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  • Rabbit  (9)
  • Deiters neurones  (6)
  • Analytical Chemistry and Spectroscopy  (5)
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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 45 (1982), S. 233-242 
    ISSN: 1432-1106
    Schlagwort(e): Gerebellum ; Flocculus ; Eye movement ; Kainic acid ; Rabbit
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The horizontal vestibulo-ocular reflex (HVOR) and optokinetic response (OKR) were examined in alert albino rabbits following unilateral flocculectomy. Chemical flocculectomy with local application of kainic acid was used to avoid the retrograde degeneration of inferior olive neurons that accompanies surgical flocculectomy. Effects of chemical flocculectomy, however, were identical to those of surgical flocculectomy. The following functional deficiencies were observed in the movements of the ipsilateral eye: (1) reduction of the HVOR gain; (2) increased lag of the HVOR phase; (3) increased non-linearity of the relationship between the HVOR gain and the amplitude of turntable rotation; (4) decreased OKR gain; (5) delay with increased variation in the OKR phase; (6) impairment of rapid visual-vestibular interaction; (7) loss of the adaptation of the HVOR. Only a transient depression of the HVOR gain was seen in the contralateral eye. Control experiments with lesions in the paraflocculus, nodulus, and uvula, or lobules VI and VII, revealed no such deficiencies, except that lesions in the nodulus and uvula produced marked advancement of the HVOR phase. The effects of flocculectomy are consistent with present knowledge of both neuronal circuitry and activity of the rabbit flocculus.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 2 (1966), S. 330-349 
    ISSN: 1432-1106
    Schlagwort(e): Deiters neurones ; IPSP ; Monosynaptic ; Purkinje cells ; Inhibitory neurones
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary During stimulation of the anterior lobe of the cerebellum, postsynaptic potentials were recorded intracellularly from ipsilateral Deiters neurones of the cat. In the majority of examined cells, the inhibitory postsynapic potentials were induced with short latency; 1.06 msec on the average from lobule III or IV. The latency was longer (1.23 msec) when the lobule V was stimulated, while it was shorter (0.86 msec) from the juxtafastigial region. It follows that the IPSP was produced via a monosynaptic pathway at a conduction velocity of 15 to 20 m/sec. Recording of the extracellular field potentials and focal stimulation within and around Deiters' nucleus further indicated that the inhibitory impulses propagated out of the cerebellum along a remarkable bundle of fibres which terminated within Deiters' nucleus. These results are all explicable by assuming that the cerebellar Purkinje cells are inhibitory in nature and so produce IPSPs monosynaptically in Deiters neurones via the long corticofugal fibres. Monosynaptic EPSPs were also detected in some Deiters neurones. They are considered to be mediated by the other pathways formed of axon collaterals of the cerebellar afferents.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 6 (1968), S. 247-264 
    ISSN: 1432-1106
    Schlagwort(e): Deiters neurones ; Disinhibition ; Cerebellum ; Cats
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Following the stimulation of cerebellar cortex, a slow depolarization developed in the neurones which were impaled with microelectrodes in the dorsal portion of the nucleus of Deiters. Characteristically, it was produced bilaterally from a wide area of the culmen and, with double shock stimulation at brief intervals, showed a marked potentiation, often in association with a later depression. After repetitive stimulation of the cerebellar cortex the slow depolarization was prolonged for a period of many seconds. Even stimulation of the spinal cord caused similar depolarization. By intracellular injection of currents and ions, the depolarization was shown to be disinhibition, i. e., removal of background inhibition. Accordingly, it was confirmed that there was a steady production of IPSPs in dorsal Deiters neurones, which diminished during the phase of disinhibition. As the possible source of these background IPSPs, the Purkinje cell axons within the nucleus of Deiters were found to be discharging rhythmically at a rate of 20–90/sec, and in fact they were depressed very effectively after cerebellar stimulation. At the same time, volleys along Purkinje cell axons produced by a testing cerebellar stimulation also were diminished, indicating a depression in the excitability of Purkinje cells.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 26 (1976), S. 89-103 
    ISSN: 1432-1106
    Schlagwort(e): Vestibular ; Oculomotor ; Canal ; Inhibition ; Rabbit
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary In anesthetized albino rabbits, electric pulse stimulation was applied to ampullary branches of the vestibular nerve. Reflex discharges evoked from a canal in an extraocular muscle were depressed very effectively by conditioning stimulation at a certain other canal. The present systematic survey revealed that this reflex depression occurred specifically in 3 combinations of conditioning and testing canals; 1. anterior and posterior canals of the same side; 2. anterior and posterior canals of the opposite sides; and 3. horizontal canals of the two sides. Occurrence of postsynaptic inhibition in oculomotor neurons, on the other hand, was indicated by appearance of slow muscle potentials in extraocular muscles. It was confirmed that this motoneuronal inhibition did not contribute to the reflex depression in the above combination (1). Even in combinations (2) and (3), the accompanying motoneuronal inhibition was eliminated by adjusting intensities of canal stimuli or by severing its pathway in the medulla, or it was discriminated from the reflex depression by their different latencies and time courses. Hence, it was concluded that the reflex depression was attributable, at least largely, to non-motoneuronal inhibition, presumably postsynaptic inhibition at relay neurons for vestibulo-ocular reflexes. Slow muscle potentials evoked from a canal were also used as testing responses, but their depression could not be detected after conditioning at other canals.
    Materialart: Digitale Medien
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  • 5
    ISSN: 1432-1106
    Schlagwort(e): Deiters neurones ; Inhibition ; Climbing fibre responses ; Inferior olive
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Intracellular recording with microelectrodes has been employed to reveal the causal relationship between the trans-synaptic activation of cerebellar Purkinje cells and the postsynaptic inhibition of Deiters neurones. Cerebellar stimulation produced in Deiters neurones not only monosynaptic IPSPs with latency of 0.9–1.5 msec, but also the delayed IPSPs at 1.5–9 msec. Correspondng to the latter, Purkinje cells were found to be activated orthodromically with the characteristic climbing fibre responses (CFRs), the latency varying from 0.8 up to 10 msec. On the other hand, stimulation of the inferior olive first induced EPSPs in Deiters neurones, presumably monosynaptically, then with a short delay of less than a millisecond CRFs in Purkinje cells of the anterior lobe, which in turn were succeeded by IPSPs in Deiters neurones after a further delay of a millisecond. Spinal stimulation activated the inferior olive trans-synaptically and thereby produced CFRs in Purkinje cells and a sequence of EPSPs and IPSPs in Deiters neurones. Close correlation between these spinal-induced events in both neurone species was further indicated by the concurrence of their fluctuations in intensity, these fluctuations being characteristic of the spino-olivary transmission mechanism. These results strongly support the postulate that the cerebellar Purkinje cells are inhibitory in their action upon Deiters neurones.
    Materialart: Digitale Medien
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  • 6
    ISSN: 1432-1106
    Schlagwort(e): Vestibulospinal ; VIIIth nerve ; Deiters' nucleus ; Rabbit
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary In anaesthetized rabbits, the medulla was surveyed with recording microelectrodes to identify different types of vestibulospinal tract neurones. Field potentials, unitary extracellular spikes and intracellular potentials were recorded during antidromic stimulation at C1 and C6 segments and during orthodromic stimulation through VIIIth nerve. The lateral and medial vestibulospinal tracts (LVST and MVST) were stimulated discriminately with the method developed in Appendix. On the basis of different axonal courses and conduction velocities, three major groups were distinguished for those cells which were activated monosynaptically by the primary vestibular afferents; 1. fast conducting LVST; 2. fast conducting MVST; and 3. slowly conducting MVST. Three other groups were discriminated for those cells which received only a polysynaptic or no action from primary vestibular afferents. These were; 4. fast conducting LVST; 5. slowly conducting LVST and 6. slowly conducting MVST. All of these six types of VST cells were represented within Deiters' nucleus. Only a relatively small number of MVST cells were found in the medial vestibular nucleus.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 8 (1969), S. 249-268 
    ISSN: 1432-1106
    Schlagwort(e): Axon reflex ; Deiters neurones ; Cerebellar afferents ; Cats
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary When recording intracellularly from cat's Deiters neurones, stimulation of the anterior lobe of the cerebellar cortex produced excitatory postsynaptic potentials (EPSPs) monosynaptically, in addition to the inhibitory ones (IPSPs) that were identified previously as being produced via Purkinje cell axons. The EPSPs were induced bilaterally from a wide area of the anterior and posterior lobes of the cerebellum, in contrast to the IPSPs that were evoked only ipsilaterally, mainly from the vermal cortex. The latency of the EPSPs was slightly, but significantly, shorter than that of the IPSPs. The presynaptic impulses responsible for these EPSPs were represented by the discrete field potentials and also by unit spikes of individual fibres. The pathway for these EPSPs and presynaptic impulses was pursued by testing their interference, in the manner of impulse collision and refractoriness, with those induced from various spots within or outside the cerebellum. It is found that the excitatory fibres for Deiters neurones extend transversely, and probably longitudinally too, over the culmen and pass out of the cerebellum through cerebellar peduncles. The major portion of them appears to originate from the medulla and a minority from the spinal cord. It is postulated that cerebellar afferents from these structures have synapses with Deiters neurones via their collateral branches, through which a kind of axon reflex occurs to Deiters neurones during stimulation of the cerebellar cortex.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 13 (1971), S. 306-326 
    ISSN: 1432-1106
    Schlagwort(e): Vestibular ; IIIrd nucleus ; PSPs ; Picrotoxin ; Rabbit
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Microelectrodes were inserted into IIIrd cranial nucleus of anaesthetized rabbit. IIIrd nucleus was identified by observing the field potentials evoked antidromically by stimulation of IIIrd cranial nerve. After stimulation of VIIIth nerve extracellular field potentials, spike potentials in secondary vestibular fibers, and postsynaptic potentials in IIIrd nucleus neurones were recorded. VIIIth nerve impulses either excite or inhibit IIIrd nucleus neurones postsynaptically with disynaptic latencies around 1.7 msec. By local stimulation of the medulla, it was found that the secondary vestibular impulses inhibiting IIIrd nucleus neurones are mediated by the superior nucleus. The excitatory impulses are relayed by the rostral half of the medial nucleus as well as a certain structure(s) relevant to the brachium conjunctivum. Preliminary pharmacological investigations on the inhibition of IIIrd nucleus neurones are reported.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 24 (1976), S. 257-271 
    ISSN: 1432-1106
    Schlagwort(e): Semicircular canal ; Vestibulo-ocular reflex ; Rabbit
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary In anesthetized albino rabbits, ampullary branches of the vestibular nerve were stimulated electrically. Prominent and stable reflex contraction was induced in extra-ocular muscles by applying single current pulses of relatively long duration, 3–5 msec. Survey with a glass microelectrode revealed that, during application of relatively wide pulses to a canal, primary vestibular fibers discharged impulses repetitively at a rate as high as 300–1400/sec and that after being transmitted across second-order vestibular neurons these impulses built up summated EPSPs in oculomotor neurons, large enough to trigger off motoneuronal discharges. From each semicircular canal, prominent reflex contraction was evoked selectively in two muscles; from the anterior canal in the ipsilateral superior rectus and contralateral inferior oblique; from the horizontal canal in the ipsilateral medial rectus and contralateral lateral rectus; and from the posterior canal in the ipsilateral superior oblique and contralateral inferior rectus. Acute lesion experiments indicated that signals for this excitation reached IIIrd and IVth nuclei via three different pathways; from the anterior canal through the ipsilateral brachium conjunctivum, from the horizontal canal through the ipsilateral fasciculus longitudinalis medialis and from the posterior canal through the contralateral fasciculus longitudinalis medialis.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 10
    ISSN: 1432-1106
    Schlagwort(e): Inferior olive ; Cerebellum ; Flocculus ; Rabbit ; Eye movement
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary After the dorsal cap and adjacent ventrolateral outgrowth regions of the inferior olive had been chronically destroyed in the rabbits, the eye movements evoked by local stimulation of the flocculus were reduced in amplitude and reversed in direction, indicating that the inhibition by flocculus Purkinje cells of vestibulo-ocular relay neurons could no longer be actuated by the stimulation.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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