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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 9 (1969), S. 1-15 
    ISSN: 1432-1106
    Keywords: Frog cerebellum ; Purkinje cells ; Climbing fibers ; Mossy fibers ; Vestibular efferents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The relationships between the frog vestibular afferents and the cerebellum as well as the efferent vestibular system, have been studied by electron microscopy and Nauta degeneration technique. The primary vestibular fibers were found to have synaptic boutons in both the granular and the molecular layers of the cerebellar marginal zone. In the granular layer synaptic contacts are made with the granule cell dendrites while the molecular layer projection is directed to the main dendrites of the Purkinje cells in a manner similar to that of the climbing fibers. As for the efferent system, the vestibular receptor cells of the macula saccularis are contacted by vesicle-filled boutons which terminate synaptically in relation to a submembranous sac within the cell. The efferent fibers contain neurofilaments and a few neurotubules. Following lesions at different sites, it was found that all the above fibers and boutons degenerated after a) vestibular nerve section, and that b) most of them were lost when the brain stem was hemisected above the vestibular nerve. On the other hand, brain stem sectioning above the Vth nerve produced degeneration of 35% of these boutons while cerebellar undercutting produced 20% degeneration. The Nauta technique shows that following cerebellar undercutting a small efferent bundle leaves the ventral caudal side of the nerve. These findings demonstrate the existence of a cerebello-vestibular efferent system originating most possibly from the auricular lobe Purkinje cells.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 8 (1969), S. 327-345 
    ISSN: 1432-1106
    Keywords: Cerebellar unit responses ; Purkinje cells ; Click response ; Mossy fibers ; Surface negativities ; Firing patterns
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Unit activities evoked by auditory stimulation in the cerebellar cortex have been studied in the encéphale isolé cat. Poststimulus-time histograms (PSTH) of 1/sec, click-evoked unit discharges have different response patterns with respect to the onset and time course of unit firing. 2. Units have been classified as type I and type II responses based on their preferred firing time relative to the first surface-negative component (N1) of the click evoked folial response. 3. Laminar analysis of the click evoked slow activity centered on an 8–12 msec negative wave in the molecular layer that corresponded with the N1 surface component. An earlier, sharp, negative-positive sequence was found at depths approaching and deep within the granule cell layer. 4. Units considered to be Purkinje cells based on antidromic stimulation or the appearance of typical climbing fiber responses (CFR's) were found exclusively within the type II unit category. Non-identified click units, including various types of cortical interneurons, were found to be either type I or type II units. 5. Evidence that cerebellar click responses are mediated predominately by mossy fiber afferents derives in part from the inhibitory effect of local folial conditioning stimulation upon N1 waves. In addition, the irregular, recurrent CFR's found in click responsive Purkinje cells were temporally unrelated to the acoustic stimulus. Thus click responses in these units appeared to be initiated by mossy fiber activity.
    Type of Medium: Electronic Resource
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