scholarly journals Paired-pulse facilitation at recurrent Purkinje neuron synapses is independent of calbindin and parvalbumin during high-frequency activation

2013 ◽  
Vol 591 (13) ◽  
pp. 3355-3370 ◽  
Author(s):  
Grit Bornschein ◽  
Oliver Arendt ◽  
Stefan Hallermann ◽  
Simone Brachtendorf ◽  
Jens Eilers ◽  
...  
Keyword(s):  
High Frequency ◽  
Purkinje Neuron ◽  
Paired Pulse ◽  
Paired Pulse Facilitation

scholarly journals Ultrafast glutamate sensors resolve high-frequency release at Schaffer collateral synapses

2017 ◽  
Author(s):  
Nordine Helassa ◽  
Céline D. Dürst ◽  
Catherine Coates ◽  
Silke Kerruth ◽  
Urwa Arif ◽  
...  
Keyword(s):  
Glutamate Receptors ◽  
High Frequency ◽  
Glutamate Release ◽  
Synaptic Cleft ◽  
Spike Trains ◽  
Slice Culture ◽  
Schaffer Collateral ◽  
Paired Pulse ◽  
Paired Pulse Facilitation ◽  
Hippocampal Slice Culture

ABSTRACTGlutamatergic synapses display a rich repertoire of plasticity mechanisms on many different time scales, involving dynamic changes in the efficacy of transmitter release as well as changes in the number and function of postsynaptic glutamate receptors. The genetically encoded glutamate sensor iGluSnFR enables visualization of glutamate release from presynaptic terminals at frequencies up to ∼10 Hz. However, to resolve glutamate dynamics during high frequency bursts, faster indicators are required. Here we report the development of fast (iGluf) and ultrafast (iGluu) variants with comparable brightness, but increased Kd for glutamate (137 μM and 600 μM, respectively). Compared to iGluSnFR, iGluu has a 6-fold faster dissociation rate in vitro and 5-fold faster kinetics in synapses. Fitting a three-state model to kinetic data, we identify the large conformational change after glutamate binding as the rate-limiting step. In rat hippocampal slice culture stimulated at 100 Hz, we find that iGluu is sufficiently fast to resolve individual glutamate release events, revealing that glutamate is rapidly cleared from the synaptic cleft. Depression of iGluu responses during 100 Hz trains correlates with depression of postsynaptic EPSPs, indicating that depression during high frequency stimulation is purely presynaptic in origin. At individual boutons, the recovery from depression could be predicted from the amount of glutamate released on the second pulse (paired pulse facilitation/depression), demonstrating differential frequency-dependent filtering of spike trains at Schaffer collateral boutons.Significance StatementExcitatory synapses convert presynaptic action potentials into chemical signals that are sensed by postsynaptic glutamate receptors. To eavesdrop on synaptic transmission, genetically encoded fluorescent sensors for glutamate have been developed. However, even the best available sensors lag behind the very fast glutamate dynamics in the synaptic cleft. Here we report the development of an ultrafast genetically encoded glutamate sensor, iGluu, which allowed us to image glutamate clearance and synaptic depression during 100 Hz spike trains. We found that only boutons showing paired-pulse facilitation were able to rapidly recover from depression. Thus, presynaptic boutons act as frequency-specific filters to transmit select features of the spike train to specific postsynaptic cells.

Paired-pulse facilitation in the dentate gyrus: a patch-clamp study in rat hippocampus in vitro

1994 ◽  
Vol 72 (1) ◽  
pp. 326-336 ◽  
Author(s):  
M. Andreasen ◽  
J. J. Hablitz
Keyword(s):  
Patch Clamp ◽  
Dentate Gyrus ◽  
Time Constant ◽  
Rise Time ◽  
Time Course ◽  
Nmda Antagonist ◽  
Paired Pulse ◽  
Stimulation Intensity ◽  
Paired Pulse Facilitation ◽  
Epsc Amplitude

1. Whole-cell patch-clamp recordings were used to study paired-pulse facilitation (PPF) of the lateral perforant path input to the dentate gyrus in thin hippocampal slices. 2. Orthodromic stimulation of the lateral perforant pathway evoked a excitatory postsynaptic current (EPSC) with a latency of 3.3 +/- 0.1 ms (mean +/- SE) that fluctuated in amplitude. The EPSC had a rise time (10-90%) of 2.79 +/- 0.06 ms (n = 35) and decayed with a single exponential time course with a time-constant of 9.14 +/- 0.24 ms (n = 35). No correlation was found between the amplitude of the EPSC and the rise time or decay time-constant. The non-N-methyl-D-aspartate (NMDA) antagonist 6-cyano-7-nitroquinoxaline-2,3-dione completely blocked the EPSC whereas the NMDA antagonist D-aminophosphonovaleric acid (APV) had modest effects. 3. When a test (T-)EPSC was preceded at an interval of 100 ms by a conditioning (C-)EPSC, a significant increase in the amplitude of the T-EPSC was seen in 38 out of 44 trials analyzed from a total of 27 granule cells. The average amount of PPF was 35.7 +/- 2.1%. There was no apparent correlation between the amount of PPF and the stimulation intensity or mean amplitude of the C-EPSC. The time course of the facilitated T-EPSC was not significantly different from that of the C-EPSC. 4. No correlation was found between the amplitude of the C-EPSC and that of the T-EPSC. Estimates of quantal content (mcv) were determined by calculating the ratio of the squared averaged EPSC amplitude (from 48 responses) to the variance of these responses (M2/sigma 2) whereas quantal amplitudes (qcv) were estimated by calculating the ratio of the response variance to average EPSC amplitude (sigma 2/M). PPF was found to be associated with an average increase in mcv of 64.8 +/- 7.2% (n = 38) whereas qcv was decreased by 12.1 +/- 3.8%. 5. The time course of PPF was studied by varying the interval between the C- and T-pulse from 10 to 400 ms while keeping the stimulation intensity constant. Maximal facilitation of the T-EPSC was obtained with interpulse intervals < or = 25 ms where the average facilitation amounted to approximately 70% (n = 6). The decline of facilitation was nearly exponential and was no longer evident with intervals > 350 ms.(ABSTRACT TRUNCATED AT 400 WORDS

scholarly journals Visualization of Oxytocin Release that Mediates Paired Pulse Facilitation in Hypothalamic Pathways to Brainstem Autonomic Neurons

PLoS ONE ◽  
2014 ◽  
Vol 9 (11) ◽  
pp. e112138 ◽  
Author(s):  
Ramón A. Piñol ◽  
Heather Jameson ◽  
Anastas Popratiloff ◽  
Norman H. Lee ◽  
David Mendelowitz
Keyword(s):  
Paired Pulse ◽  
Paired Pulse Facilitation ◽  
Autonomic Neurons ◽  
Oxytocin Release

scholarly journals A fresh look at paired-pulse facilitation

2001 ◽  
Vol 2 (5) ◽  
pp. 307-307 ◽  
Author(s):  
Juan Carlos López
Keyword(s):  
Paired Pulse ◽  
Paired Pulse Facilitation
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