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  • 1
    ISSN: 1432-1106
    Keywords: Fastigial ; Reticular formation ; Vestibular nuclei ; PSP ; Disfacilitation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In anaesthetized cats, the fastigial nucleus of cerebellum was stimulated with electric pulse currents, and the effects thereby induced were investigated by recording intracellularly from cells in the medullary reticular formation, the nucleus of Deiters and the descending vestibular nucleus. The early effect commonly seen in these cells was initiation of excitatory postsynaptic potentials (EPSPs) with monosynaptic latencies from both sides of the fastigial nuclei. These EPSPs appeared to be produced in part by a kind of axon reflex through cerebellar afferent fibres, but a certain portion of them was ascribable to the crossed fastigiobulbar axons, as they were influenced by stimulation of the cerebellar cortex in the manner to be expected from the previous study on cerebellar nuclei. These EPSPs were followed by a sequence of a prolonged disfacilitatory hyperpolarization and a late facilitatory depolarization, which apparently reflected the inhibition and disinhibition, respectively, produced in fastigial neurones via Purkinje cell axons of the corticonuclear projection. Either EPSPs or IPSPs were also induced in both reticular and vestibular neurones through polysynaptic pathways in which the fastigiobulbar projection might have been involved.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1106
    Keywords: Vestibulospinal ; Cervical ; Thoracic ; PSPs ; Deiters'
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In anaesthetized rabbits, the effects of VIIIth nerve stimulation were studied in the cervicothoracic segments of the spinal cord by recording spike field potentials representing the secondary vestibular volleys, postsynaptic potentials in spinal neurones and corresponding field potentials. It was revealed that an excitatory action was conveyed by the medial vestibulospinal tract (MVST) fibers bilaterally and also by the lateral vestibulospinal tract (LVST) fibers ipsilaterally. Both of these two excitatory fiber groups conducted the secondary vestibular volleys with relatively fast velocities. An inhibitory action was effected bilateraly by those MVST fibers which conducted secondary vestibular volleys with a relatively slow velocity, as previously described in oats. By direct stimulation of the medulla it was demonstrated that both excitatory and inhibitory MVST fibers arise from the middle portion of the vestibular nuclear complex in and around Deiters' nucleus.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1106
    Keywords: Vestibulospinal ; VIIIth nerve ; Deiters' nucleus ; Rabbit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 18 (1973), S. 446-463 
    ISSN: 1432-1106
    Keywords: Cerebellum ; Vestibular ; Spinocerebellar ; Purkinje ; Deiters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The organization of the cerebellar, vestibular and spinal inputs to the lateral and medial vestibulospinal tract (LVST and MVST) cells was studied in anaesthetized rabbits. Synaptic actions of these inputs were determined by recording postsynaptic potentials intracellularly and also unit spike discharges extracellularly from a number of LVST and MVST cells. As reported previously in cats, inhibition was evoked very frequently from the vermal cortex of the cerebellar anterior lobe and less frequently from that of the posterior lobe. However, no such inhibition was derived from the flocculus. The cerebellar inhibition was exerted upon both LVST and MVST cells, whether they received monosynaptic activation from the primary vestibular afferents (second-order) or not and whether they conducted impulses fast or slowly. However, the inhibition was frequently absent in “slow” “second-order” MVST cells. The vast majority of LVST and MVST cells received an excitatory input from the spinocerebellar afferents ascending the funiculus posterolateralis. This input was particularly prominent from the upper cervical cord. The spinal excitation thus obtained occurred in close connection with the cerebellar inhibition. Hence, it appears that the cerebellar vermis receives the spinal signals that drive LVST and MVST cells and in turn sends out inhibitory signals to adjust the reflex activity in these cells.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 10 (1970), S. 64-80 
    ISSN: 1432-1106
    Keywords: Intracerebellar nuclei ; Purkinje cells ; Inhibition ; Excitation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In anaesthetized cats, synaptic events in cerebellar nuclei neurones were investigated with intracellular microelectrode techniques. These cells were identified by their antidromic activation along their axons and/or by their location in histological sections. In the cells of lateral nucleus IPSPs were induced monosynaptically during stimulation of the overlying hemispheral cortex of the cerebellum. In the cells of nuclei interpositus and fastigii, similar IPSPs were produced from the paravermal and vermal cortices, respectively. The postulate that the Purkinje cells exert an inhibitory action upon their target neurones thus applies not only to Deiters neurones, as previously proposed, but also to cells in the cerebellar nuclei. Stimulation of the cerebellar afferents at the inferior olive, the pontine nucleus and the lateral reticular nucleus produced EPSPs in cerebellar nuclei cells with relatively brief latencies, probably through axon collaterals of these afferents. The EPSPs were followed by IPSPs and slow depolarizations of disinhibitory nature, which, as studied previously in Deiters neurones, might be caused respectively by activation and subsequent depression of Purkinje cells through the cerebellar intracortical mechanisms.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 12 (1971), S. 223-237 
    ISSN: 1432-1106
    Keywords: Deiters ; Purkinje Cell ; Mossy fibre ; Granule Cell ; IPSP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In anaesthetized cats, electric pulse stimuli were applied at various lateralities to the anterior lobe of the cerebellum. In dorsal Deiters neurones delayed IPSPs with latencies of 3–6 msec were evoked from the entire area of the culmen including the paravermis bilaterally. The delayed IPSPs had a summit time of about 2 msec and a duration of about 7 msec. They showed a marked temporal facilitation and subsequent depression with double shock stimulation. Corticovestibular fibers were penetrated within the nucleus of Deiters and showed delayed, labile responses to cortical stimulation, corresponding to the delayed IPSPs in Deiters neurones. During stimulation of the anterior lobe at any laterality, field potentials recorded in the cerebellar cortex further revealed that there was activation, presumably through axon collaterals of mossy fibers, of granule cells and subsequently of Purkinje cells in the vermal cortex. Cortical events exhibited a prominent temporal facilitation and subsequent depression, in parallel with that observed for the delayed IPSPs in Deiters neurones. The delayed IPSPs in Deiters neurones arising from a wide area of the cerebellar cortex thus were attributed to activation through mossy fiber-granule cell pathway of Purkinje cells of the corticovestibular projection.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 14 (1972), S. 511-526 
    ISSN: 1432-1106
    Keywords: Vestibular ; IIIrd nucleus ; Flocculus ; Inhibition ; Picrotoxin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In anaesthetized rabbits, the vestibulo-ocular reflex was evoked by electric stimulation of VIIIth nerve and was observed by recording postsynaptic potentials and relevant field potentials in Illrd nucleus. The electric stimulation of flocculus produced a prominent inhibition of the vestibulo-ocular reflex in both the inhibitory component relayed by the superior vestibular nucleus and the excitatory component mediated by the brachium conjunctivum. The excitatory component mediated by the medial vestibular nucleus appeared to be free of the flocculus inhibition. The flocculus inhibition was blocked very effectively by systemic injection of picrotoxin. That the flocculus inhibitory action is due to monosynaptic postsynaptic inhibition of secondary vestibular neurones was demonstrated by direct stimulation of, and also by recording from, the superior nucleus. Recording from the superior nucleus was also performed in anaesthetized cats. All of these above results indicate that Purkinje cells in flocculus projecting to vestibular and cerebellar nuclei cells have inhibitory synaptic action. Flocculus stimulation produced also an excitatory effect upon vestibular nuclei neurones. However, this effect could be attributed to intracerebellar activation of the primary vestibular fibers which pass into the flocculus.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 13 (1971), S. 306-326 
    ISSN: 1432-1106
    Keywords: Vestibular ; IIIrd nucleus ; PSPs ; Picrotoxin ; Rabbit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 26 (1970), S. 1408-1414 
    ISSN: 1600-5740
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 27 (1971), S. 1477-1477 
    ISSN: 1600-5740
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
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