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  • 1
    Electronic Resource
    Electronic Resource
    Changes in extracellular potassium concentration in cat spinal cord in response to innocuous and noxious stimulation of legs with healthy and inflamed knee joints (1990)
    Springer
    Experimental brain research 79 (1990), S. 283-292 
    Details
    ISSN: 1432-1106
    Keywords: [K+]0 Spinal cord ; Posterior articular nerve ; Knee joint ; Inflammation ; Pain ; Arthritis ; Nociception ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In 20 cats anaesthetized with alpha-chloralose and spinalized at the thoracolumbar junction we investigated the role of stimulation induced accumulation of extracellular potassium in the spinal cord in the processing of nociceptive discharges from the knee joint. For that we electrically stimulated the posterior articular nerve of the knee. We further performed innocuous and noxious stimulation of the knee and of other parts of the leg and studied the effect of an acute inflammation of the knee on [K+]0 in the spinal cord. Innocuous stimulation of the skin (brushing or touching) and innocuous movements in the knee joint all induced rises in [K+]0 which were maximal at recording depths of 1500 to 2200 μm below the surface of the cord dorsum. Peak increases were 0.4 mM for touching the leg and 1.7 mM during rhythmic flexion/ extension of the knee joint. Noxious stimulation of the skin, the paw, the tendon and noxious movements of the knee joint also produced rises in [K+]0, which were somewhat larger for the individual types of stimuli than those produced by innocuous intensities. Electrical stimulation of the posterior articular nerve induced rises in [K+]0 by up to 0.6 mM. Stimulus intensities sufficient to activate unmyelinated group IV fibers were only slightly effective in raising [K+]0 above the levels reached during stimulation of myelinated group II and III fibers. During development of an acute inflammation of the knee joint (induced by kaolin and carrageenan), increases in [K+]0 and associated field potentials became larger by about 25%. We assume that this reflects an increase in neuronal responses. In conclusion, changes in [K+]0 in the spinal cord are some-what larger during noxious stimulation than during innocuous stimulation. The absolute level reached depended more on the site and type of stimulation than on the actual stimulus intensity itself. Hence a critical role of spinal K+ accumulation for nociception is unlikely.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00608237
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  • 2
    Electronic Resource
    Electronic Resource
    Responses of lateral thalamic neurons to algesic chemical stimulation of the cat knee joint (1994)
    Springer
    Experimental brain research 101 (1994), S. 452-464 
    Details
    ISSN: 1432-1106
    Keywords: Somatosensory thalamus ; Knee joint ; Nociception ; Bradykinin ; Capsaicin ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In order to gain insight into the representation of articular pain of the knee at the supraspinal level, recordings were made from lateral thalamic neurons receiving input from afferent fibres of the knee joint in chloralose-anaesthetized cats. Dorsoventral penetrations were made through the ventral posterior lateral nucleus (VPL) using high intensity electrical stimulation of the medial articular nerve (MAN), which contains a high proportion (80%) of Aδ and C afferent fibres. All recording sites were verified histologically. Close retrograde injections (300 μl over 6 s) into geniculate artery of KCl (2 × isotonic), bradykinin (BK, 2.6 or 26 μg) and capsaicin (200 μM) were used to test the response properties of thalamic neurons. Of the 50 MAN-positive units tested, 20 showed a response to intra-arterial KCl; of these 20, 12 had a response to BK; 8 of these 12 units were additionally tested with capsaicin and all responded. KCl and capsaicin injections had similar mean response latencies (4.5 and 6.8 s), whereas BK had a longer mean latency (18.6 s). The mean peak response was greatest for capsaicin (168 impulses/s), then KCl (87.5 imp/s) and least with BK (36.4 imp/s). The mean response duration was longest with capsaicin (118 s), followed by BK (67.5 s) and least with KCl (27.9 s). Most of these were convergent wide dynamic range (WDR) neurons with a deep receptive field in the knee joint and hindlimb muscle and/or cutaneous distal hind limb digit, located to the dorsal or ventral periphery of the lateral division of the VPL, the VPLl. In addition, 8 neurons showed inhibitory responses to KCl and/or BK injections. The background activity of the VPLl neurons activated by saphenous nerve stimulation was inhibited by the nociceptive articular stimulus with a magnitude and time course which mirrored the excitatory responses in the periphery of VPLl. These results support the concept that the lateral thalamus plays an important role in mediating discriminative aspects of joint pain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00227338
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  • 3
    Electronic Resource
    Electronic Resource
    Cutaneous mechanoreceptors influencing impulse discharges in cerebellar cortex. III. In Purkyně cells by climbing fiber input (1972)
    Springer
    Experimental brain research 15 (1972), S. 484-497 
    Details
    ISSN: 1432-1106
    Keywords: Cerebellum ; Cutaneous mechanoreceptors ; Climbing fibers ; Purkyně cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary An account is given of single Purkyně cell responses that are evoked by cutaneous mechanoreceptors acting via climbing fibers (CF). There was no complication by mossy fiber input, which was selectively depressed by light pentothal anesthesia. Brief mechanical pulses (taps) to the footpads and air jets on hairy skin were very effective in evoking CF responses, the usual range of latencies being 25–35 msec for the hindfoot and 19–30 msec for the forefoot. There was often a considerable difference in the effectiveness of the different pads of the same foot. For any particular Purkyně cell there was a close correspondence between the receptive fields for footpads and hairy skin. The threshold was often below 0.02 mm taps for the most sensitive pads, and was even lower for more prolonged mechanical displacements. Mechanical pulses of 80 to several hundred msec in duration were effective in evoking CF responses of Purkyně cells at “off” as well as at “on.” This finding and the very low threshold strongly suggest Pacinian corpuscles as the principal receptors concerned in activating the CF system. Repetitive taps to footpads were effective at slow frequencies, 5 or 10 Hz, but there was a response only to the first tap with a frequency of 65 Hz.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236404
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  • 4
    Electronic Resource
    Electronic Resource
    Integration by Purkyně cells of mossy and climbing fiber inputs from cutaneous mechanoreceptors (1972)
    Springer
    Experimental brain research 15 (1972), S. 498-520 
    Details
    ISSN: 1432-1106
    Keywords: Cerebellum ; Cutaneous mechanoreceptors ; Mossy fibers ; Climbing fibers ; Integration ; Purkyně cell groups
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The preceding two papers gave accounts of mossy fiber (MF) or of climbing fiber (CF) inputs to Purkyně cells under conditions where the other input was depressed by the experimental procedure. By utilizing either chloralose anesthesia or decerebration with sparing of the pyramidal tracts it has been possible to study the convergence of MF and CF inputs onto single Purkyně cells. The stimulation of cutaneous mechanoreceptors, the recording procedures for unitary Purkyně cell discharges and the computer averaging techniques were as previously described. Testing by taps to the footpads evoked a combined MF and CF response more commonly than either response alone, and often both inputs were very effective. There was a tendency for such phasic CF responses to be more frequently observed than the tonic responses to pad pressure, but such responses did occur. Purkyně cells were located by the usual procedure along the microelectrode tracks later identified in serial sections. Those cells activated by the fast MF inputs from the pad receptors were found to be closely associated in groups or colonies. The delayed MF inputs probably via spino-reticular pathways were more widely dispersed. The topographical relationships of these colonies are displayed on maps of the unfolded cerebellar cortex for lobules II to VI of both vermis and pars intermedia. In general these distributions of Purkyně cells activated from forefoot and hindfoot appear as islands in the larger fields that degeneration procedures exhibit for the cuneocerebellar and dorsal spinocerebellar tracts respectively. The CF inputs from the footpads also project to these same colonies, so that there are conjoint MF and CF colonies. The several modalities of the cutaneous mechanoreceptors of the forefoot or hindfoot often participate in the receptive fields of individual Purkyně cells. Such a field may be restricted to one or other side of the foot, all tested cutaneous mechanoreceptors then sharing approximately in the same restriction. Finally it is shown how these experimental findings relate to the theories of cerebellar function, particularly to the dynamic loop hypothesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236405
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    Paper (German National Licenses)
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