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https://www.readbyqxmd.com/read/29443098/a-novel-in-vitro-live-imaging-assay-of-astrocyte-mediated-phagocytosis-using-ph-indicator-conjugated-synaptosomes
#1
Youkyeong Gloria Byun, Won-Suk Chung
Astrocytes are the major cell type in the brain and directly contact synapses and blood vessels. Although microglial cells have been considered the major immune cells and only phagocytes in the brain, recent studies have shown that astrocytes also participate in various phagocytic processes, such as developmental synapse elimination and clearance of amyloid beta plaques in Alzheimer's disease (AD). Despite these findings, the efficiency of astrocyte engulfment and degradation of their targets is unclear compared with that of microglia...
February 5, 2018: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/29431275/burst-spinal-cord-stimulation-review-of-preclinical-studies-and-comments-on-clinical-outcomes
#2
REVIEW
Krishnan Chakravarthy, Alexander R Kent, Adil Raza, Fang Xing, Thomas M Kinfe
BACKGROUND: Burst spinal cord stimulation (SCS) technology uses a novel waveform that consists of closely packed high-frequency electrical impulses followed by a quiescent period. Within the growing field of neuromodulation, burst stimulation is unique in that it mimics the natural burst firing of the nervous system, in particular the thalamo-cingulate rhythmicity, resulting in modulation of the affective and attentional components of pain processing (e.g., medial thalamic pathways). STUDY DESIGN: A review of preclinical and clinical studies regarding burst SCS for various chronic pain states...
February 12, 2018: Neuromodulation: Journal of the International Neuromodulation Society
https://www.readbyqxmd.com/read/29414768/lipids-and-phosphates-at-odds-in-synaptic-depression
#3
Anton Omelchenko, Bonnie L Firestein
Long-term depression (LTD) is a reduction in the efficacy of neuronal synapses, but the molecular basis of LTD signaling and how these signals lead to phenotypic outcomes, such as the shrinkage of synaptic regions, is not clear. In a new report, Woolfrey et al use chemically-induced LTD and a multitude of in vitro biochemical assays to provide evidence that synaptic removal of the scaffolding protein AKAP79/150 promotes LTD-induced spine shrinkage. The further identification of CaMKII, a kinase primarily associated with long-term potentiation (LTP), as a requirement for AKAP79/150 removal, uncovers unexpected interplay between different post-translational modifications and points to a new model of LTD...
February 2, 2018: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/29379174/structural-basis-for-recognition-of-diverse-antidepressants-by-the-human-serotonin-transporter
#4
Jonathan A Coleman, Eric Gouaux
Selective serotonin reuptake inhibitors are clinically prescribed antidepressants that act by increasing the local concentrations of neurotransmitters at synapses and in extracellular spaces via blockade of the serotonin transporter. Here we report X-ray structures of engineered thermostable variants of the human serotonin transporter bound to the antidepressants sertraline, fluvoxamine, and paroxetine. The drugs prevent serotonin binding by occupying the central substrate-binding site and stabilizing the transporter in an outward-open conformation...
January 29, 2018: Nature Structural & Molecular Biology
https://www.readbyqxmd.com/read/29360035/excitatory-motor-neurons-are-local-oscillators-for-backward-locomotion
#5
Shangbang Gao, Sihui Asuka Guan, Anthony D Fouad, Jun Meng, Taizo Kawano, Yung-Chi Huang, Yi Li, Salvador Alcaire, Wesley Hung, Yangning Lu, Yingchuan Billy Qi, Yishi Jin, Mark Alkema, Christopher Fang-Yen, Mei Zhen
Cell- or network-driven oscillators underlie motor rhythmicity. The identity of C. elegans oscillators remains unknown. Through cell ablation, electrophysiology, and calcium imaging, we show: (1) forward and backward locomotion is driven by different oscillators; (2) the cholinergic and excitatory A-class motor neurons exhibit intrinsic and oscillatory activity that is sufficient to drive backward locomotion in the absence of premotor interneurons; (3) the UNC-2 P/Q/N high-voltage-activated calcium current underlies A motor neuron's oscillation; (4) descending premotor interneurons AVA, via an evolutionarily conserved, mixed gap junction and chemical synapse configuration, exert state-dependent inhibition and potentiation of A motor neuron's intrinsic activity to regulate backward locomotion...
January 23, 2018: ELife
https://www.readbyqxmd.com/read/29358677/collective-responses-in-electrical-activities-of-neurons-under-field-coupling
#6
Ying Xu, Ya Jia, Jun Ma, Tasawar Hayat, Ahmed Alsaedi
Synapse coupling can benefit signal exchange between neurons and information encoding for neurons, and the collective behaviors such as synchronization and pattern selection in neuronal network are often discussed under chemical or electric synapse coupling. Electromagnetic induction is considered at molecular level when ion currents flow across the membrane and the ion concentration is fluctuated. Magnetic flux describes the effect of time-varying electromagnetic field, and memristor bridges the membrane potential and magnetic flux according to the dimensionalization requirement...
January 22, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29353084/creating-diverse-synapses-from-the-same-molecules
#7
REVIEW
Zoltan Nusser
Research over the past half a century has revealed remarkable diversity among chemical synapses of the CNS. The structural, functional and molecular diversity of synapses was mainly concluded from studying different synapses in distinct brain regions and preparations. It is not surprising that synapses made by molecularly distinct pre-synaptic and post-synaptic cells display different morphological and functional properties with distinct underlying molecular mechanisms. However, synapses made by a single presynaptic cell onto distinct types of postsynaptic cells, or distinct presynaptic inputs onto a single postsynaptic cell, also show remarkable heterogeneity...
January 17, 2018: Current Opinion in Neurobiology
https://www.readbyqxmd.com/read/29347189/turing-mechanism-for-homeostatic-control-of-synaptic-density-during-c-elegans-growth
#8
Heather A Brooks, Paul C Bressloff
We propose a mechanism for the homeostatic control of synapses along the ventral cord of Caenorhabditis elegans during development, based on a form of Turing pattern formation on a growing domain. C. elegans is an important animal model for understanding cellular mechanisms underlying learning and memory. Our mathematical model consists of two interacting chemical species, where one is passively diffusing and the other is actively trafficked by molecular motors, which switch between forward and backward moving states (bidirectional transport)...
July 2017: Physical Review. E
https://www.readbyqxmd.com/read/29324422/assimilation-of-biophysical-neuronal-dynamics-in-neuromorphic-vlsi
#9
Jun Wang, Daniel Breen, Abraham Akinin, Frederic Broccard, Henry D I Abarbanel, Gert Cauwenberghs
Representing the biophysics of neuronal dynamics and behavior offers a principled analysis-by-synthesis approach toward understanding mechanisms of nervous system functions. We report on a set of procedures assimilating and emulating neurobiological data on a neuromorphic very large scale integrated (VLSI) circuit. The analog VLSI chip, NeuroDyn, features 384 digitally programmable parameters specifying for 4 generalized Hodgkin-Huxley neurons coupled through 12 conductance-based chemical synapses. The parameters also describe reversal potentials, maximal conductances, and spline regressed kinetic functions for ion channel gating variables...
December 2017: IEEE Transactions on Biomedical Circuits and Systems
https://www.readbyqxmd.com/read/29298905/gliotransmission-beyond-black-and-white
#10
Iaroslav Savtchouk, Andrea Volterra
Astrocytes are highly complex cells with many emerging putative roles in brain function. Of these, gliotransmission (active information transfer from glia to neurons) has probably the widest implications on our understanding of how the brain works: do astrocytes really contribute to information processing within the neural circuitry? "Positive evidence" for this stems from work of multiple laboratories reporting many examples of modulatory chemical signaling from astrocytes to neurons in the timeframe of hundreds of milliseconds to several minutes...
January 3, 2018: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/29286422/methodology-for-biomimetic-chemical-neuromodulation-of-rat-retinas-with-the-neurotransmitter-glutamate-in-vitro
#11
Corey M Rountree, John B Troy, Laxman Saggere
Photoreceptor degenerative diseases cause irreparable blindness through the progressive loss of photoreceptor cells in the retina. Retinal prostheses are an emerging treatment for photoreceptor degenerative diseases that seek to restore vision by artificially stimulating the surviving retinal neurons in the hope of eliciting comprehensible visual perception in patients. Current retinal prostheses have demonstrated success in restoring limited vision to patients using an array of electrodes to electrically stimulate the retina but face substantial physical barriers in restoring high acuity, natural vision to patients...
December 19, 2017: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/29275163/cast-its-molecular-structure-and-phosphorylation-dependent-regulation-of-presynaptic-plasticity
#12
REVIEW
Shun Hamada, Toshihisa Ohtsuka
Our brain functions rely on sophisticated communication between synapses in the nervous system. Most synapses utilize a specialized submembranous structure, the so-called 'active zone', for the efficient transmission of chemical signals. The presynaptic active zone plays pivotal roles in the precise regulation of neurotransmitter release from the nerve terminals in a temporally and spatially coordinated manner. During the last two decades, several active zone-specific proteins have been isolated and characterized, including Bassoon, Piccolo/Aczonin, RIM, Munc13-1, ELKS, and CAST...
December 21, 2017: Neuroscience Research
https://www.readbyqxmd.com/read/29275162/vesicle-release-site-organization-at-synaptic-active-zones
#13
REVIEW
Alexander M Walter, Mathias A Böhme, Stephan J Sigrist
Information transfer between nerve cells (neurons) forms the basis of behavior, emotion, and survival. Signal transduction from one neuron to another occurs at synapses, and relies on both electrical and chemical signal propagation. At chemical synapses, incoming electrical action potentials trigger the release of chemical neurotransmitters that are sensed by the connected cell and here reconverted to an electrical signal. The presynaptic conversion of an electrical to a chemical signal is an energy demanding, highly regulated process that relies on a complex, evolutionarily conserved molecular machinery...
December 21, 2017: Neuroscience Research
https://www.readbyqxmd.com/read/29258853/drosophila-active-zones-from-molecules-to-behaviour
#14
REVIEW
Nadine Ehmann, David Owald, Robert J Kittel
In a constantly changing environment, neuronal circuits need to be updated and adjusted to elicit directed actions. Synaptic plasticity plays an important role in modulating such globally and locally acting networks. The active zone (AZ) is a protein-rich compartment of chemical synapses, where precisely orchestrated molecular interactions control synaptic vesicle (SV) fusion with the presynaptic membrane. The subsequent release of neurotransmitter substances onto postsynaptic receptor fields forms the basis of neuronal communication...
December 16, 2017: Neuroscience Research
https://www.readbyqxmd.com/read/29246857/new-cav2-calcium-channel-gating-modifiers-with-agonist-activity-and-therapeutic-potential-to-treat-neuromuscular-disease
#15
Man Wu, Hayley V White, Blake Boehm, Christopher J Meriney, Kaylan Kerrigan, Michael Frasso, Mary Liang, Erika M Gotway, Madeleine Wilcox, Jon W Johnson, Peter Wipf, Stephen D Meriney
Voltage-gated calcium channels (VGCCs) are critical regulators of many cellular functions, including the activity-dependent release of chemical neurotransmitter from nerve terminals. At nerve terminals, the Cav2 family of VGCCs are closely positioned with neurotransmitter-containing synaptic vesicles. The relationship between calcium ions and transmitter release is such that even subtle changes in calcium flux through VGCCs have a strong influence on the magnitude of transmitter released. Therefore, modulators of the calcium influx at nerve terminals have the potential to strongly affect transmitter release at synapses...
December 12, 2017: Neuropharmacology
https://www.readbyqxmd.com/read/29238291/modulation-of-neocortical-development-by-early-neuronal-activity-physiology-and-pathophysiology
#16
REVIEW
Sergei Kirischuk, Anne Sinning, Oriane Blanquie, Jenq-Wei Yang, Heiko J Luhmann, Werner Kilb
Animal and human studies revealed that patterned neuronal activity is an inherent feature of developing nervous systems. This review summarizes our current knowledge about the mechanisms generating early electrical activity patterns and their impact on structural and functional development of the cerebral cortex. All neocortical areas display distinct spontaneous and sensory-driven neuronal activity patterns already at early phases of development. At embryonic stages, intermittent spontaneous activity is synchronized within small neuronal networks, becoming more complex with further development...
2017: Frontiers in Cellular Neuroscience
https://www.readbyqxmd.com/read/29236724/the-role-of-cortical-oscillations-in-a-spiking-neural-network-model-of-the-basal-ganglia
#17
Zafeirios Fountas, Murray Shanahan
Although brain oscillations involving the basal ganglia (BG) have been the target of extensive research, the main focus lies disproportionally on oscillations generated within the BG circuit rather than other sources, such as cortical areas. We remedy this here by investigating the influence of various cortical frequency bands on the intrinsic effective connectivity of the BG, as well as the role of the latter in regulating cortical behaviour. To do this, we construct a detailed neural model of the complete BG circuit based on fine-tuned spiking neurons, with both electrical and chemical synapses as well as short-term plasticity between structures...
2017: PloS One
https://www.readbyqxmd.com/read/29229967/electrical-synapses-convey-orientation-selectivity-in-the-mouse-retina
#18
Amurta Nath, Gregory W Schwartz
Sensory neurons downstream of primary receptors are selective for specific stimulus features, and they derive their selectivity both from excitatory and inhibitory synaptic inputs from other neurons and from their own intrinsic properties. Electrical synapses, formed by gap junctions, modulate sensory circuits. Retinal ganglion cells (RGCs) are diverse feature detectors carrying visual information to the brain, and receive excitatory input from bipolar cells and inhibitory input from amacrine cells (ACs). Here we describe a RGC that relies on gap junctions, rather than chemical synapses, to convey its selectivity for the orientation of a visual stimulus...
December 11, 2017: Nature Communications
https://www.readbyqxmd.com/read/29225307/millisecond-ca2-dynamics-activate-multiple-protein-cascades-for-synaptic-vesicle-control
#19
Sumiko Mochida
For reliable transmission at chemical synapses, neurotransmitters must be released dynamically in response to neuronal activity in the form of action potentials. Stable synaptic transmission is dependent on the efficacy of transmitter release and the rate of resupplying synaptic vesicles to their release sites. Accurate regulation is conferred by proteins sensing Ca2+ entering through voltage-gated Ca2+ channels opened by an action potential. Presynaptic Ca2+ concentration changes are dynamic functions in space and time, with wide fluctuations associated with different rates of neuronal activity...
2017: Proceedings of the Japan Academy. Series B, Physical and Biological Sciences
https://www.readbyqxmd.com/read/29222785/neuronal-cell-morphology-in-primary-cerebellar-granule-cells-using-high-content-analysis
#20
Nicholas Radio, Steven Frank
Neurite outgrowth, one of the underlying cellular processes that defines the development and functionality of the mammalian nervous system, is also a sensitive indicator of neuronal cell health. From screening libraries of putative neurotherapeutic compounds to analyzing the millions of environmental pollutants for which we have inadequate neurotoxicity safety data, the large volume of chemical compounds that require evaluation is a major obstacle for manual imaging and analysis methods. In this context, high-content analysis (HCA) has emerged as a sensitive and accurate method for detecting changes in neuronal cell morphology within a format applicable to screening large chemical libraries...
2018: Methods in Molecular Biology
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