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  • 1
    Electronic Resource
    Electronic Resource
    Influence of neck afferents on vestibulospinal neurons (1980)
    Springer
    Experimental brain research 38 (1980), S. 285-292 
    Details
    ISSN: 1432-1106
    Keywords: Neck afferents ; Neck-labyrinth interaction ; Vestibulospinal neurons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effects of neck afferent stimulation on vestibulospinal neurons in Deiters' nucleus and in the descending nucleus, and the interaction of cervical and vestibular input, were examined extracellularly in decerebrate, decerebellate cats. Many of the vestibulospinal neurons were identified as having axons in the lateral or medial vestibulospinal tract (LVST or MVST) and as being driven antidromically from C3 or C6. Half of the spontaneously active neurons were excited with a latency of 2.5–5.5 ms (early excitation) by stimulation of the contralateral C2 ganglion. In some neurons early excitation was followed by late excitation (latency 〉 6 ms), which was in other neurons the only effect seen. Early excitation was due to stimulation of proximal afferents because stimulation of the C2 dorsal or ventral rami usually produced late excitation only. Early excitation was seen in LVST and MVST neurons terminating between C3 and C6 and in those projecting beyond C6. Neurons with early excitation were scattered throughout Deiters' nucleus and the rostral part of the descending nucleus. In some neurons, mainly in the descending nucleus, the initial effect of contralateral C2 ganglion stimulation was inhibition. Inhibition could be evoked by stimulation of the ganglion or dorsal rami bilaterally. The axons of all tested inhibited neurons were in the MVST. Thirty-five percent of the population studied received convergence of early excitation and short-latency input from the labyrinth, sometimes from the semicircular canals. There was also convergence between late excitation or inhibition and vestibular input. The influence of neck afferent input on vestibulospinal neurons provides one pathway for this input to the neck and limb segments of the spinal cord. This pathway may be part of the substrate of the tonic neck reflex. In addition, vestibulospinal neurons are one site of interaction between neck and vestibular reflexes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236647
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Dynamic properties of vestibular reflexes in the decerebrate cat (1982)
    Springer
    Experimental brain research 47 (1982), S. 343-352 
    Details
    ISSN: 1432-1106
    Keywords: Vestibular reflexes ; Vestibulocollic ; Vestibulo-ocular ; Transfer function ; Medial longitudinal fasciculus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Vestibulocollic (VCR) and vestibulo-ocular (VOR) reflexes were studied during angular rotation in the horizontal plane in precollicular decerebrate cats. Angular position was modulated by sinusoids or sums of sinusoids with frequencies ranging from 0.05 to 5 Hz. Reflex motor output was measured by recording electromyographic (EMG) activity of the lateral rectus and dorsal neck muscles and discharge of abducens motoneurons. Measured with respect to input angular acceleration VCR motor output displayed a second order lag at low frequencies, bringing mean EMG phase (−136 °) and gain slope (−35 dB/ decade) close to those of an angular position signal at 0.2 Hz. At higher frequencies the lag was counteracted by a second order lead bringing mean phase (−52 °) and gain slope (−5.6 dB/decade) back close to those of an angular acceleration signal at 3 Hz. By contrast, mean phase (−113 ° to −105 °) and gain slope (−21 to −28 dB/decade) of the VOR motor output remained close to those of an angular velocity signal across the entire frequency range. The data suggest that neural pathways producing the VCR receive selective input from “irregular type” horizontal semicircular canal afferents which provide one lag and one lead in the overall transfer function while the other lag and lead are produced by central pathways. Transaction of the medial longitudinal fasciculus (MLF), which eliminates all of the most direct (three neuron) arcs of the horizontal VCR, did not cause any detectable change in the horizontal VCR at either low or high frequencies. Reductions in overall gain occurred in some cases but these could be attributed to damage to axons outside the MLF. Less direct pathways, probably including vestibulo-reticulospinal pathways, are thus able to produce both the low-frequency, phase-lagging and high-frequency, phase-leading components of the horizontal VCR.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00239353
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Responses of different compartments of cat's splenius muscle to optokinetic stimulation (1983)
    Springer
    Experimental brain research 50 (1983), S. 153-156 
    Details
    ISSN: 1432-1106
    Keywords: Neck muscle ; Head-Eye movements ; Optokinetic stimulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The EMG in different compartments of the splenius muscle was recorded simultaneously with the horizontal electrooculogram in the alert, head restrained and head freed cat during optokinetic and vestibular stimulation. All compartments of the splenius muscle behaved qualitatively similarly. Tonic and phasic muscle activity was closely related to eye position.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00238243
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Interaction of tonic neck and vestibular reflexes in the forelimb of the decerebrate cat (1984)
    Springer
    Experimental brain research 54 (1984), S. 289-292 
    Details
    ISSN: 1432-1106
    Keywords: Tonic neck reflex ; Vestibulo-forelimb reflex ; Neck-vestibular interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Tonic neck reflexes, studied with EMG recording, have similar dynamics in forelimb extensor muscles of acutely labyrinthectomized cats, and in cats with intact labyrinths. The reflex occurs more frequently in the latter and its gain is higher. In intact preparations we evoked vestibular and tonic neck reflexes separately or in combination, at frequencies of 0.05–0.5 Hz. As expected from earlier work, the two reflexes oppose each other and frequently cancel; the two reflexes add linearly.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236229
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  • 5
    Electronic Resource
    Electronic Resource
    Compartmentalization of the cervicocollic reflex in cat splenius muscle (1983)
    Springer
    Experimental brain research 51 (1983), S. 397-404 
    Details
    ISSN: 1432-1106
    Keywords: Cervicocollic reflex ; Muscle Compartmentalization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We have examined the cervicocollic reflex (CCR), evoked by horizontal rotation of the head of decerebrate cats, in the dorsal neck extensor muscle splenius. This muscle is divided into compartments which are innervated by three or four spinal segments; an analogous Compartmentalization may be observed in the CCR. When the CCR is evoked by rotation of the head about a vertical axis centered over C1–C2, the modulation of EMG activity is higher in the rostral than in the caudal compartments; in some cases, the rostral compartments can be modulated selectively. The rostrocaudal gradient of modulation is absent if the axis of rotation is shifted caudally to C4–C5. In muscles which had been completely detached from their origin and insertion, the pattern of activation of the CCR was similar to that observed in intact muscle, although the gain of the reflex fell by two thirds. This suggests that significant inputs to this reflex arise both from within splenius itself and from receptors outside this muscle. The typical CCR disappears if the C1–C4 dorsal roots ipsilateral to splenius are cut; furthermore, the reflex appears normal in animals with spinal transections above C1. A significant component of the CCR in splenius appears to be a segmental stretch reflex, originating partly in splenius and partly from receptors outside the muscle.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237876
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    Paper (German National Licenses)
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