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electrical synapse

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https://www.readbyqxmd.com/read/29449585/electrical-coupling-between-a17-cells-enhances-reciprocal-inhibitory-feedback-to-rod-bipolar-cells
#1
Claudio Elgueta, Felix Leroy, Alex H Vielma, Oliver Schmachtenberg, Adrian G Palacios
A17 amacrine cells are an important part of the scotopic pathway. Their synaptic varicosities receive glutamatergic inputs from rod bipolar cells (RBC) and release GABA onto the same RBC terminal, forming a reciprocal feedback that shapes RBC depolarization. Here, using patch-clamp recordings, we characterized electrical coupling between A17 cells of the rat retina and report the presence of strongly interconnected and non-coupled A17 cells. In coupled A17 cells, evoked currents preferentially flow out of the cell through GJs and cross-synchronization of presynaptic signals in a pair of A17 cells is correlated to their coupling degree...
February 15, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29447392/activity-dependent-functions-of-non-electrical-glial-cells
#2
Daisuke Kato, Kei Eto, Junichi Nabekura, Hiroaki Wake
Electrical activity is essential for brain function. However, neurons, the electrically active cells, are less numerous than the non-electrical glial cells in the central nervous system. The non-electrical components modify the function of neural circuits, depending on the electrical neuronal activity, by wrapping synapses, myelinating axons, and phagocytozing the neuronal components. Moreover, recent evidence has suggested that they contribute to neurological and psychiatric disease by regulating neuronal circuits, ultimately affecting their behavior...
February 13, 2018: Journal of Biochemistry
https://www.readbyqxmd.com/read/29431275/burst-spinal-cord-stimulation-review-of-preclinical-studies-and-comments-on-clinical-outcomes
#3
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/29387787/ultralow-power-artificial-synapses-using-nanotextured-magnetic-josephson-junctions
#4
Michael L Schneider, Christine A Donnelly, Stephen E Russek, Burm Baek, Matthew R Pufall, Peter F Hopkins, Paul D Dresselhaus, Samuel P Benz, William H Rippard
Neuromorphic computing promises to markedly improve the efficiency of certain computational tasks, such as perception and decision-making. Although software and specialized hardware implementations of neural networks have made tremendous accomplishments, both implementations are still many orders of magnitude less energy efficient than the human brain. We demonstrate a new form of artificial synapse based on dynamically reconfigurable superconducting Josephson junctions with magnetic nanoclusters in the barrier...
January 2018: Science Advances
https://www.readbyqxmd.com/read/29386403/hydrodynamics-govern-the-pre-fusion-docking-time-of-synaptic-vesicles
#5
Pankaj Singh, Chung-Yuen Hui
Synaptic vesicle fusion is a crucial step in the neurotransmission process. Neurotransmitter-filled vesicles are pre-docked at the synapse by the mediation of ribbon structures and SNARE proteins at the ribbon synapses. An electrical impulse triggers the fusion process of pre-docked vesicles, leading to the formation of a fusion pore and subsequently resulting in the release of neurotransmitter into the synaptic cleft. In this study, a continuum model of lipid membrane along with lubrication theory is used to determine the traverse time of the synaptic vesicle under the influence of hydrodynamic forces...
January 2018: Journal of the Royal Society, Interface
https://www.readbyqxmd.com/read/29374274/membrane-potential-synchrony-of-neurons-in-anterior-cingulate-cortex-plays-a-pivotal-role-in-generation-of-neuropathic-pain
#6
Zhiyu Chen, Xiaolu Shen, La Huang, Hai Wu, Mazhong Zhang
The pathophysiology of neuropathic pain generation has not been fully investigated. Previous studies have primarily focused on changes in the properties of single neurons in the brain after nerve injury; however, little is known concerning the role of neuron-to-neuron connections in neuropathic pain pathogenesis. Synaptic transmission potentiation in anterior cingulate cortex (ACC) has been confirmed to be responsible for the formation of neuropathic pain. Thus, analysis of interneuronal connections in the ACC is an important approach for understanding the mechanism of neuropathic pain since it provides information on the potency of synaptic transmission...
January 26, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29358677/collective-responses-in-electrical-activities-of-neurons-under-field-coupling
#7
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/29357245/optogenetics-inspired-tunable-synaptic-functions-in-memristors
#8
Xiaojian Zhu, Wei D Lu
Two-terminal memristors with internal Ca2+-like dynamics can be used to faithfully emulate biological synaptic functions, and have been intensively studied for neural network implementations. Inspired by the optogenetic technique that utilizes light to tune the Ca2+ dynamics and subsequently the synaptic plasticity, we develop a CH3NH3PbI3 (MAPbI3) based memristor that exhibits light-tunable synaptic behaviors. Specifically, we show that by increasing the formation energy of iodine vacancy, light illumination can be used to control the iodine vacancy generation and annihilation dynamics, resembling light-controlled Ca2+ influx in biological synapses...
January 22, 2018: ACS Nano
https://www.readbyqxmd.com/read/29349480/posture-modulates-the-sensitivity-of-the-h-reflex
#9
Serpil Cecen, Imran Khan Niazi, Rasmus Wiberg Nedergaard, Alice Cade, Kathryn Allen, Kelly Holt, Heidi Haavik, Kemal S Türker
The effect of body posture on the human soleus H-reflex via electrical stimulation of the tibial nerve at the popliteal fossa was studied. All parameters that may influence the reflex were controlled stringently. H-reflexes were elicited in three different body postures while keeping the level of background muscle activation to a minimum. The H-reflex curve relative to the M-wave curve did not change significantly in any of the body postures. However, the maximal H-reflex amplitude significantly increased in the prone position compared with the sitting (p = 0...
January 18, 2018: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
https://www.readbyqxmd.com/read/29349292/membrane-insertion-of-and-membrane-potential-sensing-by-semiconductor-voltage-nanosensors-feasibility-demonstration
#10
Kyoungwon Park, Yung Kuo, Volodymyr Shvadchak, Antonino Ingargiola, Xinghong Dai, Lawrence Hsiung, Wookyeom Kim, Hong Zhou, Peng Zou, Alex J Levine, Jack Li, Shimon Weiss
We developed membrane voltage nanosensors that are based on inorganic semiconductor nanoparticles. We provide here a feasibility study for their utilization. We use a rationally designed peptide to functionalize the nanosensors, imparting them with the ability to self-insert into a lipid membrane with a desired orientation. Once inserted, these nanosensors could sense membrane potential via the quantum confined Stark effect, with a single-particle sensitivity. With further improvements, these nanosensors could potentially be used for simultaneous recording of action potentials from multiple neurons in a large field of view over a long duration and for recording electrical signals on the nanoscale, such as across one synapse...
January 2018: Science Advances
https://www.readbyqxmd.com/read/29328623/mimicking-biological-synaptic-functionality-with-an-indium-phosphide-synaptic-device-on-silicon-for-scalable-neuromorphic-computing
#11
Debarghya Sarkar, Jun Tao, Wei Wang, Qingfeng Lin, Matthew Yeung, Chenhao Ren, Rehan Kapadia
Neuromorphic or "brain-like" computation is a leading candidate for efficient, fault-tolerant processing of large-scale data, as well as real-time sensing and transduction of complex multivariate systems and networks such as self-driving vehicles or Internet of Things applications. In biology, the synapse serves as an active memory unit in the neural system, and is the component responsible for learning and memory. Electronically emulating this element via a compact, scalable technology which can be integrated in a 3-D architecture is critical for future implementations of neuromorphic processors...
January 12, 2018: ACS Nano
https://www.readbyqxmd.com/read/29327340/shank3-deficient-thalamocortical-neurons-show-hcn-channelopathy-and-alterations-in-intrinsic-electrical-properties
#12
Mengye Zhu, VinayKumar Idikuda, Jianbing Wang, Fusheng Wei, Virang Kumar, Nikhil Shah, Christopher B Waite, Qinglian Liu, Lei Zhou
Shank3 is a scaffolding protein that is highly enriched in excitatory synapses. Mutations in Shank3 gene have been linked to neuropsychiatric disorders especially the Autism Spectrum Disorders (ASD). Shank3 deficiency is known to cause impairments in synaptic transmission, but its effects on basic neuronal electrical properties that are more localized to the soma and proximal dendrites remain unclear. Here we confirmed that in heterologous expression systems two different Shank3 isoforms, Shank3A and Shank3C, significant increase the surface expression of the hyperpolarization-activated, cyclic-nucleotide-gated (HCN) channel...
January 12, 2018: Journal of Physiology
https://www.readbyqxmd.com/read/29324422/assimilation-of-biophysical-neuronal-dynamics-in-neuromorphic-vlsi
#13
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/29305530/role-of-purinergic-receptor-p2y1-in-spatiotemporal-ca2-dynamics-in-astrocytes
#14
Eiji Shigetomi, Yukiho J Hirayama, Kazuhiro Ikenaka, Kenji F Tanaka, Schuichi Koizumi
Fine processes of astrocytes enwrap synapses and are well-positioned to sense neuronal information via synaptic transmission. In rodents, astrocyte processes sense synaptic transmission via Gq-protein coupled receptors (GqPCR), including the P2Y1 receptor (P2Y1R), to generate Ca2+ signals. Astrocytes display numerous spontaneous microdomain Ca2+ signals; however, it is not clear if such signals are due to local synaptic transmission and/or in what timeframe astrocytes sense local synaptic transmission. To ask if GqPCRs mediate microdomain Ca2+ signals, we engineered mice (both sexes) to specifically overexpress P2Y1Rs in astrocytes and we visualized Ca2+ signals via a genetically encoded Ca2+ indicator, GCaMP6f, in astrocytes from adult mice...
January 5, 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
#15
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/29280494/bidirectional-modulation-of-glutamatergic-synaptic-transmission-by-mglu7-receptors-at-sc-ca1-hippocampal-synapses
#16
Ricardo Martín, José Javier Ferrero, Andrea Collado-Alsina, Carolina Aguado, Rafael Luján, Magdalena Torres, José Sánchez-Prieto
Neurotransmitter release is driven by Ca2+ influx at synaptic boutons that acts on synaptic vesicles ready to undergo exocytosis. Neurotransmitter release is inhibited when mGlu7 receptors provoke a reduction in Ca2+ influx, although the reduced release from synapses lacking this receptor suggests that they may also prime synaptic vesicles for release. These mGlu7 receptors activate phospholipase C (PLC) and generate inositol trisphosphate (IP3 ), which in turn releases Ca2+ from intracellular stores and produces diacylglycerol (DAG), an activator of proteins containing DAG-binding domains like Munc13 and protein kinase C (PKC)...
December 27, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/29275162/vesicle-release-site-organization-at-synaptic-active-zones
#17
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/29273736/vglut1-functions-as-a-glutamate-proton-exchanger-with-chloride-channel-activity-in-hippocampal-glutamatergic-synapses
#18
Magalie Martineau, Raul E Guzman, Christoph Fahlke, Jürgen Klingauf
Glutamate is the major excitatory transmitter in the vertebrate nervous system. To maintain synaptic efficacy, recycling synaptic vesicles (SV) are refilled with glutamate by vesicular glutamate transporters (VGLUTs). The dynamics and mechanism of glutamate uptake in intact neurons are still largely unknown. Here, we show by live-cell imaging with pH- and chloride-sensitive fluorescent probes in cultured hippocampal neurons of wild-type and VGLUT1-deficient mice that in SVs VGLUT functions as a glutamate/proton exchanger associated with a channel-like chloride conductance...
December 22, 2017: Nature Communications
https://www.readbyqxmd.com/read/29249288/dendritic-spines-prevent-synaptic-voltage-clamp
#19
Lou Beaulieu-Laroche, Mark T Harnett
Synapses are the fundamental units of information processing in the mammalian brain. Much of our understanding of their functional properties comes from voltage-clamp analysis, the predominant approach for investigating synaptic physiology. Here, we reveal that voltage clamp is completely ineffective for most excitatory synapses due to spine electrical compartmentalization. Under local dendritic voltage clamp, single-spine activation produced large spine head depolarizations that severely distorted measurements and recruited voltage-dependent channels...
December 13, 2017: Neuron
https://www.readbyqxmd.com/read/29245058/quantitative-eeg-power-and-synchronization-correlate-with-alzheimer-s-disease-csf-biomarkers
#20
Una Smailovic, Thomas Koenig, Ingemar Kåreholt, Thomas Andersson, Milica Gregoric Kramberger, Bengt Winblad, Vesna Jelic
Synaptic dysfunction is the best anatomical correlate of early cognitive impairment in Alzheimer's disease (AD). Electroencephalography (EEG) directly reflects brain electrical activity at the level of synapses. The aim of the present study was to investigate correlations of quantitative EEG measures, global field power (GFP) and global field synchronization (GFS), with conventional cerebrospinal fluid (CSF) biomarkers of neurodegeneration in patients diagnosed with subjective cognitive decline (n = 210), mild cognitive impairment (n = 230), and AD (n = 197)...
November 16, 2017: Neurobiology of Aging
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