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  • 1
    Electronic Resource
    Electronic Resource
    Analysis of bimodal interspike interval histograms of primary muscle spindle endings in active triceps surae muscles of cats (1982)
    Springer
    Pflügers Archiv 393 (1982), S. 148-156 
    Details
    ISSN: 1432-2013
    Keywords: Primary muscle spindle endings ; Discharge statistics ; Isometric muscle contraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A feature frequently observed in interspike interval histograms (IH) derived from stationary Ia fibre discharge patterns was a bimodality suggesting a mixed population composed of two sub-populations of possibly different origins. To verify this hypothesis a separation of these subpopulations was attempted by assuming a Gaussian distribution for the longer intervals. The success of such a separation depended on the distinctness of the histogram peaks and the relative sizes of each mode. Both factors in turn depended on the overall muscle length and, hence, on the mean spindle discharge rate. The smaller intervals were then isolated from the spike trains and submitted to further statistical analysis. By averaging overall muscle tension with respect to the smaller intervals, the latter could often be linked to tension trajectories which were of higher amplitude and faster time course than the trajectories obtained by averaging with respect to the rest of the spikes. In some cases, autocorrelation histograms of isolated small intervals as well as serial correlograms computed for all intervals indicated that some muscle spindle afferents responded sensitively to activity of single motor units. This would confirm recent results of Cameron et al. (1980).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00582938
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  • 2
    Electronic Resource
    Electronic Resource
    The use of frequency domain techniques in the study of signal transmission in skeletal muscle (1984)
    Springer
    Pflügers Archiv 400 (1984), S. 100-105 
    Details
    ISSN: 1432-2013
    Keywords: Spike train ; Spectral analysis ; Coherence ; Frequency response ; Motor unit ; Muscle spindle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Spectral analysis provides a description of the moments of random signals and enables the characterization of the behaviour of systems in terms of input-output relations. The merits of such an approach in the study of signal transmission in skeletal muscle are described in this paper. The representation of neural spike trains as impulse sequences and the subsequent treatment appropriate for this kind of analysis are discussed together with some practical problems. Spectral analysis of muscle afferent signals is applied to data obtained from cat experiments, and the use of the related frequency-domain techniques is demonstrated on a subsystem of the stretch reflex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00670543
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Event-related cross-correlations between spike trains illustrated on interactions between motor units and muscle spindle afferents (1987)
    Springer
    Pflügers Archiv 408 (1987), S. 196-203 
    Details
    ISSN: 1432-2013
    Keywords: Event-related cross-correlation ; Spike train analysis ; Signal transmission ; Motor units ; Muscle spindle afferents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A method is presented for computing correlation coefficients of two (or more) output spike trains in temporal relation to one (or more) input event trains. These event-related correlation functions are computed by convolving the output spike trains, represented as point processes, with rectangular pulses of selectable width, and by then calculating linear correlation coefficients for the pairs of amplitude values obtained from the two convolved processes in temporal relation to the input events. The merits of this technique are illustrated on stimulus trains delivered to motor units (MUs) and output spike trains recorded from muscle spindle afferents of the same cat hindlimb muscle. The correlation functions obtained show the temporal course of the correlated firings of the two afferents (mostly Ia afferents from primary muscle spindle endings) as a function of time from MU activation; they are compared with the conventional cross-correlation histograms (CCHs) between afferents and with peri-stimulus time histograms (PSTHs) between stimulus and afferent firing patterns. Stimulus-related cross-correlation functions as displayed here can be calculated for any three spike trains. Possible extensions of the method to larger numbers of input and output channels are also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00581352
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  • 4
    Electronic Resource
    Electronic Resource
    A method to estimate the effects of parallel inputs on neuronal discharge probability (1989)
    Springer
    Pflügers Archiv 413 (1989), S. 622-628 
    Details
    ISSN: 1432-2013
    Keywords: Random inputs ; Cross-correlation ; Nonlinear analysis ; Synchronous inputs ; Renshaw cells ; Dorsal horn neurones
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We here present a method to study the interaction of parallel neural input channels regarding their effects on a neurone. In particular, the method allows to disclose the effects of oligosynaptic pathways that may exist in parallel to direct monosynaptic connections to the cell. Two (or more) inputs (nerves) are stimulated with random patterns of stimuli. The response of the cell to these patterns is evaluated by the computation of peristimulus-time histograms (PSTHs). One of the two stimulus trains is selected as the one to yield reference events for the PSTH computation. From this stimulus train are selected those stimuli as reference events which are preceded, at defined mean intervals, by stimuli in the same or a parallel channel. These “conditioning” stimuli are determined (1) separately from each single stimulus train and (2) concomitantly from the two trains as events occurring simultaneously in both. The effects exerted by these various conditioning events on the effects of the “test” pulses on the cell response yield insights into the interactions between the two (or more) inputs. These methods are demonstrated on spinal Renshaw cells activated by independent random stimulation of two muscle nerves and on dorsal horn neurones responding to cutaneous nerve stimulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00581812
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  • 5
    Electronic Resource
    Electronic Resource
    Interactions between motor units in modulating discharge patterns of primary muscle spindle endings (1982)
    Springer
    Experimental brain research 45 (1982), S. 417-427 
    Details
    ISSN: 1432-1106
    Keywords: Primary muscle spindle endings ; Motor units ; Tremor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Discharge patterns of group Ia afferents of muscle spindles in the (isometric) cat semitendinosus muscle were recorded when subjected to the influence of contractions of three motor units elicited by stimulation of three α-efferents with different regular or stochastic stimulus patterns. In order to study conditioning interactions between motor unit contractions, defined time constellations of stimuli to different motor units were isolated from the stimulus trains by electronic means. This technique was also applied to discharge patterns of two Ia fibres to isolate “correlated discharges”. The effects of defined time constellations of stimuli upon discharge patterns of single Ia afferents or “correlated discharges” of pairs of Ia afferents were assessed by poststimulus time histograms (PSTHs). It turned out that the influence exerted by one motor unit on spindle discharges was more or less strongly modulated by actions of the other motor units, dependent on the relative timing of their contractions. These effects could in part be explained by the relative locations of motor units and spindles within the muscle. These results are discussed with respect to possible mechanisms of low-amplitude physiological tremor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01208602
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Origin and nature of correlations in the Ia feedback pathway of the muscle control system (1978)
    Springer
    Biological cybernetics 31 (1978), S. 71-79 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract Mammalian primary muscle spindle endings receive two inputs from fusimotor fibers and length changes of their extrafusal environment. Both inputs are also powerful noise sources disturbing the discharge patterns of the receptors. In this paper emphasis is laid on the extrafusal component. It is shown that extrafusal muscle activity can be viewed as a stochastic process which, acting as a common source, can correlate discharge patterns of adjacent muscle spindles. Some quantitative characteristics of these correlations and their relation to the underlying mechanical events are investigated in some detail in order to provide data for more theoretical considerations on their possible physiological importance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00344237
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  • 7
    Electronic Resource
    Electronic Resource
    Auxiliary spinal networks for signal focussing in the segmental stretch reflex system (1979)
    Springer
    Biological cybernetics 34 (1979), S. 125-135 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract In continuation of a previous paper, the auxiliary signal focussing properties of more complicated spinal neuronal networks are considered here. Special emphasis is put on the distributive function of the recurrent feedback system of α-motoeurones, but also the inhomogeneous distribution of excitatory and inhibitor input to motoneurones is taken into account as an essential prerequisite for signal focussing. Simple hypothetical calculations for steady-state conditions yield a more vivid insight into the interaction of the two types of neuronal circuitry contributing to signal focussing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00336964
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  • 8
    Electronic Resource
    Electronic Resource
    A possible partitioning of segmental muscle stretch reflex into incompletely de-coupled parallel loops (1979)
    Springer
    Biological cybernetics 34 (1979), S. 205-213 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract Based on previous investigations on focussed signal transmission through the muscle stretch reflex system, a model is presented suggesting that different muscle areas (especially in large complex muscles such as the triceps surae muscle) may be regulated rather independently with respect to certain internal state variables, particularly internal length. Since the parallel localized reflex loops necessary for such local control tasks are inevitably coupled peripherally through the muscle and connective tissues, compensatory de-coupling elements would be required to reestablish at least partial independence. Whether and how this can be achieved at the level of spinal neuronal circuitry is investigated in connection with a discussion of the advantages of partially de-coupled reflex loops.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00337427
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  • 9
    Electronic Resource
    Electronic Resource
    Neural activity states in different forms of physiological tremor. Facts and hypotheses (1984)
    Springer
    Biological cybernetics 50 (1984), S. 143-154 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract This paper attempts to combine (and thereby briefly review) various sets of physiological data in order to outline a qualitative model of the different states of stochastic neural activity underlying different forms of physiological tremor. Particular emphasis in put on spatial distributions of the properties of neural elements and their interconnexions, and on discharge characteristics of motor units and muscle spindle afferents including so-called “early discharges” and nonlinearities. It is argued that the wide variety of internal anatomical and functional structures of skeletal muscles and of their reflex organization must be considered when dealing with stability problems. Computer simulations of stochastic population models of the involved neuromuscular elements are advocated as means to investigate the relative importance of the many factors possibly contributing to stabilizing or de-stabilizing neuromuscular systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00337161
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  • 10
    Electronic Resource
    Electronic Resource
    Responses of the spinal α-motoneurone-Renshaw cell system to various differentially distributed segmental afferent and descending inputs (1985)
    Springer
    Biological cybernetics 51 (1985), S. 417-426 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract A previously presented multi-loop model of the mammalian spinal α-motoneurone-Renshaw cell system was extended to incorporate different physiological input patterns: Ia fibres from primary muscle spindle endings, spinal input systems descending in the ventral quadrant and from the nucleus ruber. The main goal of the computer simulation calculations was to present a number of dynamic input-output relations between these inputs which are distributed inhomogenously to different types of α-MNs (that is, S-, FR-, and FF-type MNs) and the outputs of pools of the latter, for the purpose of experimental testing. The main outcome was that the phase relations of the outputs of the different types of MNs depend very much on the overall strength of recurrent inhibition, such that small changes of this strength, which appears to be small anyway, can significantly alter these phase relations. Since this strength is alterable through descending and segmental afferent inputs, this provides a physiological means of phase-decorrelation although it is unlikely to put the discharges of different MN types totally out of phase (by about 180°). Also, the inhomogeneity of recurrent inhibition would help to prevent a strong phase separation of this kind. Yet a decorrelation at the microscopic level could help suppress physiological tremor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00350782
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    Paper (German National Licenses)
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