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  • 1
    Electronic Resource
    Electronic Resource
    Pattern of monosynaptic heteronymous Ia connections in the human lower limb (1993)
    Springer
    Experimental brain research 96 (1993), S. 534-544 
    Details
    ISSN: 1432-1106
    Keywords: Ia EPSP ; Monosynaptic Ia pathways ; Spinal reflexes ; Man
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Changes in the firing probability of single motor units in response to electrical stimulation of muscle nerves were used to derive the projections of muscle spindle Ia afferents to the motoneurones of various leg and thigh muscles. Discharges of units in soleus, gastrocnemius medialis, peroneus brevis, tibialis anterior, quadriceps, biceps femoris and semitendinosus were investigated after stimulation of inferior soleus, gastrocnemius medialis, superficial peroneal, deep peroneal and femoral nerves. Homonymous facilitation, occurring at the same latency as the H reflex and therefore attributed to monosynaptic Ia EPSPs, was found in virtually all the sampled units. In many motor nuclei an early facilitation was also evoked by heteronymous low-threshold afferents. The heteronymous facilitation was considered to be mediated through a monosynaptic pathway when the difference between the central latencies of heteronymous and homonymous peaks was not more than 0.2 ms. The heteronymous Ia connections were widely distributed. In particular, monosynaptic coupling between muscles operating at different joints appears to be the rule in humans, though it is rare between ankle and knee muscles in the cat and the baboon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00234121
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Pattern of heteronymous recurrent inhibition in the human lower limb (1994)
    Springer
    Experimental brain research 102 (1994), S. 149-159 
    Details
    ISSN: 1432-1106
    Keywords: Recurrent inhibition ; Renshaw cells ; Spinal reflexes ; Man
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Changes in the firing probability of motor units belonging to leg and thigh muscles were used to describe the pattern of distribution of recurrent inhibition evoked by motor discharges from various motor nuclei in the human lower limb. Discharges of units in soleus, gastrocnemius medialis, peroneus brevis, tibialis anterior, quadriceps and biceps femoris were investigated following a conditioning stimulation which evoked either a monosynaptic reflex in quadriceps, triceps surae or peroneal motor neurones, or an antidromic motor volley in one of the following nerves: inferior soleus, gastrocnemius medialis, superficial peroneal, deep peroneal, or femoral nerve. In many motor unit-nerve combinations a trough in the post-stimulus time histogram, indicating an inhibition, appeared immediately after the heteronymous Ia excitation. This inhibition is thought to be Renshaw in origin, because it appeared and increased with the conditioning motor discharge, was independent of the conditioning stimulus intensity per se and had a long duration. These recurrent connections were widely distributed with a pattern very similar to that described for heteronymous monosynaptic Ia excitation. In particular Renshaw coupling between muscles operating at different joints seems to be the rule in the human lower limb.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00232447
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Further evidence for non-monoynaptic group I excitation of motoneurones in the human lower limb (1997)
    Springer
    Experimental brain research 115 (1997), S. 35-46 
    Details
    ISSN: 1432-1106
    Keywords: Key words Non-monosynaptic group I excitation ; Group II excitation ; Spinal reflexes ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Non-monosynaptic group I and group II excitation of human lower limb motoneurones was investigated. Changes in the firing probability of individual voluntarily activated motor units belonging to various muscles (soleus, gastrocnemius medialis, tibialis anterior, peroneus brevis, quadriceps and biceps femoris) were investigated after stimulation of various nerves (posterior tibial, common peroneal and femoral nerves) with weak (0.4–0.6×motor threshold) electrical stimuli. In all investigated motor nuclei, stimulation of the ”homonymous” nerve evoked a peak of increased firing probability with a latency that was 3–7 ms longer than the monosynaptic Ia latency. The more caudal the motor nucleus explored, the greater the central delay. This strongly suggests a transmission through neurones located above the lumbar enlargement. If one excepts the sural-induced excitation of peroneus brevis units, which seems to be mediated through a particular pathway, the main peripheral input to neurones mediating non-monosynaptic excitation evoked by these weak stimuli is group I in origin. The pattern of distribution of non-monosynaptic group I excitation was very diffuse, since stimulation of each nerve was able to evoke excitation in all investigated nuclei. In most cases, non-monosynaptic excitation evoked in a given motor unit by stimulation of one nerve was depressed on combined stimulation of two nerves, and evidence is presented that this lateral inhibition is exerted at a premotoneuronal level. By contrast, there was no evidence that increasing the afferent input in a given pathway evokes an ”autogenetic” inhibition in this pathway. The negative correlation found between non-monosynaptic group I-induced and late group II-induced facilitation of the quadriceps H-reflex when using high stimulus intensities applied on the common peroneal nerve suggests that these two effects could be mediated through common interneurones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00005683
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Two-dimensional separations and behaviour of alkaloids of various polarities on unmodified silica gel in polar and very polar neutral or acidic mobile phases (1980)
    Springer
    Chromatographia 13 (1980), S. 259-262 
    Details
    ISSN: 1612-1112
    Keywords: Two-dimensional separations ; Alkaloids ; Chromatography under mild conditions ; Unmodified silica gel ; TLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary New separation procedures for alkaloids of similar polarity and structure or of very different polarity and structure, based upon two-dimensional thin-layer chromatography on unmodified silica gel under mild conditions are described. Separation factors and separation mechanisms based on the structure of the bases and mobile phase composition are discussed for some examples of very efficient procedures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02265638
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    Paper (German National Licenses)
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