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  • 1
    Electronic Resource
    Electronic Resource
    A mathematical model of caloric nystagmus (1977)
    Springer
    Biological cybernetics 27 (1977), S. 27-32 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract A mathematical model is proposed to explain the rise of nystagmic eye movements in response to caloric stimulation of the external meatus. For this purpose, equations are set up to describe the physical processes involved in caloric nystagmus. The mathematical description of heat transport from the meatus to the lateral semicircular canal includes heat transmission through the meatus wall and heat conduction in the petrous bone. The influence of blood perfusion is taken into account as well as the greater heat conductivity of the bone situated between the external and internal edge of the semicircular canal. The model is represented in Laplace notation, as is usually done in system modelling. The endolymph flow induced by a temperature gradient across the lateral canal, and the eye movements resulting from endolymph rotation are described by means of established models of other authors. Thus, the time-course of nystagmus can be computed for a given duration and temperature of caloric irrigation. The predicted nystagmus is in good agreement with experimental results of common clinical tests. Long-term stimulation results in complete adaptation in the model, whereas preliminary experiments suggest sustained nystagmus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00357707
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  • 2
    Electronic Resource
    Electronic Resource
    Regression analysis of non-stationary discharges in neurons; Adaptation in the electrosensory afferent of dogfish (1977)
    Springer
    Biological cybernetics 28 (1977), S. 41-49 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract Interspike interval histograms, as usually regarded for the estimation of statistical variabilities in neuronal spike trains, were applied to non-stationary dynamic responses of a PD receptor. Sliding mean values were introduced describing the average receptor response on defined, recurrent stimuli; mean spike frequencies and interspike intervals were computed a) for fixed sequential analysis periods (of e.g. 500 ms), b) for analysis periods shifted by every consecutive interspike interval (thus the number of spikes being constant), and c) by fitting the dynamic responses for suitable analytic functions (e.g. exponential functions). With these methods variabilities in the non-stationary neuronal impulse patterns were investigated for electrosensory PD afferents in Lorenzinian ampulla of dogfish (Scyliorhinus canicula) with electric stimuli up to 50 nA and defined temperatures between 7° C and 25° C. In this temperature range all investigated ampullae were spontaneously active, the irregularities in neuronal discharges and averaged spike frequencies depended strongly on temperature, the latter showing maxima between 13° C and 19° C. In preparations with small disturbances we generally found static interspike interval histograms following approximatively a Gaussian distribution. The same was true for the momentary spike frequency and its deviation during the dynamic response to given electrical stimuli. A suprathreshold rectangular current (e.g.-0.5 nA) led to a marked but transient synchronisation in spike generation; the higher the stimulus strength, the smaller the standard deviation (s.d.) from mean spike frequency in the beginning of the dynamic response; during adaptation the s.d. increased up to that of the static response frequency. Relating, however, s.d. for different currents, times, and temperatures to the corresponding mean spike frequency led to fairly constant coefficients of variation; s.d. was approximatively a linear function of the sliding mean value even in the dynamic response of the electroreceptor (scaling).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00360912
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  • 3
    Electronic Resource
    Electronic Resource
    Responses of human cutaneous afferents to CO2 laser stimuli causing pain (1984)
    Springer
    Experimental brain research 55 (1984), S. 158-166 
    Details
    ISSN: 1432-1106
    Keywords: C-nociceptor ; Pain ratings ; Microelectroneurography ; Man ; Signal detection theory ; CO2 laser stimuli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Microelectroneurographic studies in man allow the comparison of stimulus induced activity in the single peripheral nerve unit with the subject's ratings of sensation. Relationships between stimulus intensity, single unit discharges, and pain ratings were investigated using a CO2 laser stimulator which delivers radiant heat pulses of 50 ms duration. Recordings were performed percutaneously from the radial nerve at the wrist. Receptor types were identified by their response to different stimulus modalities and by their reaction delay to electrical test stimuli within the receptive field. Receptive fields of identified units were stimulated with randomised series of different radiant heat intensities between half and double the individual pain threshold (5 to 20 W; stimulation area 64 mm2). The largest receptor class observed to be activated by CO2 laser stimuli were polymodal C-nociceptors. None of them was spontaneously active. High discharge rates up to 75/s were not necessarily associated with pain but, if pain was felt, the impulse trains usually lasted for more than 60 ms. Inter-spike intervals were distributed over a wide range between 8 and 145 ms with a peak at about 25 ms. This peak was only slightly shifted by increasing the stimulus intensity. Higher correlations were found between the number of spikes and stimulus intensity. Measures of Signal Detection Theory indicated that the single unit discharges discriminated stimulus intensities better than the subjects' ratings. These findings underline the importance of temporal summation in the processing of C-fibre input with a considerable loss of information in the nociceptive system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00240510
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  • 4
    Electronic Resource
    Electronic Resource
    Human cerebral potentials evoked by CO2 laser stimuli causing pain (1987)
    Springer
    Experimental brain research 67 (1987), S. 153-162 
    Details
    ISSN: 1432-1106
    Keywords: C-fibres ; Evoked cerebral potentials ; Ultralate components ; Pain ; Man ; Adaptive filter ; Single trial EEG analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Brief radiant heat pulses, generated by a CO2 laser, were used to activate slowly conducting afferents in the hairy skin in man. In order to isolate C-fibre responses a preferential A-fibre block was applied by pressure to the radial nerve at the wrist. Stimulus estimation and evoked cerebral potentials (EP), as well as reaction times, motor and sudomotor activity were recorded in response to each stimulus. With intact nerve, the single supra-threshold stimulus induced a double pain sensation: A first sharp and stinging component (mean reaction time 480 ms) was followed by a second burning component lasting for seconds (mean reaction time 1350 ms). Under A-fibre block only one sensation remained with characteristics and latencies of second pain. The heat pulse evoked potential consisted of a late vertex negativity at 240 ms (N240) followed by a prominent late positive peak at 370 ms (P370). Later activity was not reliably present. Under A-fibre block this late EP was replaced by an ultralate EP beyond 1000 ms, which in the conventional average looked like a slow halfwave of 800 ms duration. This potential was distinct from eye movements, skin potentials or muscle artefacts. With cross-correlation methods waveforms similar to the N240/P370 were detected in the latency range from 900 to 1500 ms during A-fibre block, indicating a much greater latency jitter of the ultralate EP. Latency corrected averaging with a modified Woody filter yielded a grand mean ultralate EP (N1050/P1250), the shape of which was surprisingly similar to the late EP (N240/P370). The similarity of these components indicates that both EPs may be secondary responses to afferent input into neural centers, onto which myelinated and unmyelinated fibres converge. Such convergence may also explain through the known mechanisms of short term habituation and selective attention, why ultralate EPs are not reliably present without peripheral nerve block.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00269463
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  • 5
    Electronic Resource
    Electronic Resource
    How best to fight that nasty itch – from new insights into the neuroimmunological, neuroendocrine, and neurophysiological bases of pruritus to novel therapeutic approaches (2005)
    Oxford, UK; Malden, USA : Munksgaard International Publishers
    Experimental dermatology 14 (2005), S. 0 
    Details
    ISSN: 1600-0625
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: While the enormous clinical and psychosocial importance of pruritus in many areas of medicine and the detrimental effects of chronic ‘itch’ on the quality of life of an affected individual are widely appreciated, the complexity of this sensation is still often grossly underestimated. The current Controversies feature highlights this complexity by portraying pruritus as a truly interdisciplinary problem at the crossroads of neurophysiology, neuroimmunology, neuropharmacology, protease research, internal medicine, and dermatology, which is combated most successfully if one keeps the multilayered nature of ‘itch’ in mind and adopts a holistic treatment approach – beyond the customary, frequently frustrane monotherapy with histamine receptor antagonists. In view of the often unsatisfactory, unidimensional, and altogether rather crude standard instruments for pruritus management that we still tend to use in clinical practice today, an interdisciplinary team of pruritus experts here critically examines recent progress in pruritus research that future itch management must take into consideration. Focusing on new insights into the neuroimmunological, neuroendocrine, and neurophysiological bases of pruritus, and discussing available neuropharmacological tools, specific research avenues are highlighted, whose pursuit promises to lead to novel, and hopefully more effective, forms of pruritus management.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.0906-6705.2005.0321a.x
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  • 6
    Electronic Resource
    Electronic Resource
    Phenobarbital induces slow recovery from sodium inactivation at the nodal membrane
    Amsterdam : Elsevier
    Biochimica et Biophysica Acta (BBA)/Biomembranes 597 (1980), S. 384-390 
    Details
    ISSN: 0005-2736
    Keywords: (Na^+ channel, R. esculenta) ; Myelinated nerve fiber ; Phenobarbital ; Voltage clamp
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Medicine , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0005-2736(80)90114-5
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  • 7
    Electronic Resource
    Electronic Resource
    A three-state model for inactivation of sodium permeability
    Amsterdam : Elsevier
    Biochimica et Biophysica Acta (BBA)/Biomembranes 645 (1981), S. 243-252 
    Details
    ISSN: 0005-2736
    Keywords: (Myelinated nerve) ; Inactivation model ; Na^+ permeability
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Medicine , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0005-2736(81)90195-4
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  • 8
    Electronic Resource
    Electronic Resource
    Skin testing of the pruritogenic activity of histamine and cytokines (interleukin-2 and tumour necrosis factor-α) at the dermal–epidermal junction (1997)
    Oxford, UK : Blackwell Publishing Ltd
    British journal of dermatology 137 (1997), S. 0 
    Details
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Cytokines have been proposed as histamine-independent itch mediators. To investigate this hypothesis, single doses of interleukin-2 (IL-2, 10MU/mL) and tumour necrosis factor α (TNF-α, 10 μg/mL) were delivered to the epidermis of 10 healthy volunteers with a controlled skin-prick model; 1% histamine and solvent controls were included in a double-blind, randomized crossover design. Itch ratings (computerized visual analogue scale) were obtained every 20s for 15 min and cutaneous reactions (weal, flare and temperature) were measured. Reactions were also recorded after 2, 24 and 48 h. The mean itch ratings were: histamine 35·5, IL-2 3·3 (both P〈0·01 compared with control), TNF-α 1.6 and solvent control 1.75 (not significant). Weal and flare occurred only with histamine. In two volunteers, an inflammatory papule with transient pruritus developed 12–18 h after applying IL-2. In conclusion, IL-2 showed a rapid, low pruritogenic effect, which may be followed by an inflammatory response. TNF-α induced no itching in this setting. Skin-prick testing with appropriate doses of potential pruritogens provides a safe and sensitive model for further chemoreceptor studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2133.1997.18601953.x
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  • 9
    Electronic Resource
    Electronic Resource
    Tonic pain inhibits phasic pain: Evoked cerebral potential correlates in man
    Amsterdam : Elsevier
    Psychiatry Research 14 (1985), S. 343-351 
    Details
    ISSN: 0165-1781
    Keywords: Phasic pain ; analgesia ; evoked cerebral potential ; man ; tonic pain
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0165-1781(85)90102-7
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  • 10
    Electronic Resource
    Electronic Resource
    The electrosensitivity of the isolated ampulla of lorenzini in the dogfish (1976)
    Springer
    Journal of comparative physiology 111 (1976), S. 127-136 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. Threshold currents as function of temperature were determined on the isolated Lorenzinian ampullae of the dogfish. Currents were applied via microelectrodes in the orifice of the ampullary canal. Response frequencies of single afferent units were averaged for at least 100 successive identical stimulus pulses by means of autocorrelation functions and periodograms. The threshold was defined by a 10% change of response frequency caused by the stimulus. 2. The lowest threshold current for the single ampulla was found to be about 0.01 nA at temperatures between 13 °C and 19 °C. This current corresponded to a current density of ca. 8 nA/cm2, or to a potential difference of 2 μV between the ampullary canal and the grounded exterior. 3. There was a strong temperature dependence of electrosensitivity of the ampulla: the threshold currents increased with lower (7 °C) and higher temperatures (25 °C) by a factor of about 10. 4. The threshold currents found by computer averaging were smaller by a factor of at least 10 than those given up to now for the single isolated ampulla, and corresponded well to the values estimated in behavioural experiments on the living animal. This fact might be explained by spatial summation in the electrosensory system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00605528
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