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Synaptic scaling

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https://www.readbyqxmd.com/read/28104799/muscles-innervated-by-a-single-motor-neuron-exhibit-divergent-synaptic-properties-on-multiple-time-scales
#1
Dawn M Blitz, Amy E Pritchard, John K Latimer, Andrew T Wakefield
Adaptive changes in the output of neural circuits underlying rhythmic behaviors are relayed to muscles via motor neuron activity. Pre- and postsynaptic properties of neuromuscular junctions can impact the transformation from motor neuron activity to muscle response. Further, synaptic plasticity occurring on the time scale of inter-spike intervals can differ between multiple muscles innervated by the same motor neuron. In rhythmic behaviors, motor neuron bursts can elicit additional synaptic plasticity. However, it is unknown if plasticity regulated by the longer time scale of inter-burst intervals also differs between synapses from the same neuron, and whether any such distinctions occur across a physiological activity range...
January 19, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28103235/real-time-multiplicative-memory-amplification-mediated-by-whole-cell-scaling-of-synaptic-response-in-key-neurons
#2
Iris Reuveni, Sourav Ghosh, Edi Barkai
Intense spiking response of a memory-pattern is believed to play a crucial role both in normal learning and pathology, where it can create biased behavior. We recently proposed a novel model for memory amplification where the simultaneous two-fold increase of all excitatory (AMPAR-mediated) and inhibitory (GABAAR-mediated) synapses in a sub-group of cells that constitutes a memory-pattern selectively amplifies this memory. Here we confirm the cellular basis of this model by validating its major predictions in four sets of experiments, and demonstrate its induction via a whole-cell transduction mechanism...
January 2017: PLoS Computational Biology
https://www.readbyqxmd.com/read/28102151/pleiotropic-genetic-effects-influencing-sleep-and-neurological-disorders
#3
REVIEW
Olivia J Veatch, Brendan T Keenan, Philip R Gehrman, Beth A Malow, Allan I Pack
Research evidence increasingly points to the large impact of sleep disturbances on public health. Many aspects of sleep are heritable and genes influencing traits such as timing, EEG characteristics, sleep duration, and response to sleep loss have been identified. Notably, large-scale genome-wide analyses have implicated numerous genes with small effects on sleep timing. Additionally, there has been considerable progress in the identification of genes influencing risk for some neurological sleep disorders. For restless legs syndrome, implicated variants are typically in genes associated with neuronal development...
February 2017: Lancet Neurology
https://www.readbyqxmd.com/read/28097513/stable-control-of-firing-rate-mean-and-variance-by-dual-homeostatic-mechanisms
#4
Jonathan Cannon, Paul Miller
Homeostatic processes that provide negative feedback to regulate neuronal firing rates are essential for normal brain function. Indeed, multiple parameters of individual neurons, including the scale of afferent synapse strengths and the densities of specific ion channels, have been observed to change on homeostatic time scales to oppose the effects of chronic changes in synaptic input. This raises the question of whether these processes are controlled by a single slow feedback variable or multiple slow variables...
December 2017: Journal of Mathematical Neuroscience
https://www.readbyqxmd.com/read/28096877/efficacy-and-safety-of-bitopertin-in-patients-with-schizophrenia-and-predominant-negative-symptoms-subgroup-analysis-of-japanese-patients-from-the-global-randomized-phase-2-trial
#5
Yoshio Hirayasu, Shin-Ichi Sato, Norifumi Shuto, Miwa Nakano, Teruhiko Higuchi
OBJECTIVE: The aim of the present study was to perform a subgroup analysis of data from a phase II global, multi-center, randomized, double-blind, placebo-controlled study to evaluate the efficacy and safety of bitopertin, a glycine reuptake inhibitor that activates N-methyl-D-aspartate receptors by increasing the concentration of glycine in the synaptic cleft, in Japanese and non-Japanese patients with schizophrenia and predominant negative symptoms. METHODS: Patients with schizophrenia and predominant negative symptoms on one or two antipsychotic drugs, including atypical antipsychotic drugs (olanzapine, risperidone, quetiapine, aripiprazole, and paliperidone) as the primary treatment, received bitopertin (10, 30, or 60 mg/day) or placebo once daily for 8 weeks as an add-on treatment...
January 2017: Psychiatry Investigation
https://www.readbyqxmd.com/read/28093558/glutamatergic-synapses-are-structurally-and-biochemically-complex-because-of-multiple-plasticity-processes-long-term-potentiation-long-term-depression-short-term-potentiation-and-scaling
#6
REVIEW
John Lisman
Synapses are complex because they perform multiple functions, including at least six mechanistically different forms of plasticity. Here, I comment on recent developments regarding these processes. (i) Short-term potentiation (STP), a Hebbian process that requires small amounts of synaptic input, appears to make strong contributions to some forms of working memory. (ii) The rules for long-term potentiation (LTP) induction in CA3 have been clarified: induction does not depend obligatorily on backpropagating sodium spikes but, rather, on dendritic branch-specific N-methyl-d-aspartate (NMDA) spikes...
March 5, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
https://www.readbyqxmd.com/read/28093551/multiple-shared-mechanisms-for-homeostatic-plasticity-in-rodent-somatosensory-and-visual-cortex
#7
REVIEW
Melanie A Gainey, Daniel E Feldman
We compare the circuit and cellular mechanisms for homeostatic plasticity that have been discovered in rodent somatosensory (S1) and visual (V1) cortex. Both areas use similar mechanisms to restore mean firing rate after sensory deprivation. Two time scales of homeostasis are evident, with distinct mechanisms. Slow homeostasis occurs over several days, and is mediated by homeostatic synaptic scaling in excitatory networks and, in some cases, homeostatic adjustment of pyramidal cell intrinsic excitability. Fast homeostasis occurs within less than 1 day, and is mediated by rapid disinhibition, implemented by activity-dependent plasticity in parvalbumin interneuron circuits...
March 5, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
https://www.readbyqxmd.com/read/28093550/experience-dependent-homeostasis-of-noise-at-inhibitory-synapses-preserves-information-coding-in-adult-visual-cortex
#8
Ming Gao, Jessica L Whitt, Shiyong Huang, Angela Lee, Stefan Mihalas, Alfredo Kirkwood, Hey-Kyoung Lee
Synapses are intrinsically 'noisy' in that neurotransmitter is occasionally released in the absence of an action potential. At inhibitory synapses, the frequency of action potential-independent release is orders of magnitude higher than that at excitatory synapses raising speculations that it may serve a function. Here we report that the frequency of action potential-independent inhibitory synaptic 'noise' (i.e. miniature inhibitory postsynaptic currents, mIPSCs) is highly regulated by sensory experience in visual cortex...
March 5, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
https://www.readbyqxmd.com/read/28093546/time-course-and-mechanisms-of-homeostatic-plasticity-in-layers-2-3-and-5-of-the-barrel-cortex
#9
Stanislaw Glazewski, Stuart Greenhill, Kevin Fox
Recent studies have shown that ocular dominance plasticity in layer 2/3 of the visual cortex exhibits a form of homeostatic plasticity that is related to synaptic scaling and depends on TNFα. In this study, we tested whether a similar form of plasticity was present in layer 2/3 of the barrel cortex and, therefore, whether the mechanism was likely to be a general property of cortical neurons. We found that whisker deprivation could induce homeostatic plasticity in layer 2/3 of barrel cortex, but not in a mouse strain lacking synaptic scaling...
March 5, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
https://www.readbyqxmd.com/read/28087334/the-short-and-long-term-proteomic-effects-of-sleep-deprivation-on-the-cortical-and-thalamic-synapses
#10
Attila Simor, Balázs András Györffy, Péter Gulyássy, Katalin Völgyi, Vilmos Tóth, Mihail Ivilinov Todorov, Viktor Kis, Zsolt Borhegyi, Zoltán Szabó, Tamás Janáky, László Drahos, Gábor Juhász, Katalin Adrienna Kékesi
Acute total sleep deprivation (SD) impairs memory consolidation, attention, working memory and perception. Structural, electrophysiological and molecular experimental approaches provided evidences for the involvement of sleep in synaptic functions. Despite the wide scientific interest on the effects of sleep on the synapse, there is a lack of systematic investigation of sleep-related changes in the synaptic proteome. We isolated parietal cortical and thalamic synaptosomes of rats after 8h of total SD by gentle handling and 16h after the end of deprivation to investigate the short- and longer-term effects of SD on the synaptic proteome, respectively...
January 10, 2017: Molecular and Cellular Neurosciences
https://www.readbyqxmd.com/read/28079521/isoform-specific-subcellular-localization-and-function-of-protein-kinase-a-identified-by-mosaic-imaging-of-mouse-brain
#11
Ronit Ilouz, Varda Lev-Ram, Eric A Bushong, Travis L Stiles, Dinorah Friedmann-Morvinski, Christopher Douglas, Geoffrey Goldberg, Mark H Ellisman, Susan S Taylor
Protein kinase A (PKA) plays critical roles in neuronal function that are mediated by different regulatory (R) subunits. Deficiency in either RIβ or RIIβ subunits results in distinct neuronal phenotypes. Although RIβ contributes to synaptic plasticity, it is the least studied isoform. Using isoform-specific antibodies we generated high-resolution large-scale immunohistochemical mosaic images of mouse brain that provide global views of several brain regions, including the hippocampus and cerebellum. The isoforms concentrate in discrete brain regions and we then zoom-in to show distinct patterns of subcellular localization...
January 12, 2017: ELife
https://www.readbyqxmd.com/read/28073926/mutations-of-pqbp1-in-renpenning-syndrome-promote-ubiquitin-mediated-degradation-of-fmrp-and-cause-synaptic-dysfunction
#12
Xiao-Yan Zhang, Junxia Qi, Yu-Qian Shen, Xian Liu, An Liu, Zikai Zhou, Junhai Han, Zi Chao Zhang
Renpenning syndrome is a group of X-linked intellectual disability (XLID) syndromes caused by mutations in human polyglutamine-binding protein 1 (PQBP1) gene. Little is known about the molecular pathogenesis of the various mutations that cause the notable variability in patients. In this study, we examine the cellular and synaptic functions of the most common mutations found in the patients: c.461_462delAG, c.459_462delAGAG, and c.463_464dupAG in an AG hexamer in PQBP1 exon 4. We discovered that PQBP1 c.459_462delAGAG and c...
January 10, 2017: Human Molecular Genetics
https://www.readbyqxmd.com/read/28070120/the-protocadherin-17-gene-affects-cognition-personality-amygdala-structure-and-function-synapse-development-and-risk-of-major-mood-disorders
#13
H Chang, N Hoshina, C Zhang, Y Ma, H Cao, Y Wang, D-D Wu, S E Bergen, M Landén, C M Hultman, M Preisig, Z Kutalik, E Castelao, M Grigoroiu-Serbanescu, A J Forstner, J Strohmaier, J Hecker, T G Schulze, B Müller-Myhsok, A Reif, P B Mitchell, N G Martin, P R Schofield, S Cichon, M M Nöthen, H Walter, S Erk, A Heinz, N Amin, C M van Duijn, A Meyer-Lindenberg, H Tost, X Xiao, T Yamamoto, M Rietschel, M Li
Major mood disorders, which primarily include bipolar disorder and major depressive disorder, are the leading cause of disability worldwide and pose a major challenge in identifying robust risk genes. Here, we present data from independent large-scale clinical data sets (including 29 557 cases and 32 056 controls) revealing brain expressed protocadherin 17 (PCDH17) as a susceptibility gene for major mood disorders. Single-nucleotide polymorphisms (SNPs) spanning the PCDH17 region are significantly associated with major mood disorders; subjects carrying the risk allele showed impaired cognitive abilities, increased vulnerable personality features, decreased amygdala volume and altered amygdala function as compared with non-carriers...
January 10, 2017: Molecular Psychiatry
https://www.readbyqxmd.com/read/28065609/sexually-dimorphic-differentiation-of-a-c-%C3%A2-elegans-hub-neuron-is-cell-autonomously-controlled-by-a-conserved-transcription-factor
#14
Esther Serrano-Saiz, Meital Oren-Suissa, Emily A Bayer, Oliver Hobert
Functional and anatomical sexual dimorphisms in the brain are either the result of cells that are generated only in one sex or a manifestation of sex-specific differentiation of neurons present in both sexes. The PHC neuron pair of the nematode C. elegans differentiates in a strikingly sex-specific manner. In hermaphrodites the PHC neurons display a canonical pattern of synaptic connectivity similar to that of other sensory neurons, but in males PHC differentiates into a densely connected hub sensory neuron/interneuron, integrating a large number of male-specific synaptic inputs and conveying them to both male-specific and sex-shared circuitry...
January 2, 2017: Current Biology: CB
https://www.readbyqxmd.com/read/28054433/insertion-of-neurotransmitters-into-lipid-bilayer-membrane-and-its-implication-on-membrane-stability-a-molecular-dynamics-study
#15
Chun Shen, Minmin Xue, Hu Qiu, Wanlin Guo
The signaling molecules in neuron called neurotransmitters play an essential role in transportation of neural signal, during which the neurotransmitters interact with not only specific receptors but also cytomembranes such as synaptic vesicle membranes and postsynaptic membranes. Here we investigate by extensive molecular dynamics simulations the atomic-scale insertion dynamics of typical neurotransmitters, including methionine enkephalin (ME), leucine enkephalin (LE), dopamine (DA), acetylcholine (ACh) and aspartic acid (ASP), into lipid bilayers...
January 5, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28052248/hox2-genes-are-required-for-tonotopic-map-precision-and-sound-discrimination-in-the-mouse-auditory-brainstem
#16
Kajari Karmakar, Yuichi Narita, Jonathan Fadok, Sebastien Ducret, Alberto Loche, Taro Kitazawa, Christel Genoud, Thomas Di Meglio, Raphael Thierry, Joao Bacelo, Andreas Lüthi, Filippo M Rijli
Tonotopy is a hallmark of auditory pathways and provides the basis for sound discrimination. Little is known about the involvement of transcription factors in brainstem cochlear neurons orchestrating the tonotopic precision of pre-synaptic input. We found that in the absence of Hoxa2 and Hoxb2 function in Atoh1-derived glutamatergic bushy cells of the anterior ventral cochlear nucleus, broad input topography and sound transmission were largely preserved. However, fine-scale synaptic refinement and sharpening of isofrequency bands of cochlear neuron activation upon pure tone stimulation were impaired in Hox2 mutants, resulting in defective sound-frequency discrimination in behavioral tests...
January 3, 2017: Cell Reports
https://www.readbyqxmd.com/read/28052116/functional-maturation-of-human-stem-cell-derived-neurons-in-long-term-cultures
#17
Rebecca S Lam, Felix M Töpfer, Phillip G Wood, Volker Busskamp, Ernst Bamberg
Differentiated neurons can be rapidly acquired, within days, by inducing stem cells to express neurogenic transcription factors. We developed a protocol to maintain long-term cultures of human neurons, called iNGNs, which are obtained by inducing Neurogenin-1 and Neurogenin-2 expression in induced pluripotent stem cells. We followed the functional development of iNGNs over months and they showed many hallmark properties for neuronal maturation, including robust electrical and synaptic activity. Using iNGNs expressing a variant of channelrhodopsin-2, called CatCh, we could control iNGN activity with blue light stimulation...
2017: PloS One
https://www.readbyqxmd.com/read/28041884/synaptic-correlates-of-working-memory-capacity
#18
Yuanyuan Mi, Mikhail Katkov, Misha Tsodyks
Psychological studies indicate that human ability to keep information in readily accessible working memory is limited to four items for most people. This extremely low capacity severely limits execution of many cognitive tasks, but its neuronal underpinnings remain unclear. Here we show that in the framework of synaptic theory of working memory, capacity can be analytically estimated to scale with characteristic time of short-term synaptic depression relative to synaptic current time constant. The number of items in working memory can be regulated by external excitation, enabling the system to be tuned to the desired load and to clear the working memory of currently held items to make room for new ones...
January 18, 2017: Neuron
https://www.readbyqxmd.com/read/28041634/weighing-the-evidence-in-peters-rule-does-neuronal-morphology-predict-connectivity
#19
REVIEW
Christopher L Rees, Keivan Moradi, Giorgio A Ascoli
Although the importance of network connectivity is increasingly recognized, identifying synapses remains challenging relative to the routine characterization of neuronal morphology. Thus, researchers frequently employ axon-dendrite colocations as proxies of potential connections. This putative equivalence, commonly referred to as Peters' rule, has been recently studied at multiple levels and scales, fueling passionate debates regarding its validity. Our critical literature review identifies three conceptually distinct but often confused applications: inferring neuron type circuitry, predicting synaptic contacts among individual cells, and estimating synapse numbers within neuron pairs...
December 29, 2016: Trends in Neurosciences
https://www.readbyqxmd.com/read/28039376/a-mammalian-retinal-ganglion-cell-implements-a-neuronal-computation-that-maximizes-the-snr-of-its-postsynaptic-currents
#20
Jan Homann, Michael A Freed
Neurons perform computations by integrating excitatory and inhibitory synaptic inputs. Yet it is rarely understood what computation is being performed, or how much excitation or inhibition this computation requires. Here we present evidence for a neuronal computation that maximizes signal-to-noise power ratio (SNR). We recorded from OFF delta retinal ganglion cells in the guinea pig retina and monitored synaptic currents that were evoked by visual stimulation (flashing dark spots). These synaptic currents were mediated by a decrease in an outward current from inhibitory synapses (disinhibition) combined with an increase in an inward current from excitatory synapses...
December 30, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
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