only useful for modeling neuronal dynamics in a realistic environment but also provides a conceptual basis for interpreting experiments. Based on this modeling framework, we explore the role of astrocytes for neuronal network behavior such as synchrony and correlations and compare with experimental data from cultured networks.

  2. Localization of mineralocorticoid receptors at mammalian synapses.

    Directory of Open Access Journals (Sweden)

    Eric M Prager

    Full Text Available In the brain, membrane associated nongenomic steroid receptors can induce fast-acting responses to ion conductance and second messenger systems of neurons. Emerging data suggest that membrane associated glucocorticoid and mineralocorticoid receptors may directly regulate synaptic excitability during times of stress when adrenal hormones are elevated. As the key neuron signaling interface, the synapse is involved in learning and memory, including traumatic memories during times of stress. The lateral amygdala is a key site for synaptic plasticity underlying conditioned fear, which can both trigger and be coincident with the stress response. A large body of electrophysiological data shows rapid regulation of neuronal excitability by steroid hormone receptors. Despite the importance of these receptors, to date, only the glucocorticoid receptor has been anatomically localized to the membrane. We investigated the subcellular sites of mineralocorticoid receptors in the lateral amygdala of the Sprague-Dawley rat. Immunoblot analysis revealed the presence of mineralocorticoid receptors in the amygdala. Using electron microscopy, we found mineralocorticoid receptors expressed at both nuclear including: glutamatergic and GABAergic neurons and extra nuclear sites including: presynaptic terminals, neuronal dendrites, and dendritic spines. Importantly we also observed mineralocorticoid receptors at postsynaptic membrane densities of excitatory synapses. These data provide direct anatomical evidence supporting the concept that, at some synapses, synaptic transmission is regulated by mineralocorticoid receptors. Thus part of the stress signaling response in the brain is a direct modulation of the synapse itself by adrenal steroids.

  3. Elastohydrodynamics and kinetics of protein patterning in the immunological synapse

    CERN Document Server

    Carlson, Andreas

    2015-01-01

    The cellular basis for the adaptive immune response during antigen recognition relies on a specialized protein interface known as the immunological synapse (IS). Understanding the biophysical basis for protein patterning by deciphering the quantitative rules for their formation and motion is an important aspect of characterizing immune cell recognition and thence the rules for immune system activation. We propose a minimal mathematical model for the physical basis of membrane protein patterning in the IS, which encompass membrane mechanics, protein binding kinetics and motion, and fluid flow in the synaptic cleft. Our theory leads to simple predictions for the spatial and temporal scales of protein cluster formation, growth and arrest as a function of membrane stiffness, rigidity and kinetics of the adhesive proteins, and the fluid in the synaptic cleft. Numerical simulations complement these scaling laws by quantifying the nucleation, growth and stabilization of proteins domains on the size of the cell. Dire...

  4. Multi-proxy constraints on sapropel formation during the late Pliocene of central Mediterranean (southwest Sicily)

    Science.gov (United States)

    Plancq, Julien; Grossi, Vincent; Pittet, Bernard; Huguet, Carme; Rosell-Melé, Antoni; Mattioli, Emanuela

    2015-06-01

    The late Pliocene (Piacenzian) in the Mediterranean region was punctuated by short-lived episodes of widespread deposition of organic-rich sedimentary layers known as sapropels. The causes of their formation remain a long-standing debate in the science community, and require disentangling the roles of climatic/oceanographic processes that triggered higher primary productivity or enhanced organic matter preservation. The lack of data, especially of sea temperatures at sufficient temporal resolution, is one of the main challenges to solve this debate. Here, we present new organic geochemistry and micropaleontological data from the late Pliocene at Punta Grande/Punta Piccola sections (southwest Sicily) that allow untangling the mechanisms that favored the formation of two sapropel series (noted S and A) in the central Mediterranean area during this period. Sea surface (SSTs) and subsurface temperatures were estimated using three distinct organic geochemical proxies namely the alkenone unsaturation index (UK‧37), the long-chain diol index (LDI) and the tetraether index (TEX86). Reconstructed SSTs are relatively stable throughout the late Pliocene and ∼4 °C higher than modern Mediterranean SSTs, which is consistent with the climatic conditions inferred for this period from paleoclimate modeling. An increase in SST is, however, recorded by UK‧37 and LDI proxies across each sapropel horizon, supporting that the two sapropel series S and A were formed during warmer climate conditions. The comparison of SST data with variations in accumulation rates of total organic carbon and lipid-biomarkers (alkenones, long-chain alkyl diols, archaeal and bacterial tetraethers), and with changes in calcareous nannofossil assemblages, indicates that the studied sapropels might have formed under different environmental conditions. The first series of sapropels (S), deposited between 3.1 and 2.8 Ma, is likely due to a better preservation of organic matter, induced by the development

  5. AGN Feedback, Host Halo Mass and Central Cooling Time: Implications for Galaxy Formation Efficiency and $M_{BH} - \\sigma$

    CERN Document Server

    Main, Robert; Nulsen, Paul; Russell, Helen; Vantyghem, Adrian

    2015-01-01

    We derive X-ray mass, luminosity, and temperature profiles for 45 galaxy clusters to explore relationships between halo mass, AGN feedback, and central cooling time. We find that radio--mechanical feedback power (referred to here as "AGN power") in central cluster galaxies correlates with halo mass, but only in halos with central atmospheric cooling times shorter than 1 Gyr. This timescale corresponds approximately to the cooling time (entropy) threshold for the onset of cooling instabilities and star formation in central galaxies (Rafferty et al. 2008). No correlation is found in systems with central cooling times greater than 1 Gyr. The trend with halo mass is consistent with self-similar scaling relations assuming cooling is regulated by feedback. The trend is also consistent with galaxy and central black hole co-evolution along the $M_{BH} - \\sigma $ relation. AGN power further correlates with X-ray gas mass and the host galaxy's K-band luminosity. AGN power in clusters with central atmospheric cooling ti...

  6. Stratigraphic and laterial variations of source rock attributes of the Pematang Formation, Central Sumatra

    Energy Technology Data Exchange (ETDEWEB)

    Katz, B.J. (Texaco Inc., Houston, TX (United States))

    1994-07-01

    The Pematang Formation of the Central Sumatra basin has been shown to be the primary, if not the only, source for the basin's 10+ billion bbl of recoverable oil. This lacustrine unit, which is restricted to a series of Paleogene half grabens, typifies the variability present in many rift source rock systems. Differences in organic facies occur both stratigraphically and laterally as a result of a series of complex interactions. The stratigraphic controls on organic facies within the Pematang appear to be (1) the challenging relationship between subsidence and sedimentation, (2) long-term climate trends influencing both lake level and regional vegetation patterns, and (3) the evolution of the lake basins' nutrient pool. These controls result in an increase in both the level of organic enrichment and oil-proneness toward the top of the unit. Superimposed on this pattern are changes in organic matter content and character caused by short-term climatic oscillations. The lateral controls on organic facies can be examined at two different scales: basinal and subbasinal. Basinal variations can be related to (1) different relative subsidence rates among the various subbasins and (2) variations in lake-water chemistry as a result of the nature of the paleodrainage basin. On a subbasinal scale, organic facies appear to be controlled by (1) hydrodynamic processes and circulation and (2) variations in water depth. These lateral variations are manifested in the level of organic enrichment, the proportions of oil- and gas-prone kerogen, and variations in oil composition.

  7. Both pre- and postsynaptic activity of Nsf prevents degeneration of hair-cell synapses.

    Directory of Open Access Journals (Sweden)

    Weike Mo

    Full Text Available Vesicle fusion contributes to the maintenance of synapses in the nervous system by mediating synaptic transmission, release of neurotrophic factors, and trafficking of membrane receptors. N-ethylmaleimide-sensitive factor (NSF is indispensible for dissociation of the SNARE-complex following vesicle fusion. Although NSF function has been characterized extensively in vitro, the in vivo role of NSF in vertebrate synaptogenesis is relatively unexplored. Zebrafish possess two nsf genes, nsf and nsfb. Here, we examine the function of either Nsf or Nsfb in the pre- and postsynaptic cells of the zebrafish lateral line organ and demonstrate that Nsf, but not Nsfb, is required for maintenance of afferent synapses in hair cells. In addition to peripheral defects in nsf mutants, neurodegeneration of glutamatergic synapses in the central nervous system also occurs in the absence of Nsf function. Expression of an nsf transgene in a null background indicates that stabilization of synapses requires Nsf function in both hair cells and afferent neurons. To identify potential targets of Nsf-mediated fusion, we examined the expression of genes implicated in stabilizing synapses and found that transcripts for multiple genes including brain-derived neurotrophic factor (bdnf were significantly reduced in nsf mutants. With regard to trafficking of BDNF, we observed a striking accumulation of BDNF in the neurites of nsf mutant afferent neurons. In addition, injection of recombinant BDNF protein partially rescued the degeneration of afferent synapses in nsf mutants. These results establish a role for Nsf in the maintenance of synaptic contacts between hair cells and afferent neurons, mediated in part via the secretion of trophic signaling factors.

  8. Unsupervised learning in neural networks with short range synapses

    Science.gov (United States)

    Brunnet, L. G.; Agnes, E. J.; Mizusaki, B. E. P.; Erichsen, R., Jr.

    2013-01-01

    Different areas of the brain are involved in specific aspects of the information being processed both in learning and in memory formation. For example, the hippocampus is important in the consolidation of information from short-term memory to long-term memory, while emotional memory seems to be dealt by the amygdala. On the microscopic scale the underlying structures in these areas differ in the kind of neurons involved, in their connectivity, or in their clustering degree but, at this level, learning and memory are attributed to neuronal synapses mediated by longterm potentiation and long-term depression. In this work we explore the properties of a short range synaptic connection network, a nearest neighbor lattice composed mostly by excitatory neurons and a fraction of inhibitory ones. The mechanism of synaptic modification responsible for the emergence of memory is Spike-Timing-Dependent Plasticity (STDP), a Hebbian-like rule, where potentiation/depression is acquired when causal/non-causal spikes happen in a synapse involving two neurons. The system is intended to store and recognize memories associated to spatial external inputs presented as simple geometrical forms. The synaptic modifications are continuously applied to excitatory connections, including a homeostasis rule and STDP. In this work we explore the different scenarios under which a network with short range connections can accomplish the task of storing and recognizing simple connected patterns.

  9. Cell adhesion molecules in the central nervous system

    OpenAIRE

    Togashi, Hideru; Sakisaka, Toshiaki; Takai, Yoshimi

    2009-01-01

    Cell-cell adhesion molecules play key roles at the intercellular junctions of a wide variety of cells, including interneuronal synapses and neuron-glia contacts. Functional studies suggest that adhesion molecules are implicated in many aspects of neural network formation, such as axon-guidance, synapse formation, regulation of synaptic structure and astrocyte-synapse contacts. Some basic cell biological aspects of the assembly of junctional complexes of neurons and glial cells resemble those ...

  10. Changes in rat hippocampal CA1 synapses following imipramine treatment

    DEFF Research Database (Denmark)

    Chen, Fenghua; Madsen, Torsten M; Wegener, Gregers;

    2008-01-01

    synapses) in subregions of the hippocampus by quantifying number of neurons and synapses. Adult male Sprague-Dawley rats were injected with imipramine or saline (i.p.) daily for 14 days. Unbiased stereological methods were used to quantify the number of neurons and synapses. No differences in the volume...... and number of neurons of hippocampal subregions following imipramine treatment were found. However, the number and percentage of CA1 asymmetric spine synapses increased significantly and, conversely, the percentage of asymmetric shaft synapses significantly decreased in the imipramine treated group....... Our results indicate that administration of imipramine for 14 days in normal rats could significantly increase the excitatory spine synapses, and change the relative distribution of spine and shaft synapses. We speculate that the present findings may be explained by the establishment of new synaptic...

  11. Super resolution imaging of genetically labelled synapses in Drosophila brain tissue

    Directory of Open Access Journals (Sweden)

    Isabelle Ayumi Spühler

    2016-05-01

    Full Text Available Understanding synaptic connectivity and plasticity within brain circuits and their relationship to learning and behavior is a fundamental quest in neuroscience. Visualizing the fine details of synapses using optical microscopy remains however a major technical challenge. Super resolution microscopy opens the possibility to reveal molecular features of synapses beyond the diffraction limit. With direct stochastic optical reconstruction microscopy, dSTORM, we image synaptic proteins in the brain tissue of the fruit fly, Drosophila melanogaster. Super resolution imaging of brain tissue harbors difficulties due to light scattering and the density of signals. In order to reduce out of focus signal, we take advantage of the genetic tools available in the Drosophila and have fluorescently tagged synaptic proteins expressed in only a small number of neurons. These neurons form synapses within the calyx of the mushroom body, a distinct brain region involved in associative memory formation. Our results show that super resolution microscopy, in combination with genetically labelled synaptic proteins, is a powerful tool to investigate synapses in a quantitative fashion providing an entry point for studies on synaptic plasticity during learning and memory formation

  12. New players tip the scales in the balance between excitatory and inhibitory synapses

    Directory of Open Access Journals (Sweden)

    El-Husseini Alaa

    2005-03-01

    Full Text Available Abstract Synaptogenesis is a highly controlled process, involving a vast array of players which include cell adhesion molecules, scaffolding and signaling proteins, neurotransmitter receptors and proteins associated with the synaptic vesicle machinery. These molecules cooperate in an intricate manner on both the pre- and postsynaptic sides to orchestrate the precise assembly of neuronal contacts. This is an amazing feat considering that a single neuron receives tens of thousands of synaptic inputs but virtually no mismatch between pre- and postsynaptic components occur in vivo. One crucial aspect of synapse formation is whether a nascent synapse will develop into an excitatory or inhibitory contact. The tight control of a balance between the types of synapses formed regulates the overall neuronal excitability, and is thus critical for normal brain function and plasticity. However, little is known about how this balance is achieved. This review discusses recent findings which provide clues to how neurons may control excitatory and inhibitory synapse formation, with focus on the involvement of the neuroligin family and PSD-95 in this process.

  13. The Formation of New Monetary Policies: Decisions of Central Banks on the Great Recession

    Directory of Open Access Journals (Sweden)

    Ana Esther Castro

    2014-05-01

    Full Text Available The effect that the Great Recession had on monetary policies has led to the profound reorientation of central banks’ actions from 2007 to 2013. The purpose of this work is to analyze the monetary policies applied by the main central banks, mainly the European Central Bank, the Federal Reserve System of USA and the Bank of Japan, in order to raise thoughts on the guidelines that central banks should follow in the future. In the first section the bases of monetary policy before the crisis are described; in the second we explain the change in the orientation of the role of central banks during the crisis; and finally, we synthesize the bases on which the economic debate is taking place on the orientation of future monetary policies. We conclude that, in so far as the inoperativeness of transmission mechanisms still persists, monetary policies will remain in a process of change.

  14. Current denudation rates in dolostone karst from central Spain: Implications for the formation of unroofed caves

    Science.gov (United States)

    Krklec, Kristina; Domínguez-Villar, David; Carrasco, Rosa M.; Pedraza, Javier

    2016-07-01

    Rock tablets of known weight were buried in the soil of a karst region in Central Spain to evaluate the carbonate weathering during a period of a year. The experiment was conducted at two different soil depths: 5-10 and 50-55 cm from the surface. The parental rock used in the experiment is composed of dolomite and magnesite with variable proportion of accessory minerals and minor elements. Soil mineral and chemical composition as well as its texture was also characterized. Meteorological conditions at the site together with temperature and CO2 in both soil levels were monitored. Sets of tablets were retrieved after 6 and 12 months of the start of the experiment to account for seasonal weathering. Different lithologies do not exhibit significant differences in weathering, although a large inter-sample variability is attributed to variable size and distribution of the porosity. Results show an enhanced weathering during the wet and cold season that accounts for 78 ± 1% of the total annual weathering. Rock tablets examined under scanning electron microscopy prior and after exposure to natural environment show that most of the material lost occurred along cracks, edges or large pores. Although dissolution is a common process, most of the weathering is due to crystal detachment. Rock tablets at the depth of 5-10 cm were weathered 68 ± 1% more than those set at 50-55 cm from the surface. Higher soil moisture and concentration of CO2 were found deeper in the soil, which likely enhanced the dissolution of carbonate. However, physical weathering dominated weight loss of rock tablets at both soil depths; especially at the 5-10 cm level where soil thermal and moisture cycles were more frequent and greater. Denudation rate calculated from the 12 months set provides values of 2.48 ± 1.07 μm/yr and 1.75 ± 0.66 μm/yr at the depths of 5-10 and 50-55 cm, respectively. Since the conditions at the average contact between soil and bedrock are similar to those at the 50-55 cm

  15. Monoacylated Cellular Prion Proteins Reduce Amyloid-β-Induced Activation of Cytoplasmic Phospholipase A2 and Synapse Damage

    Science.gov (United States)

    West, Ewan; Osborne, Craig; Nolan, William; Bate, Clive

    2015-01-01

    Alzheimer’s disease (AD) is a progressive neurodegenerative disease characterized by the accumulation of amyloid-β (Aβ) and the loss of synapses. Aggregation of the cellular prion protein (PrPC) by Aβ oligomers induced synapse damage in cultured neurons. PrPC is attached to membranes via a glycosylphosphatidylinositol (GPI) anchor, the composition of which affects protein targeting and cell signaling. Monoacylated PrPC incorporated into neurons bound “natural Aβ”, sequestering Aβ outside lipid rafts and preventing its accumulation at synapses. The presence of monoacylated PrPC reduced the Aβ-induced activation of cytoplasmic phospholipase A2 (cPLA2) and Aβ-induced synapse damage. This protective effect was stimulus specific, as treated neurons remained sensitive to α-synuclein, a protein associated with synapse damage in Parkinson’s disease. In synaptosomes, the aggregation of PrPC by Aβ oligomers triggered the formation of a signaling complex containing the cPLA2.a process, disrupted by monoacylated PrPC. We propose that monoacylated PrPC acts as a molecular sponge, binding Aβ oligomers at the neuronal perikarya without activating cPLA2 or triggering synapse damage. PMID:26043272

  16. Monoacylated Cellular Prion Proteins Reduce Amyloid-β-Induced Activation of Cytoplasmic Phospholipase A2 and Synapse Damage

    Directory of Open Access Journals (Sweden)

    Ewan West

    2015-06-01

    Full Text Available Alzheimer’s disease (AD is a progressive neurodegenerative disease characterized by the accumulation of amyloid-β (Aβ and the loss of synapses. Aggregation of the cellular prion protein (PrPC by Aβ oligomers induced synapse damage in cultured neurons. PrPC is attached to membranes via a glycosylphosphatidylinositol (GPI anchor, the composition of which affects protein targeting and cell signaling. Monoacylated PrPC incorporated into neurons bound “natural Aβ”, sequestering Aβ outside lipid rafts and preventing its accumulation at synapses. The presence of monoacylated PrPC reduced the Aβ-induced activation of cytoplasmic phospholipase A2 (cPLA2 and Aβ-induced synapse damage. This protective effect was stimulus specific, as treated neurons remained sensitive to α-synuclein, a protein associated with synapse damage in Parkinson’s disease. In synaptosomes, the aggregation of PrPC by Aβ oligomers triggered the formation of a signaling complex containing the cPLA2.a process, disrupted by monoacylated PrPC. We propose that monoacylated PrPC acts as a molecular sponge, binding Aβ oligomers at the neuronal perikarya without activating cPLA2 or triggering synapse damage.

  17. On the peritidal cycles and their diagenetic evolution in the Lower Jurassic carbonates of the Calcare Massiccio Formation (Central Apennines)

    OpenAIRE

    Brandano Marco; Corda Laura; Tomassetti Laura; Testa Davide

    2015-01-01

    This paper shows the environmental changes and high-frequency cyclicity recorded by Lower Jurassic shallow-water carbonates known as the Calcare Massiccio Formation which crop out in the central Apennines of Italy. Three types of sedimentary cycle bounded by subaerial erosion have been recognized: Type I consists of a shallowing upward cycle with oncoidal floatstones to rudstones passing gradationally up into peloidal packstone alternating with cryptoalgal laminites and often bounded by desic...

  18. Signaling at the inhibitory natural killer cell immune synapse regulates lipid raft polarization but not class I MHC clustering.

    Science.gov (United States)

    Fassett, M S; Davis, D M; Valter, M M; Cohen, G B; Strominger, J L

    2001-12-01

    Natural killer (NK) cell cytotoxicity is determined by a balance of positive and negative signals. Negative signals are transmitted by NK inhibitory receptors (killer immunoglobulin-like receptors, KIR) at the site of membrane apposition between an NK cell and a target cell, where inhibitory receptors become clustered with class I MHC ligands in an organized structure known as an inhibitory NK immune synapse. Immune synapse formation in NK cells is poorly understood. Because signaling by NK inhibitory receptors could be involved in this process, the human NK tumor line YTS was transfected with signal-competent and signal-incompetent KIR2DL1. The latter were generated by truncating the KIR2DL1 cytoplasmic tail or by introducing mutations in the immunoreceptor tyrosine-based inhibition motifs. The KIR2DL1 mutants retained their ability to cluster class I MHC ligands on NK cell interaction with appropriate target cells. Therefore, receptor-ligand clustering at the inhibitory NK immune synapse occurs independently of KIR2DL1 signal transduction. However, parallel examination of NK cell membrane lipid rafts revealed that KIR2DL1 signaling is critical for blocking lipid raft polarization and NK cell cytotoxicity. Moreover, raft polarization was inhibited by reagents that disrupt microtubules and actin filaments, whereas synapse formation was not. Thus, NK lipid raft polarization and inhibitory NK immune synapse formation occur by fundamentally distinct mechanisms. PMID:11724921

  19. Neurotrophic regulation of synapse development and plasticity

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Neurotrophic factors are traditionally thought to be secretory proteins that regulate long-tern survival and differe, ntiation of neurons. Recent studies have revealed a previously unexpected role for these factors in synaptie de velopment ami plasticity in diverse neuronal populations. Here we review experimeuts carried oul in our own laboratory in the last few years.. We have made two important discoveries.First,we were among the first to report that brain-derived. neurotrophie faclor (BDNF) facilitates hippocampal hmg-term potentiation (LTP), a form of synaptic plaslicity believed to be involved in learning and memory. BDNF modulates LTP al CAI synapses by enhaneing synaptic responses to high frequency, tetanic slimulalion. This is achieved primafily by facilitating synaptie vesicle doeking, possibly due to an in crease in the levels of the vesicle prolein synaptobrevin and synaptoplysin in the nerve terminals. Gene knockout study demonstrates thai the effects of BDNF are primarily mediated through presynaptic mechanisms. Second, we demonstrated a form of long-term, neurotrophin-mediated synaptic regulation. We showed that long-term treatment of the neuromuscu lar synapses with neurotrophin-3 (NT3) resulted in an enhancement of both spontaneous and evoked synaptic currcuts, as well as profound changes in thc number of synaptic varicosities and syuaptic vesicle proteins in motoneurons, all of which are indicative of more mature synapses. Our current work addresses the following issues:(i) activity-dependent trafficking of neurotrophin receptors, and its role in synapse-specific modulation; (ii) signal transduction mechanisms medialing the acute enhancement of synaplic transmission by neurotrophins; (iii) acute and long-tenn synaptie actions of the GDNF family; (iv) role of BDNF in late-phase LTP and in the development of hippocampal circuit.

  20. Comparative Anatomy of Phagocytic and immunological Synapses

    OpenAIRE

    Niedergang, Florence; Di Bartolo, Vincenzo; Alcover, Andrés

    2016-01-01

    The generation of phagocytic cups and immunological synapses are crucial events of the innate and adaptive immune responses, respectively. They are triggered by distinct immune receptors and performed by different cell types. However, growing experimental evidence shows that a very close series of molecular and cellular events control these two processes. Thus, the tight and dynamic interplay between receptor signaling, actin and microtubule cytoskeleton, and targeted vesicle traffic are all ...

  1. SynDB: a Synapse protein DataBase based on synapse ontology.

    Science.gov (United States)

    Zhang, Wuxue; Zhang, Yong; Zheng, Hui; Zhang, Chen; Xiong, Wei; Olyarchuk, John G; Walker, Michael; Xu, Weifeng; Zhao, Min; Zhao, Shuqi; Zhou, Zhuan; Wei, Liping

    2007-01-01

    A synapse is the junction across which a nerve impulse passes from an axon terminal to a neuron, muscle cell or gland cell. The functions and building molecules of the synapse are essential to almost all neurobiological processes. To describe synaptic structures and functions, we have developed Synapse Ontology (SynO), a hierarchical representation that includes 177 terms with hundreds of synonyms and branches up to eight levels deep. associated 125 additional protein keywords and 109 InterPro domains with these SynO terms. Using a combination of automated keyword searches, domain searches and manual curation, we collected 14,000 non-redundant synapse-related proteins, including 3000 in human. We extensively annotated the proteins with information about sequence, structure, function, expression, pathways, interactions and disease associations and with hyperlinks to external databases. The data are stored and presented in the Synapse protein DataBase (SynDB, http://syndb.cbi.pku.edu.cn). SynDB can be interactively browsed by SynO, Gene Ontology (GO), domain families, species, chromosomal locations or Tribe-MCL clusters. It can also be searched by text (including Boolean operators) or by sequence similarity. SynDB is the most comprehensive database to date for synaptic proteins. PMID:17098931

  2. D-serine and serine racemase are associated with PSD-95 and glutamatergic synapse stability

    Directory of Open Access Journals (Sweden)

    Hong eLin

    2016-02-01

    Full Text Available D-serine is an endogenous coagonist at the glycine site of synaptic NMDA receptors (NMDARs, synthesized by serine racemase (SR through conversion of L-serine. It is crucial for synaptic plasticity and is implicated in schizophrenia. Our previous studies demonstrated specific loss of SR, D-serine-responsive synaptic NMDARs, and glutamatergic synapses in cortical neurons lacking alpha7 nicotinic acetylcholine receptors, which promotes glutamatergic synapse formation and maturation during development. We thus hypothesize that D-serine and SR (D-serine/SR are associated with glutamatergic synaptic development. Using morphological and molecular studies in cortical neuronal cultures, we demonstrate that D-serine/SR are associated with PSD-95 and NMDARs in postsynaptic neurons and with glutamatergic synapse stability during synaptic development. Endogenous D-serine and SR colocalize with PSD-95, but not presynaptic vesicular glutamate transporter 1 (VGLUT1, in glutamatergic synapses of cultured cortical neurons. Low-density astrocytes in cortical neuronal cultures lack SR expression but contain enriched D-serine in large vesicle-like structures, suggesting possible synthesis of D-serine in postsynaptic neurons and storage in astrocytes. More interestingly, endogenous D-serine and SR colocalize with PSD-95 in the postsynaptic terminals of glutamatergic synapses during early and late synaptic development, implicating involvement of D-serine/SR in glutamatergic synaptic development. Exogenous application of D-serine enhances the interactions of SR with PSD-95 and NR1, and increases the number of VGLUT1- and PSD-95-positive glutamatergic synapses, suggesting that exogenous D-serine enhances postsynaptic SR/PSD-95 signaling and stabilizes glutamatergic synapses during cortical synaptic development. This is blocked by NMDAR antagonist 2-amino-5-phosphonopentanoic acid (AP5 and 7-chlorokynurenic acid (7-CK, a specific antagonist at the glycine site of NMDARs

  3. D-Serine and Serine Racemase Are Associated with PSD-95 and Glutamatergic Synapse Stability

    Science.gov (United States)

    Lin, Hong; Jacobi, Ariel A.; Anderson, Stewart A.; Lynch, David R.

    2016-01-01

    D-serine is an endogenous coagonist at the glycine site of synaptic NMDA receptors (NMDARs), synthesized by serine racemase (SR) through conversion of L-serine. It is crucial for synaptic plasticity and is implicated in schizophrenia. Our previous studies demonstrated specific loss of SR, D-serine-responsive synaptic NMDARs, and glutamatergic synapses in cortical neurons lacking α7 nicotinic acetylcholine receptors, which promotes glutamatergic synapse formation and maturation during development. We thus hypothesize that D-serine and SR (D-serine/SR) are associated with glutamatergic synaptic development. Using morphological and molecular studies in cortical neuronal cultures, we demonstrate that D-serine/SR are associated with PSD-95 and NMDARs in postsynaptic neurons and with glutamatergic synapse stability during synaptic development. Endogenous D-serine and SR colocalize with PSD-95, but not presynaptic vesicular glutamate transporter 1 (VGLUT1), in glutamatergic synapses of cultured cortical neurons. Low-density astrocytes in cortical neuronal cultures lack SR expression but contain enriched D-serine in large vesicle-like structures, suggesting possible synthesis of D-serine in postsynaptic neurons and storage in astrocytes. More interestingly, endogenous D-serine and SR colocalize with PSD-95 in the postsynaptic terminals of glutamatergic synapses during early and late synaptic development, implicating involvement of D-serine/SR in glutamatergic synaptic development. Exogenous application of D-serine enhances the interactions of SR with PSD-95 and NR1, and increases the number of VGLUT1- and PSD-95-positive glutamatergic synapses, suggesting that exogenous D-serine enhances postsynaptic SR/PSD-95 signaling and stabilizes glutamatergic synapses during cortical synaptic development. This is blocked by NMDAR antagonist 2-amino-5-phosphonopentanoic acid (AP5) and 7-chlorokynurenic acid (7-CK), a specific antagonist at the glycine site of NMDARs, demonstrating

  4. Visual Deprivation Increases Accumulation of Dense Core Vesicles in Developing Optic Tectal Synapses in Xenopus laevis

    OpenAIRE

    Li, Jianli; Cline, Hollis T.

    2010-01-01

    Despite considerable progress in understanding the molecular components of synapses in the central nervous system, the ultrastructural rearrangements underlying synaptic development remain unclear. We used serial section transmission electron microscopy and three-dimensional reconstructions of the optic tectal neuropil of Xenopus laevis tadpoles to detect and quantify changes in synaptic ultrastructure over a 1-week period from stages 39 and 47, during which time the visual system of Xenopus ...

  5. The central role of heat shock factor 1 in synaptic fidelity and memory consolidation.

    Science.gov (United States)

    Hooper, Philip L; Durham, Heather D; Török, Zsolt; Hooper, Paul L; Crul, Tim; Vígh, László

    2016-09-01

    Networks of neuronal synapses are the fundamental basis for making and retaining memory. Reduced synapse number and quality correlates with loss of memory in dementia. Heat shock factor 1 (HSF1), the major transcription factor regulating expression of heat shock genes, plays a central role in proteostasis, in establishing and sustaining synaptic fidelity and function, and in memory consolidation. Support for this thesis is based on these observations: (1) heat shock induces improvements in synapse integrity and memory consolidation; (2) synaptic depolarization activates HSF1; (3) activation of HSF1 alone (independent of the canonical heat shock response) augments formation of essential synaptic elements-neuroligands, vesicle transport, synaptic scaffolding proteins, lipid rafts, synaptic spines, and axodendritic synapses; (4) HSF1 coalesces and activates memory receptors in the post-synaptic dendritic spine; (5) huntingtin or α-synuclein accumulation lowers HSF1 while HSF1 lowers huntingtin and α-synuclein aggregation-a potential vicious cycle; and (6) HSF1 agonists (including physical activity) can improve cognitive function in dementia models. Thus, via direct gene expression of synaptic elements, production of HSPs that assure high protein fidelity, and activation of other neuroprotective signaling pathways, HSF1 agonists could provide breakthrough therapy for dementia-associated disease. PMID:27283588

  6. Aging Impairs the Late Phase of Long-Term Potentiation at the Medial Perforant Path-CA3 Synapse in Awake Rats

    OpenAIRE

    Dieguez, Dario; Barea-Rodriguez, Edwin J.

    2004-01-01

    The effects of aging on long-term potentiation (LTP) in the dentate gyrus (DG) and CA1 are well documented, but LTP at the medial perforant path (MPP)-CA3 synapse of aged animals has remained unexplored. Because the MPP-DG and Schaffer-collateral-CA1 synapses account for only about 20% of total hippocampal synapses, global understanding of how aging affects hippocampal plasticity has remained limited. Much is known about LTP induction in the hippocampal formation, whereas the mechanisms that ...

  7. Generation of functional inhibitory synapses incorporating defined combinations of GABA(A or glycine receptor subunits

    Directory of Open Access Journals (Sweden)

    Christine Laura Dixon

    2015-12-01

    Full Text Available Fast inhibitory neurotransmission in the brain is mediated by wide range of GABAA receptor (GABAAR and glycine receptor (GlyR isoforms, each with different physiological and pharmacological properties. Because multiple isoforms are expressed simultaneously in most neurons, it is difficult to define the properties of inhibitory postsynaptic currents mediated by individual isoforms in vivo. Although recombinant expression systems permit the expression of individual isoforms in isolation, they require exogenous agonist application which cannot mimic the dynamic neurotransmitter profile characteristic of native synapses. We describe a neuron-HEK293 cell co-culture technique for generating inhibitory synapses incorporating defined combinations of GABAAR or GlyR subunits. Primary neuronal cultures, prepared from embryonic rat cerebral cortex or spinal cord, are used to provide presynaptic GABAergic and glycinergic terminals, respectively. When the cultures are mature, HEK293 cells expressing the subunits of interest plus neuroligin 2A are plated onto the neurons, which rapidly form synapses onto HEK293 cells. Patch clamp electrophysiology is then used to analyze the physiological and pharmacological properties of the inhibitory postsynaptic currents mediated by the recombinant receptors. The method is suitable for investigating the kinetic properties or the effects of drugs on inhibitory postsynaptic currents mediated by defined GABAAR or GlyR isoforms of interest, the effects of hereditary disease mutations on the formation and function of both types of synapses, and synaptogenesis and synaptic clustering mechanisms. The entire cell preparation procedure takes 2 – 5 weeks.

  8. NeuroD2 regulates the development of hippocampal mossy fiber synapses

    Directory of Open Access Journals (Sweden)

    Wilke Scott A

    2012-02-01

    Full Text Available Abstract Background The assembly of neural circuits requires the concerted action of both genetically determined and activity-dependent mechanisms. Calcium-regulated transcription may link these processes, but the influence of specific transcription factors on the differentiation of synapse-specific properties is poorly understood. Here we characterize the influence of NeuroD2, a calcium-dependent transcription factor, in regulating the structural and functional maturation of the hippocampal mossy fiber (MF synapse. Results Using NeuroD2 null mice and in vivo lentivirus-mediated gene knockdown, we demonstrate a critical role for NeuroD2 in the formation of CA3 dendritic spines receiving MF inputs. We also use electrophysiological recordings from CA3 neurons while stimulating MF axons to show that NeuroD2 regulates the differentiation of functional properties at the MF synapse. Finally, we find that NeuroD2 regulates PSD95 expression in hippocampal neurons and that PSD95 loss of function in vivo reproduces CA3 neuron spine defects observed in NeuroD2 null mice. Conclusion These experiments identify NeuroD2 as a key transcription factor that regulates the structural and functional differentiation of MF synapses in vivo.

  9. Stratigraphy of the Lower and Middle Triassic Union Wash Formation, east-central California

    Science.gov (United States)

    Stone, Paul; Stevens, Calvin H.; Orchard, Michael J.

    The authors describe the lithology, stratigraphy, and contact relations of the Union Wash Formation at its type locality and at two additional localities: the Cerro Gordo area near the crest of the Inyo Mountians, 25 km southeast of Union Wash, and the Darwin area, another 35 km to the southeast. The descriptions given are largely based on recent work and are intended to supercede previous descriptions of the formation by the authors and their coworkers. In addition, they list new conodont identifications that, together with ammonoids identified by previous workers, constrain the age of the Union Wash Formation in those three areas to Early and Middle Triassic.

  10. The central dark matter content of early-type galaxies: scaling relations and connections with star formation histories

    CERN Document Server

    Napolitano, Nicola R; Tortora, Crescenzo

    2010-01-01

    We examine correlations between the masses, sizes, and star formation histories for a large sample of low-redshift early-type galaxies, using a simple suite of dynamical and stellar populations models. We confirm an anti-correlation between size and stellar age, and survey for trends with the central content of dark matter (DM). An average relation between central DM density and galaxy size of ~ Reff^-2 provides the first clear indication of cuspy DM haloes in these galaxies -- akin to standard LCDM haloes that have undergone adiabatic contraction. The DM density scales with galaxy mass as expected, deviating from suggestions of a universal halo profile for dwarf and late-type galaxies. We introduce a new fundamental constraint on galaxy formation by finding that the central DM fraction decreases with stellar age. This result is only partially explained by the size-age dependencies, and the residual trend is in the opposite direction to basic DM halo expectations. Therefore we suggest that there may be a con...

  11. Environmental parameters of a coral assemblage from the Akerchi Formation (Carboniferous), Adarouch Area, central Morocco

    OpenAIRE

    Said, I; Rodríguez, Sergio; Berkhli, M.; Cózar, Pedro; Gómez-Herguedas, Alberto

    2010-01-01

    [EN] Rich assemblages of rugose corals occur in the Tizra, Akerchi and Idmarrach formations (Mississippian) near El-Hajeb City. The Akerchi Formation, approximately 140 m thick, is divided into two members. The upper part of the lower member contains a biostrome 2 to 5 m thick, composed mainly of rugose corals and gigantoproductid brachiopods embedded in marly limestone. Its local thickness increases from southwest to northeast in an outcrop extending for more than one kilometre. ...

  12. The molecular physiology of the axo-myelinic synapse.

    Science.gov (United States)

    Micu, Ileana; Plemel, Jason R; Lachance, Celia; Proft, Juliane; Jansen, Andrew J; Cummins, Karen; van Minnen, Jan; Stys, Peter K

    2016-02-01

    Myelinated axons efficiently transmit information over long distances. The apposed myelin sheath confers favorable electrical properties, but restricts access of the axon to its extracellular milieu. Therefore, axonal metabolic support may require specific axo-myelinic communication. Here we explored activity-dependent glutamate-mediated signaling from axon to myelin. 2-Photon microscopy was used to image Ca(2+) changes in myelin in response to electrical stimulation of optic nerve axons ex vivo. We show that optic nerve myelin responds to axonal action potentials by a rise in Ca(2+) levels mediated by GluN2D and GluN3A-containing NMDA receptors. Glutamate is released from axons in a vesicular manner that is tetanus toxin-sensitive. The Ca(2+) source for vesicular fusion is provided by ryanodine receptors on axonal Ca(2+) stores, controlled by L-type Ca(2+) channels that sense depolarization of the internodal axolemma. Genetic ablation of GluN2D and GluN3A subunits results in greater lability of the compact myelin. Our results support the existence of a novel synapse between the axon and its myelin, suggesting a means by which traversing action potentials can signal the overlying myelin sheath. This may be an important physiological mechanism by which an axon can signal companion glia for metabolic support or adjust properties of its myelin in a dynamic manner. The axo-myelinic synapse may contribute to learning, while its disturbances may play a role in the pathophysiology of central nervous system disorders such as schizophrenia, where subtle abnormalities of myelinated white matter tracts have been shown in the human, or to frank demyelinating disorders such as multiple sclerosis. PMID:26515690

  13. A Reinterpretation of the Baturetno Formation: Stratigraphic Study of the Baturetno Basin, Wonogiri, Central Java

    Directory of Open Access Journals (Sweden)

    Purna Sulastya Putra

    2015-09-01

    Full Text Available This paper focuses on the Quaternary Baturetno Formation. An earlier research concluded that the black clay of the Baturetno Formation formed as a ‘palaeolake’ deposit. The ‘palaeolake’ was interpreted to form due to the shifting course of the Bengawan Solo Purba River in relation to Pliocene tectonic tilting in the southern Java. The stratigraphy of the Baturetno Formation was observed in the western part of the Baturetno Basin, and based on marker beds, the Baturetno Formation was classified into three units: (1 Gravel unit (GR in the upper part, (2 clay unit (CU in the middle part, and (3 sand-gravel unit (SG in the lower part. There are floating gravel fragments of andesite, claystone, coral, and limestone with diameters of up to 10 cm in the clay unit. The particle size of sediment reflects the environment, but the lake deposition occurs under very quiet conditions. The occurrence of these fragments within the clay cannot be explained if the clay was deposited within a lake environment. The occurrence of floating fragments in the black clay of Baturetno Formation can best be explained through mudflow process. The cohesive strength of the mudflow is responsible for the ability of large fragments to float within the mud matrix. In general, the Baturetno Formation is inferred to be an alluvial fan deposit. The presence of sand, gravel, and mud are characteristics of alluvial fan deposits.

  14. Stretching morphogenesis of the roof plate and formation of the central canal.

    Directory of Open Access Journals (Sweden)

    Igor Kondrychyn

    Full Text Available BACKGROUND: Neurulation is driven by apical constriction of actomyosin cytoskeleton resulting in conversion of the primitive lumen into the central canal in a mechanism driven by F-actin constriction, cell overcrowding and buildup of axonal tracts. The roof plate of the neural tube acts as the dorsal morphogenetic center and boundary preventing midline crossing by neural cells and axons. METHODOLOGY/PRINCIPAL FINDINGS: The roof plate zebrafish transgenics expressing cytosolic GFP were used to study and describe development of this structure in vivo for a first time ever. The conversion of the primitive lumen into the central canal causes significant morphogenetic changes of neuroepithelial cells in the dorsal neural tube. We demonstrated that the roof plate cells stretch along the D-V axis in parallel with conversion of the primitive lumen into central canal and its ventral displacement. Importantly, the stretching of the roof plate is well-coordinated along the whole spinal cord and the roof plate cells extend 3× in length to cover 2/3 of the neural tube diameter. This process involves the visco-elastic extension of the roof place cytoskeleton and depends on activity of Zic6 and the Rho-associated kinase (Rock. In contrast, stretching of the floor plate is much less extensive. CONCLUSIONS/SIGNIFICANCE: The extension of the roof plate requires its attachment to the apical complex of proteins at the surface of the central canal, which depends on activity of Zic6 and Rock. The D-V extension of the roof plate may change a range and distribution of morphogens it produces. The resistance of the roof plate cytoskeleton attenuates ventral displacement of the central canal in illustration of the novel mechanical role of the roof plate during development of the body axis.

  15. Analog VLSI Circuits for Short-Term Dynamic Synapses

    Directory of Open Access Journals (Sweden)

    Shih-Chii Liu

    2003-06-01

    Full Text Available Short-term dynamical synapses increase the computational power of neuronal networks. These synapses act as additional filters to the inputs of a neuron before the subsequent integration of these signals at its cell body. In this work, we describe a model of depressing and facilitating synapses derived from a hardware circuit implementation. This model is equivalent to theoretical models of short-term synaptic dynamics in network simulations. These circuits have been added to a network of leaky integrate-and-fire neurons. A cortical model of direction-selectivity that uses short-term dynamic synapses has been implemented with this network.

  16. Extrinsic sound stimulations and development of periphery auditory synapses

    Institute of Scientific and Technical Information of China (English)

    Kun Hou; Shiming Yang; Ke Liu

    2015-01-01

    The development of auditory synapses is a key process for the maturation of hearing function. However, it is still on debate regarding whether the development of auditory synapses is dominated by acquired sound stimulations. In this review, we summarize relevant publications in recent decades to address this issue. Most reported data suggest that extrinsic sound stimulations do affect, but not govern the development of periphery auditory synapses. Overall, periphery auditory synapses develop and mature according to its intrinsic mechanism to build up the synaptic connections between sensory neurons and/or interneurons.

  17. Silent Synapse-Based Circuitry Remodeling in Drug Addiction.

    Science.gov (United States)

    Dong, Yan

    2016-05-01

    Exposure to cocaine, and likely other drugs of abuse, generates α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor-silent glutamatergic synapses in the nucleus accumbens. These immature synaptic contacts evolve after drug withdrawal to redefine the neurocircuital properties. These results raise at least three critical questions: (1) what are the molecular and cellular mechanisms that mediate drug-induced generation of silent synapses; (2) how are neurocircuits remodeled upon generation and evolution of drug-generated silent synapses; and (3) what behavioral consequences are produced by silent synapse-based circuitry remodeling? This short review analyzes related experimental results, and extends them to some speculations. PMID:26721952

  18. Seven hundred years of peat formation recorded throughout a deep floating mire profile from Central Italy

    Science.gov (United States)

    Lobianco, Daniela; D'Orazio, Valeria; Miano, Teodoro; Zaccone, Claudio

    2016-04-01

    Floating mires are defined by the occurrence of emergent vegetation rooted in highly organic buoyant mats that rise and fall with changes in water level. Islands floating and moving on a lake naturally were already described by Pliny the Elder in his Naturalis historia almost two millennia ago. Actually, he devoted a whole chapter of Naturalis historia to "Of Islands Ever Floating and Swimming", reporting how certain isles were always waving and never stood still. The status of "flotant" has been defined transitory; in fact, these small isles often disappear, in most of the cases because of a transition from floating island to firm land during decades is likely to happen. That is why most of the floating islands described by Pliny the Elder (e.g., Lacus Fundanus, Lacus Cutiliensis, Lacus Mutinensis, Lacus Statoniensis, Lacus Tarquiniensis, Lydia Calaminae, Lacus Vadimonis) do not exist anymore. In the present study, peat formation and organic matter evolution were investigated in order to understand how these peculiar environments form, and how stable actually they are. In fact, it is hoped that peat-forming floating mires could provide an exceptional tool for environmental studies, since much of their evolution, as well as the changes of the surrounding areas, is recorded in their peat deposits. A complete, 4-m deep peat core was collected in July 2012 from the floating island of Posta Fibreno, a relic mire in the Central Italy. This floating island has a diameter of ca. 30 m, a submerged thickness of about 3 m, and the vegetation is organized in concentric belts, from the Carex paniculata palisade to the Sphagnum centre. Here, some of the southernmost Italian populations of Sphagnum palustre occur. The 14C age dating of organic sediments isolated from the sample at 385 cm of depth revealed that the island formed ca. 700 yrs ago (620±30 yr BP). The top 100 cm, consisting almost exclusively of Sphagnum mosses, show a very low bulk density (avg., 0.03±0.01 g cm

  19. A study of the role of presenilin (1) in regulating synaptic function at hippocampal synapses

    OpenAIRE

    Yu, L. M. Y.

    2010-01-01

    Synapse dysfunction is emerging as a major factor in the pathogenesis of Alzheimer’s disease (AD). Key insights into the pathological mechanisms have been provided through studies of familial AD (FAD) genes. Mutations in the PSEN1 gene account for the vast majority of FAD cases, which are typified by the formation of amyloid plaques, neurofibrillary tangles and neuronal loss. The PSEN1 gene encodes presenilin 1, a polytopic transmembrane protein, which is the catalytic core ...

  20. Control of CNS synapse development by γ-protocadherin-mediated astrocyte-neuron contact

    OpenAIRE

    Garrett, Andrew M.; Weiner, Joshua A.

    2009-01-01

    Recent studies indicate that astrocytes, whose processes enwrap synaptic terminals, promote synapse formation both by releasing soluble factors and through contact-dependent mechanisms. While astrocyte-secreted synaptogenic factors have been identified, the molecules underlying perisynaptic astroctye-neuron contacts are unknown. Here we show that the γ-Protocadherins (γ-Pcdhs), a family of 22 neuronal adhesion molecules encoded by a single gene cluster, are also expressed by astrocytes and lo...

  1. Effects of Trace Metal Profiles Characteristic for Autism on Synapses in Cultured Neurons

    OpenAIRE

    2015-01-01

    Various recent studies revealed that biometal dyshomeostasis plays a crucial role in the pathogenesis of neurological disorders such as autism spectrum disorders (ASD). Substantial evidence indicates that disrupted neuronal homeostasis of different metal ions such as Fe, Cu, Pb, Hg, Se, and Zn may mediate synaptic dysfunction and impair synapse formation and maturation. Here, we performed in vitro studies investigating the consequences of an imbalance of transition metals on glutamatergic syn...

  2. Collagen-derived matricryptins promote inhibitory nerve terminal formation in the developing neocortex.

    Science.gov (United States)

    Su, Jianmin; Chen, Jiang; Lippold, Kumiko; Monavarfeshani, Aboozar; Carrillo, Gabriela Lizana; Jenkins, Rachel; Fox, Michael A

    2016-03-14

    Inhibitory synapses comprise only ∼20% of the total synapses in the mammalian brain but play essential roles in controlling neuronal activity. In fact, perturbing inhibitory synapses is associated with complex brain disorders, such as schizophrenia and epilepsy. Although many types of inhibitory synapses exist, these disorders have been strongly linked to defects in inhibitory synapses formed by Parvalbumin-expressing interneurons. Here, we discovered a novel role for an unconventional collagen-collagen XIX-in the formation of Parvalbumin(+) inhibitory synapses. Loss of this collagen results not only in decreased inhibitory synapse number, but also in the acquisition of schizophrenia-related behaviors. Mechanistically, these studies reveal that a proteolytically released fragment of this collagen, termed a matricryptin, promotes the assembly of inhibitory nerve terminals through integrin receptors. Collectively, these studies not only identify roles for collagen-derived matricryptins in cortical circuit formation, but they also reveal a novel paracrine mechanism that regulates the assembly of these synapses. PMID:26975851

  3. A CHANDRA X-RAY ANALYSIS OF ABELL 1664: COOLING, FEEDBACK, AND STAR FORMATION IN THE CENTRAL CLUSTER GALAXY

    International Nuclear Information System (INIS)

    The brightest cluster galaxy (BCG) in the Abell 1664 cluster is unusually blue and is forming stars at a rate of ∼ 23 M sun yr-1. The BCG is located within 5 kpc of the X-ray peak, where the cooling time of 3.5 x 108 yr and entropy of 10.4 keV cm2 are consistent with other star-forming BCGs in cooling flow clusters. The center of A1664 has an elongated, 'barlike' X-ray structure whose mass is comparable to the mass of molecular hydrogen, ∼1010 M sun in the BCG. We show that this gas is unlikely to have been stripped from interloping galaxies. The cooling rate in this region is roughly consistent with the star formation rate, suggesting that the hot gas is condensing onto the BCG. We use the scaling relations of BIrzan et al. to show that the active galactic nucleus (AGN) is underpowered compared to the central X-ray cooling luminosity by roughly a factor of three. We suggest that A1664 is experiencing rapid cooling and star formation during a low state of an AGN feedback cycle that regulates the rates of cooling and star formation. Modeling the emission as a single-temperature plasma, we find that the metallicity peaks 100 kpc from the X-ray center, resulting in a central metallicity dip. However, a multi-temperature cooling flow model improves the fit to the X-ray emission and is able to recover the expected, centrally peaked metallicity profile.

  4. FOREX Microstructure, Invisible Price Determinants, and the Central Bank's Understanding of Exchange Rate Formation

    OpenAIRE

    Derviz, Alexis

    2003-01-01

    The paper investigates the transmission of macroeconomic factors into the price-setting behavior of a specific dealer in the FX market. This problem is viewed from the perspective of a central banker who observes the price evolution but does not make the market in the home currency. The analysis is based on a model of a multiple dealer market under two organizations: direct inter-dealer and brokered.

  5. Nitrous oxide formation in and emissions from grazed upland grasslands in Central Europe

    Czech Academy of Sciences Publication Activity Database

    Šimek, Miloslav; Čuhel, Jiří; Hynšt, Jaroslav

    New York : Nova Science Publishers, 2009, s. 67-83. ISBN 978-1-60692-267-5 R&D Projects: GA AV ČR IAA600660605; GA ČR GA526/09/1570; GA MŠk LC06066 Institutional research plan: CEZ:AV0Z60660521 Keywords : nitrous oxide * grazed upland grasslands * Central Europe Subject RIV: EH - Ecology, Behaviour

  6. Soil formation on a calcic chronosequence of Ancient Lake Konya in Central Anatolia, Turkey

    Science.gov (United States)

    Ozaytekin, Hasan Huseyin; Mutlu, Hasan Huseyin; Dedeoglu, Mert

    2012-11-01

    With the passage of time, different soils show a wide range of variation in their formation. The passage of time in soil formation affects both soil features and the rates of weathering. The aim of this research is to study and compare the pedogenic evolution of soils developed on the terraces of Ancient Lake Konya using weathering indices such as Chemical Index of Alteration (CIA), Chemical Index of Weathering (CIW), and Eu and Ce anomalies. The study will also take into account other features, such as the physical and chemical properties, the analytical characteristics and how soil formation is determined according to the passage of time. For this purpose, four representative profiles were dug at different levels. After the macro-morphological identifications were completed in all the profiles, the samples were then collected from the horizons and were analysed for their physical, chemical, mineralogical and geochemical properties. Although the soils in the study field were formed in different terrace levels, no significant relationship between the age of the soil and the soil properties was found. The lone exception was the clay movement in profile 1, which resulted from the limitation in profile development caused by erosion. Moreover, this erosion was the result of an increasing slope from the low terrace to the high coastal terraces. Similar physical, chemical and mineralogical characteristics were determined in the profiles. Using geochemical characteristics, the determined weathering indexes and their anomalies showed a very limited variation between the profiles, which suggests that though they differ in terms of age, the profiles have similar weathering levels. The climatological factors continuing along the Holocene were not efficient enough to change the effect of the other soil formation factors in the last period of the Quaternary. Therefore, it was concluded that the main factors determining soil formation are climate and topography, both of which

  7. Circadian rhythmicity of synapses in mouse somatosensory cortex.

    Science.gov (United States)

    Jasinska, Malgorzata; Grzegorczyk, Anna; Woznicka, Olga; Jasek, Ewa; Kossut, Malgorzata; Barbacka-Surowiak, Grazyna; Litwin, Jan A; Pyza, Elzbieta

    2015-10-01

    The circadian rhythmicity displayed by motor behavior of mice: activity at night and rest during the day; and the associated changes in the sensory input are reflected by cyclic synaptic plasticity in the whisker representations located in the somatosensory (barrel) cortex. It was not clear whether diurnal rhythmic changes in synapse density previously observed in the barrel cortex resulted from changes in the activity of the animals, from daily light/dark (LD) rhythm or are driven by an endogenous clock. These changes were investigated in the barrel cortex of C57BL/6 mouse strain kept under LD 12 : 12 h conditions and in constant darkness (DD). Stereological analysis of serial electron microscopic sections was used to assess numerical density of synapses. In mice kept under LD conditions, the total density of synapses and the density of excitatory synapses located on dendritic spines was higher during the light period (rest phase). In contrast, the density of inhibitory synapses located on dendritic spines increased during the dark period (activity phase). Under DD conditions, the upregulation of the inhibitory synapses during the activity phase was retained, but the cyclic changes in the density of excitatory synapses were not observed. The results show that the circadian plasticity concerns only synapses located on spines (and not those on dendritic shafts), and that excitatory and inhibitory synapses are differently regulated during the 24 h cycle: the excitatory synapses are influenced by light, whilst the inhibitory synapses are driven by the endogenous circadian clock. PMID:26274013

  8. Revisions to the stratigraphic nomenclature of the Abiquiu Formation, Abiquiu and contiguous areas, north-central New Mexico

    Science.gov (United States)

    Maldonado, Florian; Kelley, Shari A.

    2009-01-01

    Stratigraphic studies and geologic mapping on the Abiquiu 7.5-min quadrangle have led to revision of the stratigraphic nomenclature for the Oligocene to Miocene Abiquiu Formation in north-central New Mexico. The Abiquiu Formation had previously been defined to include informal upper, middle (Pedernal chert member), and lower members. The basement-derived conglomeratic lower member in the northern Jemez Mountains and Abiquiu embayment is here redefined. We propose removing the "lower member" from the Abiquiu Formation because provenance of these coarse sediments is dramatically different than the volcaniclastic strata of the "upper member." Furthermore, we propose that the term "lower member of the Abiquiu Formation" be replaced with an existing unit name, the Ritito Conglomerate of Barker (1958), and that the name Abiquiu Formation be restricted to the volcaniclastic succession. The lower part of the Ritito Conglomerate in Arroyo del Cobre on the Abiquiu quadrangle is 47 m (155 ft) thick and is composed of arkosic conglomeratic beds interbedded with arkosic sands and siltstones. Clasts include, in descending order of abundance, Proterozoic quartzite, granite, metavolcanic rocks, quartz, schist, and gneiss and a trace of Mesozoic sandstone and Paleozoic chert. Clasts are predominantly of pebble and cobble size but range from granule to boulder size. Paleocurrent data collected in the Arroyo del Cobre area indicate that the Ritito Conglomerate was deposited by a south-flowing river system during the Oligocene, eroding Laramide highlands such as the Tusas Mountains to the northeast, which contain predominantly Proterozoic rocks. This depositional setting has also been suggested by previous workers. The middle member or Pedernal chert member is present both at the top of the Ritito Conglomerate and as lenses within the lower part of the Abiquiu Formation. This post-depositional diagenetic chert remains an informal unit called the Pedernal chert.

  9. FORMATIVE MECHANISM OF AKAISHI MOUNTAINS AND ENREI BASIN IN CENTRAL JAPAN

    Institute of Scientific and Technical Information of China (English)

    Yasu'uchi KUBOTA; Takao YANO

    2001-01-01

    @@ 1 Introduction It is common in mobile belts that uplifting mountains are neighbored by synchronously subsiding basins.The coupling mechanism of such subsidence and uplift is an important target to clarify the dynamics of mobile belts.We investigate the coupled mountain uplift and basin subsidence in the Central Japan highland,the junction of three island arcs (the Northeast Japan,the Southwest Japan and the Izu-Ogasawara arcs).The highland over 3 000 m in height is composed of mountain ranges,plateaus and intramountain basins (Fig.1).

  10. FORMATIVE MECHANISM OF AKAISHI MOUNTAINS AND ENREI BASIN IN CENTRAL JAPAN

    Institute of Scientific and Technical Information of China (English)

    Yasu'uchi; KUBOTA; Takao; YANO

    2001-01-01

    1 Introduction  It is common in mobile belts that uplifting mountains are neighbored by synchronously subsiding basins.The coupling mechanism of such subsidence and uplift is an important target to clarify the dynamics of mobile belts.We investigate the coupled mountain uplift and basin subsidence in the Central Japan highland,the junction of three island arcs (the Northeast Japan,the Southwest Japan and the Izu-Ogasawara arcs).The highland over 3 000 m in height is composed of mountain ranges,plateaus and intramountain basins (Fig.1).……

  11. Natural gas transport and storage markets in central Europe - trends of development and price formation

    International Nuclear Information System (INIS)

    The final consumer price is to a large part determined by the costs of natural gas transport, which thus often also becomes a determinant of the structure of natural gas markets. The present paper restricts itself to current developments in central Europe. It is intended to show that there is an increase in demand for 'unbundled' storage and transport services across markets of different strufctures. It is not possible to give more than a scanty outline of the principles governing tariff and price fixing. (orig.)

  12. Biostratigraphy of the Hawthorn formation in northeast and north central Florida

    Science.gov (United States)

    Hoenstine, R. W.

    Cores recently drilled along Florida's east coast by the Florida Bureau of Geology have yielded a record of the most complete Florida Hawthorn fossiliferous sediments heretofor available for biostratigraphic analysis. The record of Hawthorn deposition extends from the Early Miocene in sediments near the base of this formation in Nassau County to what appears to be Early Pliocene time in core sediments present in Indian River and St. Lucie counties. A diversity of microfossil groups including diatoms, silicoflagellates, foraminifera and coccoliths were identified in the Hawthorn sediments. Diatoms, which represented the largest and most definitive number of species, where the primary group used to determine the biochronology and paleoenvironmental interpretations of this important phosphate-bearing formation. Three biostratigraphic zones of Middle Miocene to Late Middle Miocene age can be recognized in the Hawthorn sediments (Coscinodiscus plicatus, Coscinodiscus plicatus/Delphineis penelliptica, Delphineis penelliptica zones).

  13. Glimepiride protects neurons against amyloid-β-induced synapse damage.

    Science.gov (United States)

    Osborne, Craig; West, Ewan; Nolan, William; McHale-Owen, Harriet; Williams, Alun; Bate, Clive

    2016-02-01

    Alzheimer's disease is associated with the accumulation within the brain of amyloid-β (Aβ) peptides that damage synapses and affect memory acquisition. This process can be modelled by observing the effects of Aβ on synapses in cultured neurons. The addition of picomolar concentrations of soluble Aβ derived from brain extracts triggered the loss of synaptic proteins including synaptophysin, synapsin-1 and cysteine string protein from cultured neurons. Glimepiride, a sulphonylurea used for the treatment of diabetes, protected neurons against synapse damage induced by Aβ. The protective effects of glimepiride were multi-faceted. Glimepiride treatment was associated with altered synaptic membranes including the loss of specific glycosylphosphatidylinositol (GPI)-anchored proteins including the cellular prion protein (PrP(C)) that acts as a receptor for Aβ42, increased synaptic gangliosides and altered cell signalling. More specifically, glimepiride reduced the Aβ-induced increase in cholesterol and the Aβ-induced activation of cytoplasmic phospholipase A2 (cPLA2) in synapses that occurred within cholesterol-dense membrane rafts. Aβ42 binding to glimepiride-treated neurons was not targeted to membrane rafts and less Aβ42 accumulated within synapses. These studies indicate that glimepiride modified the membrane micro-environments in which Aβ-induced signalling leads to synapse damage. In addition, soluble PrP(C), released from neurons by glimepiride, neutralised Aβ-induced synapse damage. Such observations raise the possibility that glimepiride may reduce synapse damage and hence delay the progression of cognitive decline in Alzheimer's disease. PMID:26432105

  14. STAR FORMATION IN THE CENTRAL 400 PC OF THE MILKY WAY: EVIDENCE FOR A POPULATION OF MASSIVE YOUNG STELLAR OBJECTS

    International Nuclear Information System (INIS)

    The central kpc of the Milky Way might be expected to differ significantly from the rest of the Galaxy with regard to gasdynamics and the formation of young stellar objects (YSOs). We probe this possibility with mid-infrared observations obtained with Infrared Array Camera and Multiband Imaging Photometer on Spitzer and with Midcourse Space Experiment. We use color-color diagrams and spectral energy distribution (SED) fits to explore the nature of YSO candidates (including objects with 4.5 μm excesses possibly due to molecular emission). There is an asymmetry in the distribution of the candidate YSOs, which tend to be found at negative Galactic longitudes; this behavior contrasts with that of the molecular gas, approximately 2/3 of which is at positive longitudes. The small-scale height of these objects suggests that they are within the Galactic center region and are dynamically young. They lie between two layers of infrared dark clouds and may have originated from these clouds. We identify new sites for this recent star formation by comparing the mid-IR, radio, submillimeter, and methanol maser data. The methanol masers appear to be associated with young, embedded YSOs characterized by 4.5 μm excesses. We use the SEDs of these sources to estimate their physical characteristics; their masses appear to range from ∼10 to ∼20 Msun. Within the central 400 x 50 pc (|l| 03 and |b| sun yr-1. Given that the majority of the sources in the population of YSOs are classified as Stage I objects, we suggest that a recent burst of star formation took place within the last 105 yr. This suggestion is also consistent with estimates of SFRs within the last ∼107 yr showing a peak around 105 yr ago. Lastly, we find that the Schmidt-Kennicutt Law applies well in the central 400 pc of the Galaxy. This implies that star formation does not appear to be dramatically affected by the extreme physical conditions in the Galactic center region.

  15. Dew formation on the surface of biological soil crusts in central European sand ecosystems

    Directory of Open Access Journals (Sweden)

    T. Fischer

    2012-11-01

    Full Text Available Dew formation was investigated in three developmental stages of biological soil crusts (BSC, which were collected along a catena of an inland dune and in the initial substrate. The Penman equation, which was developed for saturated surfaces, was modified for unsaturated surfaces and used for prediction of dewfall rates. The levels of surface saturation required for this approach were predicted using the water retention functions and the thicknesses of the BSCs. During a first field campaign (2–3 August 2011, dewfall increased from 0.042 kg m−2 for the initial sandy substrate to 0.058, 0.143 and 0.178 kg m−2 for crusts 1 to 3, respectively. During a second field campaign (17–18 August 2011, where dew formation was recorded in 1.5 to 2.75-h intervals after installation at 21:30 CEST, dewfall increased from 0.011 kg m−2 for the initial sandy substrate to 0.013, 0.028 and 0.055 kg m−2 for crusts 1 to 3, respectively. Dewfall rates remained on low levels for the substrate and for crust 1, and decreased overnight for crusts 2 and 3 (with crust 3 > crust 2 > crust 1 throughout the campaign. Dew formation was well reflected by the model response. The suggested mechanism of dew formation involves a delay in water saturation in near-surface soil pores and extracellular polymeric substances (EPS where the crusts were thicker and where the water capacity was high, resulting in elevated vapor flux towards the surface. The results also indicate that the amount of dewfall was too low to saturate the BSCs and to observe water flow into deeper soil. Analysis of the soil water retention curves revealed that, despite the sandy mineral matrix, moist crusts clogged by swollen EPS pores exhibited a clay-like behavior. It is hypothesized that BSCs gain double benefit from suppressing their competitors by runoff generation and from improving their water supply by dew collection. Despite higher amounts of dew, the

  16. Nonlinear Synapses for Large-Scale Models: An Efficient Representation Enables Complex Synapse Dynamics Modeling in Large-Scale Simulations

    Directory of Open Access Journals (Sweden)

    Eric eHu

    2015-09-01

    Full Text Available Chemical synapses are comprised of a wide collection of intricate signaling pathways involving complex dynamics. These mechanisms are often reduced to simple spikes or exponential representations in order to enable computer simulations at higher spatial levels of complexity. However, these representations cannot capture important nonlinear dynamics found in synaptic transmission. Here, we propose an input-output (IO synapse model capable of generating complex nonlinear dynamics while maintaining low computational complexity. This IO synapse model is an extension of a detailed mechanistic glutamatergic synapse model capable of capturing the input-output relationships of the mechanistic model using the Volterra functional power series. We demonstrate that the IO synapse model is able to successfully track the nonlinear dynamics of the synapse up to the third order with high accuracy. We also evaluate the accuracy of the IO synapse model at different input frequencies and compared its performance with that of kinetic models in compartmental neuron models. Our results demonstrate that the IO synapse model is capable of efficiently replicating complex nonlinear dynamics that were represented in the original mechanistic model and provide a method to replicate complex and diverse synaptic transmission within neuron network simulations.

  17. Formation mechanism of carbonate cemented zones adjacent to the top overpressured surface in the central Junggar Basin,NW China

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Carbonate cemented zones are normally adjacent to the top overpressured surface in the central Junggar Basin,NW China.Stable carbon and oxygen isotopic compositions and petrological investigations of carbonate cements in the carbonate cemented zones indicate that:(1) carbonate cements are composed dominantly of ferrocalcite,ferroan dolomite,and ankerite;(2) carbonate cements are formed under a high temperature circumstance in the subsurface,and organic fluid migration has an important effect on the formation of them;and(3) carbon and oxygen ions in the carbonate cements migrate from the underlying overpressured system.This suggests that the occurrence of carbonate cemented zones in this region results from multiple phases of organic fluid expulsion out of the overpressure compartment through geological time.This study provides a plausible mechanism of the formation of carbonate cemented zones adjacent to the top overpressured surface in the clastic sedimentary basins,and has an important implication for understanding the internal correlation between the formation of carbonate cemented zones adjacent to top overpressured surface and geofluids expulsion out of overpressured system.

  18. Dew formation on the surface of biological soil crusts in central European sand ecosystems

    Directory of Open Access Journals (Sweden)

    T. Fischer

    2012-07-01

    Full Text Available Dew formation was investigated in three developmental stages of biological soil crusts (BSC, which were collected along a catena of an inland dune and in the initial substrate. The Penman equation, which was developed for saturated surfaces, was modified for unsaturated surfaces and used for prediction of dewfall rates. The levels of surface saturation required for this approach were predicted using the water retention functions and the thicknesses of the BSCs. During a single event, dewfall increased with crust development from 0.08 kg m−2 for the initial substrate to 0.10, 0.20 and 0.25 kg m−2 for crusts stages 1 to 3, respectively, which was well reflected by the model response. The suggested mechanism of dew formation involves a delay in water saturation in near-surface soil pores and EPS where the crusts were thicker and where the water capacity was high, resulting in elevated vapor flux towards the surface. The results also indicate that the amount of dewfall was too low to observe water flow into deeper soil. Analysis of the soil water retention curves revealed that, despite the sandy mineral matrix, moist crusts with clogged by swollen EPS pores exhibited a clay-like behavior. It is hypothesized that BSCs gain double benefit from suppressing their competitors by runoff generation and from improving their water supply by dew collection. Despite higher amounts of dew, the water availability to the crust community decreases with crust development, which may be compensated by ecophysiological adaptation of crust organisms, and which may further suppress higher vegetation or mosses.

  19. Central Nervous Insulin Signaling in Sleep-Associated Memory Formation and Neuroendocrine Regulation.

    Science.gov (United States)

    Feld, Gordon B; Wilhem, Ines; Benedict, Christian; Rüdel, Benjamin; Klameth, Corinna; Born, Jan; Hallschmid, Manfred

    2016-05-01

    The neurochemical underpinnings of sleep's contribution to the establishment and maintenance of memory traces are largely unexplored. Considering that intranasal insulin administration to the CNS improves memory functions in healthy and memory-impaired humans, we tested whether brain insulin signaling and sleep interact to enhance memory consolidation in healthy participants. We investigated the effect of intranasal insulin on sleep-associated neurophysiological and neuroendocrine parameters and memory consolidation in 16 men and 16 women (aged 18-30 years), who learned a declarative word-pair task and a procedural finger sequence tapping task in the evening before intranasal insulin (160 IU) or placebo administration and 8 h of nocturnal sleep. On the subsequent evening, they learned interfering word-pairs and a new finger sequence before retrieving the original memories. Insulin increased growth hormone concentrations in the first night-half and EEG delta power during the second 90 min of non-rapid-eye-movement sleep. Insulin treatment impaired the acquisition of new contents in both the declarative and procedural memory systems on the next day, whereas retrieval of original memories was unchanged. Results indicate that sleep-associated memory consolidation is not a primary mediator of insulin's acute memory-improving effect, but that the peptide acts on mechanisms that diminish the subsequent encoding of novel information. Thus, by inhibiting processes of active forgetting during sleep, central nervous insulin might reduce the interfering influence of encoding new information. PMID:26448203

  20. Recent star formation in the inner Galactic Bulge seen by ISOGAL II -- The Central Molecular Zone

    CERN Document Server

    Immer, K; Omont, A; Menten, K M

    2011-01-01

    We present 5--38 $\\mu$m spectroscopic observations of a sample of 68 ISOGAL sources with unknown natures, taken with the Spitzer Infrared Spectrograph. Based on the characteristics and the slope of their spectra we classified the sources as young or late-type evolved objects. These sources were selected to test selection criteria based on the ISOGAL [7]--[15] color and the spatial extent parameter $\\sigma_{\\rm 15}$. We revised these criteria until they reliably distinguished between young and late-type evolved objects and then applied them to all ISOGAL sources in the central molecular zone (CMZ), resulting in the selection of 485 sources believed to be young. Furthermore, we added 656 Midcourse Space Experiment (MSX) sources to the CMZ sample that fulfilled $F_{\\rm E}/F_{\\rm D} > 2$ with $F{\\rm D}$ and $F_{\\rm E}$ being the flux densities in the D (15 $\\mu$m) and E (21 $\\mu$m) bands. After obtaining $\\frac{L_{\\rm bol}}{F_{\\rm 15}}$ conversion factors, we calculated the bolometric luminosity, $L_{\\rm bol}$, v...

  1. Quantal concept of T-cell activation: adhesion domains as immunological synapses

    Science.gov (United States)

    Sackmann, Erich

    2011-06-01

    Adhesion micro-domains (ADs) formed during encounters of lymphocytes with antigen-presenting cells (APC) mediate the genetic expression of quanta of cytokines interleukin-2 (IL-2). The IL-2-induced activation of IL-2 receptors promotes the stepwise progression of the T-cells through the cell cycle, hence their name, immunological synapses. The ADs form short-lived reaction centres controlling the recruitment of activators of the biochemical pathway (the kinases Lck and ZAP) while preventing the access of inhibitors (phosphatase CD45) through steric repulsion forces. CD45 acts as the generator of adhesion domains and, through its role as a spacer protein, also as the promoter of the reaction. In a second phase of T-cell-APC encounters, long-lived global reaction spaces (called supramolecular activation complexes (SMAC)) form by talin-mediated binding of the T-cell integrin (LFA-1) to the counter-receptor ICAM-1, resulting in the formation of ring-like tight adhesion zones (peripheral SMAC). The ADs move to the centre of the intercellular adhesion zone forming the central SMAC, which serve in the recycling of the AD. We propose that cell stimulation is triggered by integrating the effect evoked by the short-lived adhesion domains. Similar global reaction platforms are formed by killer cells to destruct APC. We present a testable mechanical model showing that global reaction spaces (SMAC or dome-like contacts between cytotoxic cells and APC) form by self-organization through delayed activation of the integrin-binding affinity and stabilization of the adhesion zones by F-actin recruitment. The mechanical stability and the polarization of the adhering T-cells are mediated by microtubule-actin cross-talk.

  2. Quantal concept of T-cell activation: adhesion domains as immunological synapses

    Energy Technology Data Exchange (ETDEWEB)

    Sackmann, Erich, E-mail: sackmann@ph.tum.de [Physics Department E22, Technical University Munich, D-85748 Garching (Germany)

    2011-06-15

    Adhesion micro-domains (ADs) formed during encounters of lymphocytes with antigen-presenting cells (APC) mediate the genetic expression of quanta of cytokines interleukin-2 (IL-2). The IL-2-induced activation of IL-2 receptors promotes the stepwise progression of the T-cells through the cell cycle, hence their name, immunological synapses. The ADs form short-lived reaction centres controlling the recruitment of activators of the biochemical pathway (the kinases Lck and ZAP) while preventing the access of inhibitors (phosphatase CD45) through steric repulsion forces. CD45 acts as the generator of adhesion domains and, through its role as a spacer protein, also as the promoter of the reaction. In a second phase of T-cell-APC encounters, long-lived global reaction spaces (called supramolecular activation complexes (SMAC)) form by talin-mediated binding of the T-cell integrin (LFA-1) to the counter-receptor ICAM-1, resulting in the formation of ring-like tight adhesion zones (peripheral SMAC). The ADs move to the centre of the intercellular adhesion zone forming the central SMAC, which serve in the recycling of the AD. We propose that cell stimulation is triggered by integrating the effect evoked by the short-lived adhesion domains. Similar global reaction platforms are formed by killer cells to destruct APC. We present a testable mechanical model showing that global reaction spaces (SMAC or dome-like contacts between cytotoxic cells and APC) form by self-organization through delayed activation of the integrin-binding affinity and stabilization of the adhesion zones by F-actin recruitment. The mechanical stability and the polarization of the adhering T-cells are mediated by microtubule-actin cross-talk.

  3. Proteomic studies of a single CNS synapse type: the parallel fiber/purkinje cell synapse.

    OpenAIRE

    Fekrije Selimi; Cristea, Ileana M.; Elizabeth Heller; Brian T Chait; Nathaniel Heintz

    2009-01-01

    Author Summary The brain is composed of many different types of neurons that form very specific connections: synapses are formed with specific cellular partners and on precise subcellular domains. It has been proposed that different combinations of molecules encode the specificity of neuronal connections, implying the existence of a “molecular synaptic code.” To test this hypothesis, we describe a new experimental strategy that allows systematic identification of the protein composition for i...

  4. Duration of inverted metamorphic sequence formation across the Himalayan Main Central Thrust (MCT), Sikkim

    Science.gov (United States)

    Cioldi, Stefania; Moulas, Evangelos; Tajcmanová, Lucie; Burg, Jean-Pierre

    2016-04-01

    Collision between the Indian and Eurasian plates since the Eocene (50 Ma) caused the closure of the Neo-Tethys and the underthrusting of India beneath the Tibetan Plateau, generating the 2500 km extended Himalayan belt. The Main Central Thrust (MCT) marks the boundary of the underlying Midland Lower Himalaya metasediments zone (LH) in the south from the overlying high grade metamorphic Higher Himalaya (HH) in the north. Several models considering petrochronology, geothermobarometry and structural geology have been discussed to explain the inverted metamorphic gradient in the LH metasediments without reaching a common agreement. This study investigates the tectonic setting and the timescale of inverted isograds related to crustal-scale thrusting at the MCT in the Sikkim region, northeast India. The aim is to contribute to the understanding of the link between mechanical and thermal evolution of major thrust zones and to clarify the nature and the origin of orogenic heat applying garnet geospeedometry. Garnets provide a sensitive record of metamorphic conditions and are potential chronometer. Their compositional zoning is used as a gauge for rate estimates of element diffusion within the mineral and allows estimating the absolute time of the thermal evolution. Inverse-fitting numerical model considering FRactIonation and Diffusion in GarnEt (FRIDGE) calculates garnet composition profiles by introducing P-T-t paths and bulk-rock composition of a specific sample. P-T conditions were estimated by convectional geothermobarometry supported by phase equilibria modelling and measured garnet chemical compositions. Simulation were compared with measured garnet profiles. Simple step function and FRIDGE preliminary results of Fe-Mg - Ca - Mn garnet fractionation-diffusion modelling indicate very short timescale (between 3 and 6 Ma) for peak metamorphic conditions in the northeast Himalayan collisional system. This duration does not allow thermal re-equilibration. It is an

  5. The main principles of formation of structure of cultural-historical landscapes of Central Russia.

    Science.gov (United States)

    Nizovtsev, Vyacheslav; Natalia, Erman

    2014-05-01

    The forming and development of cultural-historical landscapes (CH) are obligate result of evolution of society and nature, as well as, man and landscapes during their coherent growth. CH landscapes are holistic historic-cultural and nature creations. They reflect the history of land use and spiritual development of ethnic community of concrete territory with determine homogeneous landscape characteristics. The majority of them appertain to the category of relict landscapes, which completed their evolution growth. That means that these are anthropogenic (AL) and cultural (CL) landscapes. They lost anthropogenic management and continue their growth obeying natural logic. These landscapes include elements of morphological structure and natural components, which have been transformed by men, and also artefacts, sociofacts and mental facts. These facts can be considered as peculiar "biographical chronicle" of activity of population in determinate landscape conditions in determinate historical period. These facts are evidences of material and spiritual cultural of society. The first AL begin to arise simultaneously with conversation of appropriating economy into generating economy. There was such conversation in Central Russia (Neolithic revolution) only in Bronze Age. Anthropogenic transformed landscape complexes and even man-made landscape complexes have been formed in Bronze Age. Some of these complexes exist now. Actual anthropogenic and cultural landscapes began to form only in Iron Age while permanent, long existed settlement and agriculture structure has organized. First, These are small settlement anthropogenic landscape complexes (selischa and gorodischa) with applied permanent miniature arable areas. These complexes located on the capes and on the areas between river banks and banks of streams. Second, these are pasture anthropogenic landscape complexes (on the level of podurochische and urochische), located in flood plain and valley-cavin position (pasture

  6. Czech alien flora and the historical pattern of its formation: what came first to Central Europe?

    Science.gov (United States)

    Pysek, Petr; Sádlo, Jirí; Mandák, Bohumil; Jarosík, Vojtech

    2003-03-01

    Temporal patterns of immigration to the country were analysed using 668 alien species in the flora of the Czech Republic for which the dates of the first record were available (64.8% of the total number of 1031 so-called neophytes, i.e. aliens introduced after the year 1500). After a period of initial slow increase lasting to the 1840s, the accumulation of neophytes over time could be best fitted by a linear model that explained 97% of the variance. The intensity of floristic research, which varied between periods, did not significantly affect the overall increase in the number of aliens. The effect of species traits on the year of introduction was evaluated, with continent of origin, introduction type (deliberate or accidental), life history, Grime's life strategy, onset of flowering, mode of dispersal and propagule size as explanatory variables. Species of European origin and CSR strategists arrived earlier than those with other origins and strategies. Deliberately introduced species appeared earlier than accidental arrivals, and those cultivated for utilitary reasons on average arrived earlier than ornamentals. Species capable of early flowering were remarkably more prevalent among early newcomers. A separate analysis of accidentally introduced American species also identified life history as a significant predictor of immigration time, with annuals being introduced earlier than biennials and perennials. The data contribute to an understanding of a crucial stage of the invasion process that has received little attention in the literature. The model "early alien" to Central Europe is a European species with a CSR strategy deliberately brought for cultivation as a utilitary plant. Once it escaped from cultivation, its establishment in the wild was favoured by its ability to flower early and, therefore, complete the life cycle. PMID:12647111

  7. Formation and Accumulation of Hydrocarbons in the Central Uplift, Dongying Depression

    Institute of Scientific and Technical Information of China (English)

    Li Sumei; Qiu Guiqiang; Gao Yongjin; Jiang Zhenxue

    2006-01-01

    A large number of crude oil and rock samples from various oil pools of the Central Uplift in Dongying Depression were investigated to reveal the origin and accumulation of hydrocarbons. The results showed that the composition and areal distribution of hydrocarbons vary with the location of the oil pools. An increasing trend of gammacerane/C30-hopane and steranes/hopanes but a decreasing trend of prystane/phytane (Pr/Ph) and 18(H)-/17(H)-trisnorhopane (Ts/Tm) ratios were observed from southwest to northeast. This indicates a variation of source rocks and hydrocarbon properties. An increasing trend of water salinity with much more input of algae-rich microorganisms in the deposition environment of the source rock was observed from southwest to northeast. However, the thermal maturity of the source rocks showed a decreasing trend in the same direction. Oil-to-oil and oil-to-source rock correlations showed that most oils were sourced from Es3 and Es4 members with a burial depth of more than 3,000-3,150 m and 2,700 m respectively. The oils in the Shinan and Ying 11 sand bodies, which were generally mixed with the Es4 sourced oils, came mostly from Es3 mudstones. It is quite significant that the Es4 derived oils migrated vertically for hundreds of meters and accumulated in an overlying lithologic pool of the Es3m, i.e., Ying 11 synclinal lithologic pool, which suggests that the mechanisms of migration and accumulation for subtle oil pools in the Dongying Depression are more complex than that of the previously expected.

  8. Detrital zircon geochronology of the Adams Argillite and Nation River Formation, east-central Alaska, U.S.A

    Science.gov (United States)

    Gehrels, G.E.; Johnsson, M.J.; Howell, D.G.

    1999-01-01

    The Cambrian Adams Argillite and the Devonian Nation River Formation are two sandstone-bearing units within a remarkably complete Paleozoic stratigraphic section in east-central Alaska. These strata, now foreshortened and fault-bounded, were originally contiguous with miogeoclinal strata to the east that formed as a passive-margin sequence along the northwestern margin of the North American continent. Seventy-five detrital zircon grains from the Adams Argillite and the Nation River Formation were analyzed in an effort to provide constraints on the original sources of the grains, and to generate a detrital zircon reference for miogeoclinal strata in the northern Cordillera. Thirty-five single zircon grains from a quartzite in the Adams Argillite yield dominant age clusters of 1047-1094 (n = 6), 1801-1868 (n = 10), and 2564-2687 (n = 5) Ma. Forty zircons extracted from a sandstone in the Nation River Formation yield clusters primarily of 424-434 (n = 6), 1815-1838 (n = 6), 1874-1921 (n = 7), and 2653-2771 (n = 4) Ma. The Early Proterozoic and Archean grains in both units probably originated in basement rocks in a broad region of the Canadian Shield. In contrast, the original igneous sources for mid-Protcrozoic grains in the Adams Argillite and ??? 430 Ma grains in the Nation River Formation are more difficult to identify. Possible original sources for the mid-Proterozoic grains include: (1) the Grenville Province of eastern Laurentia, (2) the Pearya terrane along the Arctic margin, and (3) mid-Proterozoic igneous rocks that may have been widespread along or outboard of the Cordilleran margin. The ??? 430 Ma grains may have originated in: (1) arc-type sources along the Cordilleran margin, (2) the Caledonian orogen, or (3) a landmass, such as Pearya, Siberia, or crustal fragments now in northern Asia, that resided outboard of the Innuitian orogen during mid-Paleozoic time. Copyright ?? 1999, SEPM (Society for Sedimentary Geology).

  9. A new upper jurassic ophthalmosaurid ichthyosaur from the Slottsmoya Member, Agardhfjellet formation of central Spitsbergen.

    Directory of Open Access Journals (Sweden)

    Aubrey Jane Roberts

    Full Text Available Abundant new ichthyosaur material has recently been documented in the Slottsmøya Member of the Agardhfjellet Formation from the Svalbard archipelago of Norway. Here we describe a partial skeleton of a new taxon, Janusaurus lundi, that includes much of the skull and representative portions of the postcranium. The new taxon is diagnosed by a suite of cranial character states including a very gracile stapedial shaft, the presence of a dorsal process on the prearticular and autapomorphic postcranial features such as the presence of an interclavicular trough and a conspicuous anterodorsal process of the ilium. The peculiar morphology of the ilia indicates a previously unrecognized degree of morphological variation in the pelvic girdle of ophthalmosaurids. We also present a large species level phylogenetic analysis of ophthalmosaurids including new and undescribed ichthyosaur material from the Upper Jurassic of Svalbard. Our results recover all Svalbard taxa in a single unresolved polytomy nested within Ophthalmosaurinae, which considerably increases the taxonomic composition of this clade. The paleobiogeographical implications of this result suggest the presence of a single clade of Boreal ophthalmosaurid ichthyosaurs that existed during the latest Jurassic, a pattern also reflected in the high degree of endemicity among some Boreal invertebrates, particularly ammonoids. Recent and ongoing descriptions of marine reptiles from the Slottsmøya Member Lagerstätte provide important new data to test hypotheses of marine amniote faunal turnover at the Jurassic-Cretaceous boundary.

  10. Nuclear Disk Formation by Direct Collisions of Gas Clouds with the Central Black Hole

    CERN Document Server

    Alig, Christian; Johansson, Peter H; Schartmann, Marc

    2009-01-01

    We simulate clouds in the Galactic Centre (GC) crossing over the black hole in parts and present this as a possible formation mechanism for the observed stellar disks in the GC through the redistribution of angular momentum by colliding material with opposite angular momentum. A parameter study using six high resolution simulations of an isothermal cloud of constant density falling onto the black hole and crossing over it in parts demonstrates that this mechanism is able to reproduce the observed disk properties in the GC. The evolution of the ensuing accretion disks is highly non-linear with the redistribution of the angular momentum through dissipative processes being a dominant effect. We analyse the resulting Toomre unstable, eccentric gaseous disk and show that this already yields a good comparison with the observed stellar disk size and eccentricity in the GC. The best simulation results in an outer radius of 1 pc, a mass of 10$^4$ M$_{\\sun}$ and an eccentricity of 0.24 for the Toomre unstable disk, whi...

  11. Sequential palynostratigraphy of the Queen City and Weches formations (Middle Eocene Claiborne Group), southeast central Texas

    Energy Technology Data Exchange (ETDEWEB)

    Elsik, W.C. (MycoStrat Connection, Houston, TX (United States))

    1993-02-01

    Palynomorph sequences of several orders of magnitude were found in the Queen City and Weches formations respectively at Six Mile and Burleson bluffs on the Brazos River, Milam and Burleson counties, Texas. The long term development of the subtropical to tropical Claibornian palynoflora included Engelhardtia spp., Friedrichipollis claibornensis, Nudopollis terminalis, Pollenites laesius and Symplocoipollenites spp. Shorter term fluctuations in sea level were reflected by common herbaceous pollen in the Queen City, and common mangrove pollen in the Weches. Paleoenvironments were marginally to fully marine; dinocysts occurred throughout. The Wetzeliella group of dinocysts were present only in the Queen City at Six Mile Bluff. Late Paleocene to Early Eocene pollen, and Early Middle Eocene pollen with last effective occurrences near the Queen City and Weches boundary included Aesculiidites circumstriatus, Annona foveoreticulata and a new species of Platycarya. Five short term warmer-cooler couplet events were represented by successive abundance peaks of Juglandaceae followed by Ulmus; Alnus supports the three upper Ulmus peaks. One deep water event was recorded by an abundance of fresh water Pediastrum at the Queen City and Weches boundary. That boundary event was bracketed by two of the Alnus and Ulmus peaks.

  12. Excitatory synapses are stronger in the hippocampus of Rett syndrome mice due to altered synaptic trafficking of AMPA-type glutamate receptors.

    Science.gov (United States)

    Li, Wei; Xu, Xin; Pozzo-Miller, Lucas

    2016-03-15

    Deficits in long-term potentiation (LTP) at central excitatory synapses are thought to contribute to cognitive impairments in neurodevelopmental disorders associated with intellectual disability and autism. Using the methyl-CpG-binding protein 2 (Mecp2) knockout (KO) mouse model of Rett syndrome, we show that naïve excitatory synapses onto hippocampal pyramidal neurons of symptomatic mice have all of the hallmarks of potentiated synapses. Stronger Mecp2 KO synapses failed to undergo LTP after either theta-burst afferent stimulation or pairing afferent stimulation with postsynaptic depolarization. On the other hand, basal synaptic strength and LTP were not affected in slices from younger presymptomatic Mecp2 KO mice. Furthermore, spine synapses in pyramidal neurons from symptomatic Mecp2 KO are larger and do not grow in size or incorporate GluA1 subunits after electrical or chemical LTP. Our data suggest that LTP is occluded in Mecp2 KO mice by already potentiated synapses. The higher surface levels of GluA1-containing receptors are consistent with altered expression levels of proteins involved in AMPA receptor trafficking, suggesting previously unidentified targets for therapeutic intervention for Rett syndrome and other MECP2-related disorders. PMID:26929363

  13. Fractures Patterns of Tight Carbonates of Upper Jurassic Arab-D Member and Upper Jubaila Formation Outcrops, Central Saudi Arabia

    Science.gov (United States)

    Abdullatif, Osman; Abdlmutalib, Ammar

    2015-04-01

    This study investigates the fracture patterns of the upper Jurassic Arab-D member and upper Jubaila Formation outcropping in central Saudi Arabia. These strata represent the outcrop equivalent for Arab-D reservoir. The upper Jubaila Formation was deposited in the lower to upper slope to ramp crest leading to deposition Stromatoporoid lithofacies association, while Arab-D member deposited under deep to shallow lagoonal settings including skeletal bank and tidal flat lithofacies associations. This study utilized high resolution outcrop scale integrated fracture analysis, sedimentological and stratigraphical approach and methods.The field data included lithofacies, stratigraphic hierarchy, cyclicity and fracture measurements of orientation, length, spacing, intensity, and aperture. The Arab-D member is affected by five fracture patterns: (a) regular large scale fractures NW striking, several meters widely spaced, vertically dipping and cutting through several beds; (b) regular medium scale fractures striking NE and vertically dipping, moderately spaced and extending from two to three meters in length and cut through two or three beds; (c) regular small scale fractures that are arrested near the bed boundary vertically dipping and having less than one meter length and spacing; (d) irregular fractures filled with chemically weathered materials; (e) large scale fractures oriented perpendicular to the first fracture pattern in (a) along the outcrop strike and also cut on the top of the resistive sandy grainstone lithofacies of Arab D member. In contrast, the Upper Jubaila Formation is characterized mostly by medium scale NW and NE striking fractures that near vertically dipping and extended within one or two beds. Irregular small scale fractures also occur within parts of the beds of this group.Fracture formation and development in the Arab D and Jubaila Formation are partially attributed to regional tectonics affected the study area and locally to stratigraphic and

  14. Axonal synapses utilize multiple synaptic ribbons in the mammalian retina.

    Directory of Open Access Journals (Sweden)

    Hong-Lim Kim

    Full Text Available In the mammalian retina, bipolar cells and ganglion cells which stratify in sublamina a of the inner plexiform layer (IPL show OFF responses to light stimuli while those that stratify in sublamina b show ON responses. This functional relationship between anatomy and physiology is a key principle of retinal organization. However, there are at least three types of retinal neurons, including intrinsically photosensitive retinal ganglion cells (ipRGCs and dopaminergic amacrine cells, which violate this principle. These cell types have light-driven ON responses, but their dendrites mainly stratify in sublamina a of the IPL, the OFF sublayer. Recent anatomical studies suggested that certain ON cone bipolar cells make axonal or ectopic synapses as they descend through sublamina a, thus providing ON input to cells which stratify in the OFF sublayer. Using immunoelectron microscopy with 3-dimensional reconstruction, we have identified axonal synapses of ON cone bipolar cells in the rabbit retina. Ten calbindin ON cone bipolar axons made en passant ribbon synapses onto amacrine or ganglion dendrites in sublamina a of the IPL. Compared to the ribbon synapses made by bipolar terminals, these axonal ribbon synapses were characterized by a broad postsynaptic element that appeared as a monad and by the presence of multiple short synaptic ribbons. These findings confirm that certain ON cone bipolar cells can provide ON input to amacrine and ganglion cells whose dendrites stratify in the OFF sublayer via axonal synapses. The monadic synapse with multiple ribbons may be a diagnostic feature of the ON cone bipolar axonal synapse in sublamina a. The presence of multiple ribbons and a broad postsynaptic density suggest these structures may be very efficient synapses. We also identified axonal inputs to ipRGCs with the architecture described above.

  15. The central region of M83: Massive star formation, kinematics, and the location and origin of the nucleus

    CERN Document Server

    Knapen, J H; Ryder, S D; Falcon-Barroso, J; Fathi, K; Gutierrez, L

    2010-01-01

    We report new near-IR integral field spectroscopy of the central starburst region of the barred spiral galaxy M83 obtained with CIRPASS on Gemini-S, which we analyse in conjunction with GHaFaS Fabry-Perot data, an AAT IRIS2 Ks-band image, and near- and mid-IR imaging from the Hubble and Spitzer space telescopes. The bulk of the current star formation activity is hidden from optical view by dust extinction, but is seen in the near- and mid-IR to the north of the nucleus. This region is being fed by inflow of gas through the bar of M83, traced by the prominent dust lane entering into the circumnuclear region from the north. An analysis of stellar ages confirms that the youngest stars are indeed in the northwest. A gradual age gradient, with older stars further to the south, characterises the well-known star-forming arc in the central region of M83. Detailed analyses of the Pa beta ionised gas kinematics and near-IR imaging confirm that the kinematic centre coincides with the photometric centre of M83, and that ...

  16. Field Demonstration of Carbon Dioxide Miscible Flooding in the Lansing-Kansas City Formation, Central Kansas

    Energy Technology Data Exchange (ETDEWEB)

    Alan Byrnes; G. Paul Willhite; Don Green; Richard Pancake; JyunSyung Tsau; W. Lynn Watney; John Doveton; Willard Guy; Rodney Reynolds; Dave Murfin; James Daniels; Russell Martin; William Flanders; Dave Vander Griend; Eric Mork; Paul Cantrell

    2010-03-07

    A pilot carbon dioxide miscible flood was initiated in the Lansing Kansas City C formation in the Hall Gurney Field, Russell County, Kansas. The reservoir zone is an oomoldic carbonate located at a depth of about 2900 feet. The pilot consists of one carbon dioxide injection well and three production wells. Continuous carbon dioxide injection began on December 2, 2003. By the end of June 2005, 16.19 MM lb of carbon dioxide was injected into the pilot area. Injection was converted to water on June 21, 2005 to reduce operating costs to a breakeven level with the expectation that sufficient carbon dioxide was injected to displace the oil bank to the production wells by water injection. By March 7,2010, 8,736 bbl of oil were produced from the pilot. Production from wells to the northwest of the pilot region indicates that oil displaced from carbon dioxide injection was produced from Colliver A7, Colliver A3, Colliver A14 and Graham A4 located on adjacent leases. About 19,166 bbl of incremental oil were estimated to have been produced from these wells as of March 7, 2010. There is evidence of a directional permeability trend toward the NW through the pilot region. The majority of the injected carbon dioxide remains in the pilot region, which has been maintained at a pressure at or above the minimum miscibility pressure. Estimated oil recovery attributed to the CO2 flood is 27,902 bbl which is equivalent to a gross CO2 utilization of 4.8 MCF/bbl. The pilot project is not economic.

  17. First radiometric age (U-Pb, LA-ICP-MS, on detrital zircons) from the Punta Topocalma Formation: insights on Late Cretaceous marine deposition in central Chile

    International Nuclear Information System (INIS)

    Upper Cretaceous marine rocks crop out along the Pacific coast of central and south-central Chile between 33o and 37oS. These strata constitute an important reference for the Upper Cretaceous of South America due to their diverse fossil fauna and flora. The type unit of these deposits is the Quiriquina Formation, near Concepcion. This unit is considered Maastrichtian in age based on ammonites. Upper Cretaceous marine strata from other localities of central and south-central Chile are largely unstudied and their biostratigraphic ages are not precisely known. We present the first radiometric dating (U-Pb on detrital zircons) for Upper Cretaceous marine strata of the Chilean forearc at Punta Topocalma that indicates a probable depositional age of 71.9+0.9 Ma (latest Campanian-earliest Maastrichtian). Provenance analysis indicates that the source of sediments of the Punta Topocalma Formation was plutonic and volcano-sedimentary rocks from the Coastal Cordillera and the Central Depression of central Chile. The Lo Valle Formation, a volcano-sedimentary unit in the Central Depression, recorded deposition of the Upper Cretaceous volcanic arc that was coeval with marine sedimentation in the Topocalma area

  18. Star Formation in the Central 400 pc of the Milky Way: Evidence for a Population of Massive YSOs

    CERN Document Server

    Yusef-Zadeh, F; Arendt, R G; Whitney, B; Rieke, G; Wardle, M; Hinz, J L; Stolovy, S; Lang, C C; Burton, M G; Ramírez, S

    2009-01-01

    The central kpc of the Milky Way might be expected to differ significantly from the rest of the Galaxy with regard to gas dynamics and the formation of YSOs. We probe this possibility with mid-infrared observations obtained with IRAC and MIPS on Spitzer and with MSX. We use color-color diagrams and SED fits to explore the nature of YSO candidates (including objects with 4.5 micron excesses possibly due to molecular emission). There is an asymmetry in the distribution of the candidate YSOs, which tend to be found at negative Galactic longitudes; this behavior contrasts with that of the molecular gas, approximately 2/3 of which is at positive longitudes. The small scale height of these objects suggests that they are within the Galactic center region and are dynamically young. They lie between two layers of infrared dark clouds and may have originated from these clouds. We identify new sites for this recent star formation. The methanol masers appear to be associated with young, embedded YSOs characterized by 4.5...

  19. The role of vegetation in the formation of anabranching channels in an ephemeral river, Northern plains, arid central Australia

    Science.gov (United States)

    Tooth, Stephen; Nanson, Gerald C.

    2000-10-01

    As the distribution and abundance of vegetation in drylands is often controlled by the greater availability of water along river channels, riparian vegetation has the potential to influence significantly dryland river form, process and behaviour. This paper demonstrates how a small indigenous shrub, the inland teatree (Melaleuca glomerata), influences the formation and maintenance of anabranching channels in a reach of the ephemeral Marshall River, Northern Plains, arid central Australia. Here, the Marshall is characterized by ridge-form anabranching, where water and sediment are routed through subparallel, multiple channels of variable size which occur within a typically straight channel-train. Channels are separated by channel-train ridges - narrow, flow-aligned, vegetated features - or by wider islands. By providing a substantial element of boundary roughness, dense stands of teatrees growing on channel beds or atop the ridges and islands influence flow velocities, flow depths and sediment transport, resulting in flow diversion, bank and floodplain erosion, and especially sediment deposition. Ridges and islands represent a continuum of forms, and their formation and development can be divided into a three-stage sequence involving teatree growth and alluvial sedimentation.1Teatrees colonize a flat, sandy channel bed, initiating the formation of ridges by lee-side accretion. Individual ridges grow laterally, vertically and longitudinally and maintain a geometrically similar streamlined (lemniscate) form that presents minimum drag.2Individual ridges grow in size, and interact with neighbouring ridges, causing the lemniscate forms to become distorted. Ridges in the lee of other ridges tend to be protected from the erosive effects of floods and survive, whereas individual teatrees or small ridges exposed to flow concentrated between larger ridges, tend to be removed.3organized system of ridge-form anabranches. In the moderate- to low-gradient Marshall River, which is

  20. Astrocytic Ca2+ signals are required for the functional integrity of tripartite synapses

    Directory of Open Access Journals (Sweden)

    Tanaka Mika

    2013-01-01

    Full Text Available Abstract Background Neuronal activity alters calcium ion (Ca2+ dynamics in astrocytes, but the physiologic relevance of these changes is controversial. To examine this issue further, we generated an inducible transgenic mouse model in which the expression of an inositol 1,4,5-trisphosphate absorbent, “IP3 sponge”, attenuates astrocytic Ca2+ signaling. Results Attenuated Ca2+ activity correlated with reduced astrocytic coverage of asymmetric synapses in the hippocampal CA1 region in these animals. The decreased astrocytic ‘protection’ of the synapses facilitated glutamate ‘spillover’, which was reflected by prolonged glutamate transporter currents in stratum radiatum astrocytes and enhanced N-methyl-D-aspartate receptor currents in CA1 pyramidal neurons in response to burst stimulation. These mice also exhibited behavioral impairments in spatial reference memory and remote contextual fear memory, in which hippocampal circuits are involved. Conclusions Our findings suggest that IP3-mediated astrocytic Ca2+ signaling correlates with the formation of functional tripartite synapses in the hippocampus.

  1. 沉默突触的激活机制及其功能意义%Silent Synapse:A Review

    Institute of Scientific and Technical Information of China (English)

    蔡靓; 苏朝芬; 罗焕敏

    2012-01-01

    沉默突触(silent synapse)是指具有突触结构,但在生理情况下没有传递功能的突触。沉默突触在某些情况下能转变为功能性突触并能增加突触联系(即能与其他末梢形成新的突触),突触功能与结构上的变化统称为突触的可塑性,它的这一性质与神经修复、记忆改善等过程密切相关。所以,研究沉默突触的形成、功能、激活机制等意义重大。%Silent synapse is defined as a synapse that is incapable of exerting neurotransmission in physiological conditions but could be activated under certain conditions. The change of function and structure of synapses are defined as plasticity of synapse, and this property of synapses is related to restoration of the neurons and memory improvement. It is essential to understand the mechanisms of formation, function and activation of silent synapse.

  2. Temporal dynamics in an immunological synapse: Role of thermal fluctuations in signaling

    Science.gov (United States)

    Bush, Daniel R.; Chattopadhyay, Amit K.

    2015-07-01

    The article analyzes the contribution of stochastic thermal fluctuations in the attachment times of the immature T-cell receptor TCR: peptide-major-histocompatibility-complex pMHC immunological synapse bond. The key question addressed here is the following: how does a synapse bond remain stabilized in the presence of high-frequency thermal noise that potentially equates to a strong detaching force? Focusing on the average time persistence of an immature synapse, we show that the high-frequency nodes accompanying large fluctuations are counterbalanced by low-frequency nodes that evolve over longer time periods, eventually leading to signaling of the immunological synapse bond primarily decided by nodes of the latter type. Our analysis shows that such a counterintuitive behavior could be easily explained from the fact that the survival probability distribution is governed by two distinct phases, corresponding to two separate time exponents, for the two different time regimes. The relatively shorter timescales correspond to the cohesion:adhesion induced immature bond formation whereas the larger time reciprocates the association:dissociation regime leading to TCR:pMHC signaling. From an estimate of the bond survival probability, we show that, at shorter timescales, this probability PΔ(τ ) scales with time τ as a universal function of a rescaled noise amplitude D/Δ2, such that PΔ(τ ) ˜τ-(Δ/√{D }+1/2 ) ,Δ being the distance from the mean intermembrane (T cell:Antigen Presenting Cell) separation distance. The crossover from this shorter to a longer time regime leads to a universality in the dynamics, at which point the survival probability shows a different power-law scaling compared to the one at shorter timescales. In biological terms, such a crossover indicates that the TCR:pMHC bond has a survival probability with a slower decay rate than the longer LFA-1:ICAM-1 bond justifying its stability.

  3. Direct imaging of lateral movements of AMPA receptors inside synapses

    CERN Document Server

    Tardin, Catherine; Bats, Cécile; Lounis, Brahim; Choquet, Daniel

    2003-01-01

    Trafficking of AMPA receptors in and out of synapses is crucial for synaptic plasticity. Previous studies have focused on the role of endo/exocytosis processes or that of lateral diffusion of extra-synaptic receptors. We have now directly imaged AMPAR movements inside and outside synapses of live neurons using single-molecule fluorescence microscopy. Inside individual synapses, we found immobile and mobile receptors, which display restricted diffusion. Extra-synaptic receptors display free diffusion. Receptors could also exchange between these membrane compartments through lateral diffusion. Glutamate application increased both receptor mobility inside synapses and the fraction of mobile receptors present in a juxtasynaptic region. Block of inhibitory transmission to favor excitatory synaptic activity induced a transient increase in the fraction of mobile receptors and a decrease in the proportion of juxtasynaptic receptors. Altogether, our data show that rapid exchange of receptors between a synaptic and ext...

  4. Synapse Loss in Olfactory Local Interneurons Modifies Perception

    OpenAIRE

    Acebes-Vindel, José Ángel; Martín-Peña, Alfonso; Chevalier, Valérie; Ferrús, Alberto

    2011-01-01

    Synapse loss correlates with cognitive decline in aging and most neurological pathologies. Sensory perception changes often represent subtle dysfunctions that precede the onset of a neurodegenerative disease. However, a cause–effect relationship between synapse loss and sensory perception deficits is difficult to prove and quantify due to functional and structural adaptation of neural systems. Here we modified a PI3K/AKT/GSK3 signaling pathway to reduce the number of synapses—without affectin...

  5. Opposite actions of nitric oxide on cholinergic synapses: which pathways?

    OpenAIRE

    Mothet, J P; Fossier, P; Tauc, L; Baux, G

    1996-01-01

    Nitric oxide (NO) produced opposite effects on acetylcholine (ACh) release in identified neuroneuronal Aplysia synapses depending on the excitatory or the inhibitory nature of the synapse. Extracellular application of the NO donor, SIN-1, depressed the inhibitory postsynaptic currents (IPSCs) and enhanced the excitatory postsynaptic currents (EPSCs) evoked by presynaptic action potentials (1/60 Hz). Application of a membrane-permeant cGMP analog mimicked the effect of SIN-1 suggesting the par...

  6. A New Efficient-Silicon Area MDAC Synapse

    OpenAIRE

    Zied Gafsi; Nejib Hassen; Mongia Mhiri; Kamel Besbes

    2007-01-01

    Using the binary representation in the Multiplier digital to analog converter (MDAC) synapse designs have crucial drawbacks. Silicon area of transistors, constituting the MDAC circuit, increases exponentially according to the number of bits. This latter is generated by geometric progression of common ratio equal to 2. To reduce this exponential increase to a linear growth, a new synapse named Arithmetic MDAC (AMDAC) is designed. It functions with a new representation based on arithmetic progr...

  7. Low voltage and time constant organic synapse-transistor

    OpenAIRE

    Desbief, Simon; Kyndiah, Adrica; Guerin, David; Gentili, Denis; Murgia, Mauro; Lenfant, Stéphane; Alibart, Fabien; Cramer, Tobias; Biscarini, Fabio; Vuillaume, Dominique

    2015-01-01

    We report on an artificial synapse, an organic synapse-transistor (synapstor) working at 1 volt and with a typical response time in the range 100-200 ms. This device (also called NOMFET, Nanoparticle Organic Memory Field Effect Transistor) combines a memory and a transistor effect in a single device. We demonstrate that short-term plasticity (STP), a typical synaptic behavior, is observed when stimulating the device with input spikes of 1 volt. Both significant facilitating and depressing beh...

  8. Memory-Relevant Mushroom Body Output Synapses Are Cholinergic

    OpenAIRE

    Barnstedt, Oliver; Owald, David; Felsenberg, Johannes; Brain, Ruth; Moszynski, John-Paul; Talbot, Clifford B.; Perrat, Paola N.; Waddell, Scott

    2016-01-01

    Summary Memories are stored in the fan-out fan-in neural architectures of the mammalian cerebellum and hippocampus and the insect mushroom bodies. However, whereas key plasticity occurs at glutamatergic synapses in mammals, the neurochemistry of the memory-storing mushroom body Kenyon cell output synapses is unknown. Here we demonstrate a role for acetylcholine (ACh) in Drosophila. Kenyon cells express the ACh-processing proteins ChAT and VAChT, and reducing their expression impairs learned o...

  9. Structure and function of the hair cell ribbon synapse.

    OpenAIRE

    Nouvian, R.; Beutner, D.; Parsons, T D; Moser, T.

    2006-01-01

    Faithful information transfer at the hair cell afferent synapse requires synaptic transmission to be both reliable and temporally precise. The release of neurotransmitter must exhibit both rapid on and off kinetics to accurately follow acoustic stimuli with a periodicity of 1 ms or less. To ensure such remarkable temporal fidelity, the cochlear hair cell afferent synapse undoubtedly relies on unique cellular and molecular specializations. While the electron microscopy hallmark of the hair cel...

  10. Silent Synapse-Based Circuitry Remodeling in Drug Addiction

    OpenAIRE

    Dong, Yan

    2015-01-01

    Exposure to cocaine, and likely other drugs of abuse, generates α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor-silent glutamatergic synapses in the nucleus accumbens. These immature synaptic contacts evolve after drug withdrawal to redefine the neurocircuital properties. These results raise at least three critical questions: (1) what are the molecular and cellular mechanisms that mediate drug-induced generation of silent synapses; (2) how are neurocircuits remodeled upon genera...

  11. Fmr1 KO and Fenobam Treatment Differentially Impact Distinct Synapse Populations of Mouse Neocortex

    OpenAIRE

    Wang, Gordon X.; Smith, Stephen J.; MOURRAIN, PHILIPPE

    2014-01-01

    Cognitive deficits in fragile X syndrome (FXS) are attributed to molecular abnormalities of the brain’s vast and heterogeneous synapse populations. Unfortunately, the density of synapses coupled with their molecular heterogeneity presents formidable challenges in understanding the specific contribution of synapse changes in FXS. We demonstrate powerful new methods for the large-scale molecular analysis of individual synapses that allow quantification of numerous specific changes in synapse po...

  12. Synapse- and Stimulus-Specific Local Translation During Long-Term Neuronal Plasticity

    OpenAIRE

    Wang, Dan Ohtan; Kim, Sang Mok; Zhao, Yali; Hwang, Hongik; Miura, Satoru K.; Sossin, Wayne S.; Martin, Kelsey C.

    2009-01-01

    Long-term memory and synaptic plasticity require changes in gene expression and yet can occur in a synapse-specific manner. mRNA localization and regulated translation at synapses are thus critical for establishing synapse specificity. Using live cell microscopy of photoconvertible fluorescent protein translational reporters, we directly visualized local translation at synapses during long-term facilitation of Aplysia sensory-motor synapses. Translation of the reporter required multiple appli...

  13. Artificial Synapse Network on Inorganic Proton Conductor for Neuromorphic Systems Applications

    OpenAIRE

    Zhu, Li Qiang; Wan, Chang Jin; Guo, Li Qiang; Shi, Yi; Wan, Qing

    2013-01-01

    The basic units in our brain are neurons and each neuron has more than 1000 synapse connections. Synapse is the basic structure for information transfer in an ever-changing manner, and short-term plasticity allows synapses to perform critical computational functions in neural circuits. Therefore the major challenge for the hardware implementation of neuromorphic computation is to develop artificial synapse. Here, in-plane oxide-based artificial synapse network coupled by proton neurotransmitt...

  14. Daily rhythm of synapse turnover in mouse somatosensory cortex.

    Science.gov (United States)

    Jasinska, Malgorzata; Grzegorczyk, Anna; Jasek, Ewa; Litwin, Jan A; Kossut, Malgorzata; Barbacka-Surowiak, Grazyna; Pyza, Elzbieta

    2014-01-01

    The whisker representations in the somatosensory barrel cortex of mice are modulated by sensory inputs associated with animal motor behavior which shows circadian rhythmicity. In a C57/BL mouse strain kept under a light/dark (LD 12:12) regime, we observed daily structural changes in the barrel cortex, correlated with the locomotor activity level. Stereological analysis of serial electron microscopic sections of the barrel cortex of mice sacrificed during their active or rest period, revealed an increase in the total numerical density of synapses and in the density of excitatory synapses located on dendritic spines during the rest, as well as an increase in the density of inhibitory synapses located on double-synapse spines during the active period. This is the first report demonstrating a daily rhythm in remodeling of the mammalian somatosensory cortex, manifested by changes in the density of synapses and dendritic spines. Moreover, we have found that the excitatory and inhibitory synapses are differently regulated during the day/night cycle. PMID:24718049

  15. Addictive drugs and plasticity of glutamatergic synapses on dopaminergic neurons: what have we learned from genetic mouse models?

    OpenAIRE

    Jan Rodriguez Parkitna; David Engblom

    2012-01-01

    Drug-induced changes in the functional properties of neurons in the mesolimbic dopaminergic system are attractive candidates for the molecular underpinnings of addiction. A central question in this context has been how drugs of abuse affect synaptic plasticity on dopaminergic cells in the ventral tegmental area. We now know that the intake of addictive drugs is accompanied by a complex sequence of alterations in the properties of excitatory synapses on dopaminergic neurons, mainly driven by s...

  16. Differentiation of autonomic reflex control begins with cellular mechanisms at the first synapse within the nucleus tractus solitarius

    OpenAIRE

    Andresen M.C.; Doyle M.W.; Bailey T.W.; Jin Y.-H.

    2004-01-01

    Visceral afferents send information via cranial nerves to the nucleus tractus solitarius (NTS). The NTS is the initial step of information processing that culminates in homeostatic reflex responses. Recent evidence suggests that strong afferent synaptic responses in the NTS are most often modulated by depression and this forms a basic principle of central integration of these autonomic pathways. The visceral afferent synapse is uncommonly powerful at the NTS with large unitary response amplit...

  17. Assessing the role of cell-surface molecules in central synaptogenesis in the Drosophila visual system.

    Directory of Open Access Journals (Sweden)

    Sandra Berger-Müller

    Full Text Available A hallmark of the central nervous system is its spatial and functional organization in synaptic layers. During neuronal development, axons form transient contacts with potential post-synaptic elements and establish synapses with appropriate partners at specific layers. These processes are regulated by synaptic cell-adhesion molecules. In the Drosophila visual system, R7 and R8 photoreceptor subtypes target distinct layers and form en passant pre-synaptic terminals at stereotypic loci of the axonal shaft. A leucine-rich repeat transmembrane protein, Capricious (Caps, is known to be selectively expressed in R8 axons and their recipient layer, which led to the attractive hypothesis that Caps mediates R8 synaptic specificity by homophilic adhesion. Contradicting this assumption, our results indicate that Caps does not have a prominent role in synaptic-layer targeting and synapse formation in Drosophila photoreceptors, and that the specific recognition of the R8 target layer does not involve Caps homophilic axon-target interactions. We generated flies that express a tagged synaptic marker to evaluate the presence and localization of synapses in R7 and R8 photoreceptors. These genetic tools were used to assess how the synaptic profile is affected when axons are forced to target abnormal layers by expressing axon guidance molecules. When R7 axons were mistargeted to the R8-recipient layer, R7s either maintained an R7-like synaptic profile or acquired a similar profile to r8s depending on the overexpressed protein. When R7 axons were redirected to a more superficial medulla layer, the number of presynaptic terminals was reduced. These results indicate that cell-surface molecules are able to dictate synapse loci by changing the axon terminal identity in a partially cell-autonomous manner, but that presynapse formation at specific sites also requires complex interactions between pre- and post-synaptic elements.

  18. Duration of formation of magmatic system of polyphase paleozoic alkaline complexes of the Central Kola: U-Pb, Rb-Sr, Ar-Ar data

    International Nuclear Information System (INIS)

    Attempt was made for the determination of duration of all abyssal system formation in the central part of the Kola peninsula. System of isotope methods inclosing Rb-Sr-isochronic dating, 40Ar/39Ar-age analysis of rocks as well as U-Th-Pb-dating is applied. Formation of the Khibiny-Lovozero-Kurga volcano-plutonic system is proposed to have a multiphase character. Summary scheme of the order of events is performed

  19. Nonlinear Synapses for Large-Scale Models: An Efficient Representation Enables Complex Synapse Dynamics Modeling in Large-Scale Simulations

    OpenAIRE

    Eric eHu; Jean-Marie Charles Bouteiller; Dong eSong; Michel eBaudry; Theodore W. Berger

    2015-01-01

    Chemical synapses are comprised of a wide collection of intricate signaling pathways involving complex dynamics. These mechanisms are often reduced to simple spikes or exponential representations in order to enable computer simulations at higher spatial levels of complexity. However, these representations cannot capture important nonlinear dynamics found in synaptic transmission. Here, we propose an input-output (IO) synapse model capable of generating complex nonlinear dynamics while maintai...

  20. Overview Chapter 5: Determinants of family formation and childbearing during the societal transition in Central and Eastern Europe

    Directory of Open Access Journals (Sweden)

    Tomas Frejka

    2008-07-01

    Full Text Available Societal conditions for early and high rates of childbearing were replaced by conditions generating late and low levels of fertility common in Western countries. Central among factors shaping the latter behaviour (job insecurity, unstable partnership relationships, expensive housing, and profound changes in norms, values and attitudes were the following: increasing proportions of young people were acquiring advanced education, a majority of women were gainfully employed, yet women were performing most household maintenance and childrearing duties. Two theories prevailed to explain what caused changes in family formation and fertility trends. One argues that the economic and social crises were the principal causes. The other considered the diffusion of western norms, values and attitudes as the prime factors of change. Neither reveals the root cause: the replacement of state socialist regimes with economic and political institutions of contemporary capitalism. The extraordinarily low period TFRs around 2000 were the result of low fertility of older women born around 1960 overlapping with low fertility of young women born during the 1970s.

  1. Milankovitch insulation forcing and cyclic formation of large-scale glacial, fluvial, and eolian landforms in central Alaska

    Science.gov (United States)

    Beget, J. E.

    Continuous marine and ice-core proxy climate records indicate that the Earth's orbital geometry modulates long-term changes. Until recently, little direct evidence has been available to demonstrate correlations between Milankovitch cycles and large-scale terrestrial landforms produced during worldwide glaciations. In central Alaska large areas of loess and sand fill valleys and basins near major outwash streams. The streams themselves are bordered by sets of outwash terraces, and the terraces grade up valley into sets of moraines. The discovery of the Stampede tephra (approximately 175,000 yr ago) reworked within push moraines of the Lignite Creek glaciation suggests that this event correlates with the glaciation of marine isotope stage 6. A new occurrence of the Old Crow tephra (approximately 140,000 yr ago) on the surface of the oldest outwash terrace of the Tanana River, correlated with Delta glaciation, suggests this event also occurred at this time. The penultimate Healy glaciation apparently correlates with marine isotope stage 4, while radiocarbon dates indicate the latest Pleistocene moraines correlate with marine isotope stage 2. Recognition of the importance of orbital forcing to the cyclical formation of glacial landforms and landscapes can help in interpretations of remotely sensed glacial and proglacial land forms.

  2. Spatial Distribution of Sulfate and the Formation of Ettringite in Lime-Amended Soils of Central Texas

    Science.gov (United States)

    Kuo, L.; Markley, C. T.; Herbert, B. E.; Little, D. N.

    2004-12-01

    During road construction, the use of calcium-based stabilizers, such as calcium oxide (lime), in sulfate-bearing clay soils has historically lead to distress and heave due to the formation of ettringite and possibly thaumasite. Ettringite (Ca6(Al(OH)6)2(SO4)3*26H2O) is a hydrous calcium alumino-sulfate mineral that precipitates in environments with high pH and high sulfate activity. Field surveys of soil conductivity quantified using electromagnetics (EM31), geochemical characterization of soils, geochemical modeling of ettringite precipitation in lime-amended soils, and landscape characterization using existing geospatial databases were coupled to prediction the potential for ettringite formation along the SH 130 corridor, a new toll road being constructed in central Texas. Electromagnetic surveys of soil conductivities were conducted at two sites near HWY 290 and HWY 79, in the SH 130 corridor. Soil conductivities at the two sites were correlated extractable SO42- and other soil properties (extractable Al, Ca, and Mg) quantified by water extracts at two pHs (pH 8-9 and 12). At the HWY 290 site, the soil conductivity ranged from 111 to 184 ms/m, while the conductivity ranged from 34-48 ms/m at the HWY 79 site. The concentration of extractable SO42- in HWY 290 and HWY 79 sites are up to 7269 mg/kg and 406 mg/kg, respectively. Soils at these sites are dominated by smectitic clay with relatively high amounts of carbonate. Information from STATSGO, the USDA soil database, and the comparisons between the results of the field surveys and laboratory soil analyses show that variations in sulfate levels at the two sites are strongly influenced by topography. The HWY 79 site is fairly level and there are only very weak trends in the sulfate composition of the soils. The HWY 290 site, on the other hand, is fairly hilly, with a dry stream channel, whose soil and sediments exhibited very high sulfate concentrations. The strong topographic slope influences hydrologic flow

  3. Changes in Synapses and Axons Demonstrated by Synaptophysin Immunohistochemistry Following Spinal Cord Compression Trauma in the Rat and Mouse

    Institute of Scientific and Technical Information of China (English)

    GUI-LIN LI; MOHAMMAD FAROOQUE; JONAS ISAKSSON; YNGVE OLSSON

    2004-01-01

    and methods To evaluate synaptic changes using synaptophysin immunohistochemstry in rat and mouse, which spinal cords were subjected to graded compression trauma at the level of Th8-9. Results Normal animals showed numerous fine dots of synaptophysin immunoreactivity in the gray matter. An increase in synaptophysin immunoreactivity was observed in the neuropil and synapses at the surface of motor neurons of the anterior horns in the Th8-9 segments lost immunoreactivity at 4-hour point after trauma. The immunoreactive synapses reappeared around motor neurons at 9-day point. Unexpected accumulation of synaptophysin immunoreactivity occurred in injured axons of the white matter of the compressed spinal cord. Conclusion Synaptic changes were important components of secondary injuries in spinal cord trauma. Loss of synapses on motor neurons may be one of the factors causing motor dysfunction of hind limbs and formation of new synapses may play an important role in recovery of motor function. Synaptophysin immunohistochemistry is also a good tool for studies of axonal swellings in spinal cord injuries.

  4. Two-stage formation model of the Junggar basin basement: Constraints to the growth style of Central Asian Orogenic Belt

    Science.gov (United States)

    He, Dengfa

    2016-04-01

    Junggar Basin is located in the central part of the Central Asian Orogenic Belt (CAOB). Its basement nature is a highly controversial scientific topic, involving the basic style and processes of crustal growth. Some researchers considered the basement of the Junggar Basin as a Precambrian continental crust, which is not consistent with the petrological compositions of the adjacent orogenic belts and the crust isotopic compositions revealed by the volcanic rocks in the basin. Others, on the contrary, proposed an oceanic crust basement model that does not match with the crustal thickness and geophysical characteristics of the Junggar area. Additionally, there are several viewponits, such as the duplex basement with the underlying Precambrian crystalline rocks and the overlying pre-Carboniferous folded basement, and the collaged basement by the Precambrian micro-continent block in the central part and the Hercynian accretionary folded belts circling it. Anyway, it is necessary to explain the property of basement rock, its strong inhomogeneous compositions as well as the geophysical features. In this paper, based on the borehole data from more than 300 industry wells drilled into the Carboniferous System, together with the high-resolution gravity and magnetic data (in a scale of 1:50,000), we made a detailed analysis of the basement structure, formation timing and processes and its later evolution on a basis of core geochemical and isotopic analysis. Firstly, we defined the Mahu Pre-Cambrian micro-continental block in the juvenile crust of Junggar Basin according to the Hf isotopic analysis of the Carboniferous volcanic rocks. Secondly, the results of the tectonic setting and basin analysis suggest that the Junggar area incorporates three approximately E-W trending island arc belts (from north to south: Yemaquan- Wulungu-Chingiz, Jiangjunmiao-Luliang-Darbut and Zhongguai-Mosuowan- Baijiahai-Qitai island arcs respectively) and intervened three approximately E-W trending

  5. Fueling the central engine of radio galaxies. III. Molecular gas and star formation efficiency of 3C 293

    Science.gov (United States)

    Labiano, A.; García-Burillo, S.; Combes, F.; Usero, A.; Soria-Ruiz, R.; Piqueras López, J.; Fuente, A.; Hunt, L.; Neri, R.

    2014-04-01

    Context. Powerful radio galaxies show evidence of ongoing active galactic nuclei (AGN) feedback, mainly in the form of fast, massive outflows. But it is not clear how these outflows affect the star formation of their hosts. Aims: We investigate the different manifestations of AGN feedback in the evolved, powerful radio source 3C 293 and their impact on the molecular gas of its host galaxy, which harbors young star-forming regions and fast outflows of H i and ionized gas. Methods: We study the distribution and kinematics of the molecular gas of 3C 293 using high spatial resolution observations of the 12CO(1-0) and 12CO(2-1) lines, and the 3 mm and 1 continuum taken with the IRAM Plateau de Bure interferometer. We mapped the molecular gas of 3C 293 and compared it with the dust and star-formation images of the host. We searched for signatures of outflow motions in the CO kinematics, and re-examined the evidence of outflowing gas in the H i spectra. We also derived the star formation rate (SFR) and star formation efficiency (SFE) of the host with all available SFR tracers from the literature, and compared them with the SFE of young and evolved radio galaxies and normal star-forming galaxies. Results: The 12CO(1-0) emission line shows that the molecular gas in 3C 293 is distributed along a massive (M(H2) ~ 2.2 × 1010M⊙) ~24″(21 kpc-) diameter warped disk, that rotates around the AGN. Our data show that the dust and the star formation are clearly associated with the CO disk. The 12CO(2-1) emission is located in the inner 7 kpc (diameter) region around the AGN, coincident with the inner part of the 12CO(1-0) disk. Both the 12CO(1-0) and 12CO(2-1) spectra reveal the presence of an absorber against the central regions of 3C 293 that is associated with the disk. We do not detect any fast (≳500 km s-1) outflow motions in the cold molecular gas. The host of 3C 293 shows an SFE consistent with the Kennicutt-Schmidt law of normal galaxies and young radio galaxies, and it

  6. Short-term changes in the numerical density of synapses in the intermediate and medial hyperstriatum ventrale following one-trial passive avoidance training in the chick.

    Science.gov (United States)

    Doubell, T P; Stewart, M G

    1993-05-01

    Previous ultrastructural studies using stereological counting techniques, based on assumptions regarding shape, size, and orientation of synapses, have suggested synaptic remodeling occurred at least 24 hr after one-trial passive avoidance training in day-old chicks. The present study estimates the mean synaptic density (Nv syn) in a region of the chick forebrain known to be involved in memory formation, the intermediate and medial hyperstriatum ventrale (IMHV), 1 and 24 hr following one-trial passive avoidance training. A stereological technique, the "disector," that makes no assumptions about size, shape, and orientation of synapses was used in the synaptic analyses. The density of axospinous synapses increased by approximately 77% at 1 hr posttraining in the right IMHV of chicks (M-trained) that learned to avoid a bitter-tasting bead, compared to those (W-trained controls) that peck a water-coated bead. A measure of the postsynaptic density size, the mean projected height of synapses (H), was 57% smaller 1 hr posttraining in the right IMHV of M-trained chicks. These differences were not found at 24 hr posttraining. We suggest that structural modification of synapses may be a key part of the processes involved in short-term memory formation. PMID:8478696

  7. mGluR2 acts through inhibitory Gα subunits to regulate transmission and long-term plasticity at hippocampal mossy fiber-CA3 synapses

    OpenAIRE

    Nicholls, Russell E.; ZHANG, XIAO-LEI; Bailey, Christopher P.; Conklin, Bruce R; Kandel, Eric R.; Stanton, Patric K.

    2006-01-01

    Presynaptic inhibitory G protein-coupled receptors play a critical role in regulating transmission at a number of synapses in the central and peripheral nervous system. We generated transgenic mice that express a constitutively active form of an inhibitory Gα subunit to examine the molecular mechanisms underlying the actions of one such receptor, metabotropic glutamate receptor (mGluR) 2, at mossy fiber-CA3 synapses in the hippocampus. mGluR2 participates in at least three types of mossy fibe...

  8. Auditory nerve synapses persist in ventral cochlear nucleus long after loss of acoustic input in mice with early-onset progressive hearing loss.

    Science.gov (United States)

    McGuire, Brian; Fiorillo, Benjamin; Ryugo, David K; Lauer, Amanda M

    2015-04-24

    Perceptual performance in persons with hearing loss, especially those using devices to restore hearing, is not fully predicted by traditional audiometric measurements designed to evaluate the status of peripheral function. The integrity of auditory brainstem synapses may vary with different forms of hearing loss, and differential effects on the auditory nerve-brain interface may have particularly profound consequences for the transfer of sound from ear to brain. Loss of auditory nerve synapses in ventral cochlear nucleus (VCN) has been reported after acoustic trauma, ablation of the organ of Corti, and administration of ototoxic compounds. The effects of gradually acquired forms deafness on these synapses are less well understood. We investigated VCN gross morphology and auditory nerve synapse integrity in DBA/2J mice with early-onset progressive sensorineural hearing loss. Hearing status was confirmed using auditory brainstem response audiometry and acoustic startle responses. We found no change in VCN volume, number of macroneurons, or number of VGLUT1-positive auditory nerve terminals between young adult and older, deaf DBA/2J. Cell-type specific analysis revealed no difference in the number of VGLUT1 puncta contacting bushy and multipolar cell body profiles, but the terminals were smaller in deaf DBA/2J mice. Transmission electron microscopy confirmed the presence of numerous healthy, vesicle-filled auditory nerve synapses in older, deaf DBA/2J mice. The present results suggest that synapses can be preserved over a relatively long time-course in gradually acquired deafness. Elucidating the mechanisms supporting survival of central auditory nerve synapses in models of acquired deafness may reveal new opportunities for therapeutic intervention. PMID:25686750

  9. Isotopic and geochemical characterization of groundwater of the Carnot-Berbérati sandstone formation (Western Central African Republic)

    Science.gov (United States)

    Djebebe-Ndjiguim, Chantal; Foto, Eric; Backo, Salé; Zoudamba, Narcisse; Basse-Keke, Eric; Nguerekossi, Bruno; Alladin, Oscar; Huneau, Frederic; Garel, Emilie; Celle-Jeanton, Helene; Mabingui, Joseph

    2016-04-01

    The hydrogeology of the Cretaceous sandstone formations of Carnot-Berbérati (covering an area of 46.000 km2) in the western part of the central African Republic is poorly known. In order to improve the access of local populations to a clean and safe drinking water resource, new investigations have been carried out in order to characterize groundwater in terms of quality, origin, residence time and sustainability. Two sampling campaigns were organized in August 2014 (rainy period) and April 2015 (dry period) on respectively 31 and 43 points including boreholes, wells and river waters. Conventional hydrogeochemical tools in conjunction with isotope hydrology tools were used to evaluate the water types and the anthropogenic fingerprint on groundwater, their recharge processes and the flow organization scheme. Investigations have shown the existence of interesting amounts of groundwater within what seems a single, well hydraulically connected unconfined aquifer of max. 400m thick. Groundwaters are characterized by two main water types: CaMg-HCO3 (for deep boreholes and river waters) and CaMg-ClNO3 (shallow wells). The latter clearly showing the very strong influence of anthropogenic activities (washing, dumps, latrines) in the near vicinity of wells and boreholes used for the drinking water supply. This is also highlighting the total lack of protection zone around the wells and boreholes. Stable isotopes of the water molecule (18O and 2H) are in agreement with a local recharge of groundwater and show a relatively homogeneous composition within the whole aquifer system. Tritium data indicate a modern recharge with a high renewability potential for shallow groundwater but very low tritium levels are observed in the deepest boreholes indicating the probable occurrence of complex flow conditions within the system in some sectors. From these results and because of its extension and storage potential, the Carnot-Berbérati sandstone aquifer appears as a groundwater resource

  10. Interplay between Subthreshold Oscillations and Depressing Synapses in Single Neurons.

    Directory of Open Access Journals (Sweden)

    Roberto Latorre

    Full Text Available In this paper we analyze the interplay between the subthreshold oscillations of a single neuron conductance-based model and the short-term plasticity of a dynamic synapse with a depressing mechanism. In previous research, the computational properties of subthreshold oscillations and dynamic synapses have been studied separately. Our results show that dynamic synapses can influence different aspects of the dynamics of neuronal subthreshold oscillations. Factors such as maximum hyperpolarization level, oscillation amplitude and frequency or the resulting firing threshold are modulated by synaptic depression, which can even make subthreshold oscillations disappear. This influence reshapes the postsynaptic neuron's resonant properties arising from subthreshold oscillations and leads to specific input/output relations. We also study the neuron's response to another simultaneous input in the context of this modulation, and show a distinct contextual processing as a function of the depression, in particular for detection of signals through weak synapses. Intrinsic oscillations dynamics can be combined with the characteristic time scale of the modulatory input received by a dynamic synapse to build cost-effective cell/channel-specific information discrimination mechanisms, beyond simple resonances. In this regard, we discuss the functional implications of synaptic depression modulation on intrinsic subthreshold dynamics.

  11. Streamlined subglacial bedforms on the Närke plain, south-central Sweden - Areal distribution, morphometrics, internal architecture and formation

    Science.gov (United States)

    Möller, Per; Dowling, Thomas P. F.

    2016-08-01

    A flow set of close to 1000 drumlins has been mapped by means of LiDAR-derived digital elevation models and investigated by trenching. The area is situated on the SW part of the Närke plain and its surrounding uplands in south-central Sweden, which was deglaciated in the early Preboreal in a glacioaquatic setting. We find that there is considerable morphological difference in drumlin distribution patterns over crystalline basement areas compared to streamlined terrain over Palaeozoic sedimentary rock basement. The former area is characterized by thin Quaternary drift and the drumlins are all of the rock-cored type, built due to active deposition of sediment around obstacles to glacier flow. The latter area is characterized by deep Quaternary drift and the drumlins are more elongate and also larger in all dimensions, as compared to rock-cored drumlins. Irrespective of these geomorphological differences on local landscape scale we find that drumlin morphometric values remain part of a morphological continuum at the regional scale. Based on the internal sediment architecture as revealed in two cross-drumlin sections we find that the soft-cored drumlins were formed by compressional constructive deformation, along with excavational deformation along the flanks of the emerging drumlins, which shaped the separating troughs. Intermediate-type drumlins are those that demonstrate a coupling between underlying Palaeozoic sediment strata in areas of shallow drift sheet. These are the result of differing rheological response between incorporated sedimentary rock and a deforming bed below the ice-bed interface. An overall conclusion is that we find geomorphic and architectural compositional differences between the drumlins and the flowset they form. We can closely relate these differences to contextual geological variations with respect to basement type and drift depth. We argue that drumlin formation is better explained not by one single 'unifying' process but rather a set of

  12. Transition from marine to hypersaline conditions in the Messinian Tripoli Formation from the marginal areas of the central Sicilian Basin

    Science.gov (United States)

    Bellanca, A.; Caruso, A.; Ferruzza, G.; Neri, R.; Rouchy, J. M.; Sprovieri, M.; Blanc-Valleron, M. M.

    2001-04-01

    Three sections of the early Messinian Tripoli Formation from the northern and southern margins of the central Sicilian Basin (Serra Pirciata, Torrente Vaccarizzo, and Marianopoli) have been studied with the aim to reconstruct the sedimentary and environmental changes which occurred during the transition between marine conditions and the evaporitic events of the Salinity Crisis recorded in the overlying Calcare di Base Formation. A detailed biostratigraphic and cyclostratigraphic study provided the opportunity of cycle-by-cycle correlations between the marginal sections and the reference section of Falconara. The main paleoenvironmental changes are recorded by: (1) the evolution of calcareous microfossils towards low diversity and their complete disappearance; (2) the composition of the carbonate fraction which commonly changes from calcite, mostly related to calcareous microfossils, to authigenic carbonate phases consisting of either calcite, dolomite, and/or aragonite; (3) the appearance of shallow water deposits and evaporite pseudomorphs; (4) the variation of the stable isotope composition of the carbonate fraction, indicative of large fluctuations of the freshwater dilution/evaporation balance, with a general trend towards hypersaline conditions. Both mineralogical and isotope data indicate that the dolomite precipitated generally from concentrated pore waters while other carbonates formed in the water column submitted to large fluctuations of salinity. Except locally, the increase in salinity did not reach concentrations high enough to precipitate significant volumes of evaporites as during the deposition of the overlying Calcare di Base. The transition from normal marine to hypersaline conditions is recorded diachroneously in the three sections, respectively, in cycle 34 (6.32 Ma) at Serra Pirciata, cycle 42 (6.15 Ma) at Torrente Vaccarrizzo, and cycle 44 (6.12 Ma) at Marianopoli. These changes represent the hydrological and sedimentary response to the

  13. On the peritidal cycles and their diagenetic evolution in the Lower Jurassic carbonates of the Calcare Massiccio Formation (Central Apennines

    Directory of Open Access Journals (Sweden)

    Brandano Marco

    2015-10-01

    Full Text Available This paper shows the environmental changes and high-frequency cyclicity recorded by Lower Jurassic shallow-water carbonates known as the Calcare Massiccio Formation which crop out in the central Apennines of Italy. Three types of sedimentary cycle bounded by subaerial erosion have been recognized: Type I consists of a shallowing upward cycle with oncoidal floatstones to rudstones passing gradationally up into peloidal packstone alternating with cryptoalgal laminites and often bounded by desiccation cracks and pisolitic-peloidal wackestones indicating a period of subaerial exposure. Type II shows a symmetrical trend in terms of facies arrangement with peloidal packstones and cryptoalgal laminites present both at the base and in the upper portion of the cycle, separated by oncoidal floatstones to rudstones. Type III displays a shallowing upward trend with an initial erosion surface overlain by oncoidal floatstones to rudstones that, in turn, are capped by pisolitic-peloidal wackestones and desiccation sheet cracks. Sheet cracks at the top of cycles formed during the initial phase of subaerial exposure were successively enlarged by dissolution during prolonged subaerial exposure. The following sea-level fall produced dissolution cavities in subtidal facies, while the successive sea-level rise resulted in the precipitation of marine cements in dissolution cavities. Spectral analysis revealed six peaks, five of which are consistent with orbital cycles. While a tectonic control cannot be disregarded, the main signal recorded by the sedimentary succession points toward a main control related to orbital forcing. High frequency sea-level fluctuations also controlled diagenetic processes.

  14. High diversity and morphological convergence among melanised fungi from rock formations in the Central Mountain System of Spain.

    Science.gov (United States)

    Ruibal, C; Platas, G; Bills, G F

    2008-12-01

    Melanised fungi were isolated from rock surfaces in the Central Mountain System of Spain. Two hundred sixty six isolates were recovered from four geologically and topographically distinct sites. Microsatellite-primed PCR techniques were used to group isolates into genotypes assumed to represent species. One hundred and sixty three genotypes were characterised from the four sites. Only five genotypes were common to two or more sites. Morphological and molecular data were used to characterise and identify representative strains, but morphology rarely provided a definitive identification due to the scarce differentiation of the fungal structures or the apparent novelty of the isolates. Vegetative states of fungi prevailed in culture and in many cases could not be reliably distinguished without sequence data. Morphological characters that were widespread among the isolates included scarce micronematous conidial states, endoconidia, mycelia with dark olive-green or black hyphae, and mycelia with torulose, isodiametric or moniliform hyphae whose cells develop one or more transverse and/or oblique septa. In many of the strains, mature hyphae disarticulated, suggesting asexual reproduction by a thallic micronematous conidiogenesis or by simple fragmentation. Sequencing of the internal transcribed spacers (ITS1, ITS2) and 5.8S rDNA gene were employed to investigate the phylogenetic affinities of the isolates. According to ITS sequence alignments, the majority of the isolates could be grouped among four main orders of Pezizomycotina: Pleosporales, Dothideales, Capnodiales, and Chaetothyriales. Ubiquitous known soil and epiphytic fungi species were generally absent from the rock surfaces. In part, the mycota of the rock surfaces shared similar elements with melanised fungi from plant surfaces and fungi described from rock formations in Europe and Antarctica. The possibility that some of the fungi were lichen mycobionts or lichen parasites could not be ruled out. PMID:20396580

  15. Depositional conditions of the coal-bearing Hirka Formation beneath Late Miocene explosive volcanic products in NW central Anatolia, Turkey

    Indian Academy of Sciences (India)

    Mehmet Şener

    2007-04-01

    This work focuses on the relationship between the coal deposition and explosive volcanism of the Miocene basin, NW central Anatolia, Turkey. The coal-bearing Hirka Formation was deposited over the Galatian Andesitic Complex and/or massive lagoonal environments during the Miocene. The investigated lignite is a high ash (from 32 to 58%) and sulphur (from 1.43 to 3.03%) lignite which is petrographically characterised by a high humunite content. The mineral matter of the studied lignite samples is made up of mainly clay minerals (illite–smectite and kaolinite), plagioclase and quartz in Bolu coal field, clay minerals (illite–smectite, smectite and illite), quartz, calcite, plagioclase and gypsum in Seben coal field, quartz, K-feldspar, plagioclase and clay minerals (kaolinite and illite) in Kıbrıscık, and dolomite, quartz, clinoptilolite, opal CT and gypsum in C¸ amlıdere coal field. The differences in these four types of lignite with specific mineralogical patterns may be due to the explosive volcanic events and depositional conditions which changed from one coal field to the others. There is a zonation from SW to SE in the studied area for zeolites such as Opal CT+smectite-clinoptilolite-analcime-K-feldspar. Carbonate minerals are commonly calcite in Seben and Kıbrıscık coal fields. In Bolu, coal samples are devoid of calcite and dolomite. These analyses show that there is an increase in the amount of Mg and a decrease in the amount of Na from the northwestern part to the southern part in the study area.

  16. Reservoir Characterization for CO2 Sequestration: Assessing the Potential of the Devonian Carbonate Nisku Formation of Central Alberta

    International Nuclear Information System (INIS)

    The Wabamun Lake area of Central Alberta, Canada includes several large CO2 point source emitters, collectively producing more than 30 Mt annually. Previous studies established that deep saline aquifers beneath the Wabamun Lake area have good potential for the large-scale injection and storage of CO2. This study reports on the characterization of the Devonian carbonate Nisku Formation for evaluation as a CO2 repository. Major challenges for characterization included sparse well and seismic data, poor quality flow tests, and few modern measurements. Wire-line porosity measurements were present in only one-third of the wells, so porosity and flow capacity (permeability-thickness) were estimated using wire-line electrical measurements. The Archie cementation factor appears to vary between 2 and 3, creating uncertainty when predicting porosity using the electrical measurements; however, high-porosity zones could be identified. The electrically-based flow capacity predictions showed more favorable values using a correlation with core than the relation based on drill stem and production tests. This behavior is expected, since the flow test flow capacities are less influenced by local occurrences of very permeable vuggy and moldic rocks. Facies distributions were modeled using both pixel and object methods. The object models, using dimensions obtained from satellite imaging of modern day environments, gave results that were more consistent with the geological understanding of the Nisku and showed greater large-scale connectivity than the pixel model. Predicted volumes show considerable storage capacity in the Nisku, but flow simulations suggest injection capacities are below an initial 20 Mt/year target using vertical wells. More elaborate well designs, including fracture stimulation or multi-lateral wells may allow this goal to be reached or surpassed. (authors)

  17. An NMDA Receptor-Dependent Mechanism Underlies Inhibitory Synapse Development

    Directory of Open Access Journals (Sweden)

    Xinglong Gu

    2016-01-01

    Full Text Available In the mammalian brain, GABAergic synaptic transmission provides inhibitory balance to glutamatergic excitatory drive and controls neuronal output. The molecular mechanisms underlying the development of GABAergic synapses remain largely unclear. Here, we report that NMDA-type ionotropic glutamate receptors (NMDARs in individual immature neurons are the upstream signaling molecules essential for GABAergic synapse development, which requires signaling via Calmodulin binding motif in the C0 domain of the NMDAR GluN1 subunit. Interestingly, in neurons lacking NMDARs, whereas GABAergic synaptic transmission is strongly reduced, the tonic inhibition mediated by extrasynaptic GABAA receptors is increased, suggesting a compensatory mechanism for the lack of synaptic inhibition. These results demonstrate a crucial role for NMDARs in specifying the development of inhibitory synapses, and suggest an important mechanism for controlling the establishment of the balance between synaptic excitation and inhibition in the developing brain.

  18. Microglial interactions with synapses are modulated by visual experience.

    Directory of Open Access Journals (Sweden)

    Marie-Ève Tremblay

    Full Text Available Microglia are the immune cells of the brain. In the absence of pathological insult, their highly motile processes continually survey the brain parenchyma and transiently contact synaptic elements. Aside from monitoring, their physiological roles at synapses are not known. To gain insight into possible roles of microglia in the modification of synaptic structures, we used immunocytochemical electron microscopy, serial section electron microscopy with three-dimensional reconstructions, and two-photon in vivo imaging to characterize microglial interactions with synapses during normal and altered sensory experience, in the visual cortex of juvenile mice. During normal visual experience, most microglial processes displayed direct apposition with multiple synapse-associated elements, including synaptic clefts. Microglial processes were also distinctively surrounded by pockets of extracellular space. In terms of dynamics, microglial processes localized to the vicinity of small and transiently growing dendritic spines, which were typically lost over 2 d. When experience was manipulated through light deprivation and reexposure, microglial processes changed their morphology, showed altered distributions of extracellular space, displayed phagocytic structures, apposed synaptic clefts more frequently, and enveloped synapse-associated elements more extensively. While light deprivation induced microglia to become less motile and changed their preference of localization to the vicinity of a subset of larger dendritic spines that persistently shrank, light reexposure reversed these behaviors. Taken together, these findings reveal different modalities of microglial interactions with synapses that are subtly altered by sensory experience. These findings suggest that microglia may actively contribute to the experience-dependent modification or elimination of a specific subset of synapses in the healthy brain.

  19. Astrocyte-secreted thrombospondin-1 modulates synapse and spine defects in the fragile X mouse model.

    Science.gov (United States)

    Cheng, Connie; Lau, Sally K M; Doering, Laurie C

    2016-01-01

    Astrocytes are key participants in various aspects of brain development and function, many of which are executed via secreted proteins. Defects in astrocyte signaling are implicated in neurodevelopmental disorders characterized by abnormal neural circuitry such as Fragile X syndrome (FXS). In animal models of FXS, the loss in expression of the Fragile X mental retardation 1 protein (FMRP) from astrocytes is associated with delayed dendrite maturation and improper synapse formation; however, the effect of astrocyte-derived factors on the development of neurons is not known. Thrombospondin-1 (TSP-1) is an important astrocyte-secreted protein that is involved in the regulation of spine development and synaptogenesis. In this study, we found that cultured astrocytes isolated from an Fmr1 knockout (Fmr1 KO) mouse model of FXS displayed a significant decrease in TSP-1 protein expression compared to the wildtype (WT) astrocytes. Correspondingly, Fmr1 KO hippocampal neurons exhibited morphological deficits in dendritic spines and alterations in excitatory synapse formation following long-term culture. All spine and synaptic abnormalities were prevented in the presence of either astrocyte-conditioned media or a feeder layer derived from FMRP-expressing astrocytes, or following the application of exogenous TSP-1. Importantly, this work demonstrates the integral role of astrocyte-secreted signals in the establishment of neuronal communication and identifies soluble TSP-1 as a potential therapeutic target for Fragile X syndrome. PMID:27485117

  20. A New Efficient-Silicon Area MDAC Synapse

    Directory of Open Access Journals (Sweden)

    Zied Gafsi

    2007-01-01

    Full Text Available Using the binary representation in the Multiplier digital to analog converter (MDAC synapse designs have crucial drawbacks. Silicon area of transistors, constituting the MDAC circuit, increases exponentially according to the number of bits. This latter is generated by geometric progression of common ratio equal to 2. To reduce this exponential increase to a linear growth, a new synapse named Arithmetic MDAC (AMDAC is designed. It functions with a new representation based on arithmetic progressions. Using the AMS CMOS 0.35µm technology the silicon area is reduced by a factor of 40%.

  1. Meet the players: local translation at the synapse

    Directory of Open Access Journals (Sweden)

    Michael A Kiebler

    2014-11-01

    Full Text Available It is widely believed that activity-dependent synaptic plasticity is the basis for learning and memory. Both processes are dependent on new protein synthesis at the synapse. Here, we describe a mechanism how dendritic mRNAs are transported and subsequently translated at activated synapses. Furthermore, we present the players involved in the regulation of local dendritic translation upon neuronal stimulation and their molecular interplay that maintain local proteome homeostasis. Any dysregulation causes several types of neurological disorders including muscular atrophies, cancers, neuropathies, neurodegenerative and cognitive disorders.

  2. Electrolyte-gated organic synapse transistor interfaced with neurons

    CERN Document Server

    Desbief, Simon; Casalini, Stefano; Guerin, David; Tortorella, Silvia; Barbalinardo, Marianna; Kyndiah, Adrica; Murgia, Mauro; Cramer, Tobias; Biscarini, Fabio; Vuillaume, Dominique

    2016-01-01

    We demonstrate an electrolyte-gated hybrid nanoparticle/organic synapstor (synapse-transistor, termed EGOS) that exhibits short-term plasticity as biological synapses. The response of EGOS makes it suitable to be interfaced with neurons: short-term plasticity is observed at spike voltage as low as 50 mV (in a par with the amplitude of action potential in neurons) and with a typical response time in the range of tens milliseconds. Human neuroblastoma stem cells are adhered and differentiated into neurons on top of EGOS. We observe that the presence of the cells does not alter short-term plasticity of the device.

  3. The Jurassic of Denmark and Greenland: Sedimentology and sequence stratigraphy of the Bryne and Lulu Formations, Middle Jurassic, northern Danish Central Graben

    Directory of Open Access Journals (Sweden)

    Andsbjerg, Jan

    2003-10-01

    Full Text Available The Middle Jurassic Bryne and Lulu Formations of the Søgne Basin (northern part of the Danish Central Graben consist of fluvially-dominated coastal plain deposits, overlain by interfingering shoreface and back-barrier deposits. Laterally continuous, mainly fining-upwards fluvial channel sandstones that locally show evidence for tidal influence dominate the alluvial/coastal plain deposits of the lower Bryne Formation. The sandstones are separated by units of fine-grained floodplain sediments that show a fining-upwards - coarsening-upwards pattern and locally grade into lacustrine mudstones. A regional unconformity that separates the lower Bryne Formation from the mainly estuarine upper Bryne Formation is defined by the strongly erosional base of a succession of stacked channel sandstones, interpreted as the fill of a system of incised valleys. Most of the stacked channel sandstones show abundant mud laminae and flasers, and rare herringbone structures, suggesting that they were deposited in a tidal environment, probably an estuary. Several tens of metres of the lower Bryne Formation may have been removed by erosion at this unconformity. The estuarine channel sandstone succession is capped by coal beds that attain a thickness of several metres in the western part of the Søgne Basin, but are thin and poorly developed in the central part of the basin. Above the coal beds, the Lulu Formation is dominated by various types of tidally influenced paralic deposits in the western part of the basin and by coarsening-upwards shoreface and beach deposits in central parts. Westwards-thickening wedges of paralic deposits interfinger with eastwards-thickening wedges of shallow marine deposits. The Middle Jurassic succession is subdivided into nine sequences. In the lower Bryne Formation, sequence boundaries are situated at the base of laterally continuous fluvial channel sandstones whereas maximum flooding surfaces are placed in laterally extensive floodplain

  4. Basin formation and inversion of the back-arc, Niigata basin, central Japan: New insight from deep seismic profiling

    Science.gov (United States)

    Sato, Hiroshi; Abe, Susumu; Kawai, Nobuo; Saito, Hideo; Kato, Naoko; Shiraishi, Kazuya; Ishiyama, Tatsuya; Fukasawa, Hikaru; Inaba, Mitsuru

    2010-05-01

    Associated with the opening of the Japan Sea, rift-basins have been developed along the Japan Sea coast of northern Honshu. The Niigata basin, central Japan, is one of the such basins and filled by thick (faulting. Due to thick Neogene sediments, relationship between active faults/folds at near the surface and deep-sited seismogenic source faults is poorly understood. To reveal the crustal structure, in particular geometry of source faults, onshore-offshore integrated deep seismic profiling was undertaken along the two seismic lines in 2008 and 2009. The 2009 Aizu-Sado seismic line is a 135-km-long, onshore-offshore seismic line across Niigata basin and Sado island, which is located in the eastern part of Japan Sea. The 2008 Sanjo-Yahiko seismic line (Sato et al., 2009) is located 20 km south of the seismic line and trending parallel to it. The seismic source was air-gun (3020 cu. inch), four vibroseis trucks and explosives (cables, cable-connected-recording system and offline recorders, forming a maximum 2400 channels receiver array. The basin fill consists of early to middle Miocene volcaniclastic rocks and overlying Neogene sedimentary rocks showing upward coarsening facies deposited under bathyal to fluvial environment. Main features of basin development, such as early Miocene normal faulting, associated with the formation of Japan Sea, and shortening deformation since Pliocene, are well demonstrated on the seismic sections. Particularly, boundary between pre-Tertiary meta-sedimentary rocks and Miocene volcanics were identified by velocity profile deduced by diving wave tomography and it enabled us to identify the geometry of extensional rift-basin. It is very difficult to distinguish meta-sedimentary rocks from volcaniclastic rocks by seismic facies or pattern of reflections. Fault reactivation of Miocene normal faulting to reverse faulting is common style of deformation. The fault reactivation processes of the eastern boundary fault of the Nagaoka plane

  5. Back-Propagation Operation for Analog Neural Network Hardware with Synapse Components Having Hysteresis Characteristics

    OpenAIRE

    Ueda, Michihito; Nishitani, Yu; Kaneko, Yukihiro; Omote, Atsushi

    2014-01-01

    To realize an analog artificial neural network hardware, the circuit element for synapse function is important because the number of synapse elements is much larger than that of neuron elements. One of the candidates for this synapse element is a ferroelectric memristor. This device functions as a voltage controllable variable resistor, which can be applied to a synapse weight. However, its conductance shows hysteresis characteristics and dispersion to the input voltage. Therefore, the conduc...

  6. Learning-guided automatic three dimensional synapse quantification for drosophila neurons

    OpenAIRE

    Sanders, Jonathan; Singh, Anil; Sterne, Gabriella; Ye, Bing; Zhou, Jie

    2015-01-01

    Background The subcellular distribution of synapses is fundamentally important for the assembly, function, and plasticity of the nervous system. Automated and effective quantification tools are a prerequisite to large-scale studies of the molecular mechanisms of subcellular synapse distribution. Common practices for synapse quantification in neuroscience labs remain largely manual or semi-manual. This is mainly due to computational challenges in automatic quantification of synapses, including...

  7. No longer falling on deaf ears: mechanisms of degeneration and regeneration of cochlear ribbon synapses.

    Science.gov (United States)

    Wan, Guoqiang; Corfas, Gabriel

    2015-11-01

    Cochlear ribbon synapses are required for the rapid and precise neural transmission of acoustic signals from inner hair cells to the spiral ganglion neurons. Emerging evidence suggests that damage to these synapses represents an important form of cochlear neuropathy that might be highly prevalent in sensorineural hearing loss. In this review, we discuss our current knowledge on how ribbon synapses are damaged by noise and during aging, as well as potential strategies to promote ribbon synapse regeneration for hearing restoration. PMID:25937135

  8. A strategic analysis of synapse and Canada health infoway’s electronic health record solution blueprint

    OpenAIRE

    Labrosse, Chadwick Andre

    2007-01-01

    Synapse is a currently deployed software application that collects and presents clinical and administrative information about Mental Health & Addictions patients, in the form of an Electronic Health Record (EHR). Synapse was jointly developed by regional health authorities, federal and provincial governments and research institutions. While Synapse has enjoyed limited regional success in British Columbia, the Synapse Project Steering Committee seeks to expand its adoption with clinicians ...

  9. Predicting Quiescence: The Dependence of Specific Star Formation Rate on Galaxy Size and Central Density at 0.5

    CERN Document Server

    Whitaker, Katherine E; van Dokkum, Pieter G; Franx, Marijn; van der Wel, Arjen; Brammer, Gabriel; Forster-Schreiber, Natascha M; Giavalisco, Mauro; Labbe, Ivo; Momcheva, Ivelina G; Nelson, Erica J; Skelton, Rosalind

    2016-01-01

    In this paper, we investigate the relationship between star formation and structure, using a mass-complete sample of 27,893 galaxies at 0.50.5 dex from z~2 to z~0.7. Neither a compact galaxy size nor a high n are sufficient to assess the likelihood of quiescence for the average galaxy; rather, it is the combination of these two parameters together with stellar mass that results in a unique quenching threshold in central density or velocity.

  10. Facies characterization and depositional architecture of a mixed-influence asymmetric delta lobe: Upper Cretaceous basal Belly River Formation, central Alberta

    OpenAIRE

    Hansen, Cindy Diane

    2007-01-01

    The Campanian basal Belly River Formation (Cycle G) of central Alberta is differentiated into two mappable facies associations (FA1 and FA2). FA1 comprises uniformly coarsening-upward successions with abundant wave- and storm-generated physical structures. FA2 forms variable and markedly heterolithic coarsening-upwards successions, dominated by current-generated structures, normal grading, convolute bedding, structureless siltstones, claystone drapes, and syneresis cracks. Both facies associa...

  11. New views of the human NK cell immunological synapse: recent advances enabled by super- and high- resolution imaging techniques

    Directory of Open Access Journals (Sweden)

    Emily M. Mace

    2013-01-01

    Full Text Available Imaging technology has undergone rapid growth with the development of super resolution microscopy, which enables resolution below the diffraction barrier of light (~200 nm. In addition, new techniques for single molecule imaging are being added to the cell biologist’s arsenal. Immunologists have exploited these techniques to advance understanding of NK biology, particularly that of the immune synapse. The immune synapse’s relatively small size and complex architecture combined with its exquisitely controlled signaling milieu have made it a challenge to visualize. In this review we highlight and discuss new insights into NK cell immune synapse formation and regulation revealed by cutting edge imaging techniques, including super resolution microscopy and high resolution total internal reflection microscopy and Förster resonance energy transfer.

  12. SALM5 trans-synaptically interacts with LAR-RPTPs in a splicing-dependent manner to regulate synapse development.

    Science.gov (United States)

    Choi, Yeonsoo; Nam, Jungyong; Whitcomb, Daniel J; Song, Yoo Sung; Kim, Doyoun; Jeon, Sangmin; Um, Ji Won; Lee, Seong-Gyu; Woo, Jooyeon; Kwon, Seok-Kyu; Li, Yan; Mah, Won; Kim, Ho Min; Ko, Jaewon; Cho, Kwangwook; Kim, Eunjoon

    2016-01-01

    Synaptogenic adhesion molecules play critical roles in synapse formation. SALM5/Lrfn5, a SALM/Lrfn family adhesion molecule implicated in autism spectrum disorders (ASDs) and schizophrenia, induces presynaptic differentiation in contacting axons, but its presynaptic ligand remains unknown. We found that SALM5 interacts with the Ig domains of LAR family receptor protein tyrosine phosphatases (LAR-RPTPs; LAR, PTPδ, and PTPσ). These interactions are strongly inhibited by the splice insert B in the Ig domain region of LAR-RPTPs, and mediate SALM5-dependent presynaptic differentiation in contacting axons. In addition, SALM5 regulates AMPA receptor-mediated synaptic transmission through mechanisms involving the interaction of postsynaptic SALM5 with presynaptic LAR-RPTPs. These results suggest that postsynaptic SALM5 promotes synapse development by trans-synaptically interacting with presynaptic LAR-RPTPs and is important for the regulation of excitatory synaptic strength. PMID:27225731

  13. Origin of acid orthoderived and paraderived geologic formations of the central part of the province of Limousin (France). A possible source for uraniferous leucogranite

    International Nuclear Information System (INIS)

    Important metamorphic formations of the central part of the province of Limousin are studied by chemical investigations for characterization of their primary signature. Four large orthoderived formations are compared: Dronne, Meuzac, and Thaurion arcs and leptynite formations. The typology of the parent magmatism of orthogneiss and leptynite allows to find leack most of plutonic associations known in the Variscan chain (subalkaline, calcoalkaline, aluminous). Interpretation of primary geochemical fractionation in rocks from the Dronne are suggests cogenetism of the whole facies following a fractionated crystallization process. Moreover rocks from the Dronne arc have a peraluminous character with high U and Th content related to subalkaline magmatism which make of them a potential source of uraniferous peraluminous leucogranites. Paraderived formations are represented by 3 mica schist formations and 2 gneiss formations. Each unit is individualized by geochemical study of mica schist. Gneiss formation are chemically distinct. These differences confirm that they belong to distinct lithologic units. Trace elements are used to precise the paleogeotectonic context of original sediment deposition

  14. Synapse-Specific Metaplasticity: To Be Silenced Is Not to Silence 2B

    OpenAIRE

    Philpot, Benjamin D.; Zukin, R. Suzanne

    2010-01-01

    What happens to a single, presynaptically quiescent synapse among a population of active synapses? In this issue of Neuron, Ehlers and colleagues show that, far from being eliminated, these inactive synapses are primed for potentiation and incorporation into a new neural circuit through an upregulation of NR2B-containing NMDA receptors.

  15. Human post-mortem synapse proteome integrity screening for proteomic studies of postsynaptic complexes

    OpenAIRE

    Bayés, Alex; Collins, Mark O; Galtrey, Clare M; Simonnet, Clémence; Roy, Marcia; Croning, Mike; Gou, Gemma; van de Lagemaat, Louie N.; Milward, David; Whittle, Ian R.; Smith, Colin; Choudhary, Jyoti S.; Grant, Seth

    2014-01-01

    BackgroundSynapses are fundamental components of brain circuits and are disrupted in over 100 neurological and psychiatric diseases. The synapse proteome is physically organized into multiprotein complexes and polygenic mutations converge on postsynaptic complexes in schizophrenia, autism and intellectual disability. Directly characterising human synapses and their multiprotein complexes from post-mortem tissue is essential to understanding disease mechanisms. However, multiprotein complexes ...

  16. Human post-mortem synapse proteome integrity screening for proteomic studies of postsynaptic complexes

    OpenAIRE

    Bayés, Àlex; Collins, Mark O; Galtrey, Clare M; Simonnet, Clémence; Roy, Marcia; Croning, Mike DR; Gou, Gemma; van de Lagemaat, Louie N.; Milward, David; Whittle, Ian R.; Smith, Colin; Choudhary, Jyoti S.; Grant, Seth GN

    2014-01-01

    Background Synapses are fundamental components of brain circuits and are disrupted in over 100 neurological and psychiatric diseases. The synapse proteome is physically organized into multiprotein complexes and polygenic mutations converge on postsynaptic complexes in schizophrenia, autism and intellectual disability. Directly characterising human synapses and their multiprotein complexes from post-mortem tissue is essential to understanding disease mechanisms. However, multiprotein complexes...

  17. Short-term ionic plasticity at GABAergic synapses

    Directory of Open Access Journals (Sweden)

    Joseph Valentino Raimondo

    2012-10-01

    Full Text Available Fast synaptic inhibition in the brain is mediated by the pre-synaptic release of the neurotransmitter γ-Aminobutyric acid (GABA and the post-synaptic activation of GABA-sensitive ionotropic receptors. As with excitatory synapses, it is being increasinly appreciated that a variety of plastic processes occur at inhibitory synapses, which operate over a range of timescales. Here we examine a form of activity-dependent plasticity that is somewhat unique to GABAergic transmission. This involves short-lasting changes to the ionic driving force for the postsynaptic receptors, a process referred to as short-term ionic plasticity. These changes are directly related to the history of activity at inhibitory synapses and are influenced by a variety of factors including the location of the synapse and the post-synaptic cell’s ion regulation mechanisms. We explore the processes underlying this form of plasticity, when and where it can occur, and how it is likely to impact network activity.

  18. Liprin-alpha Proteins Regulate Neuronal Development and Synapse Function

    NARCIS (Netherlands)

    S.A. Spangler (Samantha)

    2009-01-01

    textabstractSynapses are specialized communication junctions between neurons whose plasticity provides the structural and functional basis for information processing and storage in the brain. Recent biochemical, genetic and imaging studies in diverse model systems are beginning to reveal the molecul

  19. A New Mechanism for Neuron-synapse Maturation Discovered

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ A group of CAS scientists recently made a research breakthrough in the development of synapse, the key structure of the nervous system that transmits signals from one nerve cell to another. This work was reported as a cover story in the May 4th issue of prestigious journal Neuron.

  20. Efficient supervised learning in networks with binary synapses

    CERN Document Server

    Baldassi, Carlo; Brunel, Nicolas; Zecchina, Riccardo

    2007-01-01

    Recent experimental studies indicate that synaptic changes induced by neuronal activity are discrete jumps between a small number of stable states. Learning in systems with discrete synapses is known to be a computationally hard problem. Here, we study a neurobiologically plausible on-line learning algorithm that derives from Belief Propagation algorithms. We show that it performs remarkably well in a model neuron with binary synapses, and a finite number of `hidden' states per synapse, that has to learn a random classification task. Such system is able to learn a number of associations close to the theoretical limit, in time which is sublinear in system size. This is to our knowledge the first on-line algorithm that is able to achieve efficiently a finite number of patterns learned per binary synapse. Furthermore, we show that performance is optimal for a finite number of hidden states which becomes very small for sparse coding. The algorithm is similar to the standard `perceptron' learning algorithm, with a...

  1. Sleep: The hebbian reinforcement of the local inhibitory synapses.

    Science.gov (United States)

    Touzet, Claude

    2015-09-01

    Sleep is ubiquitous among the animal realm, and represents about 30% of our lives. Despite numerous efforts, the reason behind our need for sleep is still unknown. The Theory of neuronal Cognition (TnC) proposes that sleep is the period of time during which the local inhibitory synapses (in particular the cortical ones) are replenished. Indeed, as long as the active brain stays awake, hebbian learning guarantees that efficient inhibitory synapses lose their efficiency – just because they are efficient at avoiding the activation of the targeted neurons. Since hebbian learning is the only known mechanism of synapse modification, it follows that to replenish the inhibitory synapses' efficiency, source and targeted neurons must be activated together. This is achieved by a local depolarization that may travel (wave). The period of time during which such slow waves are experienced has been named the "slow-wave sleep" (SWS). It is cut into several pieces by shorter periods of paradoxical sleep (REM) which activity resembles that of the awake state. Indeed, SWS – because it only allows local neural activation – decreases the excitatory long distance connections strength. To avoid losing the associations built during the awake state, these long distance activations are played again during the REM sleep. REM and SWS sleeps act together to guarantee that when the subject awakes again, his inhibitory synaptic efficiency is restored and his (excitatory) long distance associations are still there. PMID:26138624

  2. Supporting shared care for diabetes patients. The synapses solution.

    Science.gov (United States)

    Toussaint, P. J.; Kalshoven, M.; Ros, M.; van der Kolk, H.; Weier, O.

    1997-01-01

    In this paper we discuss the construction of a Federated Health Care Record server within the context of the European R&D project Synapses. We describe the system using the five ODP viewpoints. From an analysis of the business process to be supported by the distributed system (the shared care for diabetes patients) requirements for the server are derived. PMID:9357655

  3. CRED 20 m Gridded bathymetry of Jarvis Island, Pacific Remote Island Areas, Central Pacific (NetCDF Format)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Gridded (20 m cell size) bathymetry of the shelf and slope environments of Jarvis Island, Pacific Remote Island Areas, Central Pacific. Almost complete bottom...

  4. CRED 5 m Gridded bathymetry of Kingman Reef, Pacific Remote Island Areas, Central Pacific (Arc ASCII Format)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Gridded (5 m cell size) bathymetry of the lagoon, shelf and slope environments of Kingman Reef, Pacific Remote Island Areas, Central Pacific. Almost complete bottom...

  5. CRED 5 m Gridded bathymetry of Johnston Atoll, Pacific Remote Island Areas, Central Pacific (NetCDF Format)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Gridded bathymetry (5 m cell size) of the shelf and slope environments of Johnston Atoll, Pacific Remote Island Areas, Central Pacific. Almost complete bottom...

  6. CRED 20 m Gridded bathymetry of Johnston Atoll, Pacific Remote Island Areas, Central Pacific (Arc ASCII Format)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Gridded bathymetry (20 m cell size) of the shelf and slope environments of Johnston Atoll, Pacific Remote Island Areas, Central Pacific. Almost complete bottom...

  7. CRED 5 m Gridded bathymetry of Baker Island, Pacific Remote Island Areas, Central Pacific (NetCDF Format)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Gridded (5 m cell size) bathymetry of the shelf and slope environments of Baker Island, Pacific Remote Island Areas, Central Pacific. Almost complete bottom...

  8. CRED 5 m Gridded bathymetry of Howland Island, Pacific Remote Island Areas, Central Pacific (NetCDF Format)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Gridded (5 m cell size) bathymetry of the shelf and slope environments of Howland Island, Pacific Remote Island Areas, Central Pacific. Almost complete bottom...

  9. CRED 40 m Gridded bathymetry of Palmyra Atoll, Pacific Remote Island Areas, Central Pacific (Arc ASCII Format)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Gridded (40 m cell size) bathymetry of the lagoon, shelf and slope environments of Palmyra Atoll, Pacific Remote Island Areas, Central Pacific. Almost complete...

  10. CRED 5 m Gridded bathymetry of Jarvis Island, Pacific Remote Island Areas, Central Pacific (Arc ASCII Format)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Gridded (5 m cell size) bathymetry of the shelf and slope environments of Jarvis Island, Pacific Remote Island Areas, Central Pacific. Almost complete bottom...

  11. CRED 5 m Gridded bathymetry of Palmyra Atoll, Pacific Remote Island Areas, Central Pacific (NetCDF Format)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Gridded (5 m cell size) bathymetry of the lagoon, shelf and slope environments of Palmyra Atoll, Pacific Remote Island Areas, Central Pacific. Almost complete...

  12. CRED 40 m Gridded bathymetry of Howland Island, Pacific Remote Island Areas, Central Pacific (Arc ASCII Format)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Gridded (40 m cell size) bathymetry of the shelf and slope environments of Howland Island, Pacific Remote Island Areas, Central Pacific. Almost complete bottom...

  13. CRED 5 m Gridded bathymetry of Howland Island, Pacific Remote Island Areas, Central Pacific (Arc ASCII Format)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Gridded (5 m cell size) bathymetry of the shelf and slope environments of Howland Island, Pacific Remote Island Areas, Central Pacific. Almost complete bottom...

  14. CRED 5 m Gridded bathymetry of Johnston Atoll, Pacific Remote Island Areas, Central Pacific (Arc ASCII Format)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Gridded bathymetry (5 m cell size) of the shelf and slope environments of Johnston Atoll, Pacific Remote Island Areas, Central Pacific. Almost complete bottom...

  15. CRED 20 m Gridded bathymetry of Jarvis Island, Pacific Remote Island Areas, Central Pacific (Arc ASCII Format)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Gridded (20 m cell size) bathymetry of the shelf and slope environments of Jarvis Island, Pacific Remote Island Areas, Central Pacific. Almost complete bottom...

  16. CRED 40 m Gridded bathymetry of Howland Island, Pacific Remote Island Areas, Central Pacific (NetCDF Format)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Gridded (40 m cell size) bathymetry of the shelf and slope environments of Howland Island, Pacific Remote Island Areas, Central Pacific. Almost complete bottom...

  17. CRED 40 m Gridded bathymetry of Baker Island, Pacific Remote Island Areas, Central Pacific (Arc ASCII Format)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Gridded (40 m cell size) bathymetry of the shelf and slope environments of Baker Island, Pacific Remote Island Areas, Central Pacific. Almost complete bottom...

  18. CRED 40 m Gridded bathymetry of Palmyra Atoll, Pacific Remote Island Areas, Central Pacific (NetCDF Format)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Gridded (40 m cell size) bathymetry of the lagoon, shelf and slope environments of Palmyra Atoll, Pacific Remote Island Areas, Central Pacific. Almost complete...

  19. CRED 20 m Gridded bathymetry of Kingman Reef, Pacific Remote Island Areas, Central Pacific (NetCDF Format)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Gridded (20 m cell size) bathymetry of the lagoon, shelf and slope environments of Kingman Reef, Pacific Remote Island Areas, Central Pacific. Almost complete...

  20. CRED 20 m Gridded bathymetry of Johnston Atoll, Pacific Remote Island Areas, Central Pacific (NetCDF Format)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Gridded bathymetry (20 m cell size) of the shelf and slope environments of Johnston Atoll, Pacific Remote Island Areas, Central Pacific. Almost complete bottom...

  1. CRED 5 m Gridded bathymetry of Baker Island, Pacific Remote Island Areas, Central Pacific (Arc ASCII Format)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Gridded (5 m cell size) bathymetry of the shelf and slope environments of Baker Island, Pacific Remote Isand Areas, Central Pacific. Almost complete bottom coverage...

  2. CRED 5 m Gridded bathymetry of Jarvis Island, Pacific Remote Island Areas, Central Pacific (NetCDF Format)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Gridded (5 m cell size) bathymetry of the shelf and slope environments of Jarvis Island, Pacific Remote Island Areas, Central Pacific. Almost complete bottom...

  3. CRED Reson 8101 multibeam backscatter data of Jarvis Island, Pacific Remote Island Areas, Central Pacific in netCDF format

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Multibeam backscatter imagery extracted from gridded bathymetry of the shelf and slope environments of Jarvis Atoll, Pacific Island Areas, Central Pacific. These...

  4. CRED Reson 8101 multibeam backscatter data of Jarvis Island, Pacific Remote Island Areas, Central Pacific in GeoTIFF format

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Multibeam backscatter imagery extracted from gridded bathymetry of the shelf and slope environments of Jarvis Atoll, Pacific Island Areas, Central Pacific. These...

  5. CRED Reson 8101 multibeam backscatter data of Johnston Island, Pacific Remote Island Areas, Central Pacific in GeoTIFF format

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Multibeam backscatter imagery extracted from gridded bathymetry of the lagoon, shelf, and slope environments of Palmyra Atoll, Pacific Island Areas, Central...

  6. CRED Reson 8101 multibeam backscatter data of Howland Island, Pacific Remote Island Areas, Central Pacific in GeoTIFF format

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Multibeam backscatter imagery extracted from gridded bathymetry of the shelf and slope environments of Howland Atoll, Pacific Island Areas, Central Pacific. These...

  7. CRED Reson 8101 multibeam backscatter data of Johnston Island, Pacific Remote Island Areas, Central Pacific in netCDF format

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Multibeam backscatter imagery extracted from gridded bathymetry of the lagoon, shelf, and slope environments of Palmyra Atoll, Pacific Island Areas, Central...

  8. Investigating CNS synaptogenesis at single-synapse resolution by combining reverse genetics with correlative light and electron microscopy.

    Science.gov (United States)

    Urwyler, Olivier; Izadifar, Azadeh; Dascenco, Dan; Petrovic, Milan; He, Haihuai; Ayaz, Derya; Kremer, Anna; Lippens, Saskia; Baatsen, Pieter; Guérin, Christopher J; Schmucker, Dietmar

    2015-01-15

    Determining direct synaptic connections of specific neurons in the central nervous system (CNS) is a major technical challenge in neuroscience. As a corollary, molecular pathways controlling developmental synaptogenesis in vivo remain difficult to address. Here, we present genetic tools for efficient and versatile labeling of organelles, cytoskeletal components and proteins at single-neuron and single-synapse resolution in Drosophila mechanosensory (ms) neurons. We extended the imaging analysis to the ultrastructural level by developing a protocol for correlative light and 3D electron microscopy (3D CLEM). We show that in ms neurons, synaptic puncta revealed by genetically encoded markers serve as a reliable indicator of individual active zones. Block-face scanning electron microscopy analysis of ms axons revealed T-bar-shaped dense bodies and other characteristic ultrastructural features of CNS synapses. For a mechanistic analysis, we directly combined the single-neuron labeling approach with cell-specific gene disruption techniques. In proof-of-principle experiments we found evidence for a highly similar requirement for the scaffolding molecule Liprin-α and its interactors Lar and DSyd-1 (RhoGAP100F) in synaptic vesicle recruitment. This suggests that these important synapse regulators might serve a shared role at presynaptic sites within the CNS. In principle, our CLEM approach is broadly applicable to the developmental and ultrastructural analysis of any cell type that can be targeted with genetically encoded markers. PMID:25503410

  9. Differentiation of autonomic reflex control begins with cellular mechanisms at the first synapse within the nucleus tractus solitarius

    Directory of Open Access Journals (Sweden)

    M.C. Andresen

    2004-04-01

    Full Text Available Visceral afferents send information via cranial nerves to the nucleus tractus solitarius (NTS. The NTS is the initial step of information processing that culminates in homeostatic reflex responses. Recent evidence suggests that strong afferent synaptic responses in the NTS are most often modulated by depression and this forms a basic principle of central integration of these autonomic pathways. The visceral afferent synapse is uncommonly powerful at the NTS with large unitary response amplitudes and depression rather than facilitation at moderate to high frequencies of activation. Substantial signal depression occurs through multiple mechanisms at this very first brainstem synapse onto second order NTS neurons. This review highlights new approaches to the study of these basic processes featuring patch clamp recordings in NTS brain slices and optical techniques with fluorescent tracers. The vanilloid receptor agonist, capsaicin, distinguishes two classes of second order neurons (capsaicin sensitive or capsaicin resistant that appear to reflect unmyelinated and myelinated afferent pathways. The differences in cellular properties of these two classes of NTS neurons indicate clear functional differentiation at both the pre- and postsynaptic portions of these first synapses. By virtue of their position at the earliest stage of these pathways, such mechanistic differences probably impart important differentiation in the performance over the entire reflex pathways.

  10. Geologic Map of Upper Cretaceous and Tertiary Strata and Coal Stratigraphy of the Paleocene Fort Union Formation, Rawlins-Little Snake River Area, South-Central Wyoming

    Science.gov (United States)

    Hettinger, R.D.; Honey, J.G.; Ellis, M.S.; Barclay, C.S.V.; East, J.A.

    2008-01-01

    This report provides a map and detailed descriptions of geologic formations for a 1,250 square mile region in the Rawlins-Little Snake River coal field in the eastern part of the Washakie and Great Divide Basins of south-central Wyoming. Mapping of geologic formations and coal beds was conducted at a scale of 1:24,000 and compiled at a scale of 1:100,000. Emphasis was placed on coal-bearing strata of the China Butte and Overland Members of the Paleocene Fort Union Formation. Surface stratigraphic sections were measured and described and well logs were examined to determine the lateral continuity of individual coal beds; the coal-bed stratigraphy is shown on correlation diagrams. A structure contour and overburden map constructed on the uppermost coal bed in the China Butte Member is also provided.

  11. Reduced sensory stimulation alters the molecular make-up of glutamatergic hair cell synapses in the developing cochlea.

    Science.gov (United States)

    Barclay, M; Constable, R; James, N R; Thorne, P R; Montgomery, J M

    2016-06-14

    Neural activity during early development is known to alter innervation pathways in the central and peripheral nervous systems. We sought to examine how reduced sound-induced sensory activity in the cochlea affected the consolidation of glutamatergic synapses between inner hair cells (IHC) and the primary auditory neurons as these synapses play a primary role in transmitting sound information to the brain. A unilateral conductive hearing loss was induced prior to the onset of sound-mediated stimulation of the sensory hair cells, by rupturing the tympanic membrane and dislocating the auditory ossicles in the left ear of P11 mice. Auditory brainstem responses at P15 and P21 showed a 40-50-dB increase in thresholds for frequencies 8-32kHz in the dislocated ear relative to the control ear. Immunohistochemistry and confocal microscopy were subsequently used to examine the effect of this attenuation of sound stimulation on the expression of RIBEYE, which comprises the presynaptic ribbons, Shank-1, a postsynaptic scaffolding protein, and the GluA2/3 and 4 subunits of postsynaptic AMPA receptors. Our results show that dislocation did not alter the number of pre- or postsynaptic protein puncta. However, dislocation did increase the size of RIBEYE, GluA4, GluA2/3 and Shank-1 puncta, with postsynaptic changes preceding presynaptic changes. Our data suggest that a reduction in sound stimulation during auditory development induces plasticity in the molecular make-up of IHC glutamatergic synapses, but does not affect the number of these synapses. Up-regulation of synaptic proteins with sound attenuation may facilitate a compensatory increase in synaptic transmission due to the reduced sensory stimulation of the IHC. PMID:27012610

  12. High diversity and morphological convergence among melanised fungi from rock formations in the Central Mountain System of Spain

    NARCIS (Netherlands)

    Ruibal, C.; Platas, G.; Bills, G.F.

    2008-01-01

    Melanised fungi were isolated from rock surfaces in the Central Mountain System of Spain. Two hundred sixty six isolates were recovered from four geologically and topographically distinct sites. Microsatellite-primed PCR techniques were used to group isolates into genotypes assumed to represent spec

  13. VLA-4 integrin concentrates at the peripheral supramolecular activation complex of the immune synapse and drives T helper 1 responses

    Science.gov (United States)

    Mittelbrunn, María; Molina, Ana; Escribese, María M.; Yáñez-Mó, María; Escudero, Ester; Ursa, Ángeles; Tejedor, Reyes; Mampaso, Francisco; Sánchez-Madrid, Francisco

    2004-07-01

    The integrin 41 (VLA-4) not only mediates the adhesion and transendothelial migration of leukocytes, but also provides costimulatory signals that contribute to the activation of T lymphocytes. However, the behavior of 41 during the formation of the immune synapse is currently unknown. Here, we show that 41 is recruited to both human and murine antigen-dependent immune synapses, when the antigen-presenting cell is a B lymphocyte or a dendritic cell, colocalizing with LFA-1 at the peripheral supramolecular activation complex. However, when conjugates are formed in the presence of anti-4 antibodies, VLA-4 colocalizes with the CD3- chain at the center of the synapse. In addition, antibody engagement of 4 integrin promotes polarization toward a T helper 1 (Th1) response in human in vitro models of CD4+ T cell differentiation and naïve T cell priming by dendritic cells. The in vivo administration of anti-4 integrin antibodies also induces an immune deviation to Th1 response that dampens a Th2-driven autoimmune nephritis in Brown Norway rats. These data reveal a regulatory role of 4 integrins on T lymphocyte-antigen presenting cell cognate immune interactions.

  14. Crossbar Nanoscale HfO2-Based Electronic Synapses.

    Science.gov (United States)

    Matveyev, Yury; Kirtaev, Roman; Fetisova, Alena; Zakharchenko, Sergey; Negrov, Dmitry; Zenkevich, Andrey

    2016-12-01

    Crossbar resistive switching devices down to 40 × 40 nm(2) in size comprising 3-nm-thick HfO2 layers are forming-free and exhibit up to 10(5) switching cycles. Four-nanometer-thick devices display the ability of gradual switching in both directions, thus emulating long-term potentiation/depression properties akin to biological synapses. Both forming-free and gradual switching properties are modeled in terms of oxygen vacancy generation in an ultrathin HfO2 layer. By applying the voltage pulses to the opposite electrodes of nanodevices with the shape emulating spikes in biological neurons, spike-timing-dependent plasticity functionality is demonstrated. Thus, the fabricated memristors in crossbar geometry are promising candidates for hardware implementation of hybrid CMOS-neuron/memristor-synapse neural networks. PMID:26979725

  15. A Neuron- and a Synapse Chip for Artificial Neural Networks

    DEFF Research Database (Denmark)

    Lansner, John; Lehmann, Torsten

    1992-01-01

    A cascadable, analog, CMOS chip set has been developed for hardware implementations of artificial neural networks (ANN's):I) a neuron chip containing an array of neurons with hyperbolic tangent activation functions and adjustable gains, and II) a synapse chip (or a matrix-vector multiplier) where...... the matrix is stored on-chip as differential voltages on capacitors. In principal any ANN configuration can be made using these chips. A neuron array of 4 neurons and a 4 × 4 matrix-vector multiplier has been fabricated in a standard 2.4 ¿m CMOS process for test purposes. The propagation time through...... the synapse and neuron chips is less than 4 ¿s and the weight matrix has a 10 bit resolution....

  16. Crossbar Nanoscale HfO2-Based Electronic Synapses

    Science.gov (United States)

    Matveyev, Yury; Kirtaev, Roman; Fetisova, Alena; Zakharchenko, Sergey; Negrov, Dmitry; Zenkevich, Andrey

    2016-03-01

    Crossbar resistive switching devices down to 40 × 40 nm2 in size comprising 3-nm-thick HfO2 layers are forming-free and exhibit up to 105 switching cycles. Four-nanometer-thick devices display the ability of gradual switching in both directions, thus emulating long-term potentiation/depression properties akin to biological synapses. Both forming-free and gradual switching properties are modeled in terms of oxygen vacancy generation in an ultrathin HfO2 layer. By applying the voltage pulses to the opposite electrodes of nanodevices with the shape emulating spikes in biological neurons, spike-timing-dependent plasticity functionality is demonstrated. Thus, the fabricated memristors in crossbar geometry are promising candidates for hardware implementation of hybrid CMOS-neuron/memristor-synapse neural networks.

  17. Can dynamical synapses produce true self-organized criticality?

    Science.gov (United States)

    Costa, Ariadne de Andrade; Copelli, Mauro; Kinouchi, Osame

    2015-06-01

    Neuronal networks can present activity described by power-law distributed avalanches presumed to be a signature of a critical state. Here we study a random-neighbor network of excitable cellular automata coupled by dynamical synapses. The model exhibits a very similar to conservative self-organized criticality (SOC) models behavior even with dissipative bulk dynamics. This occurs because in the stationary regime the model is conservative on average, and, in the thermodynamic limit, the probability distribution for the global branching ratio converges to a delta-function centered at its critical value. So, this non-conservative model pertain to the same universality class of conservative SOC models and contrasts with other dynamical synapses models that present only self-organized quasi-criticality (SOqC). Analytical results show very good agreement with simulations of the model and enable us to study the emergence of SOC as a function of the parametric derivatives of the stationary branching ratio.

  18. Stimulus-specific adaptation at the synapse level in vitro

    OpenAIRE

    Haitao Wang; Yi-Fan Han; Ying-Shing Chan; Jufang He

    2014-01-01

    Stimulus-specific adaptation (SSA) is observed in many brain regions in humans and animals. SSA of cortical neurons has been proposed to accumulate through relays in ascending pathways. Here, we examined SSA at the synapse level using whole-cell patch-clamp recordings of primary cultured cortical neurons of the rat. First, we found that cultured neurons had high firing capability with 100-Hz current injection. However, neuron firing started to adapt to repeated electrically activated synaptic...

  19. A Mathematical Model of Tripartite Synapse: Astrocyte Induced Synaptic Plasticity

    OpenAIRE

    Tewari, Shivendra; Majumdar, Kaushik

    2011-01-01

    In this paper we present a biologically detailed mathematical model of tripartite synapses, where astrocytes modulate short-term synaptic plasticity. The model consists of a pre-synaptic bouton, a post-synaptic dendritic spine-head, a synaptic cleft and a peri-synaptic astrocyte controlling Ca2+ dynamics inside the synaptic bouton. This in turn controls glutamate release dynamics in the cleft. As a consequence of this, glutamate concentration in the cleft has been modeled, in which glutamate ...

  20. Experience-driven brain plasticity: beyond the synapse

    OpenAIRE

    Markham, Julie A.; Greenough, William T.

    2004-01-01

    The brain is remarkably responsive to its interactions with the environment, and its morphology is altered by experience in measurable ways. Histological examination of the brains of animals exposed to either a complex (‘enriched’) environment or learning paradigm, compared with appropriate controls, has illuminated the nature of experience-induced morphological plasticity in the brain. For example, this research reveals that changes in synapse number and morphology are associated with learni...

  1. The State of Synapses in Fragile X Syndrome

    OpenAIRE

    Pfeiffer, Brad E.; Huber, Kimberly M.

    2009-01-01

    Fragile X Syndrome is the most common inherited form of mental retardation and a leading genetic cause of autism. There is increasing evidence in both FXS and other forms of autism that alterations in synapse number, structure and function are associated and contribute to these prevalent diseases. FXS is caused by loss of function of the Fmr1 gene which encodes the RNA binding protein, FMRP. Therefore, FXS is a tractable model to understand synaptic dysfunction in cognitive disorders. FMRP is...

  2. Storage capacity of attractor neural networks with depressing synapses

    International Nuclear Information System (INIS)

    We compute the capacity of a binary neural network with dynamic depressing synapses to store and retrieve an infinite number of patterns. We use a biologically motivated model of synaptic depression and a standard mean-field approach. We find that at T=0 the critical storage capacity decreases with the degree of the depression. We confirm the validity of our main mean-field results with numerical simulations

  3. Laser programmable integrated curcuit for forming synapses in neural networks

    Science.gov (United States)

    Fu, Chi Y.

    1997-01-01

    Customizable neural network in which one or more resistors form each synapse. All the resistors in the synaptic array are identical, thus simplifying the processing issues. Highly doped, amorphous silicon is used as the resistor material, to create extremely high resistances occupying very small spaces. Connected in series with each resistor in the array is at least one severable conductor whose uppermost layer has a lower reflectivity of laser energy than typical metal conductors at a desired laser wavelength.

  4. Laser programmable integrated circuit for forming synapses in neural networks

    Science.gov (United States)

    Fu, C.Y.

    1997-02-11

    Customizable neural network in which one or more resistors form each synapse is disclosed. All the resistors in the synaptic array are identical, thus simplifying the processing issues. Highly doped, amorphous silicon is used as the resistor material, to create extremely high resistances occupying very small spaces. Connected in series with each resistor in the array is at least one severable conductor whose uppermost layer has a lower reflectivity of laser energy than typical metal conductors at a desired laser wavelength. 5 figs.

  5. Process for forming synapses in neural networks and resistor therefor

    Science.gov (United States)

    Fu, Chi Y.

    1996-01-01

    Customizable neural network in which one or more resistors form each synapse. All the resistors in the synaptic array are identical, thus simplifying the processing issues. Highly doped, amorphous silicon is used as the resistor material, to create extremely high resistances occupying very small spaces. Connected in series with each resistor in the array is at least one severable conductor whose uppermost layer has a lower reflectivity of laser energy than typical metal conductors at a desired laser wavelength.

  6. Overview Chapter 5: Determinants of family formation and childbearing during the societal transition in Central and Eastern Europe

    OpenAIRE

    Tomas Frejka

    2008-01-01

    Societal conditions for early and high rates of childbearing were replaced by conditions generating late and low levels of fertility common in Western countries. Central among factors shaping the latter behaviour (job insecurity, unstable partnership relationships, expensive housing, and profound changes in norms, values and attitudes) were the following: increasing proportions of young people were acquiring advanced education, a majority of women were gainfully employed, yet women were perfo...

  7. Synapse geometry and receptor dynamics modulate synaptic strength.

    Directory of Open Access Journals (Sweden)

    Dominik Freche

    Full Text Available Synaptic transmission relies on several processes, such as the location of a released vesicle, the number and type of receptors, trafficking between the postsynaptic density (PSD and extrasynaptic compartment, as well as the synapse organization. To study the impact of these parameters on excitatory synaptic transmission, we present a computational model for the fast AMPA-receptor mediated synaptic current. We show that in addition to the vesicular release probability, due to variations in their release locations and the AMPAR distribution, the postsynaptic current amplitude has a large variance, making a synapse an intrinsic unreliable device. We use our model to examine our experimental data recorded from CA1 mice hippocampal slices to study the differences between mEPSC and evoked EPSC variance. The synaptic current but not the coefficient of variation is maximal when the active zone where vesicles are released is apposed to the PSD. Moreover, we find that for certain type of synapses, receptor trafficking can affect the magnitude of synaptic depression. Finally, we demonstrate that perisynaptic microdomains located outside the PSD impacts synaptic transmission by regulating the number of desensitized receptors and their trafficking to the PSD. We conclude that geometrical modifications, reorganization of the PSD or perisynaptic microdomains modulate synaptic strength, as the mechanisms underlying long-term plasticity.

  8. Astrocytic mGluR5 and the tripartite synapse.

    Science.gov (United States)

    Panatier, A; Robitaille, R

    2016-05-26

    In the brain, astrocytes occupy a key position between vessels and synapses. Among their numerous functions, these glial cells are key partners of neurons during synaptic transmission. Astrocytes detect transmitter release through receptors and transporters at the level of their processes, which are in close proximity to the tow neuronal elements of synapses. In response to transmitter-mediated activation, glial cells in turn regulate synaptic transmission and neuronal excitability. This process has been reported to involve several glial receptors. One of the best known of such receptors is the metabotropic glutamatergic receptor subtype 5 (mGluR5). In the present review we will discuss the implication of mGluR5s as detectors of synaptic transmission. In particular, we will discuss how the functional properties and localization of these receptors permit the detection of the synaptic signal in a defined temporal window and a given spatial area around the synapse. Furthermore, we will review the impact of their activation on synaptic transmission. PMID:25847307

  9. Paleoecology of Benthic Foraminifera in Coral Reefs Recorded in the Jurassic Tuwaiq Mountain Formation of the Khashm Al-Qaddiyah Area, Central Saudi Arabia

    Institute of Scientific and Technical Information of China (English)

    Mohamed Youssef; Abdelbaset S El-Sorogy

    2015-01-01

    Thirty three benthic foraminiferal species belong to 23 genera and 16 families have been recorded from the coral reefs of the Callovian Tuwaiq Formation, Khashm Al-Qaddiyah area, Central Saudi Arabia. Three species:Astacolus qaddiyahensis, Nodosaria riyadhensis, Siderolites jurassica are believed to be new. Nearly all identified foraminifera are of Atlantic-Miditeranean affinity. The fo-raminiferal assemblage recorded in the present work is mixed of open marine, moderately deep ma-rine conditions associations and shallow to deep lagoon. The reefal part of upper Twiaq Formation may have been deposited in shallow water of lower to middle shelf depth (20–50 m) as indicated by abundant corals and benthic foraminifera. The coral fauna and bearing benthic foraminifera indi-cated moderate water energy.

  10. Effect of Associative Learning on Memory Spine Formation in Mouse Barrel Cortex

    Directory of Open Access Journals (Sweden)

    Malgorzata Jasinska

    2016-01-01

    Full Text Available Associative fear learning, in which stimulation of whiskers is paired with mild electric shock to the tail, modifies the barrel cortex, the functional representation of sensory receptors involved in the conditioning, by inducing formation of new inhibitory synapses on single-synapse spines of the cognate barrel hollows and thus producing double-synapse spines. In the barrel cortex of conditioned, pseudoconditioned, and untreated mice, we analyzed the number and morphological features of dendritic spines at various maturation and stability levels: sER-free spines, spines containing smooth endoplasmic reticulum (sER, and spines containing spine apparatus. Using stereological analysis of serial sections examined by transmission electron microscopy, we found that the density of double-synapse spines containing spine apparatus was significantly increased in the conditioned mice. Learning also induced enhancement of the postsynaptic density area of inhibitory synapses as well as increase in the number of polyribosomes in such spines. In single-synapse spines, the effects of conditioning were less pronounced and included increase in the number of polyribosomes in sER-free spines. The results suggest that fear learning differentially affects single- and double-synapse spines in the barrel cortex: it promotes maturation and stabilization of double-synapse spines, which might possibly contribute to permanent memory formation, and upregulates protein synthesis in single-synapse spines.

  11. Effect of Associative Learning on Memory Spine Formation in Mouse Barrel Cortex.

    Science.gov (United States)

    Jasinska, Malgorzata; Siucinska, Ewa; Jasek, Ewa; Litwin, Jan A; Pyza, Elzbieta; Kossut, Malgorzata

    2016-01-01

    Associative fear learning, in which stimulation of whiskers is paired with mild electric shock to the tail, modifies the barrel cortex, the functional representation of sensory receptors involved in the conditioning, by inducing formation of new inhibitory synapses on single-synapse spines of the cognate barrel hollows and thus producing double-synapse spines. In the barrel cortex of conditioned, pseudoconditioned, and untreated mice, we analyzed the number and morphological features of dendritic spines at various maturation and stability levels: sER-free spines, spines containing smooth endoplasmic reticulum (sER), and spines containing spine apparatus. Using stereological analysis of serial sections examined by transmission electron microscopy, we found that the density of double-synapse spines containing spine apparatus was significantly increased in the conditioned mice. Learning also induced enhancement of the postsynaptic density area of inhibitory synapses as well as increase in the number of polyribosomes in such spines. In single-synapse spines, the effects of conditioning were less pronounced and included increase in the number of polyribosomes in sER-free spines. The results suggest that fear learning differentially affects single- and double-synapse spines in the barrel cortex: it promotes maturation and stabilization of double-synapse spines, which might possibly contribute to permanent memory formation, and upregulates protein synthesis in single-synapse spines. PMID:26819780

  12. Conodonts, stratigraphy, and relative sea-level changes of the tribes hill formation (lower ordovician, east-central New York)

    Science.gov (United States)

    Landing, E.D.; Westrop, S.R.; Knox, L.A.

    1996-01-01

    Tremadocian onlap is recorded by the Tribes Hill Formation. The formation is a lower Lower Ordovician (upper conodont Fauna B Interval(?)- Rossodus manitouensis Zone) depositional sequence that unconformably overlies the Upper Cambrian Little Falls Formation. Depositional environments and stratigraphy indicate that the Tribes Hill was deposited on a wave-, not tide-, dominated shelf and that a uniform, 'layer-cake' stratigraphy is present. The deepening-shoaling sequence of the Tribes Hill includes the: 1) Sprakers Member (new; peritidal carbonate and overlying tempestite limestone and shale); 2) Van Wie Member (new; subtidal shale and limestone); 3) Wolf Hollow Member (revised; massive carbonates with thrombolitic cap); and 4) Canyon Road Member (new; glauconitic limestone and overlying evaporitic dolostone). The shoaling half-cycle of the Tribes Hill is older than a shoaling event in western Newfoundland, and suggests epeirogenic factors in earliest Ordovician sea-level change in east Laurentia. Conodont and trilobite biofacies track lithofacies, and Rossodus manitouensis Zone conodonts and Bellefontia Biofacies trilobites appear in the distal, middle Tribes Hill Formation. Twenty-four conodont species are illustrated. Ansella? protoserrata new species, lapetognathus sprakersi new species, Leukorhinion ambonodes new genus and species, and Laurentoscandodus new genus are described.

  13. The mature activating natural killer cell immunologic synapse is formed in distinct stages.

    Science.gov (United States)

    Orange, Jordan S; Harris, K Eliza; Andzelm, Milena M; Valter, Markus M; Geha, Raif S; Strominger, Jack L

    2003-11-25

    Natural killer (NK) cells form a structure at their interface with a susceptible target cell called the activating NK cell immunologic synapse (NKIS). The mature activating NKIS contains a central and peripheral supramolecular activation cluster (SMAC), and includes polarized surface receptors, filamentous actin (F-actin) and perforin. Evaluation of the NKIS in human NK cells revealed CD2, CD11a, CD11b and F-actin in the peripheral SMAC (pSMAC) with perforin in the central SMAC. The accumulation of F-actin and surface receptors was rapid and depended on Wiskott-Aldrich syndrome protein-driven actin polymerization. The accumulation at and arrangement of these molecules in the pSMAC was not affected by microtubule depolymerization. The polarization of perforin, however was slower and required intact actin, Wiskott-Aldrich syndrome protein, and microtubule function. Thus the process of CD2, CD11a, CD11b, and F-actin accumulation in the pSMAC and perforin accumulation in the central SMAC of the NKIS are sequential processes with distinct cytoskeletal requirements. PMID:14612578

  14. Temperature record and sapropel formation during the late Pliocene in central Mediterranean: a multi-proxy approach

    Science.gov (United States)

    Plancq, Julien; Grossi, Vincent; Huguet, Carme; Pittet, Bernard; Rosell-Mele, Antoni; Mattioli, Emanuela

    2014-05-01

    The late Pliocene (Piacenzian; 3.6-2.6 Myr) in the Mediterranean region is characterized by the deposition of organic-rich sedimentary layers named sapropels. Sapropel formation has been related to the strengthening of the precessionally-controlled African monsoon, triggering enhanced primary productivity and/or improved organic matter preservation. However, the relative importance of surface-ocean productivity versus deep-water preservation for sapropel formation remains a long standing debate among the science community. Here, we used a multi-proxy approach to characterize long-term environmental conditions and to discuss sapropel formation during the late Pliocene at Punta Grande/Punta Piccola sections (southwest Sicily). Sea and air temperatures were reconstructed using all the lipid biomarker-based temperature proxies currently available: the alkenone unsaturation index (UK'37), the tetraether index (TEX86), the Long-chain Diol Index (LDI), and the degree of methylation/cyclization of branched tetraether (MBT/CBT). Results show that sea-surface temperatures (SSTs) were relatively stable throughout the late Pliocene, but that consistent increases are recorded in most sapropel layers. SST record was then compared with variations in total organic carbon proportions, lipid biomarkers contents and nannofossil assemblages. Based on these observations, two mechanisms of formation can be inferred for each sapropel. A first series of sapropels is likely due to a better preservation of organic matter, due to the development of a thermohaline stratification of the water column and to oxygen depleted bottom waters. The second series of sapropels is more likely due to enhanced primary productivity in a non-stratified water column.

  15. The UK Infrared Telescope M33 monitoring project. II. The star formation history in the central square kiloparsec

    CERN Document Server

    Javadi, Atefeh; Mirtorabi, Mohammad Taghi

    2011-01-01

    We have conducted a near-infrared monitoring campaign at the UK InfraRed Telescope (UKIRT), of the Local Group spiral galaxy M33 (Triangulum). The main aim was to identify stars in the very final stage of their evolution, and for which the luminosity is more directly related to the birth mass than the more numerous less-evolved giant stars that continue to increase in luminosity. In this second paper of the series, we construct the birth mass function and hence derive the star formation history. The star formation rate has varied between ~0.002 and 0.007 M ̇ yr^-1 kpc^-2. We give evidence of two epochs of a star formation rate enhanced by a factor of a few -- one that happened \\geq 6 Gyr ago and produced \\geq 80% of the total mass in stars, and one around 250 Myr ago that lasted ~ 200 Myr and formed \\leq 6% of the mass in stars. We construct radial and azimuthal distributions in the image plane and in the galaxy plane for populations associated with old first-ascent red giant branch (RGB) stars, intermedia...

  16. Upper Cretaceous (Maastrichtian) Charophyte Gyrogonites from the Lameta Formation of Jabalpur, Central India: Palaeobiogeographic and Palaeoecological Implications

    Science.gov (United States)

    Khosla, Ashu

    2014-12-01

    A charophyte gyrogonite assemblage consisting of Platychara cf. sahnii, Nemegtichara grambastii and Microchara sp. is reported herein from two localities (Bara Simla Hill and Chui Hill sections) of the Lameta Formation at Jabalpur. he Lameta Formation locally underlying the Deccan traps has been shown to be pedogenically modified alluvial plain deposits containing one of the most extensive dinosaur nesting sites in the world. They are associated with dinosaur bones and freshwater ostracod assemblages that suggest a Late Cretaceous (Maastrichtian) age. This is the first detailed systematic account of charophyte gyrogonites from the Lameta Formation. This charophyte assemblage is compatible with the biostratigraphic attribution provided by the ostracods. From a biogeographic viewpoint, it exhibits considerable similarity to other infratrappean assemblages of the Nand, Dongargaon, and Dhamni-Pavna sections (Maharashtra), and some intertrappean assemblages of Kora in Gujarat, Rangapur in Andhra Pradesh and Gurmatkal in South India. Globally, the genus Microchara is well distributed throughout Eurasia, whereas the genus Platychara occurs richly in the Upper Cretaceous deposits of Europe, Asia, America and Africa. However, at the specific level, Platychara cf. sahnii shows close affinities with charophytes from the Maastrichtian of Iran whilst Nemegtichara grambastii shows distinct affinities with two species of Early Palaeogene deposits of China and Mongolia. The presence of charophyte gyrogonites in the Lameta sediments is attributed to local lacustrine and palustrine conditions within a flood plain environment.

  17. The adhesion protein IgSF9b is coupled to neuroligin 2 via S-SCAM to promote inhibitory synapse development.

    Science.gov (United States)

    Woo, Jooyeon; Kwon, Seok-Kyu; Nam, Jungyong; Choi, Seungwon; Takahashi, Hideto; Krueger, Dilja; Park, Joohyun; Lee, Yeunkum; Bae, Jin Young; Lee, Dongmin; Ko, Jaewon; Kim, Hyun; Kim, Myoung-Hwan; Bae, Yong Chul; Chang, Sunghoe; Craig, Ann Marie; Kim, Eunjoon

    2013-06-10

    Synaptic adhesion molecules regulate diverse aspects of synapse formation and maintenance. Many known synaptic adhesion molecules localize at excitatory synapses, whereas relatively little is known about inhibitory synaptic adhesion molecules. Here we report that IgSF9b is a novel, brain-specific, homophilic adhesion molecule that is strongly expressed in GABAergic interneurons. IgSF9b was preferentially localized at inhibitory synapses in cultured rat hippocampal and cortical interneurons and was required for the development of inhibitory synapses onto interneurons. IgSF9b formed a subsynaptic domain distinct from the GABAA receptor- and gephyrin-containing domain, as indicated by super-resolution imaging. IgSF9b was linked to neuroligin 2, an inhibitory synaptic adhesion molecule coupled to gephyrin, via the multi-PDZ protein S-SCAM. IgSF9b and neuroligin 2 could reciprocally cluster each other. These results suggest a novel mode of inhibitory synaptic organization in which two subsynaptic domains, one containing IgSF9b for synaptic adhesion and the other containing gephyrin and GABAA receptors for synaptic transmission, are interconnected through S-SCAM and neuroligin 2. PMID:23751499

  18. Reservoir Characterization for CO2 Sequestration: Assessing the Potential of the Devonian Carbonate Nisku Formation of Central Alberta Caractérisation de réservoir en vue du stockage géologique de CO2 : évaluation du potentiel offert par les carbonates dévoniens de la formation de Nisku, en Alberta central

    OpenAIRE

    Eisinger C.; Jensen J

    2011-01-01

    The Wabamun Lake area of Central Alberta, Canada includes several large CO2 point source emitters, collectively producing more than 30 Mt annually. Previous studies established that deep saline aquifers beneath the Wabamun Lake area have good potential for the large-scale injection and storage of CO2. This study reports on the characterization of the Devonian carbonate Nisku Formation for evaluation as a CO2 repository. Major challenges for characterization included sparse well and seis...

  19. Turnover of Synapse and Dynamic Nature of Synaptic Molecules In Vitro and In Vivo

    International Nuclear Information System (INIS)

    Recent advances of imaging techniques have enabled us to investigate the dynamics of synapses in living neurons. The synapse is constructed of presynaptic and postsynaptic elements which contain various kinds of structural and functional molecules. The postsynaptic density (PSD) is the most prominent structure among the excitatory postsynaptic elements. One of the main components of PSD is the scaffolding proteins which interact with multiple proteins in the synapse. Scaffolding proteins are suggested to play key roles in the emergence, maintenance, and remodeling of the excitatory synapses. Several kinds of scaffolding proteins are known to be present in the mammalian and also other vertebrate brains. These proteins were labeled with green fluorescent protein (GFP) and expressed in cultured neurons to analyze the dynamics and turnover of molecules in the synapses. In this review we describe how these molecules behave when the synapse is newly added or eliminated in the steady state and also when neuronal activity is changed

  20. A Synaptotagmin Isoform Switch during the Development of an Identified CNS Synapse.

    Science.gov (United States)

    Kochubey, Olexiy; Babai, Norbert; Schneggenburger, Ralf

    2016-06-01

    Various Synaptotagmin (Syt) isoform genes are found in mammals, but it is unknown whether Syts can function redundantly in a given nerve terminal, or whether isoforms can be switched during the development of a nerve terminal. Here, we investigated the possibility of a developmental Syt isoform switch using the calyx of Held as a model synapse. At mature calyx synapses, fast Ca(2+)-driven transmitter release depended entirely on Syt2, but the release phenotype of Syt2 knockout (KO) mice was weaker at immature calyces, and absent at pre-calyceal synapses early postnatally. Instead, conditional genetic inactivation shows that Syt1 mediates fast release at pre-calyceal synapses, as well as a fast release component resistant to Syt2 deletion in immature calyces. This demonstrates a developmental Syt1-Syt2 isoform switch at an identified synapse, a mechanism that could fine-tune the speed, reliability, and plasticity of transmitter release at fast releasing CNS synapses. PMID:27210552

  1. Petrographic and geochemical evidence for the formation of primary, bacterially induced lacustrine dolomite: La Roda 'white earth' (Pliocene, Central Spain)

    Science.gov (United States)

    Garcia, Del; Cura, M.A.; Calvo, J.P.; Ordonez, S.; Jones, B.F.; Canaveras, J.C.

    2001-01-01

    Upper Pliocene dolomites ('white earth') from La Roda, Spain, offer a good opportunity to evaluate the process of dolomite formation in lakes. The relatively young nature of the deposits could allow a link between dolomites precipitated in modern lake systems and those present in older lacustrine formations. The La Roda Mg-carbonates (dolomite unit) occur as a 3??5- to 4-m- thick package of poorly indurated, white, massive dolomite beds with interbedded thin deposits of porous carbonate displaying root and desiccation traces as well as local lenticular gypsum moulds. The massive dolomite beds consist mainly of loosely packed 1- to 2-??m-sized aggregates of dolomite crystals exhibiting poorly developed faces, which usually results in a subrounded morphology of the crystals. Minute rhombs of dolomite are sparse within the aggregates. Both knobbly textures and clumps of spherical bodies covering the crystal surfaces indicate that bacteria were involved in the formation of the dolomites. In addition, aggregates of euhedral dolomite crystals are usually present in some more clayey (sepiolite) interbeds. The thin porous carbonate (mostly dolomite) beds exhibit both euhedral and subrounded, bacterially induced dolomite crystals. The carbonate is mainly Ca-dolomite (51-54 mol% CaCO3), showing a low degree of ordering (degree of ordering ranges from 0??27 to 0??48). Calcite is present as a subordinate mineral in some samples. Sr, Mn and Fe contents show very low correlation coefficients with Mg/Ca ratios, whereas SiO2 and K contents are highly correlated. ??18O- and ??13C-values in dolomites range from -3??07??? to 5??40??? PDB (mean = 0??06, ?? = 1??75) and from -6??34??? to -0??39??? PDB (mean = -3??55, ?? = 1??33) respectively. Samples containing significant amounts of both dolomite and calcite do not in general show significant enrichment or depletion in 18O and 13C between the two minerals. The correlation coefficient between ??18O and ??13C for dolomite is extremely

  2. Prolonged synaptic currents increase relay neuron firing at the developing retinogeniculate synapse

    OpenAIRE

    Hauser, Jessica L.; Liu, Xiaojin; Litvina, Elizabeth Y.; Chen, Chinfei

    2014-01-01

    The retinogeniculate synapse, the connection between retinal ganglion cells (RGC) and thalamic relay neurons, undergoes robust changes in connectivity over development. This process of synapse elimination and strengthening of remaining inputs is thought to require synapse specificity. Here we show that glutamate spillover and asynchronous release are prominent features of retinogeniculate synaptic transmission during this period. The immature excitatory postsynaptic currents exhibit a slow de...

  3. Attenuation of age-related changes in mouse neuromuscular synapses by caloric restriction and exercise

    OpenAIRE

    Valdez, G; Tapia, J; Kang, H; Clemenson, G.D.; Gage, F.H.; Lichtman, Jeff; Sanes, Joshua R.

    2010-01-01

    The cellular basis of age-related behavioral decline remains obscure but alterations in synapses are likely candidates. Accordingly, the beneficial effects on neural function of caloric restriction and exercise, which are among the most effective anti-aging treatments known, might also be mediated by synapses. As a starting point in testing these ideas, we studied the skeletal neuromuscular junction (NMJ), a large, accessible peripheral synapse. Comparison of NMJs in young adult and aged mice...

  4. Neuronal pentraxins mediate silent synapse conversion in the developing visual system

    OpenAIRE

    Koch, Selina; Ullian, Erik M.

    2010-01-01

    Neuronal pentraxins (NPs) are hypothesized to play important roles in the recruitment of AMPA receptors (AMPARs) to immature synapses, yet a physiological role for NPs at nascent synapses in vivo has remained elusive. Here we report that the loss of NP1 and NP2 (NP1/2) leads to a dramatic and specific reduction in AMPAR-mediated transmission at developing visual system synapses. In thalamic slices taken from early postnatal mice (

  5. A Novel, Noncanonical BMP Pathway Modulates Synapse Maturation at the Drosophila Neuromuscular Junction

    OpenAIRE

    Sulkowski, Mikolaj J.; Tae Hee Han; Carolyn Ott; Qi Wang; Verheyen, Esther M.; Jennifer Lippincott-Schwartz; Mihaela Serpe

    2016-01-01

    Author Summary Synaptic activity and synapse development are intimately linked, but our understanding of the coupling mechanisms remains limited. Anterograde and retrograde signals together with trans-synaptic complexes enable intercellular communications. How synapse activity status is monitored and relayed across the synaptic cleft remains poorly understood. The Drosophila NMJ is a very powerful genetic system to study synapse development. BMP signaling modulates NMJ growth via a canonical,...

  6. Activity-Dependent Synaptic Plasticity of a Chalcogenide Electronic Synapse for Neuromorphic Systems

    OpenAIRE

    Yi Li; Yingpeng Zhong; Jinjian Zhang; Lei Xu; Qing Wang; Huajun Sun; Hao Tong; Xiaoming Cheng; Xiangshui Miao

    2014-01-01

    Nanoscale inorganic electronic synapses or synaptic devices, which are capable of emulating the functions of biological synapses of brain neuronal systems, are regarded as the basic building blocks for beyond-Von Neumann computing architecture, combining information storage and processing. Here, we demonstrate a Ag/AgInSbTe/Ag structure for chalcogenide memristor-based electronic synapses. The memristive characteristics with reproducible gradual resistance tuning are utilised to mimic the act...

  7. Trilobites from the Çal Tepe Formation (Cambrian), Near Seydişehir, Central Taurides, Southwestern Turkey

    OpenAIRE

    DEAN, WILLIAM T.

    2005-01-01

    The type section of the Çal Tepe Formation, near Seydişehir, is reviewed. The basal dolomite member is unfossiliferous, but the succeeding black limestone member (24 m), light-grey limestone member (10.15 m), and red nodular limestone member (46.7 m) are subdivided into thirty-seven numbered, often fossiliferous beds. Trilobites from the black limestone member, late Early Cambrian, exhibit affinities with Morocco, Spain and northwestern Europe; they include one new genus and species (Pamphyli...

  8. Palaeoceanographic conditions during the formation of ferromanganese crust from the Afanasiy Nikitin seamount, north central Indian Ocean: geochemical evidence

    Digital Repository Service at National Institute of Oceanography (India)

    Banakar, V.K.; Pattan, J.N.; Mudholkar, A.V.

    to subsidence due to sediment loading. Fig. 2 presents a simplified subsidence diagram of the seamount which gives a cumulative subsi- dence rate of -50 m/m.y. Assuming uniform, uninterrupted subsidence since the formation of the seamount, a simplified.... I 75 7’0 I 40 I I 60 40 30 2’0 I IO 6 Ma Fig. 2. Schematic diagram of simplified subsidence history of the Afanasiy-Nikitin seamount. The three standings of the seamount for different time periods with respect to the sea-level is based...

  9. Airborne Measurements of Ammonia and Implications for Ammonium Nitrate Formation in the Central Valley and the South Coast Air Basin of California

    Science.gov (United States)

    Nowak, J. B.; Neuman, J.; Bahreini, R.; Middlebrook, A. M.; Brock, C. A.; Frost, G. J.; Holloway, J. S.; McKeen, S. A.; Peischl, J.; Pollack, I. B.; Roberts, J. M.; Ryerson, T. B.; Trainer, M.; Parrish, D. D.

    2010-12-01

    Ammonia (NH3) is the dominant gas-phase base in the troposphere. As a consequence, NH3 abundance influences aerosol formation and composition. Ammonium nitrate aerosol is formed from the reaction of gas phase NH3 and nitric acid (HNO3). Anthropogenic emissions of NH3 and NOx (NO + NO2), which in sunlight can be oxidized to form HNO3, can react to form ammonium nitrate aerosol. Agricultural activity (i.e., dairy farms), and urban centers (i.e., Fresno, Los Angeles) are sources of ammonium nitrate gas-phase precursors in both the Central Valley and the South Coast Air Basin. Airborne measurements of NH3, HNO3, particle composition, and particle size distribution were made aboard the NOAA WP-3D research aircraft during May and June 2010 in the Central Valley and the South Coast Air Basin of California, as part of CalNex 2010 (California Research at the Nexus of Air Quality and Climate Change). The highest mixing ratios of NH3, well over 100 parts-per-billion by volume (ppbv), were measured downwind of dairy farms. The high NH3 mixing ratios were highly anti-correlated with HNO3 mixing ratios on fast time scales (~1 s) that correspond to short flight distances (~100 m). During these periods particulate nitrate (NO3-) concentrations increased, indicating ammonium nitrate formation. The meteorological and chemical environments during these periods will be studied to determine the factors driving or limiting ammonium nitrate formation and the resulting regional differences. Finally, the relationship between the NH3 observations and NH3 sources will be examined to assess the emissions and their contribution to ammonium nitrate abundance.

  10. Sialic Acid within the Glycosylphosphatidylinositol Anchor Targets the Cellular Prion Protein to Synapses.

    Science.gov (United States)

    Bate, Clive; Nolan, William; McHale-Owen, Harriet; Williams, Alun

    2016-08-12

    Although the cellular prion protein (PrP(C)) is concentrated at synapses, the factors that target PrP(C) to synapses are not understood. Here we demonstrate that exogenous PrP(C) was rapidly targeted to synapses in recipient neurons derived from Prnp knock-out((0/0)) mice. The targeting of PrP(C) to synapses was dependent upon both neuronal cholesterol concentrations and the lipid and glycan composition of its glycosylphosphatidylinositol (GPI) anchor. Thus, the removal of either an acyl chain or sialic acid from the GPI anchor reduced the targeting of PrP(C) to synapses. Isolated GPIs (derived from PrP(C)) were also targeted to synapses, as was IgG conjugated to these GPIs. The removal of sialic acid from GPIs prevented the targeting of either the isolated GPIs or the IgG-GPI conjugate to synapses. Competition studies showed that pretreatment with sialylated GPIs prevented the targeting of PrP(C) to synapses. These results are consistent with the hypothesis that the sialylated GPI anchor attached to PrP(C) acts as a synapse homing signal. PMID:27325697

  11. Effects of curcumin on synapses in APPswe/PS1dE9 mice.

    Science.gov (United States)

    He, Yingkun; Wang, Pengwen; Wei, Peng; Feng, Huili; Ren, Ying; Yang, Jinduo; Rao, Yingxue; Shi, Jing; Tian, Jinzhou

    2016-06-01

    Significant losses of synapses have been demonstrated in studies of Alzheimer's disease (AD), but structural and functional changes in synapses that depend on alterations of the postsynaptic density (PSD) area occur prior to synaptic loss and play a crucial role in the pathology of AD. Evidence suggests that curcumin can ameliorate the learning and memory deficits of AD. To investigate the effects of curcumin on synapses, APPswe/PS1dE9 double transgenic mice (an AD model) were used, and the ultra-structures of synapses and synapse-associated proteins were observed. Six months after administration, few abnormal synapses were observed upon electron microscopy in the hippocampal CA1 areas of the APPswe/PS1dE9 double transgenic mice. The treatment of the mice with curcumin resulted in improvements in the quantity and structure of the synapses. Immunohistochemistry and western blot analyses revealed that the expressions of PSD95 and Shank1 were reduced in the hippocampal CA1 areas of the APPswe/PS1dE9 double transgenic mice, but curcumin treatment increased the expressions of these proteins. Our findings suggest that curcumin improved the structure and function of the synapses by regulating the synapse-related proteins PSD95 and Shank1. PMID:26957323

  12. Mantle xenoliths from Central Vietnam: evidence for at least Meso-Proterozoic formation of the lithospheric mantle

    Science.gov (United States)

    Proßegger, Peter; Ntaflos, Theodoros; Ackerman, Lukáš; Hauzenberger, Christoph; Tran, Tuan Anh

    2016-04-01

    Intraplate Cenozoic basalts that are widely dispersed along the continental margin of East Asia belong to the Western Pacific "diffuse" igneous province. They consist mainly of alkali basalts, basanites,rarely nephelinites, which are mantle xenolith-bearing, potassic rocks and quartz tholeiites. The volcanism in this area has been attributed to the continental extension caused by the collision of India with Asia and by the subduction of the Pacific Ocean below Asia. We studied a suite of 24 mantle xenoliths from La Bang Lake, Dak Doa district and Bien Ho, Pleiku city in the Gia Province, Central Vietnam. They are predominantly spinel lherzolites (19) but spinel harburgites (3) and two garnet pyroxenites are present as well. The sizes of the xenoliths range from 5 to 40 cm in diameter with medium to coarse-grained protogranular textures. Whole rock major and trace element analyses display a wide range of compositions. The MgO concentration varies from 36.0 to 45.8 wt% whereas Al2O3 and CaO range from 0.63 to 4.36 wt% and from 0.52 to 4.21 wt% (with one sample having CaO of 6.63 wt%) respectively. Both CaO and Al2O3 positively correlate with MgO most likely indicating that the sampled rocks were derived from a common mantle source experienced variable degrees of partial melting. Mineral analyses show that the rock forming minerals are chemically homogeneous. The Fo contents of olivine vary between 89.2 and 91.2 and the Mg# of orthopyroxene and clinopyroxene range from 89 to 92 and 89 to 94 respectively. The range of Cr# for spinel is 0.06-0.26. Model calculations in both whole rock and clinopyroxenes show that lithospheric mantle underneath Central Vietnam experienced melt extractions that vary between 2-7, 12-15 and 20-30%. The majority of the primitive mantle-normalized whole rock and clinopyroxene REE patterns are parallel to each other indicating that clinopyroxene is the main repository of the trace elements. Clinopyroxenes are divided into two groups: group A

  13. Synapse:neural network for predict power consumption: users guide

    Energy Technology Data Exchange (ETDEWEB)

    Muller, C.; Mangeas, M.; Perrot, N.

    1994-08-01

    SYNAPSE is forecasting tool designed to predict power consumption in metropolitan France on the half hour time scale. Some characteristics distinguish this forecasting model from those which already exist. In particular, it is composed of numerous neural networks. The idea for using many neural networks arises from past tests. These tests showed us that a single neural network is not able to solve the problem correctly. From this result, we decided to perform unsupervised classification of the 24 consumption curves. From this classification, six classes appeared, linked with the weekdays: Mondays, Tuesdays, Wednesdays, Thursdays, Fridays, Saturdays, Sundays, holidays and bridge days. For each class and for each half hour, two multilayer perceptrons are built. The two of them forecast the power for one particular half hour, and for a day including one of the determined class. The input of these two network are different: the first one (short time forecasting) includes the powers for the most recent half hour and relative power of the previous day; the second (medium time forecasting) includes only the relative power of the previous day. A process connects the results of every networks and allows one to forecast more than one half-hour in advance. In this process, short time forecasting networks and medium time forecasting networks are used differently. The first kind of neural networks gives good results on the scale of one day. The second one gives good forecasts for the next predicted powers. In this note, the organization of the SYNAPSE program is detailed, and the user`s menu is described. This first version of synapse works and should allow the APC group to evaluate its utility. (authors). 6 refs., 2 appends.

  14. Synapse-specific inhibitory control of hippocampal feedback inhibitory circuit

    Directory of Open Access Journals (Sweden)

    Simon eChamberland

    2010-10-01

    Full Text Available Local circuit and long-range GABAergic projections provide powerful inhibitory control over the operation of hippocampal inhibitory circuits, yet little is known about the input- and target-specific organization of interacting inhibitory networks in relation to their specific functions. Using a combination of two-photon laser scanning photostimulation and whole-cell patch clamp recordings in mice hippocampal slices, we examined the properties of transmission at GABAergic synapses formed onto hippocampal CA1 stratum oriens – lacunosum moleculare (O–LM interneurons by two major inhibitory inputs: local projection originating from stratum radiatum interneurons and septohippocampal GABAergic terminals. Optical mapping of local inhibitory inputs to O–LM interneurons revealed that vasoactive intestinal polypeptide- and calretinine-positive neurons, with anatomical properties typical of type III interneuron-specific interneurons, provided the major local source of inhibition to O–LM cells. Inhibitory postsynaptic currents evoked by minimal stimulation of this input exhibited small amplitude and significant paired-pulse and multiple-pulse depression during repetitive activity. Moreover, these synapses failed to show any form of long-term synaptic plasticity. In contrast, synapses formed by septohippocampal projection produced higher amplitude and persistent inhibition and exhibited long-term potentiation induced by theta-like activity. These results indicate the input and target-specific segregation in inhibitory control, exerted by two types of GABAergic projections and responsible for distinct dynamics of inhibition in O–LM interneurons. The two inputs are therefore likely to support the differential activity- and brain state-dependent recruitment of hippocampal feedback inhibitory circuits in vivo, crucial for dendritic disinhibition and computations in CA1 pyramidal cells.

  15. Process modeling studies of physical mechanisms of the formation of an anticyclonic eddy in the central Red Sea

    KAUST Repository

    Chen, Changsheng

    2014-02-01

    Surface drifters released in the central Red Sea during April 2010 detected a well-defined anticyclonic eddy around 23°N. This eddy was ∼45–60 km in radius, with a swirl speed up to ∼0.5 m/s. The eddy feature was also evident in monthly averaged sea surface height fields and in current profiles measured on a cross-isobath, shipboard CTD/ADCP survey around that region. The unstructured-grid, Finite-Volume Community Ocean Model (FVCOM) was configured for the Red Sea and process studies were conducted to establish the conditions necessary for the eddy to form and to establish its robustness. The model was capable of reproducing the observed anticyclonic eddy with the same location and size. Diagnosis of model results suggests that the eddy can be formed in a Red Sea that is subject to seasonally varying buoyancy forcing, with no wind, but that its location and structure are significantly altered by wind forcing, initial distribution of water stratification and southward coastal flow from the upstream area. Momentum analysis indicates that the flow field of the eddy was in geostrophic balance, with the baroclinic pressure gradient forcing about the same order of magnitude as the surface pressure gradient forcing.

  16. Formation of diapiric structure in the deformation zone, central Indian Ocean: A model from gravity and seismic reflection data

    Indian Academy of Sciences (India)

    K S Krishna; D Gopala Rao; Yu P Neprochnov

    2002-03-01

    Analyses of bathymetry, gravity and seismic reflection data of the diffusive plate boundary in the central Indian Ocean reveal a new kind of deformed structure besides the well-reported structures of long-wavelength anticlinal basement rises and high-angle reverse faults. The structure (basement trough) has a length of about 150 km and deepens by up to 1 km from its regional trend (northward dipping). The basement trough includes a rise at its center with a height of about 1.5 km. The rise is about 10 km wide with rounded upper surface and bounded by vertical faults. A broad free-air gravity low of about 20 mGal and a local high of 8 mGal in its center are associated with the identified basement trough and rise structure respectively. Seismic results reveal that the horizontal crustal compression prevailing in the diffusive plate boundary might have formed the basement trough possibly in early Pliocene time. Differential loading stresses have been generated from unequal crust/sediment thickness on lower crustal and upper mantle rocks. A thin semi-ductile serpentinite layer existing near the base of the crust that is interpreted to have been formed at mid-ocean ridge and become part of the lithosphere, may have responded to the downward loading stresses generated by the sediments and crustal rocks to inject the serpentinites into the overlying strata to form a classic diapiric structure.

  17. A Neuron- and a Synapse Chip for Artificial Neural Networks

    OpenAIRE

    Lansner, John; Lehmann, Torsten

    1992-01-01

    A cascadable, analog, CMOS chip set has been developed for hardware implementations of artificial neural networks (ANN's):I) a neuron chip containing an array of neurons with hyperbolic tangent activation functions and adjustable gains, and II) a synapse chip (or a matrix-vector multiplier) where the matrix is stored on-chip as differential voltages on capacitors. In principal any ANN configuration can be made using these chips. A neuron array of 4 neurons and a 4 × 4 matrix-vector multiplie...

  18. Endosome-mediated endocytic mechanism replenishes the majority of synaptic vesicles at mature CNS synapses in an activity-dependent manner.

    Science.gov (United States)

    Park, Joohyun; Cho, Oh Yeon; Kim, Jung Ah; Chang, Sunghoe

    2016-01-01

    Whether synaptic vesicles (SVs) are recovered via endosome-mediated pathways is a matter of debate; however, recent evidence suggests that clathrin-independent bulk endocytosis (CIE) via endosomes is functional and preferentially replenishes SV pools during strong stimulation. Here, using brefeldin-A (BFA) to block CIE, we found that CIE retrieved a minority of SVs at developing CNS synapses during strong stimulation, but its contribution increased up to 61% at mature CNS synapses. Contrary to previous views, BFA not only blocked SV formation from the endosome but also blocked the endosome formation at the plasma membrane. Adaptor protein 1 and 3 (AP-1/3) have key roles in SV reformation from endosomes during CIE, and AP-1 also affects bulk endosome formation from the plasma membrane. Finally, temporary blocking of chronic or acute neuronal activity with tetrodotoxin in mature neurons redirected most SV retrieval to endosome-independent pathways. These results show that during high neuronal activity, CIE becomes the major endocytic pathway at mature CNS synapses. Moreover, mature neurons use clathrin-mediated endocytosis and the CIE pathway to different extents depending on their previous activity; this may result in activity-dependent alterations of the SV composition which ultimately influence transmitter release and contribute to synaptic plasticity. PMID:27534442

  19. Research on frost formation in air source heat pump at cold-moist conditions in central-south China

    International Nuclear Information System (INIS)

    Highlights: ►A dynamic evaporator model is built up. ► The model involves the ratio of the latent heat to sensible heat of wet air. ►A correlation considering deq is shown below to predict frost accumulation: (Mfrv3)/(Ψdeq2) =((Ta)/(Tw) )0.1((vτ)/(deq) )0.7(l/(deq) )1.378Xa1.228. ►The changing ratio can characterize the early development of system performance. ►The changing ratio can characterize the early development of frost accumulation. -- Abstract: A dynamic evaporator model of air source heat pump (ASHP), considering the ratio of the latent heat to sensible heat of wet air, is presented to analyze the performance of ASHP under frosting. The performance parameters, such as the heating capacity, COP and the outlet temperature of compressor, are simulated with CYCLEPAD. Then a semi-empirical correlation that predicts frost accumulation on the air-side of fin-tube heat exchanger is developed with dimensionless analysis and also modified by a test conducted under cold-moist conditions in winter. In addition, eight influence factors are considered involving the ambient conditions and structures of heat exchanger, whose effects are analyzed as well. Among them, the equivalent diameter of air flow cross-section in fin-tube deq is especially proposed. Lastly, the relationships between the ratio, the performance parameters and the frost accumulation are discussed in this paper, followed by an evaluation of an optimal defrosting time interval to improve the ASHP’s energy efficiency and operational reliability at cold-moist conditions in central-south China.

  20. Analysis of Dose at the Site of Second Tumor Formation After Radiotherapy to the Central Nervous System

    International Nuclear Information System (INIS)

    Purpose: Second tumors are an uncommon complication of multimodality treatment of childhood cancer. The present analysis attempted to correlate the dose received as a component of primary treatment and the site of the eventual development of a second tumor. Methods and Materials: We retrospectively identified 16 patients who had received radiotherapy to sites in the craniospinal axis and subsequently developed a second tumor. We compared the historical fields and port films of the primary treatment with the modern imaging of the second tumor locations. We classified the location of the second tumors as follows: in the boost field; marginal to the boost field, but in a whole-brain field; in a whole-brain field; marginal to the whole brain/primary treatment field; and distant to the field. We divided the dose received into 3 broad categories: high dose (>45 Gy), moderate dose (20–36 Gy), and low dose (<20 Gy). Results: The most common location of the second tumor was in the whole brain field (57%) and in the moderate-dose range (81%). Conclusions: Our data contradict previous publications that suggested that most second tumors develop in tissues that receive a low radiation dose. Almost all the second tumors in our series occurred in tissue within a target volume in the cranium that had received a moderate dose (20–36 Gy). These findings suggest that a major decrease in the brain volume that receives a moderate radiation dose is the only way to substantially decrease the second tumor rate after central nervous system radiotherapy.

  1. Sedimentology, paleontology and age of the Ayacara and Lago Ranco formations (south-central Chile, 40°- 42°S). Tectonic implications.

    Science.gov (United States)

    Encinas, Alfonso; Zambrano, Patricio; Bernabe, Pablo; Finger, Kenneth; Buatois, Luis; Duhart, Paul; Valencia, Victor; Fanning, M.; Herve, Francisco

    2010-05-01

    Deep-marine, Mio-Pliocene strata correlative with the Navidad Formation crop out in different areas along the forearc of south-central Chile (~34°-41°) and have also been recognized in boreholes drilles on the continental shelf. However, at Lago Ranco (40°S) and Ayacara (42°) there are outcrops of marine strata whose age and correlation with these units remain uncertain. These deposits consist of rhythmic successions of sandstone and siltstone representing facies similar to those of the Navidad and correlative formations. These marine successions are known ase the Estratos de Lago Ranco and Ayacara formations. They both crop out in the western Andean Cordillera near the limit with the Intermediate Depression at Lago Ranco and the submerged equivalent of this physiographic unit at Ayacara. There are very few studies carried out on these units and most of them consist on internal reports and unpublished theses.In order to unravel the sedimentary enviroment, age and tectonic history of this area during the Neogene we carried out sedimentological, ichnological and micropaleontological studies. In addition, we carried out U-Pb dating in detrital zircons (LAICPMS and SHRIMP). Our studies show the presence of sedimentary features and ichnofacies typical of deposition in a deep-marine environment for these units..In agreement, benthic foraminifers (Ciclamina incisa and Siphonodosaria sangrinensis) indicate lower bathial depths (1500 m). U-Pb (LAICPMS and SHRIMP) indicate a maximum depositional age of around 20 Ma for these units. In agreement, the occurrence of the planktic foraminifer species Globorotalia siakensis (P22-N14), Globigerinoides quadrilobatus (N6-Recent) and Globigerinoides sikanus (N8-N9) in strata of the Ayacara Formation suggest an early-middle Miocene age for this unit. These data indicate that the area corresponding to the western Main Andean Cordillera in south central Chile, was subjeted to major subsidence during the early-middle Miocene. Major

  2. Human synapses show a wide temporal window for spike-timing-dependent plasticity

    Directory of Open Access Journals (Sweden)

    Guilherme T Silva

    2010-07-01

    Full Text Available Throughout our lifetime, activity-dependent changes in neuronal connection strength enable the brain to refine neural circuits and learn based on experience. Synapses can bi-directionally alter strength and the magnitude and sign depend on the millisecond timing of presynaptic and postsynaptic action potential firing. Recent findings on laboratory animals have shown that neurons can show a variety of temporal windows for spike-timing-dependent plasticity (STDP. It is unknown what synaptic learning rules exist in human synapses and whether similar temporal windows for STDP at synapses hold true for the human brain. Here, we directly tested in human slices cut from hippocampal tissue removed for surgical treatment of deeper brain structures in drug-resistant epilepsy patients, whether adult human synapses can change strength in response to millisecond timing of pre- and postsynaptic firing. We find that adult human hippocampal synapses can alter synapse strength in response to timed pre- and postsynaptic activity. In contrast to rodent hippocampal synapses, the sign of plasticity does not sharply switch around 0 millisecond timing. Instead, both positive timing intervals, in which presynaptic firing preceded the postsynaptic action potential, and negative timing intervals, in which postsynaptic firing preceded presynaptic activity down to -80 ms, increase synapse strength (tLTP. Negative timing intervals between -80 to -130 ms induce a lasting reduction of synapse strength (tLTD. Thus, similar to rodent synapses, adult human synapses can show spike-timing-dependent changes in strength. The timing rules of STDP in human hippocampus, however, seem to differ from rodent hippocampus, and suggest a less strict interpretation of Hebb’s predictions.

  3. The specific star formation rate and stellar mass fraction of low-mass central galaxies in cosmological simulations

    CERN Document Server

    Avila-Reese, V; González-Samaniego, A; Valenzuela, O; Firmani, C; Velázquez, H; Ceverino, D

    2011-01-01

    By means of cosmological simulations of galaxies in the context of the LCDM scenario we explore the specific star formation rates (SSFR=SFR/Ms, Ms is the stellar mass) and stellar mass fractions (Fs=Ms/Mh, Mh is the halo mass) for sub-M* field galaxies at different redshifts (0

  4. Insights into the dolomitization process and porosity modification in sucrosic dolostones, Avon Park Formation (Middle Eocene), East-Central Florida, U.S.A.

    KAUST Repository

    Maliva,, Robert G.

    2011-03-01

    The Avon Park Formation (middle Eocene) in central Florida, U.S.A., contains shallow-water carbonates that have been replaced by dolomite to varying degrees, ranging from partially replaced limestones, to highly porous sucrosic dolostones, to, less commonly, low-porosity dense dolostones. The relationships between dolomitization and porosity and permeability were studied focusing on three 305-m-long cores taken in the City of Daytona Beach. Stable-isotope data from pure dolostones (mean δ 18O = +3.91% V-PDB) indicate dolomite precipitation in Eocene penesaline pore waters, which would be expected to have been at or above saturation with respect to calcite. Nuclear magnetic log-derived porosity and permeability data indicate that dolomitization did not materially change total porosity values at the bed and formation scale, but did result in a general increase in pore size and an associated substantial increase in permeability compared to limestone precursors. Dolomitization differentially affects the porosity and permeability of carbonate strata on the scale of individual crystals, beds, and formations. At the crystal scale, dolomitization occurs in a volume-for-volume manner in which the space occupied by the former porous calcium carbonate is replaced by a solid dolomite crystal with an associated reduction in porosity. Dolomite crystal precipitation was principally responsible for calcite dissolution both at the actual site of dolomite crystal growth and in the adjoining rock mass. Carbonate is passively scavenged from the formation, which results in no significant porosity change at the formation scale. Moldic pores after allochems formed mainly in beds that experienced high degrees of dolomitization, which demonstrates the intimate association of the dolomitization process with carbonate dissolution. The model of force of crystallization-controlled replacement provides a plausible explanation for key observations concerning the dolomitization process in the

  5. Stimulus-specific adaptation at the synapse level in vitro.

    Directory of Open Access Journals (Sweden)

    Haitao Wang

    Full Text Available Stimulus-specific adaptation (SSA is observed in many brain regions in humans and animals. SSA of cortical neurons has been proposed to accumulate through relays in ascending pathways. Here, we examined SSA at the synapse level using whole-cell patch-clamp recordings of primary cultured cortical neurons of the rat. First, we found that cultured neurons had high firing capability with 100-Hz current injection. However, neuron firing started to adapt to repeated electrically activated synaptic inputs at 10 Hz. Next, to activate different dendritic inputs, electrical stimulations were spatially separated. Cultured neurons showed similar SSA properties in the oddball stimulation paradigm compared to those reported in vivo. Single neurons responded preferentially to a deviant stimulus over repeated, standard stimuli considering both synapse-driven spikes and excitatory postsynaptic currents (EPSCs. Compared with two closely placed stimulating electrodes that activated highly overlapping dendritic fields, two separately placed electrodes that activated less overlapping dendritic fields elicited greater SSA. Finally, we used glutamate puffing to directly activate postsynaptic glutamate receptors. Neurons showed SSA to two separately placed puffs repeated at 10 Hz. Compared with EPSCs, GABAa receptor-mediated inhibitory postsynaptic currents showed weaker SSA. Heterogeneity of the synaptic inputs was critical for producing SSA, with glutamate receptor desensitization participating in the process. Our findings suggest that postsynaptic fatigue contributes largely to SSA at low frequencies.

  6. A Reinforcement Learning Framework for Spiking Networks with Dynamic Synapses

    Directory of Open Access Journals (Sweden)

    Karim El-Laithy

    2011-01-01

    Full Text Available An integration of both the Hebbian-based and reinforcement learning (RL rules is presented for dynamic synapses. The proposed framework permits the Hebbian rule to update the hidden synaptic model parameters regulating the synaptic response rather than the synaptic weights. This is performed using both the value and the sign of the temporal difference in the reward signal after each trial. Applying this framework, a spiking network with spike-timing-dependent synapses is tested to learn the exclusive-OR computation on a temporally coded basis. Reward values are calculated with the distance between the output spike train of the network and a reference target one. Results show that the network is able to capture the required dynamics and that the proposed framework can reveal indeed an integrated version of Hebbian and RL. The proposed framework is tractable and less computationally expensive. The framework is applicable to a wide class of synaptic models and is not restricted to the used neural representation. This generality, along with the reported results, supports adopting the introduced approach to benefit from the biologically plausible synaptic models in a wide range of intuitive signal processing.

  7. Sex-specific pruning of neuronal synapses in Caenorhabditis elegans.

    Science.gov (United States)

    Oren-Suissa, Meital; Bayer, Emily A; Hobert, Oliver

    2016-05-12

    Whether and how neurons that are present in both sexes of the same species can differentiate in a sexually dimorphic manner is not well understood. A comparison of the connectomes of the Caenorhabditis elegans hermaphrodite and male nervous systems reveals the existence of sexually dimorphic synaptic connections between neurons present in both sexes. Here we demonstrate sex-specific functions of these sex-shared neurons and show that many neurons initially form synapses in a hybrid manner in both the male and hermaphrodite pattern before sexual maturation. Sex-specific synapse pruning then results in the sex-specific maintenance of subsets of these connections. Reversal of the sexual identity of either the pre- or postsynaptic neuron alone transforms the patterns of synaptic connectivity to that of the opposite sex. A dimorphically expressed and phylogenetically conserved transcription factor is both necessary and sufficient to determine sex-specific connectivity patterns. Our studies reveal new insights into sex-specific circuit development. PMID:27144354

  8. Positioning of AMPA Receptor-Containing Endosomes Regulates Synapse Architecture

    Directory of Open Access Journals (Sweden)

    Marta Esteves da Silva

    2015-11-01

    Full Text Available Lateral diffusion in the membrane and endosomal trafficking both contribute to the addition and removal of AMPA receptors (AMPARs at postsynaptic sites. However, the spatial coordination between these mechanisms has remained unclear, because little is known about the dynamics of AMPAR-containing endosomes. In addition, how the positioning of AMPAR-containing endosomes affects synapse organization and functioning has never been directly explored. Here, we used live-cell imaging in hippocampal neuron cultures to show that intracellular AMPARs are transported in Rab11-positive recycling endosomes, which frequently enter dendritic spines and depend on the microtubule and actin cytoskeleton. By using chemically induced dimerization systems to recruit kinesin (KIF1C or myosin (MyosinV/VI motors to Rab11-positive recycling endosomes, we controlled their trafficking and found that induced removal of recycling endosomes from spines decreases surface AMPAR expression and PSD-95 clusters at synapses. Our data suggest a mechanistic link between endosome positioning and postsynaptic structure and composition.

  9. Memory Capacity of Networks with Stochastic Binary Synapses

    Science.gov (United States)

    Dubreuil, Alexis M.; Amit, Yali; Brunel, Nicolas

    2014-01-01

    In standard attractor neural network models, specific patterns of activity are stored in the synaptic matrix, so that they become fixed point attractors of the network dynamics. The storage capacity of such networks has been quantified in two ways: the maximal number of patterns that can be stored, and the stored information measured in bits per synapse. In this paper, we compute both quantities in fully connected networks of N binary neurons with binary synapses, storing patterns with coding level , in the large and sparse coding limits (). We also derive finite-size corrections that accurately reproduce the results of simulations in networks of tens of thousands of neurons. These methods are applied to three different scenarios: (1) the classic Willshaw model, (2) networks with stochastic learning in which patterns are shown only once (one shot learning), (3) networks with stochastic learning in which patterns are shown multiple times. The storage capacities are optimized over network parameters, which allows us to compare the performance of the different models. We show that finite-size effects strongly reduce the capacity, even for networks of realistic sizes. We discuss the implications of these results for memory storage in the hippocampus and cerebral cortex. PMID:25101662

  10. Power-law forgetting in synapses with metaplasticity

    International Nuclear Information System (INIS)

    The idea of using metaplastic synapses to incorporate the separate storage of long- and short-term memories via an array of hidden states was put forward in the cascade model of Fusi et al. In this paper, we devise and investigate two models of a metaplastic synapse based on these general principles. The main difference between the two models lies in their available mechanisms of decay, when a contrarian event occurs after the build-up of a long-term memory. In one case, this leads to the conversion of the long-term memory to a short-term memory of the opposite kind, while in the other, a long-term memory of the opposite kind may be generated as a result. Appropriately enough, the response of both models to short-term events is not affected by this difference in architecture. On the contrary, the transient response of both models, after long-term memories have been created by the passage of sustained signals, is rather different. The asymptotic behaviour of both models is, however, characterised by power-law forgetting with the same universal exponent

  11. Sedimentary environments and stratigraphy of the carbonate-silicilastic deposits of the Shirgesht Formation: implications for eustasy and local tectonism in the Kalmard Block, Central Iran

    Directory of Open Access Journals (Sweden)

    aram bayetgoll

    2015-10-01

    Full Text Available Introduction   Sedimentological and sequence stratigraphic analysis providing insight into the main relationships between sequence architecture and stacking pattern, syn/post-depositional tectonics, and eustatic sea-level fluctuations (Gawthorpe and Leeder 2000; Zecchin et al. 2003, 2004; Carpentier et al. 2007. Relative variations in sea level are due to tectonic activity and eustasy. The Shirgesht Formation in the Kalmard Block of Central Iran provides a useful case study for to determine the processes responsible on internal architecture and stacking pattern of depositional sequences in a half-graben basin. In the Shirgesht Formation, siliciclastic and carbonate successions of the Kalmard Basin, the cyclic stratigraphic record is the result of the complex interaction of regional uplift, eustasy, local tectonics, sediment supply, and sedimentary processes (Bayet-Goll 2009, 2014; Hosseini-Barzi and Bayet-Goll 2009.     Material & Methods   Lower Paleozoic successions in Tabas and Kalmard blocks from Central Iran share the faunal and floral characteristics with other Gondwana sectors such as south-western Europe and north Africa–Middle East (Ghaderi et al. 2009. The geology of these areas was outlined by Ruttner et al. (1968 and by Bruton et al. (2004. The Cambrian-Middle Triassic strata in the Kalmard Block were deposited in a shallow water platform that possesses lithologic dissimilarities with the Tabas area (Aghanabati 2004. The occurrence of two active faults indicates clearly that Kalmard basin formed a mobile zone throughout the Paleozoic so that lithostratigraphic units show considerably contrasting facies in comparison with Tabas basin (Hosseini-Barzi and Bayet-Goll 2009; Bayet-Goll 2014 . The Shirgesht Formation in the Block Kalmard is mainly composed of carbonate-siliciclastic successions that disconformability overlain Kalmard Formation (attributed to Pre-Cambrian and is underlain by Gachal (Carboniferous or Rahdar (Devonian

  12. The Calmodulin-Binding Transcription Activator CAMTA1 Is Required for Long-Term Memory Formation in Mice

    Science.gov (United States)

    Bas-Orth, Carlos; Tan, Yan-Wei; Oliveira, Ana M. M.; Bengtson, C. Peter; Bading, Hilmar

    2016-01-01

    The formation of long-term memory requires signaling from the synapse to the nucleus to mediate neuronal activity-dependent gene transcription. Synapse-to-nucleus communication is initiated by influx of calcium ions through synaptic NMDA receptors and/or L-type voltage-gated calcium channels and involves the activation of transcription factors by…

  13. Potentiation decay of synapses and length distributions of synfire chains self-organized in recurrent neural networks

    Science.gov (United States)

    Miller, Aaron; Jin, Dezhe Z.

    2013-12-01

    Synfire chains are thought to underlie precisely timed sequences of spikes observed in various brain regions and across species. How they are formed is not understood. Here we analyze self-organization of synfire chains through the spike-timing dependent plasticity (STDP) of the synapses, axon remodeling, and potentiation decay of synaptic weights in networks of neurons driven by noisy external inputs and subject to dominant feedback inhibition. Potentiation decay is the gradual, activity-independent reduction of synaptic weights over time. We show that potentiation decay enables a dynamic and statistically stable network connectivity when neurons spike spontaneously. Periodic stimulation of a subset of neurons leads to formation of synfire chains through a random recruitment process, which terminates when the chain connects to itself and forms a loop. We demonstrate that chain length distributions depend on the potentiation decay. Fast potentiation decay leads to long chains with wide distributions, while slow potentiation decay leads to short chains with narrow distributions. We suggest that the potentiation decay, which corresponds to the decay of early long-term potentiation of synapses, is an important synaptic plasticity rule in regulating formation of neural circuity through STDP.

  14. Microtubule dynamics and signal transduction at the immunological synapse: new partners and new connections

    OpenAIRE

    Lasserre, Rémi; Alcover, Andrés

    2012-01-01

    Antigen recognition induces T-cell polarization towards antigen presenting cells, generating the immunological synapse at the cell interface. Now, microtubule-mediated polarized vesicle transport is shown to be required for the organization of a signalling-competent synapse and hence T-cell activation.

  15. Autism-Associated Chromatin Regulator Brg1/SmarcA4 Is Required for Synapse Development and Myocyte Enhancer Factor 2-Mediated Synapse Remodeling

    OpenAIRE

    Zhang, Zilai; Cao, Mou; Chang, Chia-Wei; Wang, Cindy; Shi, Xuanming; Zhan, Xiaoming; Birnbaum, Shari G.; Bezprozvanny, Ilya; Huber, Kimberly M.; Wu, Jiang I.

    2015-01-01

    Synapse development requires normal neuronal activities and the precise expression of synapse-related genes. Dysregulation of synaptic genes results in neurological diseases such as autism spectrum disorders (ASD). Mutations in genes encoding chromatin-remodeling factor Brg1/SmarcA4 and its associated proteins are the genetic causes of several developmental diseases with neurological defects and autistic symptoms. Recent large-scale genomic studies predicted Brg1/SmarcA4 as one of the key nod...

  16. Temporal observations of a linear sand dune in the Simpson Desert, central Australia: Testing models for dune formation on planetary surfaces

    Science.gov (United States)

    Craddock, Robert A.; Tooth, Stephen; Zimbelman, James R.; Wilson, Sharon A.; Maxwell, Ted A.; Kling, Corbin

    2015-10-01

    Linear dunes are the most common dune form found on planetary surfaces, yet questions remain about their formation. Temporal observations of a linear dune located in the Simpson Desert of central Australia were made to monitor dune movement and to test competing hypotheses regarding linear dune formation. Our observations were collected on three separate occasions from 2006 to 2014. Rebar stakes were placed in a gridded pattern so that multiple measurements of sand thickness, GPS surveys, and photographs could be taken at the same locations over time. We observed widespread reworking of sand on and around the dune crest, with sand accumulation locally exceeding a meter between surveys. Overall, the height of the dune crest increased by several centimeters. We also observed fluctuations in the sand cover in the adjacent swales that often exceeded 2-3 cm between surveys, yet we did not observe any appreciable changes in the position of the dune's downwind terminus. Weather data indicate that the effective sand-transporting winds in the Simpson are widely unimodal. Net sediment flux (resultant drift direction) is toward the north-northwest, locally at an oblique angle to dune orientation. Collectively, our results suggest that the linear dune is actively maintained by vertical accretion. The implications from our observations are that linear dunes on other planetary surfaces could form in wind regimes that are widely unimodal, even where the resultant drift direction is locally oblique to dune orientation. In particular, such findings may provide support for global circulation models of Titan.

  17. Organic core-sheath nanowire artificial synapses with femtojoule energy consumption.

    Science.gov (United States)

    Xu, Wentao; Min, Sung-Yong; Hwang, Hyunsang; Lee, Tae-Woo

    2016-06-01

    Emulation of biological synapses is an important step toward construction of large-scale brain-inspired electronics. Despite remarkable progress in emulating synaptic functions, current synaptic devices still consume energy that is orders of magnitude greater than do biological synapses (~10 fJ per synaptic event). Reduction of energy consumption of artificial synapses remains a difficult challenge. We report organic nanowire (ONW) synaptic transistors (STs) that emulate the important working principles of a biological synapse. The ONWs emulate the morphology of nerve fibers. With a core-sheath-structured ONW active channel and a well-confined 300-nm channel length obtained using ONW lithography, ~1.23 fJ per synaptic event for individual ONW was attained, which rivals that of biological synapses. The ONW STs provide a significant step toward realizing low-energy-consuming artificial intelligent electronics and open new approaches to assembling soft neuromorphic systems with nanometer feature size. PMID:27386556

  18. Self-control of chaos in neural circuits with plastic electrical synapses

    Science.gov (United States)

    Zhigulin, V. P.; Rabinovich, M. I.

    2004-10-01

    Two kinds of connections are known to exist in neural circuits: electrical (also called gap junctions) and chemical. Whereas chemical synapses are known to be plastic (i. e., modifiable), but slow, electrical transmission through gap junctions is not modifiable, but is very fast. We suggest the new artificial synapse that combines the best properties of both: the fast reaction of a gap junction and the plasticity of a chemical synapse. Such a plastic electrical synapse can be used in hybrid neural circuits and for the development of neural prosthetics, i.e., implanted devices that can interact with the real nervous system. Based on the computer modelling we show that such a plastic electrical synapse regularizes chaos in the minimal neural circuit consisting of two chaotic bursting neurons.

  19. Ultrastructural analysis of neuronal synapses using state-of-the-art nano-imaging techniques

    Institute of Scientific and Technical Information of China (English)

    Changlu Tao; Chenglong Xia; Xiaobing Chen; Z. Hong Zhou; Guoqiang Bi

    2012-01-01

    Neuronal synapses are functional nodes in neural circuits.Their organization and activity define an individual's level of intelligence,emotional state and mental health.Changes in the structure and efficacy of synapses are the biological basis of learning and memory.However,investigation of the molecular architecture of synapses has been impeded by the lack of efficient techniques with sufficient resolution.Recent developments in state-of-the-art nano-imaging techniques have opened up a new window for dissecting the molecular organization of neuronal synapses with unprecedented resolution.Here,we review recent technological advances in nano-imaging techniques as well as their applications to the study of synapses,emphasizing super-resolution light microscopy and 3-dimensional electron tomography.

  20. Three-dimensional distribution of cortical synapses: a replicated point pattern-based analysis

    Directory of Open Access Journals (Sweden)

    Laura Anton-Sanchez

    2014-08-01

    Full Text Available The biggest problem when analyzing the brain is that its synaptic connections are extremely complex. Generally, the billions of neurons making up the brain exchange information through two types of highly specialized structures: chemical synapses (the vast majority and so-called gap junctions (a substrate of one class of electrical synapse. Here we are interested in exploring the three-dimensional spatial distribution of chemical synapses in the cerebral cortex. Recent research has showed that the three-dimensional spatial distribution of synapses in layer III of the neocortex can be modeled by a random sequential adsorption (RSA point process, i.e., synapses are distributed in space almost randomly, with the only constraint that they cannot overlap. In this study we hypothesize that RSA processes can also explain the distribution of synapses in all cortical layers. We also investigate whether there are differences in both the synaptic density and spatial distribution of synapses between layers. Using combined focused ion beam milling and scanning electron microscopy (FIB/SEM, we obtained three-dimensional samples from the six layers of the rat somatosensory cortex and identified and reconstructed the synaptic junctions. A total volume of tissue of approximately 4500 μm3 and around 4000 synapses from three different animals were analyzed. Different samples, layers and/or animals were aggregated and compared using RSA replicated spatial point processes. The results showed no significant differences in the synaptic distribution across the different rats used in the study. We found that RSA processes described the spatial distribution of synapses in all samples of each layer. We also found that the synaptic distribution in layers II to VI conforms to a common underlying RSA process with different densities per layer. Interestingly, the results showed that synapses in layer I had a slightly different spatial distribution from the other layers.

  1. Motor axon synapses on renshaw cells contain higher levels of aspartate than glutamate.

    Directory of Open Access Journals (Sweden)

    Dannette S Richards

    Full Text Available Motoneuron synapses on spinal cord interneurons known as Renshaw cells activate nicotinic, AMPA and NMDA receptors consistent with co-release of acetylcholine and excitatory amino acids (EAA. However, whether these synapses express vesicular glutamate transporters (VGLUTs capable of accumulating glutamate into synaptic vesicles is controversial. An alternative possibility is that these synapses release other EAAs, like aspartate, not dependent on VGLUTs. To clarify the exact EAA concentrated at motor axon synapses we performed a quantitative postembedding colloidal gold immunoelectron analysis for aspartate and glutamate on motor axon synapses (identified by immunoreactivity to the vesicular acetylcholine transporter; VAChT contacting calbindin-immunoreactive (-IR Renshaw cell dendrites. The results show that 71% to 80% of motor axon synaptic boutons on Renshaw cells contained aspartate immunolabeling two standard deviations above average neuropil labeling. Moreover, VAChT-IR synapses on Renshaw cells contained, on average, aspartate immunolabeling at 2.5 to 2.8 times above the average neuropil level. In contrast, glutamate enrichment was lower; 21% to 44% of VAChT-IR synapses showed glutamate-IR two standard deviations above average neuropil labeling and average glutamate immunogold density was 1.7 to 2.0 times the neuropil level. The results were not influenced by antibody affinities because glutamate antibodies detected glutamate-enriched brain homogenates more efficiently than aspartate antibodies detecting aspartate-enriched brain homogenates. Furthermore, synaptic boutons with ultrastructural features of Type I excitatory synapses were always labeled by glutamate antibodies at higher density than motor axon synapses. We conclude that motor axon synapses co-express aspartate and glutamate, but aspartate is concentrated at higher levels than glutamate.

  2. Brain-derived neurotrophic factor in arterial baroreceptor pathways: implications for activity-dependent plasticity at baroafferent synapses.

    Science.gov (United States)

    Martin, Jessica L; Jenkins, Victoria K; Hsieh, Hui-ya; Balkowiec, Agnieszka

    2009-01-01

    Functional characteristics of the arterial baroreceptor reflex change throughout ontogenesis, including perinatal adjustments of the reflex gain and adult resetting during hypertension. However, the cellular mechanisms that underlie these functional changes are not completely understood. Here, we provide evidence that brain-derived neurotrophic factor (BDNF), a neurotrophin with a well-established role in activity-dependent neuronal plasticity, is abundantly expressed in vivo by a large subset of developing and adult rat baroreceptor afferents. Immunoreactivity to BDNF is present in the cell bodies of baroafferent neurons in the nodose ganglion, their central projections in the solitary tract, and terminal-like structures in the lower brainstem nucleus tractus solitarius. Using ELISA in situ combined with electrical field stimulation, we show that native BDNF is released from cultured newborn nodose ganglion neurons in response to patterns that mimic the in vivo activity of baroreceptor afferents. In particular, high-frequency bursting patterns of baroreceptor firing, which are known to evoke plastic changes at baroreceptor synapses, are significantly more effective at releasing BDNF than tonic patterns of the same average frequency. Together, our study indicates that BDNF expressed by first-order baroreceptor neurons is a likely mediator of both developmental and post-developmental modifications at first-order synapses in arterial baroreceptor pathways. PMID:19054281

  3. The Jurassic of Denmark and Greenland: Volgian–Ryazanian ‘hot shales’ of the Bo Member (Farsund Formation) in the Danish Central Graben, North Sea: stratigraphy, facies and geochemistry

    OpenAIRE

    Dybkjær, Karen; Bojesen-Koefoed, Jørgen A.; Ineson, Jon I.; Nielsen, Lars Henrik

    2003-01-01

    Upper Jurassic – lowermost Cretaceous marine mudstones represent the most significant source of hydrocarbons in the Central and Northern North Sea. Of particular importance in the Danish sector of the Central Graben is a succession of radioactive ‘hot shales’ referred to the Bo Member, in the upper levels of the Farsund Formation (Kimmeridge Clay Formation equivalent). This mudstone-dominated succession is typically 15–30 m thick and has a total organic carbon (TOC) content of 3–8%, though lo...

  4. REE Provenance and U-Th Distribution on Poly-Mineralized Lithofacies, Um Bogma Formation, Allouga environs, West Central Sinai, Egypt

    International Nuclear Information System (INIS)

    The Allouga environs, West Central Sinai, are bounded by lat. 28 degree 58/ - 29 degree 03/ N and long. 33 degree 21/ and 33 degree 26/ E, covering about 100 km2. The environs are covered by late Proterozoic basement rocks overlain non conformably by Paleozoic rock succession. The Paleozoic succession attains about 450 m, comprising seven stratigraphic formations. The Um Bogma Formation, Also referred to as the middle carbonate series, attains 61 m thickness and hosts most of the polymetallic mineralization associated with Paleozoic rocks. It was deposited in shallow, warm, well agitated and oxidized transgressed marine environment. Owing to its importance, it is classified into three members: a) lower members comprising siltstone, clay stone and sandy dolomite; b) middle member comprising marly dolostone and c) upper member comprising sandy dolostone, clay stone and siltstone. The REE and trace elements investigations of the shale/siltstone/clay stone lithofacies (Um Bogma Formation), indicate that it mainly comprises graywacke provenance with small amount of litharenites. Also, the data indicates the derivation of the terrigenous material from granite-gneiss and siliceous sources characteristics of sedimentary basins developed near or around active continental margin. The Cu- mineralization occurs in all members of Umm Bog ma Formation as disseminations and encrustation of green and blue colored Cu-minerals dominated by highly oxidized minerals such as silicates, carbonates, phosphates, sulphates and chlorides. This mineral assemblage reflects the wide range of ph conditions of the mineralizing fluids. The U-Th distribution in the shale/siltstone/clay stone lithofaciesis as follows: The marly shales have U content average (261 ppm) and Th content average (7.7 ppm), black and variegated shales have U content average (56.2 ppm) and Th content average (20 ppm), The ferrgenous siltstone have U content average (38 ppm) and Th content average (17.8 ppm), the black

  5. Spin switches for compact implementation of neuron and synapse

    Energy Technology Data Exchange (ETDEWEB)

    Quang Diep, Vinh, E-mail: vdiep@purdue.edu; Sutton, Brian; Datta, Supriyo [School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907 (United States); Behin-Aein, Behtash [GLOBALFOUNDRIES, Inc., Sunnyvale, California 94085 (United States)

    2014-06-02

    Nanomagnets driven by spin currents provide a natural implementation for a neuron and a synapse: currents allow convenient summation of multiple inputs, while the magnet provides the threshold function. The objective of this paper is to explore the possibility of a hardware neural network implementation using a spin switch (SS) as its basic building block. SS is a recently proposed device based on established technology with a transistor-like gain and input-output isolation. This allows neural networks to be constructed with purely passive interconnections without intervening clocks or amplifiers. The weights for the neural network are conveniently adjusted through analog voltages that can be stored in a non-volatile manner in an underlying CMOS layer using a floating gate low dropout voltage regulator. The operation of a multi-layer SS neural network designed for character recognition is demonstrated using a standard simulation model based on coupled Landau-Lifshitz-Gilbert equations, one for each magnet in the network.

  6. Spin switches for compact implementation of neuron and synapse

    International Nuclear Information System (INIS)

    Nanomagnets driven by spin currents provide a natural implementation for a neuron and a synapse: currents allow convenient summation of multiple inputs, while the magnet provides the threshold function. The objective of this paper is to explore the possibility of a hardware neural network implementation using a spin switch (SS) as its basic building block. SS is a recently proposed device based on established technology with a transistor-like gain and input-output isolation. This allows neural networks to be constructed with purely passive interconnections without intervening clocks or amplifiers. The weights for the neural network are conveniently adjusted through analog voltages that can be stored in a non-volatile manner in an underlying CMOS layer using a floating gate low dropout voltage regulator. The operation of a multi-layer SS neural network designed for character recognition is demonstrated using a standard simulation model based on coupled Landau-Lifshitz-Gilbert equations, one for each magnet in the network

  7. Independent origins of neurons and synapses: insights from ctenophores.

    Science.gov (United States)

    Moroz, Leonid L; Kohn, Andrea B

    2016-01-01

    There is more than one way to develop neuronal complexity, and animals frequently use different molecular toolkits to achieve similar functional outcomes. Genomics and metabolomics data from basal metazoans suggest that neural signalling evolved independently in ctenophores and cnidarians/bilaterians. This polygenesis hypothesis explains the lack of pan-neuronal and pan-synaptic genes across metazoans, including remarkable examples of lineage-specific evolution of neurogenic and signalling molecules as well as synaptic components. Sponges and placozoans are two lineages without neural and muscular systems. The possibility of secondary loss of neurons and synapses in the Porifera/Placozoa clades is a highly unlikely and less parsimonious scenario. We conclude that acetylcholine, serotonin, histamine, dopamine, octopamine and gamma-aminobutyric acid (GABA) were recruited as transmitters in the neural systems in cnidarian and bilaterian lineages. By contrast, ctenophores independently evolved numerous secretory peptides, indicating extensive adaptations within the clade and suggesting that early neural systems might be peptidergic. Comparative analysis of glutamate signalling also shows numerous lineage-specific innovations, implying the extensive use of this ubiquitous metabolite and intercellular messenger over the course of convergent and parallel evolution of mechanisms of intercellular communication. Therefore: (i) we view a neuron as a functional character but not a genetic character, and (ii) any given neural system cannot be considered as a single character because it is composed of different cell lineages with distinct genealogies, origins and evolutionary histories. Thus, when reconstructing the evolution of nervous systems, we ought to start with the identification of particular cell lineages by establishing distant neural homologies or examples of convergent evolution. In a corollary of the hypothesis of the independent origins of neurons, our analyses

  8. [Central manifestations of dystrophinopathies].

    Science.gov (United States)

    Cuisset, J-M; Rivier, F

    2015-12-01

    The dystrophin gene involved in Duchenne and Becker muscular dystrophy is expressed in three main tissues resulting in clinical manifestations: skeletal muscle, heart and central nervous system. The 6 different existing dystrophins in the brain may play a role in the maturation and plasticity of neuronal synapses in particular by their functions in clustering and stabilization of different receptors at the post synaptic membrane. The possibility of an intellectual deficiency in Duchenne muscular dystrophy is known from the original description by Duchenne himself. Current data are in line with a constant cognitive impairment with a Gaussian curve shifted intellectual quotient (IQ) at -1 standard deviation from the standard population with an average IQ around 80. Clinical manifestations suggestive of a central nervous system involvement can affect all dystrophinopathies, including isolated central presentations without myopathic sign. The phenotypic spectrum appears broader and more subtle than non specific intellectual deficiency. The isolated or shared involvement of specific cognitive functions is possible (memory functions, executive functions, attention) with or without intellectual deficiency. Autism spectrum disorders are also among the encountered events. In clinical practice, it seems worth to ask for a measurement of serum creatine kinase (CK) in these different situations, keeping in mind that pure forms of central dystrophinopathies with a normal CK level have been recently reported. PMID:26773588

  9. Contesting State Forests in Post-Suharto Indonesia: Authority Formation, State Forest Land Dispute, and Power in Upland Central Java, Indonesia

    Directory of Open Access Journals (Sweden)

    Anu Lounela

    2012-01-01

    Full Text Available This article explores the ongoing conflict over state forest land between the local population and the State Forestry Corporation (SFC in a village in upland Central Java with regard to authority formation. It looks at how different agents draw on different sources of authority in the course of the conflict and its negotiations. The principal questions are to what kind of sources of authority villagers refer to and how the formation of authority informs the relations between the state and society in the land dispute. The article is based on 11 months of ethnographic fieldwork and focuses on the central figure of Pak Wahid who took a leading position in the forest land dispute and in mobilising peasants in the village. The article argues that in post-Suharto Java, leadership in the struggle for state forest land at the village level is embedded in the interaction of Javanese ideas of power and authority as well as administrative authority. Due to political and institutional reforms, new sources of authority could be invoked while there are no real changes in the power relations within the village or between the SFC and the villagers. ----- Dieser Artikel untersucht den anhaltenden Konflikt um staatliche Waldflächen zwischen der lokalen Bevölkerung und der State Forestry Corporation (SFC in einem Dorf im Hochland von Zentral- Java in Bezug auf die Entwicklung von Autorität. Es wird untersucht, wie sich unterschiedliche AkteurInnen im Rahmen des Konflikts und dessen Verhandlung auf unterschiedliche Bezugsquellen von Autorität beziehen. Die zentralen Forschungsfragen in diesem Zusammenhang sind, auf welche Bezugsquellen von Autorität sich DorfbewohnerInnen beziehen und wie die Entwicklung von Autorität die Beziehungen zwischen Staat und Gesellschaft im Rahmen des Landkonflikts beeinflusst. Der Artikel basiert auf einer 11-monatigen ethnografischen Feldforschung und fokussiert auf die Person von Pak Wahid, der eine Schlüsselrolle im Konflikt

  10. Loss of Ca(2+)-permeable AMPA receptors in synapses of tonic firing substantia gelatinosa neurons in the chronic constriction injury model of neuropathic pain.

    Science.gov (United States)

    Chen, Yishen; Derkach, Victor A; Smith, Peter A

    2016-05-01

    Synapses transmitting nociceptive information in the spinal dorsal horn undergo enduring changes following peripheral nerve injury. Indeed, such injury alters the expression of the GluA2 subunit of glutamatergic AMPA receptors (AMPARs) in the substantia gelatinosa and this predicts altered channel conductance and calcium permeability, leading to an altered function of excitatory synapses. We therefore investigated the functional properties of synaptic AMPA receptors in rat substantia gelatinosa neurons following 10-20d chronic constriction injury (CCI) of the sciatic nerve; a model of neuropathic pain. We measured their single-channel conductance and sensitivity to a blocker of calcium permeable AMPA receptors (CP-AMPARs), IEM1460 (50μM). In putative inhibitory, tonic firing neurons, CCI reduced the average single-channel conductance of synaptic AMPAR from 14.4±3.5pS (n=12) to 9.2±1.0pS (n=10, pnerve injury acting at synapses of inhibitory neurons to reduce their drive and therefore inhibitory tone in the spinal cord, therefore contributing to the central sensitization associated with neuropathic pain. PMID:26948545

  11. Similar GABAA receptor subunit composition in somatic and axon initial segment synapses of hippocampal pyramidal cells.

    Science.gov (United States)

    Kerti-Szigeti, Katalin; Nusser, Zoltan

    2016-01-01

    Hippocampal pyramidal cells (PCs) express many GABAAR subunit types and receive GABAergic inputs from distinct interneurons. Previous experiments revealed input-specific differences in α1 and α2 subunit densities in perisomatic synapses, suggesting distinct IPSC decay kinetics. However, IPSC decays evoked by axo-axonic, parvalbumin- or cholecystokinin-expressing basket cells were found to be similar. Using replica immunogold labeling, here we show that all CA1 PC somatic and AIS synapses contain the α1, α2, β1, β2, β3 and γ2 subunits. In CA3 PCs, 90% of the perisomatic synapses are immunopositive for the α1 subunit and all synapses are positive for the remaining five subunits. Somatic synapses form unimodal distributions based on their immunoreactivity for these subunits. The α2 subunit densities in somatic synapses facing Cav2.1 (i.e. parvalbumin) or Cav2.2 (cholecystokinin) positive presynaptic active zones are comparable. We conclude that perisomatic synapses made by three distinct interneuron types have similar GABAA receptor subunit content. PMID:27537197

  12. Opposing mechanisms mediate morphine- and cocaine-induced generation of silent synapses.

    Science.gov (United States)

    Graziane, Nicholas M; Sun, Shichao; Wright, William J; Jang, Daniel; Liu, Zheng; Huang, Yanhua H; Nestler, Eric J; Wang, Yu Tian; Schlüter, Oliver M; Dong, Yan

    2016-07-01

    Exposures to cocaine and morphine produce similar adaptations in nucleus accumbens (NAc)-based behaviors, yet produce very different adaptations at NAc excitatory synapses. In an effort to explain this paradox, we found that both drugs induced NMDA receptor-containing, AMPA receptor-silent excitatory synapses, albeit in distinct cell types through opposing cellular mechanisms. Cocaine selectively induced silent synapses in D1-type neurons, likely via a synaptogenesis process, whereas morphine induced silent synapses in D2-type neurons via internalization of AMPA receptors from pre-existing synapses. After drug withdrawal, cocaine-generated silent synapses became 'unsilenced' by recruiting AMPA receptors to strengthen excitatory inputs to D1-type neurons, whereas morphine-generated silent synapses were likely eliminated to weaken excitatory inputs to D2-type neurons. Thus, these cell type-specific, opposing mechanisms produced the same net shift of the balance between excitatory inputs to D1- and D2-type NAc neurons, which may underlie certain common alterations in NAc-based behaviors induced by both classes of drugs. PMID:27239940

  13. Braid-Delta Deposits from a Broad Shallow-Marine Setting:the Middle Member of the Kalpingtag Formation in the Central Tarim Basin

    Institute of Scientific and Technical Information of China (English)

    JIANG Yiming; ZHANG Jinliang

    2008-01-01

    During the early Silurian, a transgressive and vast shallow sea with flat sea-floor covered the central Tarim Basin (the Tazhong area). The depositional environment of the middle member of the Kalpingtag Formation is controversial. In order to provide a basis for the prediction of reservoir sand, the sedimentary facies are recognized according to abundant core observations and de-scriptions combined with well-log analysis, isograms, seismic interpretations and regional sedimentary background. The middle member of the Kalpingtag Formation, which shows a retrograding sequence, is interpreted as braid-delta deposits influenced by mi-nor tidal reworking. The sources of clasts are from the southern uplift. The subaqueous braid-delta deposits in the study area have some characteristics quite different from the common deltas that generally deposit in marginal seas. Four facies grouped to a delta front association are recognized, ranging from distributary-channel (Facies A), front bar (Facies B), sand sheet (Facies C) and inter-distributary bay (Facies D). The distributary channels construct the sandbody framework of the delta front. Front bar deposits, which are fine-grained with low depositionai dips, display a near-continuous sand strip around the entire periphery of the delta. Sand sheet deposits are mainly found in front of Facies B, gradationally contacting with the prodelta. The interdistributary bay is essentially the uppermost unit capping the channel sequence and generally made up of laminated and massive mudstones. The delta front deposits display extensive sheet-like bodies contrasting with the characteristic wedge shapes of common subaqueous delta bodies. The bi-modal cross-stratification and mud drapes in the fine-to medium-grained sandstone in the distal area are inferred to reflect high-energy tidal processes.

  14. Effect of synapse dilution on the memory retrieval in structured attractor neural networks

    Science.gov (United States)

    Brunel, N.

    1993-08-01

    We investigate a simple model of structured attractor neural network (ANN). In this network a module codes for the category of the stored information, while another group of neurons codes for the remaining information. The probability distribution of stabilities of the patterns and the prototypes of the categories are calculated, for two different synaptic structures. The stability of the prototypes is shown to increase when the fraction of neurons coding for the category goes down. Then the effect of synapse destruction on the retrieval is studied in two opposite situations : first analytically in sparsely connected networks, then numerically in completely connected ones. In both cases the behaviour of the structured network and that of the usual homogeneous networks are compared. When lesions increase, two transitions are shown to appear in the behaviour of the structured network when one of the patterns is presented to the network. After the first transition the network recognizes the category of the pattern but not the individual pattern. After the second transition the network recognizes nothing. These effects are similar to syndromes caused by lesions in the central visual system, namely prosopagnosia and agnosia. In both types of networks (structured or homogeneous) the stability of the prototype is greater than the stability of individual patterns, however the first transition, for completely connected networks, occurs only when the network is structured.

  15. A virtual lymph node model to dissect the requirements for T-cell activation by synapses and kinapses

    Science.gov (United States)

    Moreau, Hélène D; Bogle, Gib; Bousso, Philippe

    2016-01-01

    The initiation of T-cell responses in lymph nodes requires T cells to integrate signals delivered by dendritic cells (DCs) during long-lasting contacts (synapses) or more transient interactions (kinapses). However, it remains extremely challenging to understand how a specific sequence of contacts established by T cells ultimately dictates T-cell fate. Here, we have coupled a computational model of T-cell migration and interactions with DCs with a real-time, flow cytometry-like representation of T-cell activation. In this model, low-affinity peptides trigger T-cell proliferation through kinapses but we show that this process is only effective under conditions of high DC densities and prolonged antigen availability. By contrast, high-affinity peptides favor synapse formation and a vigorous proliferation under a wide range of antigen presentation conditions. In line with the predictions, decreasing the DC density in vivo selectively abolished proliferation induced by the low-affinity peptide. Finally, our results suggest that T cells possess a biochemical memory of previous stimulations of at least 1–2 days. We propose that the stability of T-cell–DC interactions, apart from their signaling potency, profoundly influences the robustness of T-cell activation. By offering the ability to control parameters that are difficult to manipulate experimentally, the virtual lymph node model provides new possibilities to tackle the fundamental mechanisms that regulate T-cell responses elicited by infections or vaccines. PMID:27089942

  16. cAMP-Inhibits Cytoplasmic Phospholipase A2 and Protects Neurons against Amyloid-β-Induced Synapse Damage

    OpenAIRE

    Clive Bate; Alun Williams

    2015-01-01

    A key event in Alzheimer’s disease (AD) is the production of amyloid-β (Aβ) peptides and the loss of synapses. In cultured neurons Aβ triggered synapse damage as measured by the loss of synaptic proteins. α-synuclein (αSN), aggregates of which accumulate in Parkinson’s disease, also caused synapse damage. Synapse damage was associated with activation of cytoplasmic phospholipase A2 (cPLA2), an enzyme that regulates synapse function and structure, and the production of prostaglandin (PG) E2. I...

  17. The Starburst in the Abell 1835 Cluster Central Galaxy: A Case Study of Galaxy Formation Regulated by an Outburst from a Supermassive Black Hole

    CERN Document Server

    McNamara, B R; Carilli, C L; Nulsen, P E J; Rafferty, D A; Ryan, R; Sharma, M; Steiner, J; Wise, M W

    2006-01-01

    We present an optical, X-ray, and radio analysis of the starburst in the Abell 1835 cluster's central cD galaxy. The dense gas surrounding the galaxy is radiating X-rays with a luminosity of ~1E45 erg/s consistent with a cooling rate of ~1000-2000 solar masses per year. However, new Chandra and XMM-Newton observations find less than 200 solar masses per year of gas cooling below ~2 keV, a level that is consistent with the cD's current star formation rate of 100-180 solar masses per year. One or more heating agents (feedback) must then be replenishing the remaining radiative losses. The heat fluxes from supernova explosions and thermal conduction alone are unable to do so. However, a pair of X-ray cavities from an AGN outburst has deposited ~1.7E60 erg into the surrounding gas over the past 40 Myr. The corresponding jet power 1.4E45 erg/sec is enough to offset most of the radiative losses from the cooling gas. The jet power exceeds the radio synchrotron power by ~4000 times, making this one of the most radiati...

  18. Critical avalanches and subsampling in map-based neural networks coupled with noisy synapses.

    Science.gov (United States)

    Girardi-Schappo, M; Kinouchi, O; Tragtenberg, M H R

    2013-08-01

    Many different kinds of noise are experimentally observed in the brain. Among them, we study a model of noisy chemical synapse and obtain critical avalanches for the spatiotemporal activity of the neural network. Neurons and synapses are modeled by dynamical maps. We discuss the relevant neuronal and synaptic properties to achieve the critical state. We verify that networks of functionally excitable neurons with fast synapses present power-law avalanches, due to rebound spiking dynamics. We also discuss the measuring of neuronal avalanches by subsampling our data, shedding light on the experimental search for self-organized criticality in neural networks. PMID:24032969

  19. [Changes in the ultrastructure of neuromuscular synapses in rats under the effects of space flight factors].

    Science.gov (United States)

    Pozdniakov, O M; Babakova, L L; Demorzhi, M S; Il'ina-Kakueva, E I

    1988-06-01

    The influence of a 7-day space flight on board the biosputnik "Kosmos-1669" on the neuro-muscular synapses (NMS) of soleus, gastrocnemius and diaphragm muscles distinct in their functions has been studied. The synapse restructuring on the basis of destructive- regenerative process has been discovered. It is manifested to a great extent in the soleus muscle, to a lesser extent in the gastrocnemius muscle and the least of all in the diaphragm muscle. The changes observed in synapses may be caused by the attenuation of their function in weightlessness. PMID:3390600

  20. Carbonate Sequence Stratigraphy of a Back-Arc Basin: A Case Study of the Qom Formation in the Kashan Area, Central Iran

    Institute of Scientific and Technical Information of China (English)

    XU Guoqiang; ZHANG Shaonan; LI Zhongdong; SONG Lailiang; LIU Huimin

    2007-01-01

    The Qom Formation comprises Oligo-Miocene deposits from a marine succession distributed in the Central Basin of Iran. It is composed of five members designated as A-F. Little previous work exists on the sequence stratigraphy. Based on an integrated study of sequence stratigraphy with outcrop data, wells and regional seismic profiles, the Qom Formation is interpreted as a carbonate succession deposited in a mid-Tertiary back-arc basin. There are two second-order sequences (designated as SS1 and SS2) and five third-order sequences (designated as S1-S5). Five distinct systems tracts including transgressive, highstand, forced regressive, slope margin and lowstand have been recognized. The relationship between the sequences and lithologic sub-units has been collated and defined (S1 to S5 individually corresponding to A-C1, C2-C4, D-E, the lower and upper portions of F); a relative sea level change curve and the sequence stratigraphic framework have been established and described in detail. The coincidence of relative sea level change between that of the determined back-arc basin and the world indicates that the sedimentary cycles of the Qom Formation are mainly controlled by eustatic cycles. The variable combination of the systems tracts and special tectonic-depositional setting causally underpin multiple sequence stratigraphic framework styles seen in the carbonates of the back-arc basin revealing: (1) a continental margin basin that developed some form of barrier, characterized by the development of multiple cycles of carbonate-evaporites; (2) a flat carbonate ramp, which occurred on the southern shelf formed by the lack of clastic supply from nearby magmatic islands plus mixed siliciclastics and carbonates that occurred on the northern shelf due to a sufficient clastics supply from the land; and (3) a forced regressive stratigraphic stacking pattern that occured on the southern shelf and in basin lows due to the uplifting of the southern shelf. Thick and widespread

  1. Depositional Characteristics of Lake-Floor Fan of Cretaceous Lower Yaojia Formation in Western Part of Central Depression Region,Songliao Basin

    Institute of Scientific and Technical Information of China (English)

    Xin Renchen; Li Guifan; Feng Zhiqiang; Liang Jiangping; Lin Changsong

    2009-01-01

    Based on the integrated subsurface data,including those of over 600 m drilled cores,more than 30 drilled wells and 600 km2 three-dimensional (3D) seismic-reflection data of the study area, the characteristics of the lake-floor fan of lower Yaojia(姚家) Formation have been clarified.An evident lacustrine slope break and a steep slope belt developed in the west of Songliao(松辽)basin during depositional period of Qingshankou(青山口)-Yaojia formations(K2).The slope gradient was about 15 m/km.During the depositional period of lower Yaojia Formation,the lake shrank and the shore line of the western Songliao basin shifted to the lacustrine slope-break.The wedge-shaped sediment body,which is interpreted as the lowstand system tract of SQy1 (LSTy1),developed in the area below the slope-break.The LSTyl is pinched out in the west of the study area.As to the thickness of LSTyl,ft is thicker in the east with SO m in its thickness than in the west The LSTyl,rich in sandstone,can be divided into lower part LSTylL and upper part LSTy1u based on two onlap seismic reflection phases,and core and logging data clearly.The various sediments' gravity flow deposits developed and the complex of lake-floor fan formed in the LSTyl under the slope-break in the western part of the central depression region.The lake-floor fan consists of various sediments' gravity flow deposits,including: (1) turbidity deposits with characteristics of Bouma sequences; (2) sand-bearing muddy debrite dominated by mud and mixed by sand; (3) mud-bearing sandy debrites characterized by dominated sand and mixed by mud; (4) sandy debris laminar flow deposits with massive or inclined bedding,and (5) sandy slump deposits developed as deforma tional sedimentary structure.During the lower lake-level period (LSTy1L),the western clinoform region was erosion or sediment pass-by area; the terrigenous clastic was directly transported to deep-water area,converted to channelized sandy debris flow,and combined with slump

  2. FIB/SEM technology and high-throughput 3D reconstruction of dendritic spines and synapses in GFP-labeled adult-generated neurons

    Directory of Open Access Journals (Sweden)

    Carles Bosch

    2015-05-01

    Full Text Available The fine analysis of synaptic contacts is usually performed using transmission electron microscopy (TEM and its combination with neuronal labeling techniques. However, the complex 3D architecture of neuronal samples calls for their reconstruction from serial sections. Here we show that focused ion beam/scanning electron microscopy (FIB/SEM allows efficient, complete, and automatic 3D reconstruction of identified dendrites, including their spines and synapses, from GFP/DAB-labeled neurons, with a resolution comparable to that of TEM. We applied this technology to analyze the synaptogenesis of labeled adult-generated granule cells (GCs in mice. 3D reconstruction of spines in GCs aged 3–4 and 8–9 weeks revealed two different stages of spine development and unexpected features of synapse formation, including vacant and branched spines and presynaptic terminals establishing synapses with up to 10 spines. Given the reliability, efficiency, and high resolution of FIB/SEM technology and the wide use of DAB in conventional EM, we consider FIB/SEM fundamental for the detailed characterization of identified synaptic contacts in neurons in a high-throughput manner.

  3. Growth-associated protein 43 immunoreactivity in the superficial dorsal horn of the rat spinal cord is localized in atrophic C-fiber, and not in sprouted A-fiber, central terminals after peripheral nerve injury.

    Science.gov (United States)

    Doubell, T P; Woolf, C J

    1997-09-15

    Peripheral nerve injury induces the up-regulation in dorsal root ganglion cells of growth-associated protein 43 (GAP-43) and its transport to the superficial laminae of the dorsal horn of the spinal cord, where it is located primarily in unmyelinated axons and growth-cone like structures. Peripheral nerve injury also induces the central terminals of axotomized myelinated axons to sprout and form novel synaptic contacts in lamina II of the dorsal horn. To investigate whether the sprouting of A-fiber central terminals into lamina II is the consequence of GAP-43 incorporation into their terminal membranes, we have used an ultrastructural analysis with double labelling to identify the localization of GAP-43 immunoreactivity. Transganglionic transport of wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP) was used to identify C-fiber terminals. Transganglionic transport of the B fragment of cholera toxin conjugated to horseradish peroxidase (B-HRP) was used to label A-fiber sciatic nerve central terminals in combination with GAP-43 immunocytochemistry. GAP-43 was found to colocalize only with WGA-HRP- and not with B-HRP-labelled synapses or axons. In addition, many single-labelled GAP-43 synapses were observed. Many of the WGA-HRP-labelled terminals that were characterized by degenerative changes were GAP-43 immunoreactive. Our results indicate that peripheral nerve injury induces novel synapse formation of A fibers in lamina II but that up-regulated levels of GAP-43 are present mainly in other axon projections to the superficial dorsal horn. PMID:9303528

  4. Water quality of the Ogallala Formation, central High Plains aquifer within the North Plains Groundwater Conservation District, Texas Panhandle, 2012-13

    Science.gov (United States)

    Baldys, Stanley; Haynie, Monti M.; Beussink, Amy M.

    2014-01-01

    In cooperation with the North Plains Groundwater Conservation District (NPGCD), the U.S. Geological Survey collected and analyzed water-quality samples at 30 groundwater monitor wells in the NPGCD in the Texas Panhandle. All of the wells were completed in the Ogallala Formation of the central High Plains aquifer. Samples from each well were collected during February–March 2012 and in March 2013. Depth to groundwater in feet below land surface was measured at each well before sampling to determine the water-quality sampling depths. Water-quality samples were analyzed for physical properties, major ions, nutrients, and trace metals, and 6 of the 30 samples were analyzed for pesticides. There was a strong relation between specific conductance and dissolved solids as evidenced by a coefficient of determination (R2) value of 0.98. The dissolved-solids concentration in water from five wells exceeded the secondary drinking-water standard of 500 milligrams per liter set by the U.S. Environmental Protection Agency. Water from 3 of these 5 wells was near the north central part of the NPGCD. Nitrate values exceeded the U.S. Environmental Protection Agency maximum contaminant level of 10 milligrams per liter in 2 of the 30 wells. A sodium-adsorption ratio of 23.4 was measured in the sample collected from well Da-3589 in Dallam County, with the next largest sodium-adsorption ratio measured in the sample collected from well Da-3588 (12.5), also in Dallum County. The sodium-adsorption ratios measured in all other samples were less than 10. The groundwater was generally a mixed cation-bicarbonate plus carbonate type. Twenty-three trace elements were analyzed, and no concentrations exceeded the secondary drinking-water standard or maximum contaminant level set by the U.S. Environmental Protection Agency for water supplies. In 2012, 6 of the 30 wells were sampled for commonly used pesticides. Atrazine and its degradate 2-Chloro-4-isopropylamino-6-amino-s-triazine were detected in

  5. Germinal center B cells recognize antigen through a specialized immune synapse architecture.

    Science.gov (United States)

    Nowosad, Carla R; Spillane, Katelyn M; Tolar, Pavel

    2016-07-01

    B cell activation is regulated by B cell antigen receptor (BCR) signaling and antigen internalization in immune synapses. Using large-scale imaging across B cell subsets, we found that, in contrast with naive and memory B cells, which gathered antigen toward the synapse center before internalization, germinal center (GC) B cells extracted antigen by a distinct pathway using small peripheral clusters. Both naive and GC B cell synapses required proximal BCR signaling, but GC cells signaled less through the protein kinase C-β-NF-κB pathway and produced stronger tugging forces on the BCR, thereby more stringently regulating antigen binding. Consequently, GC B cells extracted antigen with better affinity discrimination than naive B cells, suggesting that specialized biomechanical patterns in B cell synapses regulate T cell-dependent selection of high-affinity B cells in GCs. PMID:27183103

  6. The Cell Death Pathway Regulates Synapse Elimination through Cleavage of Gelsolin in Caenorhabditis elegans Neurons

    Directory of Open Access Journals (Sweden)

    Lingfeng Meng

    2015-06-01

    Full Text Available Synapse elimination occurs in development, plasticity, and disease. Although the importance of synapse elimination has been documented in many studies, the molecular mechanisms underlying this process are unclear. Here, using the development of C. elegans RME neurons as a model, we have uncovered a function for the apoptosis pathway in synapse elimination. We find that the conserved apoptotic cell death (CED pathway and axonal mitochondria are required for the elimination of transiently formed clusters of presynaptic components in RME neurons. This function of the CED pathway involves the activation of the actin-filament-severing protein, GSNL-1. Furthermore, we show that caspase CED-3 cleaves GSNL-1 at a conserved C-terminal region and that the cleaved active form of GSNL-1 promotes its actin-severing ability. Our data suggest that activation of the CED pathway contributes to selective elimination of synapses through disassembly of the actin filament network.

  7. alpha-Bungarotoxin labeling and acetylcholinesterase localization at the Mauthner fiber giant synapse in the hatchetfish

    International Nuclear Information System (INIS)

    Autoradiographic and histochemical techniques have been used to characterize further the pharmacology of transmission at the Mauthner fiber giant synapse of the South American hatchetfish. [125I]alpha-Bungarotoxin was applied to hatchetfish medullae and a standard autoradiographic procedure was carried out on 3- to 4-microns sections of glutaraldehyde-fixed tissue. All Mauthner fiber giant synapses, as identified by light microscopic criteria, had closely associated silver grains. Labeling was blocked by d-tubocurarine. Glutaraldehyde-fixed slices of hatchetfish medulla were stained histochemically for acetylcholinesterase; all giant synapses that could be identified in the light microscope showed heavy deposits of reaction product. Staining was blocked by diisopropyl-fluorophosphate, which inhibits both pseudocholinesterase and acetylcholinesterase, but was not blocked by tetraisopropylpyrophosphoramide, a specific pseudocholinesterase inhibitor. This evidence strongly supports the suggestion that the Mauthner fiber giant synapse is nicotinic cholinergic

  8. Alpha-Bungarotoxin labeling and acetylcholinesterase localization at the Mauthner fiber giant synapse in the hatchetfish

    International Nuclear Information System (INIS)

    Autoradiographic and histochemical techniques have been used to characterize further the pharmacology of transmission at the Mauthner fiber giant synapse of the South American hatchetfish. [125I]alpha-Bungarotoxin was applied to hatchetfish medullae and a standard autoradiographic procedure was carried out on 3- to 4-microns sections of glutaraldehyde-fixed tissue. All Mauthner fiber giant synapses, as identified by light microscopic criteria, had closely associated silver grains. Labeling was blocked by d-tubocurarine. Glutaraldehyde-fixed slices of hatchetfish medulla were stained histochemically for acetylcholinesterase; all giant synapses that could be identified in the light microscope showed heavy deposits of reaction product. Staining was blocked by diisopropyl-fluorophosphate, which inhibits both pseudocholinesterase and acetylcholinesterase, but was not blocked by tetraisopropylpyrophosphoramide, a specific pseudocholinesterase inhibitor. This evidence strongly supports the suggestion that the Mauthner fiber giant synapse is nicotinic cholinergic

  9. Bottleneck of using single memristor as a synapse and its solution

    CERN Document Server

    Merrikh-Bayat, Farnood

    2010-01-01

    Physical realization of the first memristor by researchers at Hewlett Packard (HP) labs attracts so much interest in this newly found circuit element which has so many applications specially in a field of neuromorphic systems. Now, it is well known that one of the main applications of memristor is for the hardware implementation of synapses because of their capability in dense fabrication and acting as a perfect analog memory. However, synapses in biological systems have this property that by progressing in the learning process, variation rate of the synapses weights should decrease which is not the case in the currently suggested memristor-based structures of neuromorphic systems. In this paper, we show that using two dissimilar memristors connected in series as a synapse perform better than the single memristor.

  10. Investigation and Manipulation of Different Analog Behaviors of Memristor as Electronic Synapse for Neuromorphic Applications

    Science.gov (United States)

    Wang, Changhong; He, Wei; Tong, Yi; Zhao, Rong

    2016-03-01

    Low-power and high-density electronic synapse is an important building block of brain-inspired systems. The recent advancement in memristor has provided an opportunity to advance electronic synapse design. However, a guideline on designing and manipulating the memristor’s analog behaviors is still lacking. In this work, we reveal that compliance current (Icomp) of electroforming process played an important role in realizing a stable analog behavior, which is attributed to the generation of conical-type conductive filament. A proper Icomp could result in a large conductance window, good stability, and low voltage analog switching. We further reveal that different pulse conditions can lead to three analog behaviors, where the conductance changes in monotonic increase, plateau after initial jump, and impulse-like shape, respectively. These behaviors could benefit the design of electronic synapse with enriched learning capabilities. This work will provide a useful guideline for designing and manipulating memristor as electronic synapses for brain-inspired systems.

  11. The Role of the Tripartite Glutamatergic Synapse in the Pathophysiology of Alzheimer’s Disease

    OpenAIRE

    Rudy, Carolyn C.; Hunsberger, Holly C.; Weitzner, Daniel S.; Reed, Miranda N.

    2015-01-01

    Alzheimer’s disease (AD) is the most common form of dementia in individuals over 65 years of age and is characterized by accumulation of beta-amyloid (Aβ) and tau. Both Aβ and tau alter synaptic plasticity, leading to synapse loss, neural network dysfunction, and eventually neuron loss. However, the exact mechanism by which these proteins cause neurodegeneration is still not clear. A growing body of evidence suggests perturbations in the glutamatergic tripartite synapse, comprised of a presyn...

  12. Reduced gap junctional coupling leads to uncorrelated motor neuron firing and precocious neuromuscular synapse elimination

    OpenAIRE

    Personius, Kirkwood E.; Chang, Qiang; Mentis, George Z.; O'Donovan, Michael J.; Rita J Balice-Gordon

    2007-01-01

    During late embryonic and early postnatal life, neuromuscular junctions undergo synapse elimination that is modulated by patterns of motor neuron activity. Here, we test the hypothesis that reduced spinal neuron gap junctional coupling decreases temporally correlated motor neuron activity that, in turn, modulates neuromuscular synapse elimination, by using mutant mice lacking connexin 40 (Cx40), a developmentally regulated gap junction protein expressed in motor and other spinal neurons. In C...

  13. Spin-Based Neuron Model with Domain Wall Magnets as Synapse

    OpenAIRE

    Sharad, Mrigank; Augustine, Charles; Panagopoulos, Georgios; Roy, Kaushik

    2012-01-01

    We present artificial neural network design using spin devices that achieves ultra low voltage operation, low power consumption, high speed, and high integration density. We employ spin torque switched nano-magnets for modelling neuron and domain wall magnets for compact, programmable synapses. The spin based neuron-synapse units operate locally at ultra low supply voltage of 30mV resulting in low computation power. CMOS based inter-neuron communication is employed to realize network-level fu...

  14. Essential role of postsynaptic NMDA receptors in developmental refinement of excitatory synapses

    OpenAIRE

    Zhang, Zhong-wei; Peterson, Matthew; Liu, Hong

    2012-01-01

    Neurons in the brains of newborns are usually connected with many other neurons through weak synapses. This early pattern of connectivity is refined through pruning of many immature connections and strengthening of the remaining ones. NMDA receptors (NMDARs) are essential for the development of excitatory synapses, but their role in synaptic refinement is controversial. Although chronic application of blockers or global knockdown of NMDARs disrupts developmental refinement in many parts of th...

  15. Super resolution imaging of genetically labeled synapses in drosophila brain tissue

    OpenAIRE

    Spühler, Isabelle A.; Conley, Gaurasundar M.; Scheffold, Frank; Sprecher, Simon G.

    2016-01-01

    Understanding synaptic connectivity and plasticity within brain circuits and their relationship to learning and behavior is a fundamental quest in neuroscience. Visualizing the fine details of synapses using optical microscopy remains however a major technical challenge. Super resolution microscopy opens the possibility to reveal molecular features of synapses beyond the diffraction limit. With direct stochastic optical reconstruction microscopy, dSTORM, we image synaptic proteins in the...

  16. Downstream Effect of Ramping Neuronal Activity through Synapses with Short-Term Plasticity.

    Science.gov (United States)

    Wei, Wei; Wang, Xiao-Jing

    2016-04-01

    Ramping neuronal activity refers to spiking activity with a rate that increases quasi-linearly over time. It has been observed in multiple cortical areas and is correlated with evidence accumulation processes or timing. In this work, we investigated the downstream effect of ramping neuronal activity through synapses that display short-term facilitation (STF) or depression (STD). We obtained an analytical result for a synapse driven by deterministic linear ramping input that exhibits pure STF or STD and numerically investigated the general case when a synapse displays both STF and STD. We show that the analytical deterministic solution gives an accurate description of the averaging synaptic activation of many inputs converging onto a postsynaptic neuron, even when fluctuations in the ramping input are strong. Activation of a synapse with STF shows an initial cubical increase with time, followed by a linear ramping similar to a synapse without STF. Activation of a synapse with STD grows in time to a maximum before falling and reaching a plateau, and this steady state is independent of the slope of the ramping input. For a synapse displaying both STF and STD, an increase in the depression time constant from a value much smaller than the facilitation time constant [Formula: see text] to a value much larger than [Formula: see text] leads to a transition from facilitation dominance to depression dominance. Therefore, our work provides insights into the impact of ramping neuronal activity on downstream neurons through synapses that display short-term plasticity. In a perceptual decision-making process, ramping activity has been observed in the parietal and prefrontal cortices, with a slope that decreases with task difficulty. Our work predicts that neurons downstream from such a decision circuit could instead display a firing plateau independent of the task difficulty, provided that the synaptic connection is endowed with short-term depression. PMID:26890350

  17. Calcium-dependent synaptic vesicle trafficking underlies indefatigable release at the hair cell afferent fiber synapse

    OpenAIRE

    Schnee, M.E.; Santos-Sacchi, J; Castellano-Muñoz, M.; Kong, J-H.; Ricci, A.J.

    2011-01-01

    Sensory hair cell ribbon synapses respond to graded stimulation in a linear, indefatigable manner, requiring that vesicle trafficking to synapses is rapid and non rate limiting. Real time monitoring of vesicle fusion identified two release components. The first was saturable with both release rate and magnitude varying linearly with Ca2+, however the magnitude was too small to account for sustained afferent firing rates. A second superlinear release component required recruitment, in a Ca2+-d...

  18. On the Relation between Bursts and Dynamic Synapse Properties: A Modulation-Based Ansatz

    OpenAIRE

    Christian Mayr; Johannes Partzsch; Rene Schüffny

    2009-01-01

    When entering a synapse, presynaptic pulse trains are filtered according to the recent pulse history at the synapse and also with respect to their own pulse time course. Various behavioral models have tried to reproduce these complex filtering properties. In particular, the quantal model of neurotransmitter release has been shown to be highly selective for particular presynaptic pulse patterns. However, since the original, pulse-iterative quantal model does not lend itself to mathematical ...

  19. A CMOS Spiking Neuron for Dense Memristor-Synapse Connectivity for Brain-Inspired Computing

    OpenAIRE

    Wu, Xinyu; Saxena, Vishal; Zhu, Kehan

    2015-01-01

    Neuromorphic systems that densely integrate CMOS spiking neurons and nano-scale memristor synapses open a new avenue of brain-inspired computing. Existing silicon neurons have molded neural biophysical dynamics but are incompatible with memristor synapses, or used extra training circuitry thus eliminating much of the density advantages gained by using memristors, or were energy inefficient. Here we describe a novel CMOS spiking leaky integrate-and-fire neuron circuit. Building on a reconfigur...

  20. Investigation and Manipulation of Different Analog Behaviors of Memristor as Electronic Synapse for Neuromorphic Applications

    OpenAIRE

    Changhong Wang; Wei He; Yi Tong; Rong Zhao

    2016-01-01

    Low-power and high-density electronic synapse is an important building block of brain-inspired systems. The recent advancement in memristor has provided an opportunity to advance electronic synapse design. However, a guideline on designing and manipulating the memristor’s analog behaviors is still lacking. In this work, we reveal that compliance current (I comp) of electroforming process played an important role in realizing a stable analog behavior, which is attributed to the generation of c...

  1. Disrupted-in-Schizophrenia (DISC1) Functions Presynaptically at Glutamatergic Synapses

    OpenAIRE

    Brady J Maher; Joseph J LoTurco

    2012-01-01

    The pathophysiology of schizophrenia is believed to involve defects in synaptic transmission, and the function of many schizophrenia-associated genes, including DISC1, have been linked to synaptic function at glutamatergic synapses. Here we develop a rodent model via in utero electroporation to assay the presynaptic function of DISC1 at glutamatergic synapses. We used a combination of mosaic transgene expression, RNAi knockdown and optogenetics to restrict both genetic manipulation and synapt...

  2. Giant ankyrin-G stabilizes somatodendritic GABAergic synapses through opposing endocytosis of GABAA receptors

    OpenAIRE

    Tseng, Wei Chou; Jenkins, Paul M.; Tanaka, Masashi; Mooney, Richard; Bennett, Vann

    2014-01-01

    GABAA-receptor-based interneuron circuitry is essential for higher order function of the human nervous system and is implicated in schizophrenia, depression, anxiety disorders, and autism. GABAergic synapses are located on neuronal cell bodies and dendritic shafts as well as axon initial segments. This study demonstrates that giant ankyrin-G forms micron-scale domains on neuronal cell bodies and dendritic shafts, and promotes somatodendritic GABAergic synapse stability through interaction wit...

  3. Pathogenic SYNGAP1 mutations impair cognitive development by disrupting the maturation of dendritic spine synapses

    OpenAIRE

    Clement, James P.; Aceti, Massimiliano; Creson, Thomas K.; Ozkan, Emin D.; Shi, Yulin; Reish, Nicholas J.; Almonte, Antoine G.; Miller, Brooke H.; Wiltgen, Brian J.; Miller, Courtney A.; Xu, Xiangmin; Rumbaugh, Gavin

    2012-01-01

    Mutations that cause Intellectual Disability (ID) and Autism Spectrum Disorder (ASD) are commonly found in genes that encode for synaptic proteins. However, it remains unclear how mutations that disrupt synapse function impact intellectual ability. In the SYNGAP1 mouse model of ID/ASD, we found that dendritic spine synapses develop prematurely during the early postnatal period. Premature spine maturation dramatically enhanced excitability in the developing hippocampus, which corresponded with...

  4. Formation and emplacement of two contrasting late-Mesoproterozoic magma types in the central Namaqua Metamorphic Complex (South Africa, Namibia): Evidence from geochemistry and geochronology

    Science.gov (United States)

    Bial, Julia; Büttner, Steffen H.; Frei, Dirk

    2015-05-01

    The Namaqua Metamorphic Complex is a Mesoproterozoic low-pressure, granulite facies belt along the southern and western margin of the Kaapvaal Craton. The NMC has formed between ~ 1.3 and 1.0 Ga and its central part consists essentially of different types of granitoids intercalated with metapelites and calc-silicate rocks. The granitoids can be subdivided into three major groups: (i) mesocratic granitoids, (ii) leucocratic granitoids and (iii) leucogranites. The high-K, ferroan mesocratic granitoids (54-75 wt% SiO2) have a variable composition ranging from granitic to tonalitic, and contain biotite and/or hornblende or orthopyroxene. They are strongly enriched in REE and LILE, indicating A-type chemical characteristics, and are depleted in Ba, Sr, Eu, Nb, Ta and Ti. The leucocratic granitoids and leucogranites (68-76 wt% SiO2) differ from the other group in having a granitic or slightly syenitic composition containing biotite and/or garnet/sillimanite. They have lower REE and MgO, FeOt, CaO, TiO2, MnO concentrations, but higher Na2O and K2O contents. Compositional variations in mesocratic granitoids indicate their formation by fractional crystallization of a mafic parental magma. Leucocratic granitoids and leucogranites lack such trends, which suggests melting of a felsic crustal source without subsequent further evolution of the generated magmas. The mineralogical and geochemical characteristics of the mesocratic granitoids are consistent magmatic differentiation of a mantle derived, hot (> 900 °C) parental magma. The leucocratic granitoids and leucogranites granites were formed from low-temperature magmas (< 730 °C), generated during fluid-present melting from metasedimentary sources. New U-Pb zircon ages reveal that both magma types were emplaced into the lower crust within a 30-40 million years interval between 1220-1180 Ma. In this time period the crust reached its thermal peak, which led to the formation of the leucocratic granitoids and leucogranites. A

  5. Rheomorphic ignimbrites of the Rogerson Formation, central Snake River plain, USA: record of mid-Miocene rhyolitic explosive eruptions and associated crustal subsidence along the Yellowstone hotspot track

    Science.gov (United States)

    Knott, Thomas R.; Reichow, Marc K.; Branney, Michael J.; Finn, David R.; Coe, Robert S.; Storey, Michael; Bonnichsen, Bill

    2016-04-01

    Rogerson Graben, USA, is critically placed at the intersection between the Yellowstone hotspot track and the southern projection of the west Snake River rift. Eleven rhyolitic members of the re-defined, ≥420-m-thick, Rogerson Formation record voluminous high-temperature explosive eruptions, emplacing extensive ashfall and rheomorphic ignimbrite sheets. Yet, each member has subtly distinct field, chemical and palaeomagnetic characteristics. New regional correlations reveal that the Brown's View ignimbrite covers ≥3300 km2, and the Wooden Shoe ignimbrite covers ≥4400 km2 and extends into Nevada. Between 11.9 and ˜8 Ma, the average frequency of large explosive eruptions in this region was 1 per 354 ky, about twice that at Yellowstone. The chemistry and mineralogy of the early rhyolites show increasing maturity with time possibly by progressive fractional crystallisation. This was followed by a trend towards less-evolved rhyolites that may record melting and hybridisation of a mid-crustal source region. Contemporaneous magmatism-induced crustal subsidence of the central Snake River Basin is recorded by successive ignimbrites offlapping and thinning up the N-facing limb of a regional basin-margin monocline, which developed between 10.59 and 8 Ma. The syn-volcanic basin topography contrasted significantly with the present-day elevated Yellowstone hotspot plateau. Concurrent basin-and-range extension produced the N-trending Rogerson Graben: early uplift of the Shoshone Hills (≥10.34 Ma) was followed by initiation of the Shoshone Fault and an E-sloping half-graben (˜10.3-10.1 Ma). The graben asymmetry then reversed with initiation of the Brown's Bench Fault (≥8 Ma), which remained intermittently active until the Pliocene.

  6. ALMA OBSERVATIONS OF WARM DENSE GAS IN NGC 1614—BREAKING OF THE STAR FORMATION LAW IN THE CENTRAL KILOPARSEC

    Energy Technology Data Exchange (ETDEWEB)

    Xu, C. K.; Cao, C.; Lu, N.; Diaz-Santos, T.; Zhao, Y.-H.; Mazzarella, J. M.; Appleton, P.; Armus, L.; Murphy, E. J. [Infrared Processing and Analysis Center, MS 100-22, California Institute of Technology, Pasadena, CA 91125 (United States); Gao, Y. [Purple Mountain Observatory, Chinese Academy of Sciences, 2 West Beijing Road, Nanjing 210008 (China); Herrero-Illana, R. [Instituto de Astrofísica de Andalucía - CSIC, Glorieta de la Astronomía, s/n, E-18008 Granada (Spain); Meijerink, R. [Leiden Observatory, Leiden University, P.O. Box 9513, NL-2300 RA Leiden (Netherlands); Privon, G.; Evans, A. S. [Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904 (United States); König, S. [Institut de Radioastronomie Millimétrique (IRAM), 300 rue de la Piscine, Domaine Universitaire, F-38406 Saint Martin d' Hères (France); Aalto, S. [Department of Earth and Space Sciences, Onsala Observatory, Chalmers University of Technology, SE-439 92 Onsala (Sweden); Charmandaris, V. [Department of Physics, University of Crete, GR-71003 Heraklion (Greece); Chu, J. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96816 (United States); Haan, S. [CSIRO Astronomy and Space Science, ATNF, P.O. Box 76, Epping 1710 (Australia); Inami, H. [National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States); and others

    2015-01-20

    We present ALMA Cycle-0 observations of the CO (6-5) line emission and of the 435 μm dust continuum emission in the central kiloparsec of NGC 1614, a local luminous infrared galaxy at a distance of 67.8 Mpc (1{sup ′′}=329 pc). The CO emission is well resolved by the ALMA beam (0.''26 × 0.''20) into a circumnuclear ring, with an integrated flux of f {sub CO(6-5)} = 898 (± 153) Jy km s{sup –1}, which is 63(± 12)% of the total CO (6-5) flux measured by Herschel. The molecular ring, located between 100 pcformation regions with Σ{sub SFR} ∼ 100 M {sub ☉} yr{sup –1} kpc{sup –2} and Σ{sub Gas}∼10{sup 4} M{sub ⊙} pc{sup −2}. The non-detections of the nucleus in both the CO (6-5) line emission and the 435 μm continuum rule out, with relatively high confidence, a Compton-thick active galactic nucleus in NGC 1614. Comparisons with radio continuum emission show a strong deviation from an expected local correlation between Σ{sub Gas} and Σ{sub SFR}, indicating a breakdown of the Kennicutt-Schmidt law on the linear scale of ∼100 pc.

  7. Diagenesis of Paleozoic playa-lake and ephemeral-stream deposits from the Pimenta Bueno Formation, Siluro-Devonian (?) of the Parecis Basin, central Brazil

    Science.gov (United States)

    Goldberg, K.; Morad, S.; Al-Aasm, I. S.; De Ros, L. F.

    2011-07-01

    The Parecis Basin is a large intracratonic rift located in central Brazil and filled with Paleozoic carbonate, evaporite and siliciclastic sediments. The occurrence of gas seeps has recently attracted significant exploration interest by the Brazilian petroleum agency and by Petrobras. The continuously cored PB-01-RO well provided the first opportunity to study the depositional environments, diagenetic evolution and hydrocarbon potential of the largely unknown sedimentary successions of the Parecis Basin. The cored lithologies, belonging to the Siluro-Devonian (?) Pimenta Bueno Formation, are interpreted as deposited in playa-lake and ephemeral-stream environments. The deposits display a strong facies control on the diagenetic mineral assemblages and evolution. Diagenetic minerals in the ephemeral-stream deposits include eogenetic hematite and smectitic clay coats and quartz cement, and the mesogenetic process includes precipitation of sulfates (anhydrite and barite) and carbonates (calcite, dolomite and kutnahorite-ankerite-huntite), followed by partial dissolution of these carbonates and sulfates, and of feldspar grains. Telogenetic processes include the precipitation of hematite and kaolinite within secondary pores, and the replacement of anhydrite by gypsum. A second burial phase and mesodiagenesis is indicated by the precipitation of discrete K-feldspar crystals within moldic pores after dissolved feldspars, and by the illitization of etched, telogenetic kaolinite. The playa-lake deposits show early diagenetic dolomitization of lime mud, precipitation of anhydrite nodules and extensive silicification. The anhydrite nodules were replaced by gypsum and chalcedony during telodiagenesis. Potential source rocks are locally represented by organic shales. The fluvial sandstones show fair reservoir quality and limited compaction, as indicated by their intergranular volume, suggesting that the succession has undergone moderate burial. Potential seals for hydrocarbon

  8. Poisson-like spiking in circuits with probabilistic synapses.

    Directory of Open Access Journals (Sweden)

    Rubén Moreno-Bote

    2014-07-01

    Full Text Available Neuronal activity in cortex is variable both spontaneously and during stimulation, and it has the remarkable property that it is Poisson-like over broad ranges of firing rates covering from virtually zero to hundreds of spikes per second. The mechanisms underlying cortical-like spiking variability over such a broad continuum of rates are currently unknown. We show that neuronal networks endowed with probabilistic synaptic transmission, a well-documented source of variability in cortex, robustly generate Poisson-like variability over several orders of magnitude in their firing rate without fine-tuning of the network parameters. Other sources of variability, such as random synaptic delays or spike generation jittering, do not lead to Poisson-like variability at high rates because they cannot be sufficiently amplified by recurrent neuronal networks. We also show that probabilistic synapses predict Fano factor constancy of synaptic conductances. Our results suggest that synaptic noise is a robust and sufficient mechanism for the type of variability found in cortex.

  9. Poisson-like spiking in circuits with probabilistic synapses.

    Science.gov (United States)

    Moreno-Bote, Rubén

    2014-07-01

    Neuronal activity in cortex is variable both spontaneously and during stimulation, and it has the remarkable property that it is Poisson-like over broad ranges of firing rates covering from virtually zero to hundreds of spikes per second. The mechanisms underlying cortical-like spiking variability over such a broad continuum of rates are currently unknown. We show that neuronal networks endowed with probabilistic synaptic transmission, a well-documented source of variability in cortex, robustly generate Poisson-like variability over several orders of magnitude in their firing rate without fine-tuning of the network parameters. Other sources of variability, such as random synaptic delays or spike generation jittering, do not lead to Poisson-like variability at high rates because they cannot be sufficiently amplified by recurrent neuronal networks. We also show that probabilistic synapses predict Fano factor constancy of synaptic conductances. Our results suggest that synaptic noise is a robust and sufficient mechanism for the type of variability found in cortex. PMID:25032705

  10. Stochastic Synapses Enable Efficient Brain-Inspired Learning Machines.

    Science.gov (United States)

    Neftci, Emre O; Pedroni, Bruno U; Joshi, Siddharth; Al-Shedivat, Maruan; Cauwenberghs, Gert

    2016-01-01

    Recent studies have shown that synaptic unreliability is a robust and sufficient mechanism for inducing the stochasticity observed in cortex. Here, we introduce Synaptic Sampling Machines (S2Ms), a class of neural network models that uses synaptic stochasticity as a means to Monte Carlo sampling and unsupervised learning. Similar to the original formulation of Boltzmann machines, these models can be viewed as a stochastic counterpart of Hopfield networks, but where stochasticity is induced by a random mask over the connections. Synaptic stochasticity plays the dual role of an efficient mechanism for sampling, and a regularizer during learning akin to DropConnect. A local synaptic plasticity rule implementing an event-driven form of contrastive divergence enables the learning of generative models in an on-line fashion. S2Ms perform equally well using discrete-timed artificial units (as in Hopfield networks) or continuous-timed leaky integrate and fire neurons. The learned representations are remarkably sparse and robust to reductions in bit precision and synapse pruning: removal of more than 75% of the weakest connections followed by cursory re-learning causes a negligible performance loss on benchmark classification tasks. The spiking neuron-based S2Ms outperform existing spike-based unsupervised learners, while potentially offering substantial advantages in terms of power and complexity, and are thus promising models for on-line learning in brain-inspired hardware. PMID:27445650

  11. Quantitative analysis of synaptic release at the photoreceptor synapse.

    Science.gov (United States)

    Duncan, Gabriel; Rabl, Katalin; Gemp, Ian; Heidelberger, Ruth; Thoreson, Wallace B

    2010-05-19

    Exocytosis from the rod photoreceptor is stimulated by submicromolar Ca(2+) and exhibits an unusually shallow dependence on presynaptic Ca(2+). To provide a quantitative description of the photoreceptor Ca(2+) sensor for exocytosis, we tested a family of conventional and allosteric computational models describing the final Ca(2+)-binding steps leading to exocytosis. Simulations were fit to two measures of release, evoked by flash-photolysis of caged Ca(2+): exocytotic capacitance changes from individual rods and postsynaptic currents of second-order neurons. The best simulations supported the occupancy of only two Ca(2+) binding sites on the rod Ca(2+) sensor rather than the typical four or five. For most models, the on-rates for Ca(2+) binding and maximal fusion rate were comparable to those of other neurons. However, the off-rates for Ca(2+) unbinding were unexpectedly slow. In addition to contributing to the high-affinity of the photoreceptor Ca(2+) sensor, slow Ca(2+) unbinding may support the fusion of vesicles located at a distance from Ca(2+) channels. In addition, partial sensor occupancy due to slow unbinding may contribute to the linearization of the first synapse in vision. PMID:20483317

  12. Investigating complex I deficiency in Purkinje cells and synapses in patients with mitochondrial disease

    Science.gov (United States)

    Chrysostomou, Alexia; Grady, John P.; Laude, Alex; Taylor, Robert W.; Turnbull, Doug M.

    2015-01-01

    Aims Cerebellar ataxia is common in patients with mitochondrial disease, and despite previous neuropathological investigations demonstrating vulnerability of the olivocerebellar pathway in patients with mitochondrial disease, the exact neurodegenerative mechanisms are still not clear. We use quantitative quadruple immunofluorescence to enable precise quantification of mitochondrial respiratory chain protein expression in Purkinje cell bodies and their synaptic terminals in the dentate nucleus. Methods We investigated NADH dehydrogenase [ubiquinone] 1 alpha subcomplex subunit 13 protein expression in 12 clinically and genetically defined patients with mitochondrial disease and ataxia and 10 age‐matched controls. Molecular genetic analysis was performed to determine heteroplasmy levels of mutated mitochondrial DNA in Purkinje cell bodies and inhibitory synapses. Results Our data reveal that complex I deficiency is present in both Purkinje cell bodies and their inhibitory synapses which surround dentate nucleus neurons. Inhibitory synapses are fewer and enlarged in patients which could represent a compensatory mechanism. Mitochondrial DNA heteroplasmy demonstrated similarly high levels of mutated mitochondrial DNA in cell bodies and synapses. Conclusions This is the first study to use a validated quantitative immunofluorescence technique to determine complex I expression in neurons and presynaptic terminals, evaluating the distribution of respiratory chain deficiencies and assessing the degree of morphological abnormalities affecting synapses. Respiratory chain deficiencies detected in Purkinje cell bodies and their synapses and structural synaptic changes are likely to contribute to altered cerebellar circuitry and progression of ataxia. PMID:26337858

  13. Regulation of dopamine D1 receptor dynamics within the postsynaptic density of hippocampal glutamate synapses.

    Directory of Open Access Journals (Sweden)

    Laurent Ladepeche

    Full Text Available Dopamine receptor potently modulates glutamate signalling, synaptic plasticity and neuronal network adaptations in various pathophysiological processes. Although key intracellular signalling cascades have been identified, the cellular mechanism by which dopamine and glutamate receptor-mediated signalling interplay at glutamate synapse remain poorly understood. Among the cellular mechanisms proposed to aggregate D1R in glutamate synapses, the direct interaction between D1R and the scaffold protein PSD95 or the direct interaction with the glutamate NMDA receptor (NMDAR have been proposed. To tackle this question we here used high-resolution single nanoparticle imaging since it provides a powerful way to investigate at the sub-micron resolution the dynamic interaction between these partners in live synapses. We demonstrate in hippocampal neuronal networks that dopamine D1 receptors (D1R laterally diffuse within glutamate synapses, in which their diffusion is reduced. Disrupting the interaction between D1R and PSD95, through genetical manipulation and competing peptide, did not affect D1R dynamics in glutamatergic synapses. However, preventing the physical interaction between D1R and the GluN1 subunit of NMDAR abolished the synaptic stabilization of diffusing D1R. Together, these data provide direct evidence that the interaction between D1R and NMDAR in synapses participate in the building of the dopamine-receptor-mediated signalling, and most likely to the glutamate-dopamine cross-talk.

  14. Functional hallmarks of GABAergic synapse maturation and the diverse roles of neurotrophins

    Directory of Open Access Journals (Sweden)

    Rosemarie eGrantyn

    2011-07-01

    Full Text Available Functional impairment of the adult brain can result from deficits in the ontogeny of GABAergic synaptic transmission. Gene defects underlying autism spectrum disorders, Rett’s syndrome or some forms of epilepsy, but also a diverse set of syndromes accompanying perinatal trauma, hormonal imbalances, intake of sleep-inducing or mood-improving drugs or, quite common, alcohol intake during pregnancy can alter GABA signaling early in life. The search for therapeutically relevant endogenous molecules or exogenous compounds able to alleviate the consequences of dysfunction of GABAergic transmission in the embryonic or postnatal brain requires a clear understanding of its site- and state-dependent development. At the level of single synapses, it is necessary to discriminate between presynaptic and postsynaptic alterations, and to define parameters that can be regarded as both suitable and accessible for the quantification of developmental changes. Here we focus on the performance of GABAergic synapses in two brain structures, the hippocampus and the superior colliculus, describe some novel aspects of neurotrophin effects during the development of GABAergic synaptic transmission and examine the applicability of the following rules: 1 Synaptic transmission starts with GABA, 2 Nascent/immature GABAergic synapses operate in a ballistic mode (multivesicular release, 3 Immature synaptic terminals release vesicles with higher probability than mature synapses, 4 Immature GABAergic synapses are prone to paired pulse and tetanic depression, 5 Synapse maturation is characterized by an increasing dominance of synchronous over asynchronous release, 6 In immature neurons GABA acts as a depolarizing transmitter, 7 Synapse maturation implies IPSC shortening due to an increase in alpha1 subunit expression, 8 Extrasynaptic (tonic conductances can inhibit the development of synaptic (phasic GABA actions.

  15. Functional and structural deficits at accumbens synapses in a mouse model of Fragile X

    Directory of Open Access Journals (Sweden)

    Daniela eNeuhofer

    2015-03-01

    Full Text Available Fragile X is the most common cause of inherited intellectual disability and a leading cause of autism. The disease is caused by mutation of a single X-linked gene called fmr1 that codes for the Fragile X mental retardation protein (FMRP, a 71 kDa protein, which acts mainly as a translation inhibitor. Fragile X patients suffer from cognitive and emotional deficits that coincide with abnormalities in dendritic spines. Changes in spine morphology are often associated with altered excitatory transmission and long-term plasticity, the most prominent deficit in fmr1-/y mice. The nucleus accumbens, a central part of the mesocortico-limbic reward pathway, is now considered as a core structure in the control of social behaviors. Although the socio-affective impairments observed in Fragile X suggest dysfunctions in the accumbens, the impact of the lack of FMRP on accumbal synapses has scarcely been studied. Here we report for the first time a new spike timing-dependent plasticity paradigm that reliably triggers NMDAR-dependent long-term potentiation (LTP of excitatory afferent inputs of medium spiny neurons (MSN in the nucleus accumbens core region. Notably, we discovered that this LTP was completely absent in fmr1-/y mice. In the fmr1-/y accumbens intrinsic membrane properties of MSNs and basal excitatory neurotransmission remained intact in the fmr1-/y accumbens but the deficit in LTP was accompanied by an increase in evoked AMPA/NMDA ratio and a concomitant reduction of spontaneous NMDAR-mediated currents. In agreement with these physiological findings, we found significantly more filopodial spines in fmr1-/y mice by using an ultrastructural electron microscopic analysis of accumbens core medium spiny neuron spines. Surprisingly, spine elongation was specifically due to the longer longitudinal axis and larger area of spine necks, whereas spine head morphology and postsynaptic density size on spine heads remained unaffected in the fmr1-/y accumbens

  16. PETROGENESIS OF THE METACARBONATE AND RELATED ROCKS OF THE SILGARÁ FORMATION, CENTRAL SANTANDER MASSIF, COLOMBIAN ANDES: AN OVERVIEW OF A “REACTION CALCIC EXOSCARN”

    Directory of Open Access Journals (Sweden)

    Castellanos O.M

    2008-06-01

    Full Text Available Metacarbonate rocks (pure and impure marbles, carbonate-silicate rocks, calc-silicate rocks and carbonate-bearing silicate rocks form a very complex group within the metamorphic sequence of the Silgará Formation at the central Santander Massif (CSM. These rocks are interpreted as derived from a sedimentary sequence (including limestones and dolostones, carbonate-bearing mudstones,  sandstones, tuffaceous and evaporitic sediments and marlstones overprinted by near-isochemical regional metamorphism. They usually appear as scarce intercalations from millimeter up to meter scale, within the high-grade pelitic rocks, in the lower part of the metamorphic section, although the proportion of metacarbonate rocks can be higher and different marble layers are exploited. We report for the first time the occurrence of a "reaction calcic exoskarn", which corresponds to
    such metacarbonate rocks, taking into account that a skarn can be developed during regional metamorphism and by different metasomatic processes, adjacent to intrusive bodies, along faults and shear zones, and what defines these rocks as a skarn is its mineralogy, which includes a variety of calc-silicate and associated minerals, usually dominated by garnet and pyroxene. Therefore, this paper focus attention to the occurrence of metacarbonate and
    related rocks, which occurs as small scale reactions zones that show a gradational contact from garnet-bearing pelitic rocks to marbles or carbonate-silicate rocks, giving particular interest to the calc-silicate rocks, which are characterized by the presence of elongated grains of banded clinopyroxene (diopside and scapolite and massive
    or scattered garnet. Several reaction-zones occur in the contact between impure calcite marble and garnet-bearing metapelite and the sequence of mineral assemblages in these reaction zones is: biotite + plagioclase K-feldspar garnet (Zone I, biotite + plagioclase K-feldspar garnet staurolite epidote

  17. Clustering of sialylated glycosylphosphatidylinositol anchors mediates PrP-induced activation of cytoplasmic phospholipase A2 and synapse damage

    OpenAIRE

    Bate, Clive; Williams, Alun

    2012-01-01

    Precisely how the accumulation of PrPSc causes the neuronal degeneration that leads to the clinical symptoms of prion diseases is poorly understood. Our recent paper showed that the clustering of specific glycosylphosphatidylinositol (GPI) anchors attached to PrP proteins triggered synapse damage in cultured neurons. First, we demonstrated that small, soluble PrPSc oligomers caused synapse damage via a GPI-dependent process. Our hypothesis, that the clustering of specific GPIs caused synapse ...

  18. Evidence for Alzheimer's disease-linked synapse loss and compensation in mouse and human hippocampal CA1 pyramidal neurons.

    Science.gov (United States)

    Neuman, Krystina M; Molina-Campos, Elizabeth; Musial, Timothy F; Price, Andrea L; Oh, Kwang-Jin; Wolke, Malerie L; Buss, Eric W; Scheff, Stephen W; Mufson, Elliott J; Nicholson, Daniel A

    2015-11-01

    Alzheimer's disease (AD) is associated with alterations in the distribution, number, and size of inputs to hippocampal neurons. Some of these changes are thought to be neurodegenerative, whereas others are conceptualized as compensatory, plasticity-like responses, wherein the remaining inputs reactively innervate vulnerable dendritic regions. Here, we provide evidence that the axospinous synapses of human AD cases and mice harboring AD-linked genetic mutations (the 5XFAD line) exhibit both, in the form of synapse loss and compensatory changes in the synapses that remain. Using array tomography, quantitative conventional electron microscopy, immunogold electron microscopy for AMPARs, and whole-cell patch-clamp physiology, we find that hippocampal CA1 pyramidal neurons in transgenic mice are host to an age-related synapse loss in their distal dendrites, and that the remaining synapses express more AMPA-type glutamate receptors. Moreover, the number of axonal boutons that synapse with multiple spines is significantly reduced in the transgenic mice. Through serial section electron microscopic analyses of human hippocampal tissue, we further show that putative compensatory changes in synapse strength are also detectable in axospinous synapses of proximal and distal dendrites in human AD cases, and that their multiple synapse boutons may be more powerful than those in non-cognitively impaired human cases. Such findings are consistent with the notion that the pathophysiology of AD is a multivariate product of both neurodegenerative and neuroplastic processes, which may produce adaptive and/or maladaptive responses in hippocampal synaptic strength and plasticity. PMID:25031178

  19. Migration of a Central Venous Catheter in a Hemodialysis Patient Resulted in Left Atrial Perforation and Thrombus Formation Requiring Open Heart Surgery.

    Science.gov (United States)

    Wong, Kevin; Marks, Barry A; Qureshi, Anwer; Stemm, Joseph J

    2016-07-01

    Central venous catheterization is widely used in patients on hemodialysis. A rare complication associated with the clinical use of central venous catheters is perforation of the heart or major vessels. We report a case of inadvertent perforation of the left atrium and thrombosis after the placement of a hemodialysis catheter in the right internal jugular vein. In such cases, surgical removal of the central venous catheter from perforation sites in the heart and vessel walls poses anesthetic challenges because of the high risk of pneumothorax, hemorrhage, arrhythmias, thrombosis, and death. PMID:27224040

  20. Abanico East Formation: petrology and geochemistry of volcanic rocks behind the Cenozoic arc front in the Andean Cordillera, central Chile (33°50'S

    Directory of Open Access Journals (Sweden)

    Marcia Muñoz

    2006-01-01

    Full Text Available The stratigraphy, chemistry and age of rocks assigned to the eastern portion of the Abanico Formation exposed along the El Volcán river valley, Principal Cordillera east of Santiago (30º50'S/70º12'-70º5'W, are reported and discussed. This ca. 3,300 m thick succession is mainly composed of basalts, basaltic andesites and volcaniclastic rocks. 40Ar/39Ar radiometric dates on plagioclase from the lava flows yield Oligocene-lower Miocene ages with a maximum age of 34.3 ±0.4 Ma for the lower part and a plateau age of 21.4±1.0 Ma for the upper part of the succession. The lava flows show calc-alkaline affinities and have chemical characteristics that are typical of arc volcanic rocks erupted in an active continental margin. A temporal chemical evolution in the sequence is indicated by upward increases in concentrations of LILE and LREE elements and LaN/YbN ratios. This pattern can be attributed to increasing contributions of fluids derived from the subducted lithosphere with time. A chemical comparison of these rocks with Oligocene-lower Miocene volcanic rocks from the Cerro Abanico and Chacabuco areas on the western border of the Principal Cordillera, east of Santiago, and at the northern end of the Central Depression reveals west to east compositional variations. From west to east these variations include: (1 increasing LILE and LREE concentrations, LaN/YbN ratios and Sr and Nd initial isotopic ratios, and (2 decreasing LILE/HFSE and LREE/HFSE ratios. These pattern can be attributed to a west to east decrease in the contribution of slab derived fluids and increase in the influence of crustal contamination processesLa formación Abanico Este: petrología y geoquímica de las rocas volcánicas detrás del arco Cenozoico en la Cordillera Andina, Chile central (33º50'S. Se presentan los resultados del estudio de la estratigrafía, química y edades de rocas asignadas a la franja oriental de la Formación Abanico expuestas en la ladera sur del R

  1. Optimal and Local Connectivity Between Neuron and Synapse Array in the Quantum Dot/Silicon Brain

    Science.gov (United States)

    Duong, Tuan A.; Assad, Christopher; Thakoor, Anikumar P.

    2010-01-01

    This innovation is used to connect between synapse and neuron arrays using nanowire in quantum dot and metal in CMOS (complementary metal oxide semiconductor) technology to enable the density of a brain-like connection in hardware. The hardware implementation combines three technologies: 1. Quantum dot and nanowire-based compact synaptic cell (50x50 sq nm) with inherently low parasitic capacitance (hence, low dynamic power approx.l0(exp -11) watts/synapse), 2. Neuron and learning circuits implemented in 50-nm CMOS technology, to be integrated with quantum dot and nanowire synapse, and 3. 3D stacking approach to achieve the overall numbers of high density O(10(exp 12)) synapses and O(10(exp 8)) neurons in the overall system. In a 1-sq cm of quantum dot layer sitting on a 50-nm CMOS layer, innovators were able to pack a 10(exp 6)-neuron and 10(exp 10)-synapse array; however, the constraint for the connection scheme is that each neuron will receive a non-identical 10(exp 4)-synapse set, including itself, via its efficacy of the connection. This is not a fully connected system where the 100x100 synapse array only has a 100-input data bus and 100-output data bus. Due to the data bus sharing, it poses a great challenge to have a complete connected system, and its constraint within the quantum dot and silicon wafer layer. For an effective connection scheme, there are three conditions to be met: 1. Local connection. 2. The nanowire should be connected locally, not globally from which it helps to maximize the data flow by sharing the same wire space location. 3. Each synapse can have an alternate summation line if needed (this option is doable based on the simple mask creation). The 10(exp 3)x10(exp 3)-neuron array was partitioned into a 10-block, 10(exp 2)x10(exp 3)-neuron array. This building block can be completely mapped within itself (10,000 synapses to a neuron).

  2. Synchronization of the small-world neuronal network with unreliable synapses

    International Nuclear Information System (INIS)

    As is well known, synchronization phenomena are ubiquitous in neuronal systems. Recently a lot of work concerning the synchronization of the neuronal network has been accomplished. In these works, the synapses are usually considered reliable, but experimental results show that, in biological neuronal networks, synapses are usually unreliable. In our previous work, we have studied the synchronization of the neuronal network with unreliable synapses; however, we have not paid attention to the effect of topology on the synchronization of the neuronal network. Several recent studies have found that biological neuronal networks have typical properties of small-world networks, characterized by a short path length and high clustering coefficient. In this work, mainly based on the small-world neuronal network (SWNN) with inhibitory neurons, we study the effect of network topology on the synchronization of the neuronal network with unreliable synapses. Together with the network topology, the effects of the GABAergic reversal potential, time delay and noise are also considered. Interestingly, we found a counter-intuitive phenomenon for the SWNN with specific shortcut adding probability, that is, the less reliable the synapses, the better the synchronization performance of the SWNN. We also consider the effects of both local noise and global noise in this work. It is shown that these two different types of noise have distinct effects on the synchronization: one is negative and the other is positive

  3. Neuron-NG2 Cell Synapses: Novel Functions for Regulating NG2 Cell Proliferation and Differentiation

    Directory of Open Access Journals (Sweden)

    Qian-Kun Yang

    2013-01-01

    Full Text Available NG2 cells are a population of CNS cells that are distinct from neurons, mature oligodendrocytes, astrocytes, and microglia. These cells can be identified by their NG2 proteoglycan expression. NG2 cells have a highly branched morphology, with abundant processes radiating from the cell body, and express a complex set of voltage-gated channels, AMPA/kainate, and GABA receptors. Neurons notably form classical and nonclassical synapses with NG2 cells, which have varied characteristics and functions. Neuron-NG2 cell synapses could fine-tune NG2 cell activities, including the NG2 cell cycle, differentiation, migration, and myelination, and may be a novel potential therapeutic target for NG2 cell-related diseases, such as hypoxia-ischemia injury and periventricular leukomalacia. Furthermore, neuron-NG2 cell synapses may be correlated with the plasticity of CNS in adulthood with the synaptic contacts passing onto their progenies during proliferation, and synaptic contacts decrease rapidly upon NG2 cell differentiation. In this review, we highlight the characteristics of classical and nonclassical neuron-NG2 cell synapses, the potential functions, and the fate of synaptic contacts during proliferation and differentiation, with the emphasis on the regulation of the NG2 cell cycle by neuron-NG2 cell synapses and their potential underlying mechanisms.

  4. LRRTM3 Regulates Excitatory Synapse Development through Alternative Splicing and Neurexin Binding

    Directory of Open Access Journals (Sweden)

    Ji Won Um

    2016-02-01

    Full Text Available The four members of the LRRTM family (LRRTM1-4 are postsynaptic adhesion molecules essential for excitatory synapse development. They have also been implicated in neuropsychiatric diseases. Here, we focus on LRRTM3, showing that two distinct LRRTM3 variants generated by alternative splicing regulate LRRTM3 interaction with PSD-95, but not its excitatory synapse-promoting activity. Overexpression of either LRRTM3 variant increased excitatory synapse density in dentate gyrus (DG granule neurons, whereas LRRTM3 knockdown decreased it. LRRTM3 also controlled activity-regulated AMPA receptor surface expression in an alternative splicing-dependent manner. Furthermore, Lrrtm3-knockout mice displayed specific alterations in excitatory synapse density, excitatory synaptic transmission and excitability in DG granule neurons but not in CA1 pyramidal neurons. Lastly, LRRTM3 required only specific splice variants of presynaptic neurexins for their synaptogenic activity. Collectively, our data highlight alternative splicing and differential presynaptic ligand utilization in the regulation of LRRTMs, revealing key regulatory mechanisms for excitatory synapse development.

  5. Abundance of gap junctions at glutamatergic mixed synapses in adult Mosquitofish spinal cord neurons

    Directory of Open Access Journals (Sweden)

    Scott E Fraser

    2014-06-01

    Full Text Available “Dye-coupling”, whole-mount immunohistochemistry for gap junction channel protein connexin 35 (Cx35, and freeze-fracture replica immunogold labeling (FRIL reveal an abundance of electrical synapses/gap junctions at glutamatergic mixed synapses in the 14th spinal segment that innervates the adult male gonopodium of Western Mosquitofish, Gambusia affinis (Mosquitofish. To study gap junctions’ role in fast motor behavior, we used a minimally-invasive neural-tract-tracing technique to introduce gap junction-permeant or -impermeant dyes into deep muscles controlling the gonopodium of the adult male Mosquitofish, a teleost fish that rapidly transfers (complete in 50 of the 62 gap junctions at mixed synapses are in the 14th spinal segment. Our results support and extend studies showing gap junctions at mixed synapses in spinal cord segments involved in control of genital reflexes in rodents, and they suggest a link between mixed synapses and fast motor behavior. The findings provide a basis for studies of specific roles of spinal neurons in the generation/regulation of sex-specific behavior and for studies of gap junctions’ role in regulating fast motor behavior. Finally, the CoPA IN provides a novel candidate neuron for future studies of gap junctions and neural control of fast motor behaviors.

  6. Impacts of hybrid synapses on the noise-delayed decay in scale-free neural networks

    International Nuclear Information System (INIS)

    Highlights: • We investigate the NDD phenomenon in a hybrid scale-free network. • Electrical synapses are more impressive on the emergence of NDD. • Electrical synapses are more efficient in suppressing of the NDD. • Average degree has two opposite effects on the appearance time of the first spike. - Abstract: We study the phenomenon of noise-delayed decay in a scale-free neural network consisting of excitable FitzHugh–Nagumo neurons. In contrast to earlier works, where only electrical synapses are considered among neurons, we primarily examine the effects of hybrid synapses on the noise-delayed decay in this study. We show that the electrical synaptic coupling is more impressive than the chemical coupling in determining the appearance time of the first-spike and more efficient on the mitigation of the delay time in the detection of a suprathreshold input signal. We obtain that hybrid networks including inhibitory chemical synapses have higher signal detection capabilities than those of including excitatory ones. We also find that average degree exhibits two different effects, which are strengthening and weakening the noise-delayed decay effect depending on the noise intensity

  7. CRED Simrad em300 multibeam backscatter data from shelf and slope environments at Howland Island, Pacific Remote Island Areas, Central Pacific in netCDF format

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Multibeam backscatter imagery extracted from gridded bathymetry of Howland Island, Pacific Remote Island Areas, Central Pacific. These data provide coverage between...

  8. CRED Simrad em300 multibeam backscatter data of Baker Island, Pacific Remote Island Areas, Central Pacific in GeoTIFF format

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Multibeam backscatter imagery extracted from gridded bathymetry of the shelf and slope environments of Baker Island, Pacific Island Areas, Central Pacific. These...

  9. CRED Simrad em300 multibeam backscatter data of Johnston Atoll, Pacific Remote Island Areas, Central Pacific in GeoTIFF format

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Multibeam backscatter imagery extracted from gridded bathymetry of the shelf and slope environments of Johnston Island, Pacific Island Areas, Central Pacific. These...

  10. CRED Reson 8101 multibeam backscatter data of Palmyra Atoll, Pacific Remote Island Areas, Central Pacific with 1 meter resolution in GeoTIFF format

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Multibeam backscatter imagery extracted from gridded bathymetry of the lagoon, shelf, and slope environments of Palmyra Atoll, Pacific Island Areas, Central...

  11. CRED Simrad em300 multibeam backscatter data of Jarvis Island, Pacific Remote Island Areas, Central Pacific in GeoTIFF format

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Multibeam backscatter imagery extracted from gridded bathymetry of the shelf and slope environments of Jarvis Atoll, Pacific Island Areas, Central Pacific. These...

  12. Induction of multiple signaling loops by MuSK during neuromuscular synapse formation

    OpenAIRE

    Moore, Chris; Leu, Marco; Müller, Ulrich; Brenner, Hans Rudolf

    2001-01-01

    At the neuromuscular junction, two motor neuron-derived signals have been implicated in the regulation of synaptogenesis. Neuregulin-1 is thought to induce transcription of acetylcholine receptor (AChR) genes in subsynaptic muscle nuclei by activating ErbB receptors. Neural agrin aggregates AChRs by activating the receptor tyrosine kinase MuSK. Here, we show that these two signals act sequentially. Agrin, by activating MuSK, induces the synthesis and aggregation of...

  13. ASSESSMENT OF SYNAPSE FORMATION IN RAT PRIMARY NEURAL CELL CULTURE USING HIGH CONTENT MICROSCOPY.

    Science.gov (United States)

    Cell-based assays can model neurodevelopmental processes including neurite growth and synaptogenesis, and may be useful for screening and evaluation of large numbers of chemicals for developmental neurotoxicity. This work describes the use of high content screening (HCS) to dete...

  14. Endpoints for Neural Connectivity Including Neurite Outgrowth, Synapse Formation, and Function

    Science.gov (United States)

    A strategy for alternative methods for developmental neurotoxicity testing (DNT) focuses on assessment of chemical effects on conserved neurodevelopmental processes. The development of the brain is an integrated series of steps from the commitment of embryonic cells to become neu...

  15. Synapse associated protein 102 (SAP102 binds the C-terminal part of the scaffolding protein neurobeachin.

    Directory of Open Access Journals (Sweden)

    Juliane Lauks

    Full Text Available Neurobeachin (Nbea is a multidomain scaffold protein abundant in the brain, where it is highly expressed during development. Nbea-null mice have severe defects in neuromuscular synaptic transmission resulting in lethal paralysis of the newborns. Recently, it became clear that Nbea is important also for the functioning of central synapses, where it is suggested to play a role in trafficking membrane proteins to both, the pre- and post-synaptic sites. So far, only few binding partners of Nbea have been found and the precise mechanism of their trafficking remains unclear. Here, we used mass spectrometry to identify SAP102, a MAGUK protein implicated in trafficking of the ionotropic glutamate AMPA- and NMDA-type receptors during synaptogenesis, as a novel Nbea interacting protein in mouse brain. Experiments in heterologous cells confirmed this interaction and revealed that SAP102 binds to the C-terminal part of Nbea that contains the DUF, PH, BEACH and WD40 domains. Furthermore, we discovered that introducing a mutation in Nbea's PH domain, which disrupts its interaction with the BEACH domain, abolishes this binding, thereby creating an excellent starting point to further investigate Nbea-SAP102 function in the central nervous system.

  16. Fear extinction causes target-specific remodeling of perisomatic inhibitory synapses.

    Science.gov (United States)

    Trouche, Stéphanie; Sasaki, Jennifer M; Tu, Tiffany; Reijmers, Leon G

    2013-11-20

    A more complete understanding of how fear extinction alters neuronal activity and connectivity within fear circuits may aid in the development of strategies to treat human fear disorders. Using a c-fos-based transgenic mouse, we found that contextual fear extinction silenced basal amygdala (BA) excitatory neurons that had been previously activated during fear conditioning. We hypothesized that the silencing of BA fear neurons was caused by an action of extinction on BA inhibitory synapses. In support of this hypothesis, we found extinction-induced target-specific remodeling of BA perisomatic inhibitory synapses originating from parvalbumin and cholecystokinin-positive interneurons. Interestingly, the predicted changes in the balance of perisomatic inhibition matched the silent and active states of the target BA fear neurons. These observations suggest that target-specific changes in perisomatic inhibitory synapses represent a mechanism through which experience can sculpt the activation patterns within a neural circuit. PMID:24183705

  17. A Model of In Vitro Plasticity at the Parallel Fiber - Molecular Layer Interneuron Synapses

    Directory of Open Access Journals (Sweden)

    William eLennon

    2015-12-01

    Full Text Available Theoretical and computational models of the cerebellum typically focus on the role of parallel fiber (PF - Purkinje cell (PKJ synapses for learned behavior, but few emphasize the role of the molecular layer interneurons (MLIs -- the stellate and basket cells. A number of recent experimental results suggest the role of MLIs is more important than previous models put forth. We investigate learning at PF - MLI synapses and propose a mathematical model to describe plasticity at this synapse. We perform computer simulations with this form of learning using a spiking neuron model of the MLI and show that it reproduces six in vitro experimental results in addition to simulating four novel protocols. Further, we show how this plasticity model can predict the results of other experimental protocols that are not simulated. Finally, we hypothesize what the biological mechanisms are for changes in synaptic efficacy that embody the phenomenological model proposed here.

  18. Dynamic Observation of Brain-Like Learning in a Ferroelectric Synapse Device

    Science.gov (United States)

    Nishitani, Yu; Kaneko, Yukihiro; Ueda, Michihito; Fujii, Eiji; Tsujimura, Ayumu

    2013-04-01

    A brain-like learning function was implemented in an electronic synapse device using a ferroelectric-gate field effect transistor (FeFET). The FeFET was a bottom-gate type FET with a ZnO channel and a ferroelectric Pb(Zr,Ti)O3 (PZT) gate insulator. The synaptic weight, which is represented by the channel conductance of the FeFET, is updated by applying a gate voltage through a change in the ferroelectric polarization in the PZT. A learning function based on the symmetric spike-timing dependent synaptic plasticity was implemented in the synapse device using the multilevel weight update by applying a pulse gate voltage. The dynamic weighting and learning behavior in the synapse device was observed as a change in the membrane potential in a spiking neuron circuit.

  19. Short-Term Plasticity and Long-Term Potentiation in Magnetic Tunnel Junctions: Towards Volatile Synapses

    Science.gov (United States)

    Sengupta, Abhronil; Roy, Kaushik

    2016-02-01

    Synaptic memory is considered to be the main element responsible for learning and cognition in humans. Although traditionally nonvolatile long-term plasticity changes are implemented in nanoelectronic synapses for neuromorphic applications, recent studies in neuroscience reveal that biological synapses undergo metastable volatile strengthening followed by a long-term strengthening provided that the frequency of the input stimulus is sufficiently high. Such "memory strengthening" and "memory decay" functionalities can potentially lead to adaptive neuromorphic architectures. In this paper, we demonstrate the close resemblance of the magnetization dynamics of a magnetic tunnel junction (MTJ) to short-term plasticity and long-term potentiation observed in biological synapses. We illustrate that, in addition to the magnitude and duration of the input stimulus, the frequency of the stimulus plays a critical role in determining long-term potentiation of the MTJ. Such MTJ synaptic memory arrays can be utilized to create compact, ultrafast, and low-power intelligent neural systems.

  20. Nanogranular SiO2 proton gated silicon layer transistor mimicking biological synapses

    Science.gov (United States)

    Liu, M. J.; Huang, G. S.; Feng, P.; Guo, Q. L.; Shao, F.; Tian, Z. A.; Li, G. J.; Wan, Q.; Mei, Y. F.

    2016-06-01

    Silicon on insulator (SOI)-based transistors gated by nanogranular SiO2 proton conducting electrolytes were fabricated to mimic synapse behaviors. This SOI-based device has both top proton gate and bottom buried oxide gate. Electrical transfer properties of top proton gate show hysteresis curves different from those of bottom gate, and therefore, excitatory post-synaptic current and paired pulse facilitation (PPF) behavior of biological synapses are mimicked. Moreover, we noticed that PPF index can be effectively tuned by the spike interval applied on the top proton gate. Synaptic behaviors and functions, like short-term memory, and its properties are also experimentally demonstrated in our device. Such SOI-based electronic synapses are promising for building neuromorphic systems.

  1. Unsupervised learning by spike timing dependent plasticity in phase change memory (PCM synapses

    Directory of Open Access Journals (Sweden)

    Stefano eAmbrogio

    2016-03-01

    Full Text Available We present a novel one-transistor/one-resistor (1T1R synapse for neuromorphic networks, based on phase change memory (PCM technology. The synapse is capable of spike-timing dependent plasticity (STDP, where gradual potentiation relies on set transition, namely crystallization, in the PCM, while depression is achieved via reset or amorphization of a chalcogenide active volume. STDP characteristics are demonstrated by experiments under variable initial conditions and number of pulses. Finally, we support the applicability of the 1T1R synapse for learning and recognition of visual patterns by simulations of fully connected neuromorphic networks with 2 or 3 layers with high recognition efficiency. The proposed scheme provides a feasible low-power solution for on-line unsupervised machine learning in smart reconfigurable sensors.

  2. A VLSI network of spiking neurons with plastic fully configurable "stop-learning" synapses

    OpenAIRE

    Giulioni, M; Camilleri, P; Dante, V; Badoni, D.; G. Indiveri; Braun, J; Del Giudice, P.

    2008-01-01

    We describe and demonstrate a neuromorphic, analog VLSI chip (termed F-LANN) hosting 128 integrate-and-fire (IF) neurons with spike-frequency adaptation, and 16,384 plastic bistable synapses implementing a self-regulated form of Hebbian, spike-driven, stochastic plasticity. The chip is designed to offer a high degree of reconfigurability: each synapse may be individually configured at any time to be either excitatory or inhibitory and to receive either recurrent input from an on-chip neuron o...

  3. Reduced cortical distribution volume of iodine-123 iomazenil in Alzheimer's disease as a measure of loss of synapses

    DEFF Research Database (Denmark)

    Soricelli, A; Postiglione, A; Grivet-Fojaja, M R;

    1996-01-01

    Iodine-123 labelled iomazenil (IMZ) is a specific tracer for the GABAA receptor, the dominant inhibitory synapse of the brain. The cerebral distribution volume (Vd) of IMZ may be taken as a quantitative measure of these synapses in Alzheimer's disease (AD), where synaptic loss tends...

  4. cAMP-Inhibits Cytoplasmic Phospholipase A2 and Protects Neurons against Amyloid-β-Induced Synapse Damage

    Directory of Open Access Journals (Sweden)

    Clive Bate

    2015-09-01

    Full Text Available A key event in Alzheimer’s disease (AD is the production of amyloid-β (Aβ peptides and the loss of synapses. In cultured neurons Aβ triggered synapse damage as measured by the loss of synaptic proteins. α-synuclein (αSN, aggregates of which accumulate in Parkinson’s disease, also caused synapse damage. Synapse damage was associated with activation of cytoplasmic phospholipase A2 (cPLA2, an enzyme that regulates synapse function and structure, and the production of prostaglandin (PG E2. In synaptosomes PGE2 increased concentrations of cyclic adenosine monophosphate (cAMP which suppressed the activation of cPLA2 demonstrating an inhibitory feedback system. Thus, Aβ/αSN-induced activated cPLA2 produces PGE2 which increases cAMP which in turn suppresses cPLA2 and, hence, its own production. Neurons pre-treated with pentoxifylline and caffeine (broad spectrum phosphodiesterase (PDE inhibitors or the PDE4 specific inhibitor rolipram significantly increased the Aβ/αSN-induced increase in cAMP and consequently protected neurons against synapse damage. The addition of cAMP analogues also inhibited cPLA2 and protected neurons against synapse damage. These results suggest that drugs that inhibit Aβ-induced activation of cPLA2 and cross the blood–brain barrier may reduce synapse damage in AD.

  5. Thermally active TRPV1 tonically drives central spontaneous glutamate release

    OpenAIRE

    Shoudai, Kiyomitsu; Peters, James H.; McDougall, Stuart J.; Fawley, Jessica A.; Andresen, Michael C.

    2010-01-01

    Central synapses spontaneously release neurotransmitter at low rates. In brainstem, cranial visceral afferent terminals in caudal solitary tract nucleus (NTS) display pronounced activity-dependent asynchronous release of glutamate and this extra release depends on TRPV1 receptors (TRPV1+). Asynchronous release is absent for afferents lacking TRPV1 (TRPV1-) and resting EPSC frequency was greater in TRPV1+. Here, we studied this basal activity difference by assessing thermal sensitivity of spon...

  6. A development-based compartmentalization of the Drosophila central brain

    OpenAIRE

    Pereanu, Wayne; Kumar, Abilasha; Jennett, Arnim; Reichert, Heinrich; Hartenstein, Volker

    2010-01-01

    The neuropile of the Drosophila brain is subdivided into anatomically discrete compartments. Compartments are rich in terminal neurite branching and synapses; they are the neuropile domains in which signal processing takes place. Compartment boundaries are defined by more or less dense layers of glial cells, as well as long neurite fascicles. These fascicles are formed during the larval period when the approximately 100 neuronal lineages that constitute the Drosophila central brain differenti...

  7. [Molecular mechanisms underlying the formation of neuromuscular junction].

    Science.gov (United States)

    Higuchi, Osamu; Yamanashi, Yuji

    2011-07-01

    The neuromuscular junction (NMJ) is a synapse between a motor neuron and skeletal muscle. The contraction of skeletal muscle is controlled by the neurotransmitter acetylcholine (ACh), which is released from the motor nerve terminal. To achieve efficient neuromuscular transmission, acetylcholine receptors (AChRs) must be densely clustered on the muscle membrane of the NMJ. Failure of AChR clustering is associated with disorders of neuromuscular transmission such as congenital myasthenic syndromes (CMS) and myasthenia gravis (MG). Motoneuronal agrin and muscle-specific receptor tyrosine kinase (MuSK) are known to play essential roles in the formation and maintenance of NMJs in the central region of each muscle. However, it had been unclear how agrin activates MuSK. Recent studies have elucidated the roles of several key molecules, including the cytoplasmic adaptor protein Dok-7 and LDL receptor-related protein 4 (Lrp4), in agrin-induced MuSK activation. Moreover, new evidence indicates that cyclin-dependent kinase 5 (Cdk5) regulates postsynaptic differentiation. In this review, we summarize the latest developments in molecular mechanisms underlying NMJ formation in vertebrates. PMID:21747134

  8. The cAMP cascade modulates the neuroinformative impact of quantal release at cholinergic synapse

    Czech Academy of Sciences Publication Activity Database

    Vyskočil, František; Bukcharaeva, E.; Samigullin, D. V.; Nikolsky, E. E.

    2001-01-01

    Roč. 2, č. 2 (2001), s. 317-323. ISSN 1539-2791 R&D Projects: GA AV ČR IAA7011902 Grant ostatní: EU(XX) Nesting; RFBR(RU) 99-04-48286 Institutional research plan: CEZ:AV0Z5011922 Keywords : frog neuromuscular synapse * noradrenaline Subject RIV: ED - Physiology

  9. Pitx3 deficiency in mice affects cholinergic modulation of GABAergic synapses in the nucleus accumbens

    NARCIS (Netherlands)

    de Rover, Mischa; Lodder, Johannes C.; Smidt, Marten P.; Brussaard, Arjen B.

    2006-01-01

    Pitx3 deficiency in mice affects cholinergic modulation of GABAergic synapses in the nucleus accumbens. J Neurophysiol 96: 2034-2041, 2006. First published July 12, 2006; doi:10.1152/jn.00333.2006. We investigated to what extent Pitx3 deficiency, causing hyperdopaminergic transmission in the nucleus

  10. In vivo knockdown of Piccolino disrupts presynaptic ribbon morphology in mouse photoreceptor synapses

    Directory of Open Access Journals (Sweden)

    Hanna Regus-Leidig

    2014-09-01

    Full Text Available Piccolo is the largest known cytomatrix protein at active zones of chemical synapses. A growing number of studies on conventional chemical synapses assign Piccolo a role in the recruitment and integration of molecules relevant for both endo- and exocytosis of synaptic vesicles, the dynamic assembly of presynaptic F-actin, as well as the proteostasis of presynaptic proteins, yet a direct function in the structural organization of the active zone has not been uncovered in part due to the expression of multiple alternatively spliced isoforms. We recently identified Piccolino, a Piccolo splice variant specifically expressed in sensory ribbon synapses of the eye and ear. Here we down regulated Piccolino in vivo via an adeno-associated virus-based RNA interference approach and explored the impact on the presynaptic structure of mouse photoreceptor ribbon synapses. Detailed immunocytochemical light and electron microscopical analysis of Piccolino knockdown in photoreceptors revealed a hitherto undescribed photoreceptor ribbon synaptic phenotype with striking morphological changes of synaptic ribbon ultrastructure.

  11. Diversity in Long-Term Synaptic Plasticity at Inhibitory Synapses of Striatal Spiny Neurons

    Science.gov (United States)

    Rueda-Orozco, Pavel E.; Mendoza, Ernesto; Hernandez, Ricardo; Aceves, Jose J.; Ibanez-Sandoval, Osvaldo; Galarraga, Elvira; Bargas, Jose

    2009-01-01

    Procedural memories and habits are posited to be stored in the basal ganglia, whose intrinsic circuitries possess important inhibitory connections arising from striatal spiny neurons. However, no information about long-term plasticity at these synapses is available. Therefore, this work describes a novel postsynaptically dependent long-term…

  12. Synapse Specificity of Long-Term Potentiation Breaks Down with Aging

    Science.gov (United States)

    Ris, Laurence; Godaux, Emile

    2007-01-01

    Memory shows age-related decline. According to the current prevailing theoretical model, encoding of memories relies on modifications in the strength of the synapses connecting the different cells within a neuronal network. The selective increases in synaptic weight are thought to be biologically implemented by long-term potentiation (LTP). Here,…

  13. Experience-Dependent Regulation of Presynaptic NMDARs Enhances Neurotransmitter Release at Neocortical Synapses

    Science.gov (United States)

    Urban-Ciecko, Joanna; Wen, Jing A.; Parekh, Puja K.; Barth, Alison L.

    2015-01-01

    Sensory experience can selectively alter excitatory synaptic strength at neocortical synapses. The rapid increase in synaptic strength induced by selective whisker stimulation (single-row experience/SRE, where all but one row of whiskers has been removed from the mouse face) is due, at least in part, to the trafficking of AMPA receptors (AMPARs)…

  14. Sparking Student Synapses, Grades 9-12: Think Critically and Accelerate Learning

    Science.gov (United States)

    Allen, Rich; Scozzi, Nigel

    2011-01-01

    Today's students must be more than good test takers. They must be able to collaborate, innovate, and think critically to solve real-world problems. As content demands increase, how can teachers make time to teach these advanced skills? "Sparking Student Synapses, Grades 9-12" describes how master teacher Nigel Scozzi used Rich Allen's Green Light…

  15. Mixed Analog/Digital Matrix-Vector Multiplier for Neural Network Synapses

    DEFF Research Database (Denmark)

    Lehmann, Torsten; Bruun, Erik; Dietrich, Casper

    1996-01-01

    In this work we present a hardware efficient matrix-vector multiplier architecture for artificial neural networks with digitally stored synapse strengths. We present a novel technique for manipulating bipolar inputs based on an analog two's complements method and an accurate current rectifier...

  16. Activity-dependent synaptic plasticity of a chalcogenide electronic synapse for neuromorphic systems.

    Science.gov (United States)

    Li, Yi; Zhong, Yingpeng; Zhang, Jinjian; Xu, Lei; Wang, Qing; Sun, Huajun; Tong, Hao; Cheng, Xiaoming; Miao, Xiangshui

    2014-01-01

    Nanoscale inorganic electronic synapses or synaptic devices, which are capable of emulating the functions of biological synapses of brain neuronal systems, are regarded as the basic building blocks for beyond-Von Neumann computing architecture, combining information storage and processing. Here, we demonstrate a Ag/AgInSbTe/Ag structure for chalcogenide memristor-based electronic synapses. The memristive characteristics with reproducible gradual resistance tuning are utilised to mimic the activity-dependent synaptic plasticity that serves as the basis of memory and learning. Bidirectional long-term Hebbian plasticity modulation is implemented by the coactivity of pre- and postsynaptic spikes, and the sign and degree are affected by assorted factors including the temporal difference, spike rate and voltage. Moreover, synaptic saturation is observed to be an adjustment of Hebbian rules to stabilise the growth of synaptic weights. Our results may contribute to the development of highly functional plastic electronic synapses and the further construction of next-generation parallel neuromorphic computing architecture. PMID:24809396

  17. Mechanisms underlying the rules for associative plasticity at adult human neocortical synapses

    NARCIS (Netherlands)

    M.B. Verhoog (Matthijs); N.A. Goriounova (Natalia); J. Obermayer (Joshua); J. Stroeder (Jasper); J.J. Johannes Hjorth (J.); G. Testa-Silva (Guilherme); J.C. Baayen; C.P.J. de Kock (Christiaan); R.M. Meredith (Rhiannon); H.D. Mansvelder (Huibert)

    2013-01-01

    textabstractThe neocortex in our brain stores long-term memories by changing the strength of connections between neurons. To date, the rules and mechanisms that govern activity-induced synaptic changes at human cortical synapses are poorly understood and have not been studied directly at a cellular

  18. Formation of sulphation deposits in cables in the electricity generation plant of Los Humeros geothermal field, Mexico; Sulfatacion de cables en la central geotermoelectrica Los Humeros, Puebla, Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Vergara Rangel, Agustin [Comision Federal de Electricidad, Perote, Veracruz (Mexico)

    2000-12-01

    In the construction of a central electrical generation plant using geothermal fluids, high quality standards are applied in all aspects of engineering. Los Humeros generation units were installed through trenches, ducts and trays according to norms for cables of control, force and power, specifically in point to point cables and connections. Performance of the power plant has been affected by electric momentary and sequence flaws due to problems of cable sulfating, which were solved by tinning the conductors. [Spanish] En la construccion de centrales generadoras de electricidad con fluidos geotermicos se aplican criterios de calidad de diseno en todos los aspectos de la ingenieria. En Los Humeros Puebla, se realizo la instalacion conforme a normas de cables de control, fuerza y potencia a traves de trincheras, ductos y charolas y especificamente en el cableado asi como en las conexiones de punta a punta. Todos estos aspectos son referidos a planos de los componentes y equipos electricos existentes en una central. Al paso del tiempo existieron fallas electricas momentaneas y secuenciales por el problema de sulfatacion en cables, los cuales fueron resueltos con el estanado de conductores.

  19. Functional and structural deficits at accumbens synapses in a mouse model of Fragile X.

    Science.gov (United States)

    Neuhofer, Daniela; Henstridge, Christopher M; Dudok, Barna; Sepers, Marja; Lassalle, Olivier; Katona, István; Manzoni, Olivier J

    2015-01-01

    Fragile X is the most common cause of inherited intellectual disability and a leading cause of autism. The disease is caused by mutation of a single X-linked gene called fmr1 that codes for the Fragile X mental retardation protein (FMRP), a 71 kDa protein, which acts mainly as a translation inhibitor. Fragile X patients suffer from cognitive and emotional deficits that coincide with abnormalities in dendritic spines. Changes in spine morphology are often associated with altered excitatory transmission and long-term plasticity, the most prominent deficit in fmr1-/y mice. The nucleus accumbens, a central part of the mesocortico-limbic reward pathway, is now considered as a core structure in the control of social behaviors. Although the socio-affective impairments observed in Fragile X suggest dysfunctions in the accumbens, the impact of the lack of FMRP on accumbal synapses has scarcely been studied. Here we report for the first time a new spike timing-dependent plasticity paradigm that reliably triggers NMDAR-dependent long-term potentiation (LTP) of excitatory afferent inputs of medium spiny neurons (MSN) in the nucleus accumbens core region. Notably, we discovered that this LTP was completely absent in fmr1-/y mice. In the fmr1-/y accumbens intrinsic membrane properties of MSNs and basal excitatory neurotransmission remained intact in the fmr1-/y accumbens but the deficit in LTP was accompanied by an increase in evoked AMPA/NMDA ratio and a concomitant reduction of spontaneous NMDAR-mediated currents. In agreement with these physiological findings, we found significantly more filopodial spines in fmr1-/y mice by using an ultrastructural electron microscopic analysis of accumbens core medium spiny neuron spines. Surprisingly, spine elongation was specifically due to the longer longitudinal axis and larger area of spine necks, whereas spine head morphology and postsynaptic density size on spine heads remained unaffected in the fmr1-/y accumbens. These findings

  20. 同质产品中心市场形成机理的博弈论模型解释%THE EXPLANATION OF THE MECHANISM OF THE CENTRAL MARKET FORMATION OF HOMOGEOUS PRODUCTS USING GAME THEORY

    Institute of Scientific and Technical Information of China (English)

    魏灿秋; 付战兵

    2000-01-01

    The extending analysis of the Hotelling model for spatial difference of homogeneous products is presented. A conclusion different from the classical one is obtained and it gives a satisfactory explanation for the central market formation mechanism of homogeneous product.%对产品空间位置差异的Hotelling模型进行了扩展分析,得到了与经典分析方法不同的结果,该结果能很好地解释同质产品中心市场形成的原因和机理.