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https://www.readbyqxmd.com/read/28334601/a-tale-of-two-inputs
#1
James Ashley, Vivian Budnik
In this issue of Neuron, Newman et al. (2017) image calcium events at single synapses of unanesthetized Drosophila larvae. Synaptic plasticity and homeostatic regulation of synapses is established to be input specific. Furthermore, plasticity forms involve selective recruitment of previously active or silent synapses.
March 22, 2017: Neuron
https://www.readbyqxmd.com/read/28315939/the-transient-potassium-outward-current-has-different-roles-in-modulating-the-pyloric-and-gastric-mill-rhythms-in-the-stomatogastric-ganglion
#2
Lin Zhu, Allen I Selverston, Joseph Ayers
The crustacean stomatogastric nervous system is a classic model for understanding the effects of modulating ionic currents and synapses at both the cell and network levels. The stomatogastric ganglion in this system contains two distinct central pattern generators: a slow gastric mill network that generates flexible rhythmic outputs (8-20 s) and is often silent, and a fast pyloric network that generates more consistent rhythmic outputs (0.5-2 s) and is always active in vitro. Different ionic conductances contribute to the properties of individual neurons and therefore to the overall dynamics of the pyloric and gastric mill networks...
March 18, 2017: Journal of Comparative Physiology. A, Neuroethology, Sensory, Neural, and Behavioral Physiology
https://www.readbyqxmd.com/read/28287992/spanner-a-self-repairing-spiking-neural-network-hardware-architecture
#3
Junxiu Liu, Jim Harkin, Liam P Maguire, Liam J McDaid, John J Wade
Recent research has shown that a glial cell of astrocyte underpins a self-repair mechanism in the human brain, where spiking neurons provide direct and indirect feedbacks to presynaptic terminals. These feedbacks modulate the synaptic transmission probability of release (PR). When synaptic faults occur, the neuron becomes silent or near silent due to the low PR of synapses; whereby the PRs of remaining healthy synapses are then increased by the indirect feedback from the astrocyte cell. In this paper, a novel hardware architecture of Self-rePAiring spiking Neural NEtwoRk (SPANNER) is proposed, which mimics this self-repairing capability in the human brain...
March 6, 2017: IEEE Transactions on Neural Networks and Learning Systems
https://www.readbyqxmd.com/read/28285823/input-specific-plasticity-and-homeostasis-at-the-drosophila-larval-neuromuscular-junction
#4
Zachary L Newman, Adam Hoagland, Krishan Aghi, Kurtresha Worden, Sabrina L Levy, Jun Ho Son, Luke P Lee, Ehud Y Isacoff
Synaptic connections undergo activity-dependent plasticity during development and learning, as well as homeostatic re-adjustment to ensure stability. Little is known about the relationship between these processes, particularly in vivo. We addressed this with novel quantal resolution imaging of transmission during locomotive behavior at glutamatergic synapses of the Drosophila larval neuromuscular junction. We find that two motor input types, Ib and Is, provide distinct forms of excitatory drive during crawling and differ in key transmission properties...
March 22, 2017: Neuron
https://www.readbyqxmd.com/read/28238793/differential-maturation-of-the-two-regulated-secretory-pathways-in-human-ipsc-derived-neurons
#5
Javier Emperador Melero, Aishwarya G Nadadhur, Desiree Schut, Jan V Weering, Vivi M Heine, Ruud F Toonen, Matthijs Verhage
Neurons communicate by regulated secretion of chemical signals from synaptic vesicles (SVs) and dense-core vesicles (DCVs). Here, we investigated the maturation of these two secretory pathways in micro-networks of human iPSC-derived neurons. These micro-networks abundantly expressed endogenous SV and DCV markers, including neuropeptides. DCV transport was microtubule dependent, preferentially anterograde in axons, and 2-fold faster in axons than in dendrites. SV and DCV secretion were strictly Ca(2+) and SNARE dependent...
March 14, 2017: Stem Cell Reports
https://www.readbyqxmd.com/read/28229400/trans-synaptic-retrograde-degeneration-in-the-human-visual-system-slow-silent-and-real
#6
REVIEW
Marc Dinkin
Degeneration of neuron and axons following injury to cells with which they synapse is termed trans-synaptic degeneration. This phenomenon may be seen in postsynaptic neurons (anterograde) or in presynaptic neurons (retrograde). Retrograde trans-synaptic degeneration (RTSD) of the retinal ganglion cells and retinal nerve fiber layer following injury to the occipital lobe has been well documented histologically in animal studies, but its occurrence in the human retina was, for many years, felt to be limited to cases of neonatal injury during a critical period of neuronal development...
February 2017: Current Neurology and Neuroscience Reports
https://www.readbyqxmd.com/read/28190519/matrix-metalloproteinase-9-and-synaptic-plasticity-in-the-central-amygdala-in-control-of-alcohol-seeking-behavior
#7
Marzena Stefaniuk, Anna Beroun, Tomasz Lebitko, Olga Markina, Szymon Leski, Ksenia Meyza, Anna Grzywacz, Jerzy Samochowiec, Agnieszka Samochowiec, Kasia Radwanska, Leszek Kaczmarek
BACKGROUND: Dysfunction of the glutamatergic system has been implicated in alcohol addiction; however, the molecular underpinnings of this phenomenon are still poorly understood. In the current study we have investigated the possible function of matrix metalloproteinase-9 (MMP-9) in alcohol addiction because this protein has recently emerged as an important regulator of excitatory synaptic plasticity. METHODS: For long-term studies of alcohol drinking in mice we used IntelliCages...
January 5, 2017: Biological Psychiatry
https://www.readbyqxmd.com/read/28122240/experience-dependent-equilibration-of-ampar-mediated-synaptic-transmission-during-the-critical-period
#8
Kyung-Seok Han, Samuel F Cooke, Weifeng Xu
Experience-dependent synapse refinement is essential for functional optimization of neural circuits. However, how sensory experience sculpts excitatory synaptic transmission is poorly understood. Here, we show that despite substantial remodeling of synaptic connectivity, AMPAR-mediated synaptic transmission remains at equilibrium during the critical period in the mouse primary visual cortex. The maintenance of this equilibrium requires neurogranin (Ng), a postsynaptic calmodulin-binding protein important for synaptic plasticity...
January 24, 2017: Cell Reports
https://www.readbyqxmd.com/read/28093559/gradation-approx-10-size-states-of-synaptic-strength-by-quantal-addition-of-structural-modules
#9
Kang K L Liu, Michael F Hagan, John E Lisman
Memory storage involves activity-dependent strengthening of synaptic transmission, a process termed long-term potentiation (LTP). The late phase of LTP is thought to encode long-term memory and involves structural processes that enlarge the synapse. Hence, understanding how synapse size is graded provides fundamental information about the information storage capability of synapses. Recent work using electron microscopy (EM) to quantify synapse dimensions has suggested that synapses may structurally encode as many as 26 functionally distinct states, which correspond to a series of proportionally spaced synapse sizes...
March 5, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
https://www.readbyqxmd.com/read/28077487/calcium-permeable-ampa-receptors-and-silent%C3%A2-synapses-in-cocaine-conditioned-place-preference
#10
Avani Shukla, Anna Beroun, Myrto Panopoulou, Peter A Neumann, Seth Gn Grant, M Foster Olive, Yan Dong, Oliver M Schlüter
Exposure to cocaine generates silent synapses in the nucleus accumbens (NAc), whose eventual unsilencing/maturation by recruitment of calcium-permeable AMPA-type glutamate receptors (CP-AMPARs) after drug withdrawal results in profound remodeling of NAc neuro-circuits. Silent synapse-based NAc remodeling was shown to be critical for several drug-induced behaviors, but its role in acquisition and retention of the association between drug rewarding effects and drug-associated contexts has remained unclear. Here, we find that the postsynaptic proteins PSD-93, PSD-95, and SAP102 differentially regulate excitatory synapse properties in the NAc...
January 11, 2017: EMBO Journal
https://www.readbyqxmd.com/read/27991850/mitochondrial-support-of-persistent-presynaptic-vesicle-mobilization-with-age-dependent-synaptic-growth-after-ltp
#11
Heather L Smith, Jennifer N Bourne, Guan Cao, Michael A Chirillo, Linnaea E Ostroff, Deborah J Watson, Kristen M Harris
Mitochondria support synaptic transmission through production of ATP, sequestration of calcium, synthesis of glutamate, and other vital functions. Surprisingly, less than 50% of hippocampal CA1 presynaptic boutons contain mitochondria, raising the question of whether synapses without mitochondria can sustain changes in efficacy. To address this question, we analyzed synapses from postnatal day 15 (P15) and adult rat hippocampus that had undergone theta-burst stimulation to produce long-term potentiation (TBS-LTP) and compared them to control or no stimulation...
December 19, 2016: ELife
https://www.readbyqxmd.com/read/27940363/evidence-for-presynaptically-silent-synapses-in-the-immature-hippocampus
#12
Jae Young Yoon, Sukwoo Choi
Silent synapses show NMDA receptor (NMDAR)-mediated synaptic responses, but not AMPAR-mediated synaptic responses. A prevailing hypothesis states that silent synapses contain NMDARs, but not AMPARs. However, alternative presynaptic hypotheses, according to which AMPARs are present at silent synapses, have been proposed; silent synapses show slow glutamate release via a fusion pore, and glutamate spillover from the neighboring synaptic terminals. Consistent with these presynaptic hypotheses, the peak glutamate concentrations at silent synapses have been estimated to be ≪170 μM, much lower than those seen at functional synapses...
January 22, 2017: Biochemical and Biophysical Research Communications
https://www.readbyqxmd.com/read/27903733/development-of-activity-in-the-mouse-visual-cortex
#13
Jing Shen, Matthew T Colonnese
A comprehensive developmental timeline of activity in the mouse cortex in vivo is lacking. Understanding the activity changes that accompany synapse and circuit formation is important to understand the mechanisms by which activity molds circuits and would help to identify critical checkpoints for normal development. To identify key principles of cortical activity maturation, we systematically tracked spontaneous and sensory-evoked activity with extracellular recordings of primary visual cortex (V1) in nonanesthetized mice...
November 30, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/27615419/angelman-syndrome-insights-into-a-rare-neurogenetic-disorder
#14
REVIEW
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
https://www.readbyqxmd.com/read/27472923/potentiation-of-synaptic-transmission-in-rat-anterior-cingulate-cortex-by-chronic-itch
#15
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
https://www.readbyqxmd.com/read/27313513/homeostatic-plasticity-achieved-by-incorporation-of-random-fluctuations-and-soft-bounded-hebbian-plasticity-in-excitatory-synapses
#16
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
https://www.readbyqxmd.com/read/27257620/glua2-containing-ampa-receptors-distinguish-ribbon-associated-from-ribbonless-afferent-contacts-on-rat-cochlear-hair-cells
#17
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
https://www.readbyqxmd.com/read/27239940/opposing-mechanisms-mediate-morphine-and-cocaine-induced-generation-of-silent-synapses
#18
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
https://www.readbyqxmd.com/read/27157711/molecular-mechanisms-controlling-synaptic-recruitment-of-glua4-subunit-containing-ampa-receptors-critical-for-functional-maturation-of-ca1-glutamatergic-synapses
#19
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...
January 2017: Neuropharmacology
https://www.readbyqxmd.com/read/27095423/low-excitatory-innervation-balances-high-intrinsic-excitability-of-immature-dentate-neurons
#20
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...
April 20, 2016: Nature Communications
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