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Silent synapse

Karin Buiting, Charles Williams, Bernhard Horsthemke
Angelman syndrome is a rare neurogenetic disorder that is characterized by microcephaly, severe intellectual deficit, speech impairment, epilepsy, EEG abnormalities, ataxic movements, tongue protrusion, paroxysms of laughter, abnormal sleep patterns, and hyperactivity. Angelman syndrome results from loss of function of the imprinted UBE3A (ubiquitin-protein ligase E3A) gene on chromosome 15q11.2-q13. This loss of function can be caused by a mutation on the maternal allele, a 5-7 Mb deletion of the maternally inherited chromosomal region, paternal uniparental disomy of chromosome 15, or an imprinting defect...
October 2016: Nature Reviews. Neurology
Ting-Ting Zhang, Feng-Yan Shen, Li-Qing Ma, Wen Wen, Bin Wang, Yuan-Zhi Peng, Zhi-Ru Wang, Xuan Zhao
Itch and pain share similar mechanisms. It has been well documented that the anterior cingulate cortex (ACC) is important for pain-related perception. ACC has also been approved to be a potential pruritus-associated brain region. However, the mechanism of sensitization in pruriceptive neurons in the ACC is not clear. In current study, a chronic itch model was established by diphenylcyclopropenone (DCP) application. We found that both the frequency and amplitude of miniature excitatory postsynaptic currents in the ACC were enhanced after the formation of chronic itch...
2016: Molecular Brain
Takashi Matsubara, Kuniaki Uehara
Homeostatic plasticity is considered to maintain activity in neuronal circuits within a functional range. In the absence of homeostatic plasticity neuronal activity is prone to be destabilized because Hebbian plasticity mechanisms induce positive feedback change. Several studies on homeostatic plasticity assumed the existence of a process for monitoring neuronal activity on a time scale of hours and adjusting synaptic efficacy by scaling up and down. However, the underlying mechanism still remains unclear. Excitatory synaptic efficacy is associated with the size of the dendritic spine, and dendritic spine size fluctuates even after neuronal activity is silenced...
2016: Frontiers in Neural Circuits
Rodrigo Martinez-Monedero, Chang Liu, Catherine Weisz, Pankhuri Vyas, Paul Albert Fuchs, Elisabeth Glowatzki
Mechanosensory hair cells release glutamate at ribbon synapses to excite postsynaptic afferent neurons, via AMPA-type ionotropic glutamate receptors (AMPARs). However, type II afferent neurons contacting outer hair cells in the mammalian cochlea were thought to differ in this respect, failing to show GluA immunolabeling and with many "ribbonless" afferent contacts. Here it is shown that antibodies to the AMPAR subunit GluA2 labeled afferent contacts below inner and outer hair cells in the rat cochlea, and that synaptic currents in type II afferents had AMPAR-specific pharmacology...
March 2016: ENeuro
Nicholas M Graziane, Shichao Sun, William J Wright, Daniel Jang, Zheng Liu, Yanhua H Huang, Eric J Nestler, Yu Tian Wang, Oliver M Schlüter, Yan Dong
Exposures to cocaine and morphine produce similar adaptations in nucleus accumbens (NAc)-based behaviors, yet produce very different adaptations at NAc excitatory synapses. In an effort to explain this paradox, we found that both drugs induced NMDA receptor-containing, AMPA receptor-silent excitatory synapses, albeit in distinct cell types through opposing cellular mechanisms. Cocaine selectively induced silent synapses in D1-type neurons, likely via a synaptogenesis process, whereas morphine induced silent synapses in D2-type neurons via internalization of AMPA receptors from pre-existing synapses...
July 2016: Nature Neuroscience
Natalia V Luchkina, Sarah K Coleman, Johanna Huupponen, Chunlin Cai, Anna Kivistö, Tomi Taira, Kari Keinänen, Sari E Lauri
Synaptic recruitment of AMPA receptors (AMPARs) represents a key postsynaptic mechanism driving functional development and maturation of glutamatergic synapses. At immature hippocampal synapses, PKA-driven synaptic insertion of GluA4 is the predominant mechanism for synaptic reinforcement. However, the physiological significance and molecular determinants of this developmentally restricted form of plasticity are not known. Here we show that PKA activation leads to insertion of GluA4 to synaptic sites with initially weak or silent AMPAR-mediated transmission...
May 5, 2016: Neuropharmacology
Cristina V Dieni, Roberto Panichi, James B Aimone, Chay T Kuo, Jacques I Wadiche, Linda Overstreet-Wadiche
Persistent neurogenesis in the dentate gyrus produces immature neurons with high intrinsic excitability and low levels of inhibition that are predicted to be more broadly responsive to afferent activity than mature neurons. Mounting evidence suggests that these immature neurons are necessary for generating distinct neural representations of similar contexts, but it is unclear how broadly responsive neurons help distinguish between similar patterns of afferent activity. Here we show that stimulation of the entorhinal cortex in mouse brain slices paradoxically generates spiking of mature neurons in the absence of immature neuron spiking...
2016: Nature Communications
Suma Priya Sudarsana Devi, James R Howe, Céline Auger
KEY POINTS: Purkinje cells of the cerebellum receive ∼180,000 parallel fibre synapses, which have often been viewed as a homogeneous synaptic population and studied using single action potentials. Many parallel fibre synapses might be silent, however, and granule cells in vivo fire in bursts. Here, we used trains of stimuli to study parallel fibre inputs to Purkinje cells in rat cerebellar slices. Analysis of train EPSCs revealed two synaptic components, phase 1 and 2. Phase 1 is initially large and saturates rapidly, whereas phase 2 is initially small and facilitates throughout the train...
July 1, 2016: Journal of Physiology
Yao-Ying Ma, Xiusong Wang, Yanhua Huang, Helene Marie, Eric J Nestler, Oliver M Schlüter, Yan Dong
Environmental enrichment (EE) has long been postulated as a behavioral treatment for drug addiction based on its preventive effects in animal models: rodents experiencing prior EE exhibit increased resistance to establishing drug taking and seeking. However, the therapeutic effects of EE, namely, the effects of EE when applied after drug exposure, are often marginal and transient. Using incubation of cue-induced cocaine craving, a rat relapse model depicting progressive intensification of cocaine seeking after withdrawal from cocaine self-administration, our present study reveals that after cocaine withdrawal, in vivo circuit-specific long-term depression (LTD) unmasks the therapeutic power of EE to achieve long-lasting anti-relapse effects...
May 3, 2016: Proceedings of the National Academy of Sciences of the United States of America
Peter A Neumann, Yicun Wang, Yijin Yan, Yao Wang, Masago Ishikawa, Ranji Cui, Yanhua H Huang, Susan R Sesack, Oliver M Schlüter, Yan Dong
Exposure to cocaine induces addiction-associated behaviors partially through remodeling neurocircuits in the nucleus accumbens (NAc). The paraventricular nucleus of thalamus (PVT), which projects to the NAc monosynaptically, is activated by cocaine exposure and has been implicated in several cocaine-induced emotional and motivational states. Here we show that disrupting synaptic transmission of select PVT neurons with tetanus toxin activated via retrograde trans-synaptic transport of cre from NAc efferents decreased cocaine self-administration in rats...
August 2016: Neuropsychopharmacology: Official Publication of the American College of Neuropsychopharmacology
Franziska Greifzu, Daniel Parthier, Bianka Goetze, Oliver M Schlüter, Siegrid Löwel
Neuronal plasticity is essential to enable rehabilitation when the brain suffers from injury, such as following a stroke. One of the most established models to study cortical plasticity is ocular dominance (OD) plasticity in the primary visual cortex (V1) of the mammalian brain induced by monocular deprivation (MD). We have previously shown that OD-plasticity in adult mouse V1 is absent after a photothrombotic (PT) stroke lesion in the adjacent primary somatosensory cortex (S1). Exposing lesioned mice to conditions which reduce the inhibitory tone in V1, such as raising animals in an enriched environment or short-term dark exposure, preserved OD-plasticity after an S1-lesion...
2016: PloS One
Daniela B Pereira, Yvonne Schmitz, József Mészáros, Paolomi Merchant, Gang Hu, Shu Li, Adam Henke, José E Lizardi-Ortiz, Richard J Karpowicz, Travis J Morgenstern, Mark S Sonders, Ellen Kanter, Pamela C Rodriguez, Eugene V Mosharov, Dalibor Sames, David Sulzer
Neurotransmission at dopaminergic synapses has been studied with techniques that provide high temporal resolution, but cannot resolve individual synapses. To elucidate the spatial dynamics and heterogeneity of individual dopamine boutons, we developed fluorescent false neurotransmitter 200 (FFN200), a vesicular monoamine transporter 2 (VMAT2) substrate that selectively traces monoamine exocytosis in both neuronal cell culture and brain tissue. By monitoring electrically evoked Ca(2+) transients with GCaMP3 and FFN200 release simultaneously, we found that only a small fraction of dopamine boutons that exhibited Ca(2+) influx engaged in exocytosis, a result confirmed with activity-dependent loading of the endocytic probe FM1-43...
April 2016: Nature Neuroscience
W Ba, M M Selten, J van der Raadt, H van Veen, L-L Li, M Benevento, A R Oudakker, R S E Lasabuda, S J Letteboer, R Roepman, R J A van Wezel, M J Courtney, H van Bokhoven, N Nadif Kasri
The molecular mechanisms that promote excitatory synapse development have been extensively studied. However, the molecular events preventing precocious excitatory synapse development so that synapses form at the correct time and place are less well understood. Here, we report the functional characterization of ARHGAP12, a previously uncharacterized Rho GTPase-activating protein (RhoGAP) in the brain. ARHGAP12 is specifically expressed in the CA1 region of the hippocampus, where it localizes to the postsynaptic compartment of excitatory synapses...
February 16, 2016: Cell Reports
Yan Dong
Exposure to cocaine, and likely other drugs of abuse, generates α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor-silent glutamatergic synapses in the nucleus accumbens. These immature synaptic contacts evolve after drug withdrawal to redefine the neurocircuital properties. These results raise at least three critical questions: (1) what are the molecular and cellular mechanisms that mediate drug-induced generation of silent synapses; (2) how are neurocircuits remodeled upon generation and evolution of drug-generated silent synapses; and (3) what behavioral consequences are produced by silent synapse-based circuitry remodeling? This short review analyzes related experimental results, and extends them to some speculations...
May 2016: International Journal of Neuropsychopharmacology
Nengyin Sheng, Yun S Shi, Richa Madan Lomash, Katherine W Roche, Roger A Nicoll
Kainate receptors (KARs) are a subfamily of glutamate receptors mediating excitatory synaptic transmission and Neto proteins are recently identified auxiliary subunits for KARs. However, the roles of Neto proteins in the synaptic trafficking of KAR GluK1 are poorly understood. Here, using the hippocampal CA1 pyramidal neuron as a null background system we find that surface expression of GluK1 receptor itself is very limited and is not targeted to excitatory synapses. Both Neto1 and Neto2 profoundly increase GluK1 surface expression and also drive GluK1 to synapses...
2015: ELife
Hitoshi Nagura, Tomoko Doi, Yoshinori Fujiyoshi
The hippocampal formation is involved in several important brain functions of animals, such as memory formation and pattern separation, and the synapses in the dentate gyrus (DG) play critical roles as the first step in the hippocampal circuit. Previous studies have reported that mice with genetic modifications of the PDZ1/2 domains of postsynaptic density (PSD)-95 exhibit altered synaptic properties in the DG and impaired hippocampus-dependent behaviors. Based on the involvement of the DG in the regulation of behaviors, these data suggest that the abnormal behavior of these knockin (KI) mice is due partly to altered DG function...
March 2016: European Journal of Neuroscience
Anna Phan, Sarah Suschkov, Luke Molinaro, Kathryn Reynolds, Jennifer M Lymer, Craig D C Bailey, Lee-Ming Kow, Neil J MacLusky, Donald W Pfaff, Elena Choleris
Dramatic increases in hippocampal spine synapse density are known to occur within minutes of estrogen exposure. Until now, it has been assumed that enhanced spinogenesis increased excitatory input received by the CA1 pyramidal neurons, but how this facilitated learning and memory was unclear. Delivery of 17β-estradiol or an estrogen receptor (ER)-α (but not ER-β) agonist into the dorsal hippocampus rapidly improved general discrimination learning in female mice. The same treatments increased CA1 dendritic spines in hippocampal sections over a time course consistent with the learning acquisition phase...
December 29, 2015: Proceedings of the National Academy of Sciences of the United States of America
Xiaobing Chen, Jonathan M Levy, Austin Hou, Christine Winters, Rita Azzam, Alioscka A Sousa, Richard D Leapman, Roger A Nicoll, Thomas S Reese
The postsynaptic density (PSD)-95 family of membrane-associated guanylate kinases (MAGUKs) are major scaffolding proteins at the PSD in glutamatergic excitatory synapses, where they maintain and modulate synaptic strength. How MAGUKs underlie synaptic strength at the molecular level is still not well understood. Here, we explore the structural and functional roles of MAGUKs at hippocampal excitatory synapses by simultaneous knocking down PSD-95, PSD-93, and synapse-associated protein (SAP)102 and combining electrophysiology and transmission electron microscopic (TEM) tomography imaging to analyze the resulting changes...
December 15, 2015: Proceedings of the National Academy of Sciences of the United States of America
Kaiwen He, Marco Huertas, Su Z Hong, XiaoXiu Tie, Johannes W Hell, Harel Shouval, Alfredo Kirkwood
In reward-based learning, synaptic modifications depend on a brief stimulus and a temporally delayed reward, which poses the question of how synaptic activity patterns associate with a delayed reward. A theoretical solution to this so-called distal reward problem has been the notion of activity-generated "synaptic eligibility traces," silent and transient synaptic tags that can be converted into long-term changes in synaptic strength by reward-linked neuromodulators. Here we report the first experimental demonstration of eligibility traces in cortical synapses...
November 4, 2015: Neuron
M Ouardouz
No abstract text is available yet for this article.
December 2015: International Journal of Developmental Neuroscience
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