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Synaptic scaling

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https://www.readbyqxmd.com/read/28336415/sncam-as-a-specific-marker-of-peripheral-demyelination
#1
Adam Niezgoda, Sławomir Michalak, Jacek Losy, Alicja Kalinowska-Łyszczarz, Wojciech Kozubski
Adhesion molecules are involved in nerve growth, synaptic plasticity and myelin formation and maintenance process. Neural cell adhesion molecule (CD56 or NCAM) seems to play a crucial role in all the above-mentioned events. Having found poly-sialylated NCAM increased re-expression on demyelinated axons within multiple sclerosis plaques we assessed soluble NCAM (sNCAM) in sera of patients with various types of peripheral nerve affections - demyelinating, axonal "inflammatory", axonal metabolic polyneuropathies and healthy controls...
March 20, 2017: Immunology Letters
https://www.readbyqxmd.com/read/28332227/general-features-of-inhibition-in-the-inner-retina
#2
Katrin Franke, Tom Baden
Visual processing starts in the retina. Within only two synaptic layers, a large number of parallel information channels emerge, each encoding a highly processed feature like edges or the direction of motion. Much of this functional diversity arises in the inner plexiform layer, where inhibitory amacrine cells modulate the excitatory signal of bipolar and ganglion cells. Studies investigating individual amacrine cell circuits like the starburst or A17 circuit have demonstrated that single types can possess specific morphological and functional adaptations to convey a particular function in one or a small number of inner retinal circuits...
March 23, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28306273/chaos-and-correlated-avalanches-in-excitatory-neural-networks-with-synaptic-plasticity
#3
Fabrizio Pittorino, Miguel Ibáñez-Berganza, Matteo di Volo, Alessandro Vezzani, Raffaella Burioni
A collective chaotic phase with power law scaling of activity events is observed in a disordered mean field network of purely excitatory leaky integrate-and-fire neurons with short-term synaptic plasticity. The dynamical phase diagram exhibits two transitions from quasisynchronous and asynchronous regimes to the nontrivial, collective, bursty regime with avalanches. In the homogeneous case without disorder, the system synchronizes and the bursty behavior is reflected into a period doubling transition to chaos for a two dimensional discrete map...
March 3, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28304362/bdnf-variants-may-modulate-long-term-visual-memory-performance-in-a-healthy-cohort
#4
Nesli Avgan, Heidi G Sutherland, Lauren K Spriggens, Chieh Yu, Omar Ibrahim, Claire Bellis, Larisa M Haupt, David H K Shum, Lyn R Griffiths
Brain-derived neurotrophic factor (BDNF) is involved in numerous cognitive functions including learning and memory. BDNF plays an important role in synaptic plasticity in humans and rats with BDNF shown to be essential for the formation of long-term memories. We previously identified a significant association between the BDNF Val66Met polymorphism (rs6265) and long-term visual memory (p-value = 0.003) in a small cohort (n = 181) comprised of healthy individuals who had been phenotyped for various aspects of memory function...
March 17, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/28290135/spinal-cord-injury-impairs-neurogenesis-and-induces-glial-reactivity-in-the-hippocampus
#5
Ignacio Jure, Luciana Pietranera, Alejandro F De Nicola, Florencia Labombarda
The incorporation of newborn neurons with increased synaptic remodeling and activity-dependent plasticity in the dentate gyrus enhances hippocampal-dependent learning performances. Astrocytes and microglial cells are components of the neurogenic niche and regulate neurogenesis under normal and neurophatological conditions leading to functional consequences for learning and memory. Although cognitive impairments were reported in patients after spinal cord injury (SCI), only few studies have considered remote changes in brain structures which are not related with sensory and motor cortex...
March 13, 2017: Neurochemical Research
https://www.readbyqxmd.com/read/28279228/erratum-to-%C3%AE-amyloid-triggers-aberrant-over-scaling-of-homeostatic-synaptic-plasticity
#6
James Gilbert, Shu Shu, Xin Yang, Youming Lu, Ling-Qiang Zhu, Heng-Ye Man
No abstract text is available yet for this article.
March 9, 2017: Acta Neuropathologica Communications
https://www.readbyqxmd.com/read/28270025/a-scalable-weight-free-learning-algorithm-for-regulatory-control-of-cell-activity-in-spiking-neuronal-networks
#7
Xu Zhang, Greg Foderaro, Craig Henriquez, Silvia Ferrari
Recent developments in neural stimulation and recording technologies are providing scientists with the ability of recording and controlling the activity of individual neurons in vitro or in vivo, with very high spatial and temporal resolution. Tools such as optogenetics, for example, are having a significant impact in the neuroscience field by delivering optical firing control with the precision and spatiotemporal resolution required for investigating information processing and plasticity in biological brains...
December 22, 2016: International Journal of Neural Systems
https://www.readbyqxmd.com/read/28269645/development-of-a-detailed-model-of-calcium-dynamics-at-the-postsynaptic-spine-of-an-excitatory-synapse
#8
Eric Y Hu, Jean-Marie C Bouteiller, Dong Song, Theodore W Berger
Postsynaptic calcium dynamics play a critical role in synaptic plasticity, but are often difficult to measure in experimental protocols due to their relatively fast rise and decay times, and the small spine dimensions. To circumvent these limitations, we propose to develop a computational model of calcium dynamics in the postsynaptic spine. This model integrates the main elements that participate in calcium concentration influx, efflux, diffusion and buffering. These consist of (i) spine geometry; (ii) calcium influx through NMDA receptors and voltage-dependent calcium channels (VDCC); (iii) calcium efflux with plasma membrane calcium pumps (PMCA) and sodium-calcium exchangers (NCX); (iv) intracellular calcium stores; and (v) calcium buffers...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28260126/neuroplasticity-and-second-messenger-pathways-in-antidepressant-efficacy-pharmacogenetic-results-from-a-prospective-trial-investigating-treatment-resistance
#9
Chiara Fabbri, Concetta Crisafulli, Raffaella Calati, Diego Albani, Gianluigi Forloni, Marco Calabrò, Rosalba Martines, Siegfried Kasper, Joseph Zohar, Alzbeta Juven-Wetzler, Daniel Souery, Stuart Montgomery, Julien Mendlewicz, Alessandro Serretti
Genes belonging to neuroplasticity, monoamine, circadian rhythm, and transcription factor pathways were investigated as modulators of antidepressant efficacy. The present study aimed (1) to replicate previous findings in an independent sample with treatment-resistant depression (TRD), and (2) to perform a pathway analysis to investigate the possible molecular mechanisms involved. 220 patients with major depressive disorder who were non-responders to a previous antidepressant were treated with venlafaxine for 4-6 weeks and in case of non-response with escitalopram for 4-6 weeks...
March 4, 2017: European Archives of Psychiatry and Clinical Neuroscience
https://www.readbyqxmd.com/read/28255461/dynamic-control-of-synaptic-adhesion-and-organizing-molecules-in-synaptic-plasticity
#10
REVIEW
Gabby Rudenko
Synapses play a critical role in establishing and maintaining neural circuits, permitting targeted information transfer throughout the brain. A large portfolio of synaptic adhesion/organizing molecules (SAMs) exists in the mammalian brain involved in synapse development and maintenance. SAMs bind protein partners, forming trans-complexes spanning the synaptic cleft or cis-complexes attached to the same synaptic membrane. SAMs play key roles in cell adhesion and in organizing protein interaction networks; they can also provide mechanisms of recognition, generate scaffolds onto which partners can dock, and likely take part in signaling processes as well...
2017: Neural Plasticity
https://www.readbyqxmd.com/read/28250467/automated-synaptic-connectivity-inference-for-volume-electron-microscopy
#11
Sven Dorkenwald, Philipp J Schubert, Marius F Killinger, Gregor Urban, Shawn Mikula, Fabian Svara, Joergen Kornfeld
Teravoxel volume electron microscopy data sets from neural tissue can now be acquired in weeks, but data analysis requires years of manual labor. We developed the SyConn framework, which uses deep convolutional neural networks and random forest classifiers to infer a richly annotated synaptic connectivity matrix from manual neurite skeleton reconstructions by automatically identifying mitochondria, synapses and their types, axons, dendrites, spines, myelin, somata and cell types. We tested our approach on serial block-face electron microscopy data sets from zebrafish, mouse and zebra finch, and computed the synaptic wiring of songbird basal ganglia...
February 27, 2017: Nature Methods
https://www.readbyqxmd.com/read/28236778/interactions-between-synaptic-homeostatic-mechanisms-an-attempt-to-reconcile-bcm-theory-synaptic-scaling-and-changing-excitation-inhibition-balance
#12
REVIEW
Tara Keck, Mark Hübener, Tobias Bonhoeffer
Homeostatic plasticity is proposed to be mediated by synaptic changes, such as synaptic scaling and shifts in the excitation/inhibition balance. These mechanisms are thought to be separate from the Bienenstock, Cooper, Munro (BCM) learning rule, where the threshold for the induction of long-term potentiation and long-term depression slides in response to changes in activity levels. Yet, both sets of mechanisms produce a homeostatic response of a relative increase (or decrease) in strength of excitatory synapses in response to overall activity-level changes...
February 22, 2017: Current Opinion in Neurobiology
https://www.readbyqxmd.com/read/28235895/spike-and-neuropeptide-dependent-mechanisms-control-gnrh-neuron-nerve-terminal-ca-2-over-diverse-time-scales
#13
Karl J Iremonger, Robert Porteous, Allan E Herbison
Fast cell-to-cell communication in the brain is achieved by action potential-dependent synaptic release of neurotransmitters. The fast kinetics of transmitter release are determined by transient Ca(2+) elevations in presynaptic nerve terminals. Neuromodulators have previously been shown to regulate transmitter release by inhibiting presynaptic Ca(2+) influx. Few studies to date have demonstrated the opposite, that is, neuromodulators directly driving presynaptic Ca(2+) rises and increases in nerve terminal excitability...
February 24, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28227903/development-of-a-detailed-model-of-calcium-dynamics-at-the-postsynaptic-spine-of-an-excitatory-synapse
#14
Eric Y Hu, Jean-Marie C Bouteiller, Dong Song, Theodore W Berger, Eric Y Hu, Jean-Marie C Bouteiller, Dong Song, Theodore W Berger, Jean-Marie C Bouteiller, Eric Y Hu, Dong Song, Theodore W Berger
Postsynaptic calcium dynamics play a critical role in synaptic plasticity, but are often difficult to measure in experimental protocols due to their relatively fast rise and decay times, and the small spine dimensions. To circumvent these limitations, we propose to develop a computational model of calcium dynamics in the postsynaptic spine. This model integrates the main elements that participate in calcium concentration influx, efflux, diffusion and buffering. These consist of (i) spine geometry; (ii) calcium influx through NMDA receptors and voltage-dependent calcium channels (VDCC); (iii) calcium efflux with plasma membrane calcium pumps (PMCA) and sodium-calcium exchangers (NCX); (iv) intracellular calcium stores; and (v) calcium buffers...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28220467/emergent-dynamical-properties-of-the-bcm-learning-rule
#15
Lawrence C Udeigwe, Paul W Munro, G Bard Ermentrout
The Bienenstock-Cooper-Munro (BCM) learning rule provides a simple setup for synaptic modification that combines a Hebbian product rule with a homeostatic mechanism that keeps the weights bounded. The homeostatic part of the learning rule depends on the time average of the post-synaptic activity and provides a sliding threshold that distinguishes between increasing or decreasing weights. There are, thus, two essential time scales in the BCM rule: a homeostatic time scale, and a synaptic modification time scale...
December 2017: Journal of Mathematical Neuroscience
https://www.readbyqxmd.com/read/28192429/co-emergence-of-multi-scale-cortical-activities-of-irregular-firing-oscillations-and-avalanches-achieves-cost-efficient-information-capacity
#16
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 2017: PLoS Computational Biology
https://www.readbyqxmd.com/read/28188914/connectivity-based-parcellation-reveals-distinct-cortico-striatal-connectivity-fingerprints-in-autism-spectrum-disorder
#17
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
#18
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
#19
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
#20
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
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