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  • 1
    Electronic Resource
    Electronic Resource
    Accommodative properties of fast and slow pyramidal tract cells and their modification by different levels of their membrane potential (1968)
    Springer
    Experimental brain research 5 (1968), S. 189-201 
    Details
    ISSN: 1432-1106
    Keywords: Accommodation ; PT cell ; Membrane potential ; Fast-slow cell groups
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Threshold-latency curves were determined by intracellular application of linearly rising currents to cat pyramidal tract (PT) cells under various conditions of impalement. The nature of the curves was found to vary considerably, depending mainly upon the resting potential level. Three different types of curves were distinguished: (1) the ceiling type at relatively high resting potentials, (2) the simple type at moderate levels and (3) the minimal gradient type under depolarized conditions. In the first type, the ceiling increased with increasing membrane potential level. The second type attained an extremely low ceiling. 2. After eliminating the effects of the resting potential, a significant difference was still found between the ceilings of fast and slow PT cells, the ceilings being higher in the former than in the latter. 3. Parameters determining the threshold-latency curve were analyzed by applying current steps intracellularly, as described in previous paper. The variations of the ceiling due to the resting potential level were found to be dominated by the first exponential component of the membrane, while those between fast and slow cells were ascribable to the second exponential component.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00238663
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Repetitive impulses generated in fast and slow pyramidal tract cells by intracellularly applied current steps (1970)
    Springer
    Experimental brain research 11 (1970), S. 263-281 
    Details
    ISSN: 1432-1106
    Keywords: Repetitive discharge ; PT cell ; Fast-slow cell groups ; Kinetictonic patterns
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Responses to current steps were recorded from pyramidal tract (PT) cells of the cat by means of intracellular microelectrodes. PT cells with resting potentials from -60 to -80 mV set up a well sustained repetitive discharge during stimulation. When comparing fast and slow PT cells, quantitative differences were found between them in the pattern of repetitive firing. Thus, (1) the rheobase is lower in slow PT cells (mean and S.D.; 0.53±0.63 nA) than in fast cells (1.57±1.11 nA). (2) Following stimulation with a current step twice rheobase the latency and the successive interspike intervals are shorter in fast PT cells than in slow cells. (3) The interspike interval distribution shows a greater irregularity in fast PT cells than in slow cells. At firing rates around 30 impulses/sec the coefficient of variation has a mean value of 0.243 for fast PT cells and 0.085 for slow cells. (4) Fast PT cells show a greater decrease of firing rate during the initial 300 msec of current stimulation (adaptation) than do slow cells. The mean value of this initial decrease is 1.85 times the later steady firing rate in fast PT cells and 0.56 times in slow cells. (5) The slope constant of the firing rate-current relationship is larger in fast PT cells, being five times or more than in slow cells. These characteristics of firing pattern are termed “kinetic” and “tonic” for fast and slow PT cells respectively, and their functional meanings are discussed in comparison with other neural organs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01474386
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Activities of the sodium pump in cat pyramidal tract cells investigated with intracellular injection of sodium ions (1972)
    Springer
    Experimental brain research 14 (1972), S. 449-462 
    Details
    ISSN: 1432-1106
    Keywords: Sodium ions ; Electrogenic Na pump ; Post-tetanic hyperpolarization ; PT cell
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Sodium ions were injected into cat pyramidal tract (PT) cells electrophoretically through an intracellular NaCl or Na glutamate-filled microelectrode. Following an injection there were decreases in the maximum rates of rise and fall of the spike potential and there was displacement of the inhibitory postsynaptic potential in a depolarizing direction. These changes recovered with an exponential time course, indicating concomitant changes in the internal sodium, potassium and chloride concentrations under the operation of the sodium pump in extruding excess sodium. From the exponential recovery curve, the rate constant of active sodium extrusion was estimated as about 60 hr−1 in fast PT cells and about 90 hr−1 in slow PT cells. It was suggested that the sodium pump was at least partly electrogenic, since the resting membrane was hyperpolarized by the sodium injection to the degree which depended on the amount of sodium-injecting current. Further support for this possibility was obtained by the experiment of high-frequency activation of PT cells, in which the sodium entry through the active membrane developed a slow post-tetanic hyperpolarization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236587
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Accommodative behavior of cat pyramidal tract cells investigated with intracellular injection of currents (1968)
    Springer
    Experimental brain research 5 (1968), S. 173-188 
    Details
    ISSN: 1432-1106
    Keywords: Accommodation ; PT cell ; Membrane impedance ; Linearly rising currents ; Current steps
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Single glass microelectrodes were inserted into pyramidal tract (PT) cells of cat's cerebral cortex. Accommodative properties of their membranes were investigated by intracellular injection of depolarizing currents. 2. The threshold-latency curve was derived by applying linearly rising currents. When the rising slope of the current was decreased gradually, the threshold intensity first decreased, and then later increased, reaching a certain constant value in the manner of a ceiling. 3. Factors determining this characteristic threshold-latency curve were analyzed by using current steps. A special form of the membrane impedance was thus revealed; the time course of the potential changes induced by current steps can be approximated by the sum of three exponential curves, just as in motoneurones. Threshold-latency curves calculated for a triple exponential model of the membrane fit closely to the actual ones. It implies that the PT cells have no genuine accommodation under normal conditions. 4. Local responses and alterations in the critical depolarization were considered to contribute only minutely to the threshold-latency curve of the PT cell membrane.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00238662
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    Paper (German National Licenses)
    Fulltext
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