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Titolo:
Differences in amplitude-voltage relations between minimal and composite mossy fibre responses of rat CA3 hippocampal neurons support the existence of intrasynaptic ephaptic feedback in large synapses
Autore:
Kasyanov, AM; Maximov, VV; Byzov, AL; Berretta, N; Sokolov, MV; Gasparini, S; Cherubini, E; Reymann, KG; Voronin, LL;
Indirizzi:
Russian Acad Sci, Brain Res Inst, Moscow 103064, Russia Russian Acad Sci Moscow Russia 103064 in Res Inst, Moscow 103064, Russia Russian Acad Sci, Inst Higher Nervous Act & Neurophysiol, Moscow 117865, Russia Russian Acad Sci Moscow Russia 117865 europhysiol, Moscow 117865, Russia Leibniz Inst Neurobiol, D-39008 Magdeburg, Germany Leibniz Inst NeurobiolMagdeburg Germany D-39008 9008 Magdeburg, Germany Russian Acad Sci, Inst Problems Informat Transmiss, Moscow 104447, Russia Russian Acad Sci Moscow Russia 104447 t Transmiss, Moscow 104447, Russia Int Sch Adv Studies, Biophys Sector, I-34014 Trieste, Italy Int Sch Adv Studies Trieste Italy I-34014 Sector, I-34014 Trieste, Italy Int Sch Adv Studies, INFM Unit, I-34014 Trieste, Italy Int Sch Adv Studies Trieste Italy I-34014 M Unit, I-34014 Trieste, Italy
Titolo Testata:
NEUROSCIENCE
fascicolo: 2, volume: 101, anno: 2000,
pagine: 323 - 336
SICI:
0306-4522(2000)101:2<323:DIARBM>2.0.ZU;2-X
Fonte:
ISI
Lingua:
ENG
Soggetto:
LONG-TERM POTENTIATION; EXCITATORY POSTSYNAPTIC POTENTIALS; PAIRED-PULSE FACILITATION; SYNAPTIC TRANSMISSION; QUANTAL ANALYSIS; PRESYNAPTIC INHIBITION; DENDRITIC SPINES; PYRAMIDAL CELLS; DENTATE GYRUS; VISUAL-CORTEX;
Keywords:
excitatory postsynaptic currents; hippocampus; membrane hyperpolarization;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
68
Recensione:
Indirizzi per estratti:
Indirizzo: Voronin, LL Russian Acad Sci, Brain Res Inst, Per Obukha 5, Moscow 103064,Russia Russian Acad Sci Per Obukha 5 Moscow Russia 103064 64, Russia
Citazione:
A.M. Kasyanov et al., "Differences in amplitude-voltage relations between minimal and composite mossy fibre responses of rat CA3 hippocampal neurons support the existence of intrasynaptic ephaptic feedback in large synapses", NEUROSCIENC, 101(2), 2000, pp. 323-336

Abstract

Computer simulations and electrophysiological experiments have been performed to test the hypothesis on the existence of an ephaptic interaction in purely chemical synapses. According to this hypothesis, the excitatory postsynaptic current would depolarize the presynaptic release site and further increase transmitter release, thus creating an intrasynaptic positive feedback. For synapses with the ephaptic feedback, computer simulations predictednon-linear amplitude-voltage relations and voltage dependence of paired-pulse facilitation. The deviation from linearity depended on the strength of the feedback determined by the value of the synaptic cleft resistance. The simulations showed that, in the presence of the intrasynaptic feedback, recruitment of imperfectly damped synapses and synapses with linear amplitude-voltage relations tended to reduce the non-linearity and voltage dependenceof paired-pulse facilitation. Therefore, the simulations predicted that the intrasynaptic feedback would particularly affect small excitatory postsynaptic currents induced by activation of electrotonically close synapses with long synaptic clefts. In electrophysiological experiments performed on hippocampal slices, the whole-cell configuration of the patch-clamp techniquewas used to record excitatory postsynaptic currents evoked in CA3 pyramidal cells by activation of large mossy fibre synapses. In accordance with thesimulation results, minimal excitatory postsynaptic currents exhibited "supralinear" amplitude-voltage relations at hyperpolarized membrane potentials, decreases in the failure rate and voltage-dependent paired-pulse facilitation. Composite excitatory postsynaptic currents evoked by activation of alarge amount of presynaptic fibres typically bear linear amplitude-voltagerelationships and voltage-independent paired-pulse facilitation. These data are consistent with the hypothesis on a strong ephaptic feedback in large mossy fibre synapses. The feedback would provide a mechanism whereby signals from large synapses would be amplified. The ephaptic feedback would be more effective on synapses activated in isolation or together withelectrotonically remote inputs. During synchronous activation of a large number of neighbouring inputs, suppression of the positive intrasynaptic feedback would prevent abnormal boosting of potent signals. (C) 2000 IBRO. Published by Elsevier Science Ltd. All rights reserved.

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Documento generato il 03/07/20 alle ore 16:50:41