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  • 1
    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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  • 2
    Electronic Resource
    Electronic Resource
    Differential effects of stimulation of the cat's red nucleus on lumbar alpha motoneurones and their Renshaw cells (1986)
    Springer
    Experimental brain research 62 (1986), S. 161-174 
    Details
    ISSN: 1432-1106
    Keywords: Red nucleus ; Renshaw cells ; Moto-neurone-Renshaw cell linkage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. The red nucleus region was stereotaxically stimulated with short trains of high-frequency alternating current pulses in anaesthetized cats. The effects were studied, in contralateral lumbar segments, on the responses of microrecorded individual Renshaw cells (RCs) to antidromic or orthodromic test shocks of ventral root or muscle nerve fibres. Monosynaptic reflexes (MRs) of their motoneurone pools were recorded from one of the cut lumbar ventral roots. Averages of 10–20 replicate test responses of the RC (converted into instantaneous frequency curves, IFCs) and of the MR shapes were computed and graphically displayed. 2. Orthodromic (afferent) test shocks induced simultaneously MRs as well as responses of a RC belonging to the same motor pool. From their paired records at systematically varied shock strengths, whole “linkage characteristics” of the relation between the two events could be obtained, representing the functional linkage from the motoraxon collaterals to the RC under study. The overall result of rubral conditioning was a change in the course of the characteristic, which indicated a reduction of this linkage (= relative inhibition of the RC against its recurrent input). 3. Sequential trials with test shocks of constant, submaximal strength were performed with 45 individual RCs. The clearest results were obtained with RC responses to antidromic ventral root shocks: 65% of the RCs were partially inhibited by rubral conditioning. Interposed minor facilitory subcomponents could be seen in the course of inhibited IFCs. Mixed sequences of manifest inhibitory/facilitory effects were observed in 11%; reversed sequences (facilitory/inhibitory) did not occur. A pure but weak facilitation was found in only one case, paralleled by an increase of the MR. RCs belonging to either extensor or flexor motor pools were affected about equally. A little over 20% of the tested RCs remained uninfluenced by rubral stimulation. 4. The MRs, induced by constant, submaximal, orthodromic test shocks, were usually enhanced with only few exceptions, by rubral stimulation. The effects on the orthodromic RC responses were mainly inhibitory, but could be more or less masked by the concurrent increase of the MR, providing a stronger recurrent input to the RC. Such inhibition could be uncovered, however, by observing the above described linkage change. 5. Variation of several parameters of rubral conditioning (train duration, timing of train with respect to test shock, strength of train) modified the inhibitory effects on antidromic RC responses to a certain extent without changing their principal character. Higher conditioning strengths frequently induced mass discharges of previously silent motoneurones, but at the same time an increased inhibition of the concurrent RC responses. 6. Spontaneous RC activity (in the absence of test stimuli) occurred infrequently and was weak and interrupted by silent periods. When this persisted long enough for testing repeated rubral stimulation, a strong initial inhibition lasting up to several hundred ms was found, sometimes followed by some oscillations of the average discharge rate. 7. The predominant combination of concurrent effects of the conditioning, namely, inhibition of RCs and facilitation of motoneurones, indicated independent (and mostly divergent) control of the two target neurones by the red nucleus. It is concluded that in this way the RCs can be flexibly and transiently decoupled to some degree from their recurrent motoneuronal input.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237412
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  • 3
    Electronic Resource
    Electronic Resource
    Time constants of facilitation and depression in Renshaw cell responses to random stimulation of motor axons (1988)
    Springer
    Experimental brain research 72 (1988), S. 117-128 
    Details
    ISSN: 1432-1106
    Keywords: Renshaw cells ; Motor axons ; Random stimulation ; Synaptic transmission ; Facilitation ; Depression ; Time constants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In 9 adult anaesthetized cats, 22 lumbosacral Renshaw cells recorded with NaCl-filled micropipettes were activated by random stimulation of ventral roots or peripheral nerves. The stimulus patterns had mean rates of 9.5–13 or 20–23 or 45 pulses per second and were pseudo-Poisson; short intervals below ca. 5 ms (except in two cases) were excluded. The Renshaw cell responses were evaluated by two kinds of peristimulus-time histograms (PSTHs). “Conventional” PSTHs were calculated by averaging the Renshaw cell discharge with respect to all the stimuli in a train. These PSTHs showed an early excitatory response which was often followed by a longer-lasting slight reduction of the discharge probability. These two response components were positively correlated. “Conditional” PSTHs were determined by averaging the Renshaw cell discharge with respect to the second (“test”) stimulus in pairs of stimuli which were separated by varied intervals, δ. The direct effect of the first “conditional” response was subtracted from the excitation following the second (“test”) stimulus so as to isolate the effect caused by the second stimulus per se. After such a correction, the effect of the first “conditioning” stimulus showed pure depression, pure facilitation or mixed facilitation/depression. Analysis of such conditioning curves yielded two time constants of facilitation (ranges: ca. 4–35 ms and 93–102 ms) and two of depression (ranges: ca. 7–25 ms and 50–161 ms). It is concluded that these time constants are compatible with processes of short-term synaptic plasticity known from other synapses. Other processes such as afterhyperpolarization and mutual inhibition probably are of less importance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00248506
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  • 4
    Electronic Resource
    Electronic Resource
    Responses of Renshaw cells to muscle ramp stretch (1974)
    Springer
    Experimental brain research 21 (1974), S. 353-360 
    Details
    ISSN: 1432-1106
    Keywords: Renshaw cells ; Muscle stretch ; Phasic tonic motoneurones
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary a) Renshaw cells (RC) were recorded during ramp stretch of the GS muscle. In 90% of the analysed cells, the frequency and duration of the phasic response were enhanced by increases in both the length and rate of stretch. b) The tonic response, which was observed in about 30% of the analysed cells, increased at higher stretch lengths. c) After application of the cholinergic blocking agent mecamylamine or after severance of the GS nerve, the Renshaw stretch response was abolished. d) The results lend some support to the hypothesis that RCs are triggered predominantly by large phasic motoneurones. The smaller tonic motoneurones seem to provide some supporting background input to the RCs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237898
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  • 5
    Electronic Resource
    Electronic Resource
    Recurrent inhibition of individual Ia inhibitory interneurones and disinhibition of their target α-motoneurones during muscle stretches (1975)
    Springer
    Experimental brain research 23 (1975), S. 13-28 
    Details
    ISSN: 1432-1106
    Keywords: Ramp-and-hold stretches ; Ia inhibitory interneurones ; Renshaw cells ; Reciprocal inhibition ; Recurrent facilitation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effects of ramp stretches applied to triceps surae muscle on the discharge patterns of single Ia inhibitory interneurones, monosynaptically invaded from various nerves, were studied in either decerebrate or anesthetized cats. Interneurones which received direct excitatory Ia input from the stretched muscle exhibited augmented activity both during the dynamic and static phase of stretch, which was, however, interrupted by a transient inhibitory influence during the dynamic phase of stretch. The influences on Ia inhibitory interneurones, monosynaptically invaded from hamstring or tibial nerve, were exclusively inhibitory. These stretch-induced inhibitions were better demonstrable in decerebrate than in anesthetized preparations. The timing of the discharge patterns of additionally recorded Renshaw cells during stretch, and the disappearance or reduction of the above described inhibitory effects after administration of DHE, strongly support the idea that these inhibitory actions are caused by Renshaw inhibition. In Ia inhibitory interneurones, monosynaptically activated from the antagonistic peroneal nerve, stretch induced also pronounced inhibitory effects, which were most probably caused by mutual inhibition between Ia inhibitory interneurones. The suppression of agonistic Ia inhibitory interneurone activity below the tonic resting activity corresponded to an enhancement of the monosynaptic reflex amplitude of the antagonistic motoneurone pool. The findings suggest that normal orthodromic activation of Renshaw cells, and consequently the recurrent inhibition of the Ia inhibitory interneurones, is predominantly linked with rapid phasic, rather than slow tonic, motoneuronal firing. The functional role of this mechanism for the performance of rapidly alternating movements and the damping of ballistic agonist contractions is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00238726
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  • 6
    Electronic Resource
    Electronic Resource
    Electron spin resonance (ESR) investigations on blood of patients with leukemia (1979)
    Springer
    Annals of hematology 39 (1979), S. 147-151 
    Details
    ISSN: 1432-0584
    Keywords: Leukämie ; Elektronenspin-Resonanz (ESR) ; Antioxidantien ; Leukemia ; ESR ; Antioxidants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary ESR investigations of lyophilized blood of patients with acute lymphatic leukemia exhibit an increase in spin concentration and an additional peak not present in control samples. This peak disappears almost completely concomittantly with a reduction in spin concentration after treating the patients with prednisolone, vincristine, and doxorubicin or after addition of 5 mM of CuCl2 to blood samples. The results show that the ESR spectra of lyophilized blood samples can be utilized to follow the effect of therapy. Moreover, they suggest that the leukemic blood possesses a high concentration of antioxidants.
    Notes: Zusammenfassung ESR-Untersuchungen an lyophilisiertem Blut von Patienten mit akuter lymphatischer Leukämie zeigten eine Zunahme in der Spinkonzentration. Außerdem trat ein zusätzliches Signal auf, welches in Kontrollproben nicht vorhanden ist. Wenn man die Patienten mit Prednisolen, Vincristin und Doxorubicin behandelt, verschwindet gleichzeitig mit einer Abnahme der Spinkonzentration dieses Signal fast vollständig. Ein ähnlicher Effekt wurde erhalten, wenn entsprechende Blutproben mit 5 mM CuCl2 versetzt wurden. Die Ergebnisse zeigen, daß die ESR-Spektren von lyophilisierten Blutproben als Indikator für den Therapie-Verlauf benutzt werden können. Diese Ergebnisse deuten darüber hinaus darauf hin, daß leukämisches Blut eine hohe Konzentration an Antioxidantien besitzt.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01008090
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  • 7
    Electronic Resource
    Electronic Resource
    On the possible involvement of ascorbic acid and copper proteins in leukemia: I. Electron spin resonance (ESR) investigations on native blood, erythrocytes, and leukocytes (1979)
    Springer
    Annals of hematology 39 (1979), S. 317-326 
    Details
    ISSN: 1432-0584
    Keywords: ESR ; LeukÄmie ; AscorbinsÄure ; Antioxidanzien ; oxidierende Substanzen ; ESR ; Leukemia ; Ascorbic acid ; Antioxidants ; Oxidizing agents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Addition of ascorbic acid to native blood or to erythrocytes and leukocytes of healthy persons results in an ESR spectrum which is identical to the one obtained with blood or its fractions of leukemic patients. After an initial increase the spin concentration decreases at higher (〉 100 mM) concentrations of ascorbic acid. These findings confirm observations made thus far that cancerous tissue, finally, exhibits a lower spin concentration and a higher concentration of antioxidants than its corresponding healthy tissue. Application of oxidizing substances, such as KMnO4 or CuCl2, to erythrocytes either before or after administration of vitamin C compensates the effect of the latter substance depending, of course, on the concentration used. The effect produced by ascorbic acid on blood and its fractions seems to be unique since neither vitamin E or vitamin A or catechol and its amines noradrenaline, adrenaline, dopamine, and its precursor amino acid dopa, cytochrome c, FMN, NADH, Na2S2O4, ethylenglycol, glyceraldehyde, or tyrosine produce this effect. Ascorbic acid seems to play, thus, an important role in the balance of health and disease, as has been pointed out by Szent-Györgyi [16]. Its possible receptor(s) and its implication in the formation of cancer, or at least leukemia, will be discussed in detail elsewhere [9].
    Notes: Zusammenfassung Eine Zugabe von AscorbinsÄure zu nativem Blut oder zu Erythrozyten und Leukozyten von gesunden Personen ergibt ein ESR-Spektrum, das identisch zu dem ist, welches mit Blut oder seinen Fraktionen von LeukÄmie-Patienten erhalten wird. Nach einer anfÄnglichen Zunahme nimmt die Spin-Konzentration bei höheren (〉 100mM) AscorbinsÄure-Konzentrationen wieder ab. Diese Ergebnisse bestÄtigen bisherige Beobachtungen, wonach Krebsgewebe im fortgeschrittenen Stadium eine niedrigere Spin-Konzentration und eine grö\ere Konzentration an Antioxidanzien als das dazugehörige gesunde Gewebe besitzt. Eine Zugabe von oxidierenden Substanzen, wie z. B. KMnO4 oder CuCl2, zu Erythrozyten entweder vor oder nach Vitamin C Zugabe kompensiert den Effekt der letzteren Substanz, was natürlich von der gebrauchten Konzentration abhÄngt. Der durch AscorbinsÄure an Blut und seinen Fraktionen erzeugte Effekt scheint spezifisch zu sein, da weder Vitamin E nach Vitamin A oder Catechol und seine Amine Noradrenalin, Adrenalin, Dopamin und sein VorlÄufer, die AminosÄure Dopa, Cytochrom c, FMN, NADH, Na2S2O4, Äthylenglykol, Glyzeraldehyd oder Tyrosin diesen Effekt erzeugen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01014194
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