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  • 1
    Electronic Resource
    Electronic Resource
    Quantal analysis of excitatory postsynaptic potentials induced in hippocampal neurons by activation of granule cells (1982)
    Springer
    Experimental brain research 46 (1982), S. 170-176 
    Details
    ISSN: 1432-1106
    Keywords: Hippocampus ; Quantal amplitude ; Quantal content ; Mossy fiber ; Frequency potentiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The values of quantal content (m) and quantal amplitude (q) of excitatory postsynaptic potentials (EPSPs) elicited in CA3 neurons by activation of granule cells were estimated in thin hippocampal sections maintained in vitro. For this purpose, DL-homocysteate was administered to granule cells, and trains of EPSPs that were typical for single granule cell activation were recorded from individual CA3 neurons. The amplitudes of the first and second EPSPs in each train were measured. From the mean and variance of the amplitudes of the EPSPs, the values of q and m were calculated. The values of m and q for the first EPSPs were estimated at 8.3 and 0.28 mV, respectively, on the average. Potentiation of the second EPSPs was accompanied by a two-fold increase in the values of m without changes in the values of q. Therefore, frequency potentiation in synapses between mossy fibers and CA3 neurons may be explained by an increase in number of released quanta. Amplitudes of EPSPs were found to fluctuate in a manner described by Poisson's law.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237173
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  • 2
    Electronic Resource
    Electronic Resource
    Suppressing action of 2-amino-4-phosphonobutyric acid on mossy fiber-induced excitation in the guinea pig hippocampus (1983)
    Springer
    Experimental brain research 51 (1983), S. 128-134 
    Details
    ISSN: 1432-1106
    Keywords: 2-Amino-4-phosphonobutyric acid ; Hippocampus ; Glutamate receptor ; Mossy fiber
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The action of 2-amino-4-phosphonobutyric acid (APB) on mossy fiber-induced excitation in CA3 neurons was studied in vitro with thin sections of guinea pig hippocampus. D- and DL-APB suppressed field potentials induced in regio CA3 by granular layer stimulation. Threshold concentration of DL-APB to induce the suppression was 2–5 μM. D-APB was about 10-fold less potent than DL-APB. Field potentials induced by fimbrial stimulation were much less affected. DL-APB was without effect on antidromic activation of granule cells. 2-Amino-phosphonovaleric acid had a similar but less potent action. Gamma-D-glutamylglycine and cis-2,3-piperidine dicarboxylic acid were almost ineffective. DL-APB suppressed excitatory postsynaptic potentials recorded intracellularly from CA3 neurons in response to granular layer stimulation but caused no marked changes in resting potentials, action potentials and membrane conductance. Single cell discharges induced by iontophoretic administration of glutamate (Glu) or aspartate (Asp) were unaffected when mossy fiber-induced excitation was suppressed by D- or DL-APB. DL-APB had no suppressing action on Glu- or Asp-induced depolarizing potentials. These results indicate that APB is a relatively specific blocker of synaptic transmission between mossy fibers and CA3 neurons, and that this action does not result from blockade of receptors for Glu or Asp.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236810
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Kainic acid induces long-lasting depolarizations in hippocampal neurons only when applied to stratum lucidum (1988)
    Springer
    Experimental brain research 72 (1988), S. 135-140 
    Details
    ISSN: 1432-1106
    Keywords: Kainic acid ; Excitatory amino acid ; Stratum lucidum ; Mossy fiber ; Hippocampus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The actions of α-kainic acid (KA) were re-examined in thin sections of the hippocampus and the cerebellum of the guinea pig in view of various discrepancies between our previous findings and reports from other laboratories. Brief pulses of KA ejected in st. lucidum in the CA3 region induced short- and long-lasting depolarizations in neurons nearby, whereas those ejected in st. radiatum or st. oriens induced only short-lasting responses. Neurons in CA1 region and Purkinje cells in the cerebellum generated only short-lasting depolarizations in response to KA pulses ejected in their dendritic fields. The short-lasting KA responses in CA1 region were sensitive to γ-D-glutamylglycine and pentobarbital. The slow KA responses were suppressed by kynurenic acid. They were not accompanied by increases in extracellular potassium concentration. These results suggest that the mossy fiber-innervated portions of the surface membrane of CA3 neurons have a type of KA receptor different from those ubiquitously distributed in central neurons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00248508
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Potentiation of excitatory postsynaptic potentials during and after repetitive stimulation in thin hippocampal sections (1980)
    Springer
    Experimental brain research 38 (1980), S. 469-477 
    Details
    ISSN: 1432-1106
    Keywords: Frequency potentiation ; Long-term potentiation ; Heterosynaptic potentiation ; Hippocampus ; Mossy fiber
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Excitatory postsynaptic potentials (EPSPs) elicited by mossy fiber stimulation were recorded intracellularly from neurons in the CA3 region in thin hippocampal sections in vitro and potentiation of the EPSPs was examined during and after repetitive stimulation. Inhibitory postsynaptic potentials (IPSPs) and seizure discharges were blocked by bicuculline and high concentrations of Mg2+. When two shocks were applied at short intervals, the second EPSP was markedly potentiated. This potentiation declined exponentially with a time-constant of about 180 ms and was unaffected by changes in ambient temperature. The amount of potentiation during a pulse train was explained by summation of potentiation by individual pulses. Post tetanic potentiation lasted longer in media containing Ca2+ at higher concentrations and Mg2+ at lower concentrations. At high Ca2+ concentrations, tetanic stimulation induced long-term potentiation which was occasionally preceded by a long-lasting suppression. Tetanus to a bundle of mossy fibers potentiated EPSPs elicited by stimulation of a separate bundle of mossy fibers (heterosynaptic potentiation) but did not augment EPSPs elicited by fimbrial stimulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237528
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  • 5
    Electronic Resource
    Electronic Resource
    Activation of hippocampal neurons by mossy fiber stimulation in thin brain sections in vitro (1972)
    Springer
    Experimental brain research 14 (1972), S. 423-435 
    Details
    ISSN: 1432-1106
    Keywords: Mossy fiber ; Magnesium ; Calcium ; Hippocampus ; Brain slices
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Transmission through the synapse between the mossy fiber and the CA3 neurons was studied in vitro in thin transverse sections from the hippocampus of the guinea-pig. 2. Stimulation to the granular layer elicited in the pyramidal cell layer of the regio CA3 a mainly negative focal potential consisting of the early and late waves. Conditioning stimulation potentiated the late wave but not the early wave. The late wave was strongly suppressed by an excess of Mg++ or a reduction in Ca++ in the medium, but the early wave was affected only a little. 3. The action potentials, EPSP, and IPSP recorded intracellularly differed little from those observed in vivo except that most of the action potentials lacked the depolarizing afterpotential. The EPSP was markedly potentiated during low frequency stimulation. At nearly threshold strength, it showed a wide fluctuation in amplitude. 4. The latency and properties of the action potential triggered by the EPSP agreed with those of the late wave, which was therefore concluded to represent activation of the CA3 neurons by chemical transmission. 5. Corresponding to the early wave in the field potential, some cells generated action potentials before the onset of the EPSP. Probable explanations were offered for the activation of the CA3 neurons without preceding EPSPs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00235037
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