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  • 1
    Electronic Resource
    Electronic Resource
    Electrotonic coupling between motoneurones in the abducens nucleus of the cat (1974)
    Springer
    Experimental brain research 21 (1974), S. 139-154 
    Details
    ISSN: 1432-1106
    Keywords: Electrotonic coupling ; Antidromic responses ; Abducens motoneurone ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The electrical stimulation of the abducens nerve provokes the classical true antidromic invasion of the abducens motoneurone and a depolarization which is often capable of generating full action potentials in the impaled motoneurone. Experiments studying these depolarizations suggest the existence of electrotonic coupling between the abducens motoneurones of the cat. Intracellular activity of the abducens motoneurones was recorded following intracellular stimulation of the impaled neurone and antidromic stimulation of the abducens nerve. Collision between the outgoing action potential and the antidromic volley differentiated the true antidromic spike from the depolarizations which can induce or not action potentials. The latency of the depolarization ranged between 100 and 1200 μsec. Collision demonstrated that the depolarization and the true antidromic action potential have an independent origin. The depolarizations and action potentials which are not conveyed to the motoneurone by its own axon are interpreted to be generated by electrotonic coupling.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00234386
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    The fine structure of neurones and cellular relationships in the abducens nucleus in the cat (1979)
    Springer
    Experimental brain research 35 (1979), S. 249-267 
    Details
    ISSN: 1432-1106
    Keywords: Abducens nucleus (cat) ; Peroxidase ; Neurones ; Synapses ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Light and electron microscope studies of the abducens nucleus in the cat have disclosed two populations of neurones: large neurones 25 to 75 μm in diameter and small neurones 10 to 25 μm in diameter. Characteristic of the large neurones are a highly developed granular endoplasmic reticulum and a large number of axo-somatic synapses. The small neurones have a poorly developed granular endoplasmic reticulum and comparative by few axo-somatic synapses. Injection of horseradish peroxidase (HRP) into the ipsilateral lateral rectus muscle has been used to identify abducens motoneurones which represent 65% of the total number of cells in the abducens nucleus and form part of the large cell population. The remaining unlabelled large neurones (30% of the large cell population) probably represent motoneurones of the retractor bulbi muscles, abducens motoneurones which have failed to transport the HRP, and possibly internuclear neurones. The small neurones (5% of the total cell population) were never labelled by HRP. Axo-somatic and axo-dendritic synapses are numerous. Many of the synaptic terminals form contacts with two or more different postsynaptic elements. Axo-axonic synapses and synapses on the initial segments of large neurones are also present. Nodal synapses and branching of myelinated axons are common findings. Finally, extended areas of close apposition between dendritic membranes are frequently observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236614
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    The vibrissal pad as a source of sensory information for the oculomotor system of the cat (1981)
    Springer
    Experimental brain research 44 (1981), S. 409-418 
    Details
    ISSN: 1432-1106
    Keywords: Oculomotricity ; Lateral rectus and retractor bulbi motoneurones ; Infraorbital nerve ; Vibrissal pad ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Responses from lateral rectus, medial rectus and retractor bulbi nerves were obtained following electrical stimulation of the vibrissal pad of the cat. Discharges in afferent fibres dissected from the infraorbital nerve were recorded during movements of the vibrissae and following electrical stimulation of the vibrissal pad. Both stimuli activated the same population of Aα fibers. Intracellular records were obtained from lateral rectus motoneurones identified antidromically in the principal abducens nucleus and from retractor bulbi motoneurones similarly identified in the accessory abducens nucleus. EPSPs (3 mV) were recorded in lateral rectus motoneurones following electrical stimulation of the ipsilateral vibrissal pad at a latency of 3.5 ms. Large-amplitude disynaptic EPSPs (15 mV) were recorded in retractor bulbi motoneurones following the same vibrissal stimulation. The synaptic excitation evoked in both lateral rectus and retractor bulbi motoneurones through stimulation of the ipsilateral vibrissal pad induced an early retraction followed by an abduction of the eye ball. The hypothesis is that the vibrissal message might complement other sensory modalities in the generation of patterned eye movements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00238833
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Morphological and electrophysiological properties of trigeminal neurones projecting to the accessory abducens nucleus of the cat (1983)
    Springer
    Experimental brain research 53 (1983), S. 118-128 
    Details
    ISSN: 1432-1106
    Keywords: Accessory abducens nucleus ; Spinal trigeminal neurones ; Axonal trigeminal trajectory ; Intracellular recordings ; Intracellular HRP ; Retractor bulbi motoneurones control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Horseradish peroxidase was injected into the somata or axons of neurones located in the nucleus oralis of the spinal trigeminal complex and projecting to the accessory abducens nucleus. A group of 43 axons with electrophysiologically identified responses to the stimulation of three different areas of the face were studied. The latencies of their orthodromic responses following trigeminal stimulation and their pattern of discharges were compared to those of secondary trigeminal neurones and retractor bulbi motoneurones. Labelled trigeminal axons were found to generate collaterals for the accessory abducens nucleus. Terminal ramifications are present in the rostro-caudal part of the motor nucleus where the dendritic arborization of the motoneurones has been described. Connections to facial and trigeminal motor nuclei were also present, suggesting that secondary trigeminal axons distributed the information to the three motor targets at the brain stem level. It is suggested that the trigemino-retractor bulbi reflex is part of facial reflexes involved in orienting reactions, and protective responses resulting in coordinated movements of the facial musculature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00239404
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  • 5
    Electronic Resource
    Electronic Resource
    Accuracy of external standardization systems in two commercially available spectrometers using gamma sources of high or low energy
    Amsterdam : Elsevier
    Analytical Biochemistry 60 (1974), S. 363-371 
    Details
    ISSN: 0003-2697
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0003-2697(74)90243-7
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Stochastic Geometry and Electrotonic Architecture of Dendritic Arborization of Brain Stem Motoneuron (1993)
    Oxford, UK : Blackwell Publishing Ltd
    European journal of neuroscience 5 (1993), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: We describe how the stochastic geometry of dendritic arborization of a single identified motoneuron of the rat affects the local details of its electrotonic structure. After describing the 3D dendritic geometry at high spatial resolution, we simulate the distribution of voltage gradients along dendritic branches under steady-state and transient conditions. We show that local variations in diameters along branches and asymmetric branchings determine the non-monotonous features of the heterogeneous electrotonic structure. This is defined by the voltage decay expressed as a function of the somatofugal paths in physical distances (voltage gradient). The fan-shaped electrotonic structure demonstrates differences between branches which are preserved when simulations are computed from different values of specific membrane resistivity although the absolute value of their voltages is changed. At given distances from soma and over long paths, some branches display similar voltages resulting in their grouping which is also preserved when specific membrane resistivity is changed. However, the mutual relation between branches inside the group is respecified when different values of specific membrane resistivity are used in the simulations. We find that there are some invariant features of the electrotonic structure which are related to the geometry and not to the electrical parameters, while other features are changed by altering the electrical parameters. Under transient conditions, the somatofugal invasion of the dendritic tree by a somatic action potential shifts membrane potentials (above 10 mV) of dendritic paths for unequal distances from the soma during several milliseconds. Electrotonic reconfigurations and membrane shifts might be a mechanism for postsynaptic plasticity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-9568.1993.tb00216.x
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  • 7
    Electronic Resource
    Electronic Resource
    Electrotonic Clusters in the Dendritic Arborization of Abducens Motoneurons of the Rat (1994)
    Oxford, UK : Blackwell Publishing Ltd
    European journal of neuroscience 6 (1994), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Following reconstruction with high spatial resolution of the 3-D geometry of the dendritic arborizations of two abducens motoneurons, we simulated the distribution of electrotonic voltage over the whole dendritic tree. Here, we demonstrate that the complex stochastic electrotonic structure of both motoneurons can be reduced to a statistically significant small set of well discriminated clusters. These clusters are formed by dendritic branches belonging to different dendrites of the neuron but with similar electrotonic properties. A cluster analysis was performed to estimate quantitatively the partition of the branches between the dendritic clusters. The contents of the clusters were analysed in relation to their stability under different values of specific membrane resistivity (Rm), to their remoteness from the soma and their location in 3-D space. The cluster analysis was executed in a 2-D parameter space in which each dendritic branch was described by the mean electrotonic voltage and gradient. The number of clusters was found to be four for each motoneuron when computations were made with Rm= 3 kΩ.cm2. An analysis of the cluster composition under different Rm revealed that each cluster contained invariant and variant branches. Mapping the clusters upon the dendritic geometry of the arborizations allowed us to describe the cluster distribution in terms of the 3-D space domain, the 2-D path distance domain and the total surface area of the tree. As the cluster behaviour reflects both the geometry and the changes in the neuronal electrotonic structure, we conclude that cluster analysis provides a tool to handle the functional complexity of the arborizations without losing relevant information. In terms of synaptic activities, the stable dendritic branches in each cluster may process the synaptic inputs in a similar manner. The high percentage of stable branches indicates that geometry is a major factor of stability for the electrotonic clusters. Conversely, the variant branches introduce the conditions for mechanisms of functional postsynaptic plasticity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-9568.1994.tb00542.x
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    Paper (German National Licenses)
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  • 8
    Electronic Resource
    Electronic Resource
    Spatial reconfiguration of charge transfer effectiveness in active bistable dendritic arborizations (2002)
    Oxford, UK : Blackwell Science, Ltd
    European journal of neuroscience 16 (2002), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The aim of this work was to explore the electrical spatial profile of the dendritic arborization during membrane potential oscillations of a bistable motoneuron. Computational simulations provided the spatial counterparts of the temporal dynamics of bistability and allowed simultaneous depiction the electrical states of any sites in the arborization. We assumed that the dendritic membrane had homogeneously distributed specific electrical properties and was equipped with a cocktail of passive extrasynaptic and NMDA synaptic conductances. The electrical conditions for evoking bistability in a single isopotential compartment and in a whole dendritic arborization were computed and showed differences, revealing a crucial effect of dendritic geometry. Snapshots of the whole arborization during bistability revealed the spatial distribution of the density of the transmembrane current generated at the synapses and the effectiveness of the current transfer from any dendritic site to the soma. These functional maps changed dynamically according to the phase of the oscillatory cycle. In the low depolarization state, the current density was low in the proximal dendrites and higher in the distal parts of the arborization while the transfer effectiveness varied in a narrow range with small differences between proximal and distal dendritic segments. When the neuron switched to high depolarization state, the current density was high in the proximal dendrites and low in the distal branches while a large domain of the dendritic field became electrically disconnected beyond 200 µm from the soma with a null transfer efficiency. These spatial reconfigurations affected dynamically the size and shape of the functional dendritic field and were strongly geometry-dependent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1460-9568.2002.02312.x
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  • 9
    Electronic Resource
    Electronic Resource
    The dendritic architecture of motoneurons: A case study (1997)
    Springer
    Neurophysiology 29 (1997), S. 112-124 
    Details
    ISSN: 1573-9007
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Within a historical perspective, different experimental approaches are reviewed that have used new tools and new concepts to gain an insight into the functional significance of the architecture of dendritic arborizations of nerve cells. A single type of neurons, the motoneurons, were taken as a case study to show how different fields, such as histology, morphology, electrophysiology, and neuronal modeling, have developed in parallel and accumulated a wealth of new data, and how consideration of these new informations led to new working hypotheses. Matching geometrical and electrical parameters of dendrites is critically analyzed as a basis for understanding of the dendritic functions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02463225
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