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  • 1
    Electronic Resource
    Electronic Resource
    Simulation of learning processes in neuronal networks of the cerebellum (1982)
    Springer
    Biological cybernetics 45 (1982), S. 79-88 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract A dynamic model of learning that is based on the specific neuronal system of the cerebellum, including some of its structural-functional peculiarities, is proposed. It allows to simulate modification processes of the parallel fiber synapse that influences the Purkinje cell. Regularities of synaptic modifications are obtained by extrapolating well-known experimental data about changes of synaptic efficiency as resulting from release, refilling and mobilization of the mediator. It is shown that a mathematical description of synaptic processes corresponds to experimental data on the changes of synaptic efficiency under rhythmical stimulation and gives objective quantitative estimates for long-term (refilling of the mediator) and short-term (mobilization of the mediator) effects which are caused by presynaptic stimulation. Computer simulations have been conducted to investigate the characteristics of learning for different values of the following parameters: intensity of unconditioned stimulus (US, activity of the climbing fibre), intensity of conditioned stimulus (CS, activity of the parallel fibre), temporal shift between US and CS, temporal interval between reinforcements. It is shown that the temporal shift between CS and US is one of the major factors that influence the learning procedures. Analysis of the data obtained shows that the model enables us to simulate the main regularities of establishment and extinction of conditioned reflexes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00335233
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Electrophysiological analysis of the vestibulospinal reflex pathway of rabbit. II. Synaptic actions upon spinal neurones (1973)
    Springer
    Experimental brain research 17 (1973), S. 497-515 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF00234864
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Electrophysiological analysis of the vestibulospinal reflex pathway of rabbit. I. Classification of tract cells (1973)
    Springer
    Experimental brain research 17 (1973), S. 477-496 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF00234863
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  • 4
    Electronic Resource
    Electronic Resource
    Cerebellar control of the vestibulospinal tract cells in rabbit (1973)
    Springer
    Experimental brain research 18 (1973), S. 446-463 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF00234131
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Increased Corticofugal Plasticity after Pyramidotomy in Adult Rats (2000)
    Springer
    Doklady biological sciences 375 (2000), S. 556-560 
    Details
    ISSN: 1608-3105
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026660915069
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    Paper (German National Licenses)
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