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Synaptic scaling

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https://www.readbyqxmd.com/read/28192429/co-emergence-of-multi-scale-cortical-activities-of-irregular-firing-oscillations-and-avalanches-achieves-cost-efficient-information-capacity
#1
Dong-Ping Yang, Hai-Jun Zhou, Changsong Zhou
The brain is highly energy consuming, therefore is under strong selective pressure to achieve cost-efficiency in both cortical connectivities and activities. However, cost-efficiency as a design principle for cortical activities has been rarely studied. Especially it is not clear how cost-efficiency is related to ubiquitously observed multi-scale properties: irregular firing, oscillations and neuronal avalanches. Here we demonstrate that these prominent properties can be simultaneously observed in a generic, biologically plausible neural circuit model that captures excitation-inhibition balance and realistic dynamics of synaptic conductance...
February 13, 2017: PLoS Computational Biology
https://www.readbyqxmd.com/read/28188914/connectivity-based-parcellation-reveals-distinct-cortico-striatal-connectivity-fingerprints-in-autism-spectrum-disorder
#2
Joshua H Balsters, Dante Mantini, Nicole Wenderoth
Autism Spectrum Disorder (ASD) has been associated with abnormal synaptic development causing a breakdown in functional connectivity. However, when measured at the macro scale using resting state fMRI, these alterations are subtle and often difficult to detect due to the large heterogeneity of the pathology. Recently, we outlined a novel approach for generating robust biomarkers of resting state functional magnetic resonance imaging (RS-fMRI) using connectivity based parcellation of gross morphological structures to improve single-subject reproducibility and generate more robust connectivity fingerprints...
February 7, 2017: NeuroImage
https://www.readbyqxmd.com/read/28181535/nanoscale-diffusion-in-the-synaptic-cleft-and-beyond-measured-with-time-resolved-fluorescence-anisotropy-imaging
#3
Kaiyu Zheng, Thomas P Jensen, Leonid P Savtchenko, James A Levitt, Klaus Suhling, Dmitri A Rusakov
Neural activity relies on molecular diffusion within nanoscopic spaces outside and inside nerve cells, such as synaptic clefts or dendritic spines. Measuring diffusion on this small scale in situ has not hitherto been possible, yet this knowledge is critical for understanding the dynamics of molecular events and electric currents that shape physiological signals throughout the brain. Here we advance time-resolved fluorescence anisotropy imaging combined with two-photon excitation microscopy to map nanoscale diffusivity in ex vivo brain slices...
February 9, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28178527/an-intrinsic-transcriptional-program-underlying-synaptic-scaling-during-activity-suppression
#4
Katie Schaukowitch, Austin L Reese, Seung-Kyoon Kim, Gokhul Kilaru, Jae-Yeol Joo, Ege T Kavalali, Tae-Kyung Kim
Homeostatic scaling allows neurons to maintain stable activity patterns by globally altering their synaptic strength in response to changing activity levels. Suppression of activity by the blocking of action potentials increases synaptic strength through an upregulation of surface α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors. Although this synaptic upscaling was shown to require transcription, the molecular nature of the intrinsic transcription program underlying this process and its functional significance have been unclear...
February 7, 2017: Cell Reports
https://www.readbyqxmd.com/read/28174614/weak-electric-fields-detectability-in-a-noisy-neural-network
#5
Jia Zhao, Bin Deng, Yingmei Qin, Cong Men, Jiang Wang, Xile Wei, Jianbing Sun
We investigate the detectability of weak electric field in a noisy neural network based on Izhikevich neuron model systematically. The neural network is composed of excitatory and inhibitory neurons with similar ratio as that in the mammalian neocortex, and the axonal conduction delays between neurons are also considered. It is found that the noise intensity can modulate the detectability of weak electric field. Stochastic resonance (SR) phenomenon induced by white noise is observed when the weak electric field is added to the network...
February 2017: Cognitive Neurodynamics
https://www.readbyqxmd.com/read/28168402/macroscopic-neural-mass-model-constructed-from-a-current-based-network-model-of-spiking-neurons
#6
Hiroaki Umehara, Masato Okada, Jun-Nosuke Teramae, Yasushi Naruse
Neural mass models (NMMs) are efficient frameworks for describing macroscopic cortical dynamics including electroencephalogram and magnetoencephalogram signals. Originally, these models were formulated on an empirical basis of synaptic dynamics with relatively long time constants. By clarifying the relations between NMMs and the dynamics of microscopic structures such as neurons and synapses, we can better understand cortical and neural mechanisms from a multi-scale perspective. In a previous study, the NMMs were analytically derived by averaging the equations of synaptic dynamics over the neurons in the population and further averaging the equations of the membrane-potential dynamics...
February 6, 2017: Biological Cybernetics
https://www.readbyqxmd.com/read/28158309/learning-by-stimulation-avoidance-a-principle-to-control-spiking-neural-networks-dynamics
#7
Lana Sinapayen, Atsushi Masumori, Takashi Ikegami
Learning based on networks of real neurons, and learning based on biologically inspired models of neural networks, have yet to find general learning rules leading to widespread applications. In this paper, we argue for the existence of a principle allowing to steer the dynamics of a biologically inspired neural network. Using carefully timed external stimulation, the network can be driven towards a desired dynamical state. We term this principle "Learning by Stimulation Avoidance" (LSA). We demonstrate through simulation that the minimal sufficient conditions leading to LSA in artificial networks are also sufficient to reproduce learning results similar to those obtained in biological neurons by Shahaf and Marom, and in addition explains synaptic pruning...
2017: PloS One
https://www.readbyqxmd.com/read/28156212/changes-in-the-hippocampal-proteome-associated-with-spatial-memory-impairment-after-exposure-to-low-20-cgy-doses-of-1-gev-n-56-fe-radiation
#8
Richard A Britten, Jessica S Jewell, Leslie K Davis, Vania D Miller, Melissa M Hadley, O John Semmes, György Lonart, Sucharita M Dutta
Exposure to low (∼20 cGy) doses of high-energy charged(HZE) particles, such as 1 GeV/n (56)Fe, results in impaired hippocampal-dependent learning and memory (e.g., novel object recognition and spatial memory) in rodents. While these findings raise the possibility that astronauts on deep-space missions may develop cognitive deficits, not all rats develop HZE-induced cognitive impairments, even after exposure to high (200 cGy) HZE doses. The reasons for this differential sensitivity in some animals that develop HZE-induced cognitive failure remain speculative...
February 3, 2017: Radiation Research
https://www.readbyqxmd.com/read/28154077/homer1a-drives-homeostatic-scaling-down-of-excitatory-synapses-during-sleep
#9
Graham H Diering, Raja S Nirujogi, Richard H Roth, Paul F Worley, Akhilesh Pandey, Richard L Huganir
Sleep is an essential process that supports learning and memory by acting on synapses through poorly understood molecular mechanisms. Using biochemistry, proteomics, and imaging in mice, we find that during sleep, synapses undergo widespread alterations in composition and signaling, including weakening of synapses through removal and dephosphorylation of synaptic AMPA-type glutamate receptors. These changes are driven by the immediate early gene Homer1a and signaling from group I metabotropic glutamate receptors mGluR1/5...
February 3, 2017: Science
https://www.readbyqxmd.com/read/28154076/ultrastructural-evidence-for-synaptic-scaling-across-the-wake-sleep-cycle
#10
Luisa de Vivo, Michele Bellesi, William Marshall, Eric A Bushong, Mark H Ellisman, Giulio Tononi, Chiara Cirelli
It is assumed that synaptic strengthening and weakening balance throughout learning to avoid runaway potentiation and memory interference. However, energetic and informational considerations suggest that potentiation should occur primarily during wake, when animals learn, and depression should occur during sleep. We measured 6920 synapses in mouse motor and sensory cortices using three-dimensional electron microscopy. The axon-spine interface (ASI) decreased ~18% after sleep compared with wake. This decrease was proportional to ASI size, which is indicative of scaling...
February 3, 2017: Science
https://www.readbyqxmd.com/read/28154034/synaptic-scaling-in-sleep
#11
László Acsády, Kenneth D Harris
No abstract text is available yet for this article.
February 3, 2017: Science
https://www.readbyqxmd.com/read/28151556/probing-nano-organization-of-astroglia-with-multi-color-super-resolution-microscopy
#12
Janosch P Heller, Piotr Michaluk, Kohtaroh Sugao, Dmitri A Rusakov
Astroglia are essential for brain development, homeostasis, and metabolic support. They also contribute actively to the formation and regulation of synaptic circuits, by successfully handling, integrating, and propagating physiological signals of neural networks. The latter occurs mainly by engaging a versatile mechanism of internal Ca(2+) fluctuations and regenerative waves prompting targeted release of signaling molecules into the extracellular space. Astroglia also show substantial structural plasticity associated with age- and use-dependent changes in neural circuitry...
February 2, 2017: Journal of Neuroscience Research
https://www.readbyqxmd.com/read/28135266/memory-replay-in-balanced-recurrent-networks
#13
Nikolay Chenkov, Henning Sprekeler, Richard Kempter
Complex patterns of neural activity appear during up-states in the neocortex and sharp waves in the hippocampus, including sequences that resemble those during prior behavioral experience. The mechanisms underlying this replay are not well understood. How can small synaptic footprints engraved by experience control large-scale network activity during memory retrieval and consolidation? We hypothesize that sparse and weak synaptic connectivity between Hebbian assemblies are boosted by pre-existing recurrent connectivity within them...
January 2017: PLoS Computational Biology
https://www.readbyqxmd.com/read/28104799/muscles-innervated-by-a-single-motor-neuron-exhibit-divergent-synaptic-properties-on-multiple-time-scales
#14
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
#15
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
#16
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
#17
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
#18
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
#19
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
#20
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
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