scholarly journals Short-term ionic plasticity at GABAergic synapses

2012 ◽  
Vol 4 ◽  
Author(s):  
Joseph V. Raimondo ◽  
Henry Markram ◽  
Colin J. Akerman
Keyword(s):  
Short Term ◽  
Gabaergic Synapses

Developmental Changes in the Fidelity and Short-Term Plasticity of GABAergic Synapses in the Neonatal Rat Dorsal Horn

2008 ◽  
Vol 99 (6) ◽  
pp. 3144-3150 ◽  
Author(s):  
Rachel A. Ingram ◽  
Maria Fitzgerald ◽  
Mark L. Baccei
Keyword(s):  
Spinal Cord ◽  
Dorsal Horn ◽  
Receptive Fields ◽  
Neuronal Firing ◽  
Neonatal Rat ◽  
Superficial Dorsal Horn ◽  
Short Term ◽  
Dorsal Horn Neurons ◽  
Gabaergic Synapses

The lower thresholds and increased excitability of dorsal horn neurons in the neonatal rat suggest that inhibitory processing is less efficient in the immature spinal cord. This is unlikely to be explained by an absence of functional GABAergic inhibition because antagonism of γ-aminobutyric acid (GABA) type A receptors augments neuronal firing in vivo from the first days of life. However, it is possible that more subtle deficits in GABAergic signaling exist in the neonate, such as decreased reliability of transmission or greater depression during repetitive stimulation, both of which could influence the relative excitability of the immature spinal cord. To address this issue we examined monosynaptic GABAergic inputs onto superficial dorsal horn neurons using whole cell patch-clamp recordings made in spinal cord slices at a range of postnatal ages (P3, P10, and P21). The amplitudes of evoked inhibitory postsynaptic currents (IPSCs) were significantly lower and showed greater variability in younger animals, suggesting a lower fidelity of GABAergic signaling at early postnatal ages. Paired-pulse ratios were similar throughout the postnatal period, whereas trains of stimuli (1, 5, 10, and 20 Hz) revealed frequency-dependent short-term depression (STD) of IPSCs at all ages. Although the magnitude of STD did not differ between ages, the recovery from depression was significantly slower at immature GABAergic synapses. These properties may affect the integration of synaptic inputs within developing superficial dorsal horn neurons and thus contribute to their larger receptive fields and enhanced afterdischarge.

L-type Ca2+ channel-mediated short-term plasticity of GABAergic synapses

10.1038/nn722 ◽  
2001 ◽  
Vol 4 (10) ◽  
pp. 975-976 ◽  
Author(s):  
Kimmo Jensen ◽  
Istvan Mody
Keyword(s):  
Short Term ◽  
Short Term Plasticity ◽  
Gabaergic Synapses

Functional Significance of Cannabinoid-Mediated, Depolarization-Induced Suppression of Inhibition (DSI) in the Hippocampus

2003 ◽  
Vol 90 (1) ◽  
pp. 55-64 ◽  
Author(s):  
Robert E. Hampson ◽  
Shou-yuan Zhuang ◽  
Jeff L. Weiner ◽  
Sam A. Deadwyler
Keyword(s):  
Hippocampal Neurons ◽  
Hippocampal Slices ◽  
Memory Task ◽  
Short Term ◽  
Firing Patterns ◽  
Pulse Trains ◽  
Hippocampal Cell ◽  
Gabaergic Synapses ◽  
Cell Firing

A number of recent studies have demonstrated that a well-known form of short-term plasticity at hippocampal GABAergic synapses, called depolarization-induced suppression of inhibition (DSI), is in fact mediated by the retrograde actions of endocannabinoids released in response to depolarization of the postsynaptic cells. These studies suggest that endogenous cannabinoids may play an important role in regulating inhibitory tone in the mammalian CNS. Despite the widespread interest and potential physiological importance of DSI, many questions regarding the physiological relevance of DSI remain. To that end, this study set out to define the specific limiting conditions that could elicit DSI at GABAergic synapses in CA1 hippocampal pyramidal neurons and to determine if DSI could be elicited with pulse trains that mimic hippocampal cell-firing patterns that occur in vivo. Whole cell recordings from hippocampal neurons under voltage-clamp configuration were made in rat hippocampal slices. Spontaneous and evoked γ-aminobutyric acid-A (GABAA) receptor-mediated inhibitory postsynaptic currents (sIPSCs and eIPSCs, respectively) were recorded prior to and following depolarization of CA1 hippocampal pyramidal cells. Depolarizing voltage pulses were shaped to evoke currents in QX-314-treated cells similar to those accompanying single spontaneous voltage-clamped action potentials recorded from the soma. Attempts were made to elicit DSI with trains of these pulses that mimicked hippocampal cell firing patterns in vivo, for instance, when animals traverse place fields or are performing a short-term memory task. DSI could not be elicited by such pulse trains or by a number of other combinations of behaviorally specific firing parameters. The minimum duration of depolarization necessary to elicit DSI in hippocampal neurons determined by paired-pulse manipulation was 50 –75 ms at a critical interval of 20 –30 ms between pulse pairs. Under the conditions tested, the normal firing patterns of hippocampal neurons that occur in vivo do not appear to elicit DSI.

Efficacy and Short-Term Plasticity at GABAergic Synapses Between Purkinje and Cerebellar Nuclei Neurons

2003 ◽  
Vol 89 (2) ◽  
pp. 704-715 ◽  
Author(s):  
Christine M. Pedroarena ◽  
Cornelius Schwarz
Keyword(s):  
Dynamic Properties ◽  
Cerebellar Nuclei ◽  
Spatial Average ◽  
Short Term ◽  
Paired Pulse ◽  
Cognitive Behaviors ◽  
Quantal Size ◽  
Pulse Ratio ◽  
Gabaergic Synapses ◽  
Patch Configuration

Although the entire output of the cerebellar cortex is conveyed to the deep cerebellar nuclei neurons (DCNs) via the GABAergic synapses established by Purkinje cells (PCs), very little is known about the strength and dynamic properties of PC-DCN connections. Here we show that activation of PC-DCN unitary connections induced large conductance changes (11.7 nS) in DCNs recorded in whole cell patch configuration in acute slices, suggesting that activity of single PCs might significantly affect the output of its target neurons. Based on the large unitary quantal content (18) inferred from calculations of PC-DCN quantal size (0.65 nS) and the near absence of failures in synaptic transmission during control conditions, we conclude that PC-DCN connections are highly multi-sited. The analysis of dynamic properties of PC-DCN synapses demonstrated remarkable paired pulse depression (PPD), maximal at short intervals (paired pulse ratio of 0.15 at 7-ms interval). We provide evidence that PPD is presynaptic in origin and release-independent. In addition, multiple pulse stimulation revealed that PC-DCN synapses exhibited larger sensitivity to dynamic than to steady signals. We postulate that the, otherwise paradoxical, combination of marked short-term depression with strong multi-sited connections is optimal to transfer dynamic information at unitary level by performing spatial average of release probability across the numerous release sites. This feature could enable these synapses to encode presynaptic time-varying signals of single PCs as moment-to-moment changes in synaptic strength, a capacity well suited to the postulated role of cerebellum in control of temporal aspects of motor or cognitive behaviors.

RIM function in short- and long-term synaptic plasticity

2005 ◽  
Vol 33 (6) ◽  
pp. 1345-1349 ◽  
Author(s):  
P.S. Kaeser ◽  
T.C. Südhof
Keyword(s):  
Synaptic Plasticity ◽  
Active Zone ◽  
Neurotransmitter Release ◽  
Mossy Fibre ◽  
Short Term ◽  
Parallel Fibre ◽  
Ca1 Region ◽  
Gabaergic Synapses ◽  
Protein Rich

RIM1α (Rab3-interacting molecule 1α) is a large multidomain protein that is localized to presynaptic active zones [Wang, Okamoto, Schmitz, Hofmann and Südhof (1997) Nature (London) 388, 593–598] and is the founding member of the RIM protein family that also includes RIM2α, 2β, 2γ, 3γ and 4γ [Wang and Südhof (2003) Genomics 81, 126–137]. In presynaptic nerve termini, RIM1α interacts with a series of presynaptic proteins, including the synaptic vesicle GTPase Rab3 and the active zone proteins Munc13, liprins and ELKS (a protein rich in glutamate, leucine, lysine and serine). Mouse KOs (knockouts) revealed that, in different types of synapses, RIM1α is essential for different forms of synaptic plasticity. In CA1-region Schaffer-collateral excitatory synapses and in GABAergic synapses (where GABA is γ-aminobutyric acid), RIM1α is required for maintaining normal neurotransmitter release and short-term synaptic plasticity. In contrast, in excitatory CA3-region mossy fibre synapses and cerebellar parallel fibre synapses, RIM1α is necessary for presynaptic long-term, but not short-term, synaptic plasticity. In these synapses, the function of RIM1α in presynaptic long-term plasticity depends, at least in part, on phosphorylation of RIM1α at a single site, suggesting that RIM1α constitutes a ‘phosphoswitch’ that determines synaptic strength. However, in spite of the progress in understanding RIM1α function, the mechanisms by which RIM1α acts remain unknown. For example, how does phosphorylation regulate RIM1α, what is the relationship of the function of RIM1α in basic release to synaptic plasticity and what is the physiological significance of different forms of RIM-dependent plasticity? Moreover, the roles of other RIM isoforms are unclear. Addressing these important questions will contribute to our view of how neurotransmitter release is regulated at the presynaptic active zone.

Differential Short-Term Changes in GABAergic or Glycinergic Synaptic Efficacy on Rat Hypoglossal Motoneurons

2001 ◽  
Vol 86 (2) ◽  
pp. 565-574 ◽  
Author(s):  
Roberta Donato ◽  
Andrea Nistri
Keyword(s):  
Neonatal Rat ◽  
Patch Clamp Recording ◽  
Short Term ◽  
Hypoglossal Motoneurons ◽  
Whole Cell Patch Clamp ◽  
Gabaergic Synapses ◽  
Synaptic Changes ◽  
Rat Brain Slice ◽  
Neonatal Rat Brain ◽  
Brain Slice Preparation

Using whole cell patch-clamp recording from hypoglossal motoneurons of a neonatal rat brain slice preparation, we investigated short-term changes in synaptic transmission mediated by GABA or glycine. In 1.5 mM extracellular Ca2+[Ca2+]o, pharmacologically isolated GABAergic or glycinergic currents were elicited by electrical stimulation of the reticular formation. At low stimulation frequency, glycinergic currents were larger and faster than GABAergic ones. GABAergic currents were strongly facilitated by pulse trains at 5 or 10 Hz without apparent depression. This phenomenon persisted after pharmacological block of GABABreceptors. Glycinergic currents were comparatively much less enhanced than GABAergic currents. One possible mechanism to account for this difference is that GABAergic currents decayed so slowly that consecutive responses summated over an incrementing baseline. However, while synaptic summation appeared at ≥10-Hz stimulation, at 5 Hz strong facilitation developed with minimal summation of GABA-mediated currents. Glycinergic currents decayed so fast that summation was minimal. As [Ca2+]o is known to shape short-term synaptic changes, we examined if varying [Ca2+]o could differentially affect facilitation of GABA- or glycine-operated synapses. With 5 mM [Ca2+]o, the frequency of spontaneous GABAergic or glycinergic currents appeared much higher but GABAergic current facilitation was blocked (and replaced by depression), whereas glycinergic currents remained slightly facilitated. [Ca2+]omanipulation thus brought about distinct processes responsible for facilitation of GABAergic or glycinergic transmission. Our data therefore demonstrate an unexpectedly robust, short-term increase in the efficiency of GABAergic synapses that can become at least as effective as glycinergic synapses.

scholarly journals Synaptic FUS accumulation triggers early misregulation of synaptic RNAs in a mouse model of ALS

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Sonu Sahadevan ◽  
Katharina M. Hembach ◽  
Elena Tantardini ◽  
Manuela Pérez-Berlanga ◽  
Marian Hruska-Plochan ◽  
...  
Keyword(s):  
Mouse Model ◽  
Mrna Stability ◽  
Rna Binding ◽  
Super Resolution ◽  
Early Disease ◽  
Short Term ◽  
Rna Targets ◽  
Gabaergic Synapses ◽  
Resolution Imaging ◽  
Lateral Sclerosis

AbstractMutations disrupting the nuclear localization of the RNA-binding protein FUS characterize a subset of amyotrophic lateral sclerosis patients (ALS-FUS). FUS regulates nuclear RNAs, but its role at the synapse is poorly understood. Using super-resolution imaging we determined that the localization of FUS within synapses occurs predominantly near the vesicle reserve pool of presynaptic sites. Using CLIP-seq on synaptoneurosomes, we identified synaptic FUS RNA targets, encoding proteins associated with synapse organization and plasticity. Significant increase of synaptic FUS during early disease in a mouse model of ALS was accompanied by alterations in density and size of GABAergic synapses. mRNAs abnormally accumulated at the synapses of 6-month-old ALS-FUS mice were enriched for FUS targets and correlated with those depicting increased short-term mRNA stability via binding primarily on multiple exonic sites. Our study indicates that synaptic FUS accumulation in early disease leads to synaptic impairment, potentially representing an initial trigger of neurodegeneration.

Conceptual short-term memory (CSTM) supports core claims of Christiansen and Chater

2016 ◽  
Vol 39 ◽  
Author(s):  
Mary C. Potter
Keyword(s):  
Working Memory ◽  
Rapid Serial Visual Presentation ◽  
Language Comprehension ◽  
Short Term Memory ◽  
Visual Presentation ◽  
Long Term Memory ◽  
Short Term ◽  
Term Memory ◽  
Use Of Knowledge

AbstractRapid serial visual presentation (RSVP) of words or pictured scenes provides evidence for a large-capacity conceptual short-term memory (CSTM) that momentarily provides rich associated material from long-term memory, permitting rapid chunking (Potter 1993; 2009; 2012). In perception of scenes as well as language comprehension, we make use of knowledge that briefly exceeds the supposed limits of working memory.

Sign in / Sign up

Export Citation Format

Share Document