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Synaptic scaling

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https://www.readbyqxmd.com/read/29157358/rng105-caprin1-an-rna-granule-protein-for-dendritic-mrna-localization-is-essential-for-long-term-memory-formation
#1
Kei Nakayama, Rie Ohashi, Yo Shinoda, Maya Yamazaki, Manabu Abe, Akihiro Fujikawa, Shuji Shigenobu, Akira Futatsugi, Masaharu Noda, Katsuhiko Mikoshiba, Teiichi Furuichi, Kenji Sakimura, Nobuyuki Shiina
Local regulation of synaptic efficacy is thought to be important for proper networking of neurons and memory formation. Dysregulation of global translation influences long-term memory in mice, but the relevance of the regulation specific for local translation by RNA granules remains elusive. Here, we demonstrate roles of RNG105/caprin1 in long-term memory formation. RNG105 deletion in mice impaired synaptic strength and structural plasticity in hippocampal neurons. Furthermore, RNG105-deficient mice displayed unprecedentedly severe defects in long-term memory formation in spatial and contextual learning tasks...
November 21, 2017: ELife
https://www.readbyqxmd.com/read/29155814/optimal-synaptic-signaling-connectome-for-locomotory-behavior-in-caenorhabditis-elegans-design-minimizing-energy-cost
#2
Franciszek Rakowski, Jan Karbowski
The detailed knowledge of C. elegans connectome for 3 decades has not contributed dramatically to our understanding of worm's behavior. One of main reasons for this situation has been the lack of data on the type of synaptic signaling between particular neurons in the worm's connectome. The aim of this study was to determine synaptic polarities for each connection in a small pre-motor circuit controlling locomotion. Even in this compact network of just 7 neurons the space of all possible patterns of connection types (excitation vs...
November 20, 2017: PLoS Computational Biology
https://www.readbyqxmd.com/read/29154130/neuropilin-2-plexina3-receptors-associate-with-glua1-and-mediate-sema3f-dependent-homeostatic-scaling-in-cortical-neurons
#3
Qiang Wang, Shu-Ling Chiu, Eleftheria Koropouli, Ingie Hong, Sarah Mitchell, Teresa P Easwaran, Natalie R Hamilton, Ahleah S Gustina, Qianwen Zhu, David D Ginty, Richard L Huganir, Alex L Kolodkin
Regulation of AMPA-type glutamate receptor (AMPAR) number at synapses is a major mechanism for controlling synaptic strength during homeostatic scaling in response to global changes in neural activity. We show that the secreted guidance cue semaphorin 3F (Sema3F) and its neuropilin-2 (Npn-2)/plexinA3 (PlexA3) holoreceptor mediate homeostatic plasticity in cortical neurons. Sema3F-Npn-2/PlexA3 signaling is essential for cell surface AMPAR homeostatic downscaling in response to an increase in neuronal activity, Npn-2 associates with AMPARs, and Sema3F regulates this interaction...
November 14, 2017: Neuron
https://www.readbyqxmd.com/read/29153862/tumor-necrosis-factor-alpha-in-sleep-regulation
#4
REVIEW
Matthew D Rockstrom, Liangyu Chen, Ping Taishi, Joseph T Nguyen, Cody M Gibbons, Sigrid C Veasey, James M Krueger
This review details tumor necrosis factor alpha (TNF) biology and its role in sleep, and describes how TNF medications influence sleep/wake activity. Substantial evidence from healthy young animals indicates acute enhancement or inhibition of endogenous brain TNF respectively promotes and inhibits sleep. In contrast, the role of TNF in sleep in most human studies involves pathological conditions associated with chronic elevations of systemic TNF and disrupted sleep. Normalization of TNF levels in such patients improves sleep...
November 16, 2017: Sleep Medicine Reviews
https://www.readbyqxmd.com/read/29139050/modeling-mesoscopic-cortical-dynamics-using-a-mean-field-model-of-conductance-based-networks-of-adaptive-exponential-integrate-and-fire-neurons
#5
Yann Zerlaut, Sandrine Chemla, Frederic Chavane, Alain Destexhe
Voltage-sensitive dye imaging (VSDi) has revealed fundamental properties of neocortical processing at macroscopic scales. Since for each pixel VSDi signals report the average membrane potential over hundreds of neurons, it seems natural to use a mean-field formalism to model such signals. Here, we present a mean-field model of networks of Adaptive Exponential (AdEx) integrate-and-fire neurons, with conductance-based synaptic interactions. We study a network of regular-spiking (RS) excitatory neurons and fast-spiking (FS) inhibitory neurons...
November 15, 2017: Journal of Computational Neuroscience
https://www.readbyqxmd.com/read/29138675/benign-effect-of-extremely-low-frequency-electromagnetic-field-on-brain-plasticity-assessed-by-nitric-oxide-metabolism-during-poststroke-rehabilitation
#6
Natalia Cichoń, Piotr Czarny, Michał Bijak, Elżbieta Miller, Tomasz Śliwiński, Janusz Szemraj, Joanna Saluk-Bijak
Nitric oxide (NO) is one of the most important signal molecules, involved in both physiological and pathological processes. As a neurotransmitter in the central nervous system, NO regulates cerebral blood flow, neurogenesis, and synaptic plasticity. The aim of our study was to investigate the effect of the extremely low-frequency electromagnetic field (ELF-EMF) on generation and metabolism of NO, as a neurotransmitter, in the rehabilitation of poststroke patients. Forty-eight patients were divided into two groups: ELF-EMF and non-ELF-EMF...
2017: Oxidative Medicine and Cellular Longevity
https://www.readbyqxmd.com/read/29122591/spiking-and-excitatory-inhibitory-input-dynamics-of-barrel-cells-in-response-to-whisker-deflections-of-varying-velocity-and-angular-direction
#7
Mainak Patel
The spiking of barrel regular-spiking (RS) cells is tuned for both whisker deflection direction and velocity. Velocity tuning arises due to thalamocortical (TC) synchrony (but not spike quantity) varying with deflection velocity, coupled with feedforward inhibition, while direction selectivity is not fully understood, though may be due partly to direction tuning of TC spiking. Data show that as deflection direction deviates from the preferred direction of an RS cell, excitatory input to the RS cell diminishes minimally, but temporally shifts to coincide with the time-lagged inhibitory input...
November 6, 2017: Neuroscience
https://www.readbyqxmd.com/read/29120672/an-electrostatic-and-probabilistic-simulation-model-to-describe-neurosecretion-at-the-synaptic-scale
#8
A E Macias-Medri, Jacinto A Liendo, Ricardo J Silva
A hybrid simulation model (macro-molecular dynamics and Monte Carlo method) is proposed to reproduce neurosecretion and exocytosis. A theory has been developed for vesicular dynamics based on quasi-static electric interactions and a simple transition-state model for the vesicular fusion. Under the non-equilibrium electric conditions in an electrolytic fluid, it is considered that the motion of each synaptic vesicle is influenced by electrostatic forces exerted by the membranes of the synaptic bouton, other vesicles, the intracellular and intravesicular fluids, and external elements to the neuron...
November 9, 2017: Network: Computation in Neural Systems
https://www.readbyqxmd.com/read/29118000/ca-2-calmodulin-binding-to-psd-95-mediates-homeostatic-synaptic-scaling-down
#9
Dhrubajyoti Chowdhury, Matthew Turner, Tommaso Patriarchi, Anne C Hergarden, David Anderson, Yonghong Zhang, Junqing Sun, Chao-Yin Chen, James B Ames, Johannes W Hell
Postsynaptic density protein-95 (PSD-95) localizes AMPA-type glutamate receptors (AMPARs) to postsynaptic sites of glutamatergic synapses. Its postsynaptic displacement is necessary for loss of AMPARs during homeostatic scaling down of synapses. Here, we demonstrate that upon Ca(2+) influx, Ca(2+)/calmodulin (Ca(2+)/CaM) binding to the N-terminus of PSD-95 mediates postsynaptic loss of PSD-95 and AMPARs during homeostatic scaling down. Our NMR structural analysis identified E17 within the PSD-95 N-terminus as important for binding to Ca(2+)/CaM by interacting with R126 on CaM...
November 8, 2017: EMBO Journal
https://www.readbyqxmd.com/read/29107522/-silent-nmda-synapses-enhance-motion-sensitivity-in-a-mature-retinal-circuit
#10
Santhosh Sethuramanujam, Xiaoyang Yao, Geoff deRosenroll, Kevin L Briggman, Greg D Field, Gautam B Awatramani
Retinal direction-selective ganglion cells (DSGCs) have the remarkable ability to encode motion over a wide range of contrasts, relying on well-coordinated excitation and inhibition (E/I). E/I is orchestrated by a diverse set of glutamatergic bipolar cells that drive DSGCs directly, as well as indirectly through feedforward GABAergic/cholinergic signals mediated by starburst amacrine cells. Determining how direction-selective responses are generated across varied stimulus conditions requires understanding how glutamate, acetylcholine, and GABA signals are precisely coordinated...
October 25, 2017: Neuron
https://www.readbyqxmd.com/read/29107520/deprivation-induced-homeostatic-spine-scaling-in%C3%A2-vivo-is-localized-to-dendritic-branches-that-have-undergone-recent-spine-loss
#11
Samuel J Barnes, Eleonora Franzoni, R Irene Jacobsen, Ferenc Erdelyi, Gabor Szabo, Claudia Clopath, Georg B Keller, Tara Keck
Synaptic scaling is a key homeostatic plasticity mechanism and is thought to be involved in the regulation of cortical activity levels. Here we investigated the spatial scale of homeostatic changes in spine size following sensory deprivation in a subset of inhibitory (layer 2/3 GAD65-positive) and excitatory (layer 5 Thy1-positive) neurons in mouse visual cortex. Using repeated in vivo two-photon imaging, we find that increases in spine size are tumor necrosis factor alpha (TNF-α) dependent and thus are likely associated with synaptic scaling...
November 15, 2017: Neuron
https://www.readbyqxmd.com/read/29103806/local-order-within-global-disorder-synaptic-architecture-of-visual-space
#12
Benjamin Scholl, Daniel E Wilson, David Fitzpatrick
Substantial evidence at the subcellular level indicates that the spatial arrangement of synaptic inputs onto dendrites could play a significant role in cortical computations, but how synapses of functionally defined cortical networks are arranged within the dendrites of individual neurons remains unclear. Here we assessed one-dimensional spatial receptive fields of individual dendritic spines within individual layer 2/3 neuron dendrites. Spatial receptive field properties of dendritic spines were strikingly diverse, with no evidence of large-scale topographic organization...
November 1, 2017: Neuron
https://www.readbyqxmd.com/read/29102542/the-association-between-serum-matricellular-protein-secreted-protein-acidic-and-rich-in-cysteine-like-1-levels-and-ischemic-stroke-severity
#13
Wojciech Ambrosius, Slawomir Michalak, Radoslaw Kazmierski, Maria Lukasik, Natalia Andrzejewska, Wojciech Kozubski
BACKGROUND: The role of matricellular proteins like secreted protein acidic and rich in cysteine-like 1 (SC1) has been shown in important functions in the central nervous system, including the regulation of synaptic stability with upregulation throughout axonal regeneration. The aim of this study was to determine whether SC1 is related to ischemic stroke severity. METHODS: A total of 132 consecutively recruited patients admitted for acute ischemic stroke were included in this observational prospective study...
November 1, 2017: Journal of Stroke and Cerebrovascular Diseases: the Official Journal of National Stroke Association
https://www.readbyqxmd.com/read/29097542/lattice-system-of-functionally-distinct-cell-types-in-the-neocortex
#14
Hisato Maruoka, Nao Nakagawa, Shun Tsuruno, Seiichiro Sakai, Taisuke Yoneda, Toshihiko Hosoya
The mammalian neocortex contains many cell types, but whether they organize into repeated structures has been unclear. We discovered that major cell types in neocortical layer 5 form a lattice structure in many brain areas. Large-scale three-dimensional imaging revealed that distinct types of excitatory and inhibitory neurons form cell type-specific radial clusters termed microcolumns. Thousands of microcolumns, in turn, are patterned into a hexagonal mosaic tessellating diverse regions of the neocortex. Microcolumn neurons demonstrate synchronized in vivo activity and visual responses with similar orientation preference and ocular dominance...
November 3, 2017: Science
https://www.readbyqxmd.com/read/29096080/transcellular-nanoalignment-of-synaptic-function
#15
REVIEW
Thomas Biederer, Pascal S Kaeser, Thomas A Blanpied
At each of the brain's vast number of synapses, the presynaptic nerve terminal, synaptic cleft, and postsynaptic specialization form a transcellular unit to enable efficient transmission of information between neurons. While we know much about the molecular machinery within each compartment, we are only beginning to understand how these compartments are structurally registered and functionally integrated with one another. This review will describe the organization of each compartment and then discuss their alignment across pre- and postsynaptic cells at a nanometer scale...
November 1, 2017: Neuron
https://www.readbyqxmd.com/read/29095069/effects-of-tryptophan-depletion-on-selective-serotonin-reuptake-inhibitor-remitted-patients-with-obsessive-compulsive-disorder
#16
Sean D Hood, Annabel Broyd, Hayley Robinson, Jessica Lee, Abdul-Rahman Hudaib, Dana A Hince
BACKGROUND: Serotonergic antidepressants are first-line medication therapies for obsessive-compulsive disorder, however it is not known if synaptic serotonin availability is important for selective serotonin reuptake inhibitor efficacy. The present study tested the hypothesis that temporary reduction in central serotonin transmission, through acute tryptophan depletion, would result in an increase in anxiety in selective serotonin reuptake inhibitor-remitted obsessive-compulsive disorder patients...
October 1, 2017: Journal of Psychopharmacology
https://www.readbyqxmd.com/read/29091966/positive-feedback-and-synchronized-bursts-in-neuronal-cultures
#17
Yu-Ting Huang, Yu-Lin Chang, Chun-Chung Chen, Pik-Yin Lai, C K Chan
Synchronized bursts (SBs) with complex structures are common in neuronal cultures. Although the phenomenon of SBs has been discovered for a long time, its origin is still unclear. Here, we investigate the properties of these SBs in cultures grown on a multi-electrode array. We find that structures of these SBs are related to the different developmental stages of the cultures and these structures can be modified by changing the magnesium concentration in the culture medium; indicating that synaptic mechanism is involved in the generation of SBs...
2017: PloS One
https://www.readbyqxmd.com/read/29084181/altered-synaptic-membrane-retrieval-after-strong-stimulation-of-cerebellar-granule-neurons-in-cyclic-gmp-dependent-protein-kinase-ii-cgkii-knockout-mice
#18
Andrea Collado-Alsina, Franz Hofmann, José Sánchez-Prieto, Magdalena Torres
The nitric oxide (NO)/cyclic guanosine monophosphate (cGMP)/cGMP-dependent protein kinase (cGK) signaling pathway regulates the clustering and the recruitment of proteins and vesicles to the synapse, thereby adjusting the exoendocytic cycle to the intensity of activity. Accordingly, this pathway can accelerate endocytosis following large-scale exocytosis, and pre-synaptic cGK type II (cGKII) plays a major role in this process, controlling the homeostatic balance of vesicle exocytosis and endocytosis. We have studied synaptic vesicle recycling in cerebellar granule cells from mice lacking cGKII under strong and sustained stimulation, combining imaging techniques and ultrastructural analyses...
October 30, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/29074575/assessing-the-role-of-inhibition-in-stabilizing-neocortical-networks-requires-large-scale-perturbation-of-the-inhibitory-population
#19
Sadra Sadeh, R Angus Silver, Thomas Mrsic-Flogel, Dylan Richard Muir
Neurons within cortical microcircuits are interconnected with recurrent excitatory synaptic connections that are thought to amplify signals (Douglas and Martin, 2007), form selective subnetworks (Ko et al., 2011) and aid feature discrimination. Strong inhibition (Haider et al., 2013) counterbalances excitation, enabling sensory features to be sharpened and represented by sparse codes (Willmore et al., 2011). This balance between excitation and inhibition makes it difficult to assess the strength, or gain, of recurrent excitatory connections within cortical networks, which is key to understanding their operational regime and the computations they perform...
October 26, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/29071065/logarithmic-distributions-prove-that-intrinsic-learning-is-hebbian
#20
Gabriele Scheler
In this paper, we document lognormal distributions for spike rates, synaptic weights and intrinsic excitability (gain) for neurons in various brain areas, such as auditory or visual cortex, hippocampus, cerebellum, striatum, midbrain nuclei. We find a remarkable consistency of heavy-tailed, specifically lognormal, distributions for rates, weights and gains in all brain areas. The difference between strongly recurrent and feed-forward connectivity (cortex vs. striatum and cerebellum), neurotransmitter (GABA (striatum) or glutamate (cortex)) or the level of activation (low in cortex, high in Purkinje cells and midbrain nuclei) turns out to be irrelevant for this feature...
2017: F1000Research
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