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  • Cutaneous mechanoreceptors  (9)
  • Cat  (8)
  • Mossy fibers  (3)
  • 11
    Digitale Medien
    Digitale Medien
    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
    Schlagwort(e): Somatosensory thalamus ; Knee joint ; Nociception ; Bradykinin ; Capsaicin ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00227338
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  • 12
    Digitale Medien
    Digitale Medien
    Somatotopic studies on the vermal cortex of the cerebellar anterior lobe of unanaesthetized cats (1977)
    Springer
    Experimental brain research 27 (1977), S. 479-490 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Unanaesthetized cat ; Cerebellum ; Cerebellar somatotopy ; Cutaneous mechanoreceptors
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary 1. In unanaesthetized cats with intact neuraxis the relation between the cutaneous receptive fields of Purkyně cells and the position of these cells in the vermis of the cerebellar anterior lobe was studied with the specific question whether this cerebellar area exhibits any kind of somatotopy in the absence of central anaesthesia. To establish the receptive fields the skin of all four limbs and of the trunk was probed with mechanical stimuli (taps, air-jets, pressure). The recording sites in the vermis were determined histologically. 2. In regard to the mossy fiber transmitted input none of the four limbs showed a dominant representation in one or more of the lobules rostral of the fissura prima or in a parasagittal section. For the ipsilateral limbs there is a greater mossy fiber input to lobule V from the forelimb than from the hindlimb (84 ∶ 59%), and a reversed preponderance for lobule II (45 ∶ 80%) but this indication of a somatotopic arrangement is not unequivocally paralleled by the other mossy fiber inputs. 3. Also in regard to the climbing fiber input no distinct somatotopical arrangement has been detected. Again it has been noted that the ipsilateral inputs have a somewhat greater input to lobule V from the forelimb than from the hindlimb (35 ∶ 22%), and the reverse finding holds true for lobule II (10∶ 45%). 4. The overall results did not change appreciably when the responses were grouped according to their latencies or when the Purkyně cells were classified according to the patterns of convergence of their receptive fields. 5. The absence of a distinct somatotopic organization in the vermis is a direct consequence of the considerable convergence from the cutaneous mechanoreceptors of the limbs onto the individual Purkyně cells which occurs via the mossy and the climbing fiber pathways. It is suggested that this convergence indicates that the vermal Purkyně cells are particularly involved in coordinating the motor activity of forelimbs and hindlimbs.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00239037
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  • 13
    Digitale Medien
    Digitale Medien
    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
    Schlagwort(e): Cerebellum ; Cutaneous mechanoreceptors ; Climbing fibers ; Purkyně cells
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00236404
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  • 14
    Digitale Medien
    Digitale Medien
    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
    Schlagwort(e): Cerebellum ; Cutaneous mechanoreceptors ; Mossy fibers ; Climbing fibers ; Integration ; Purkyně cell groups
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00236405
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  • 15
    Digitale Medien
    Digitale Medien
    Cutaneous mechanoreceptors influencing impulse discharges in cerebellar cortex. II. In Purkyně cells by mossy fiber input (1972)
    Springer
    Experimental brain research 15 (1972), S. 261-277 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Cerebellum ; Cutaneous mechanoreceptors ; Mossy fibers ; Purkyně cells ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary This paper gives an account of single Purkyně cell responses when three types of mechanical stimulation, as in the previous paper, are applied to the forefoot and hindfoot of the decerebrate unanesthetized cat. Attention was concentrated on the effects of brief mechanical pulses to the footpad. Recording was extracellular by glass microelectrodes and special precautions were taken in identifying the spike responses as being due to a single Purkyně cell and in securing its effective isolation for our computer averaging techniques, as described in the previous papers. All Purkyně cells were in the ipsilateral anterior lobe in the lateral vermis or pars intermedia of lobules III, IV, V, except for a few recordings in the extreme rostral zone of lobule VI. Mechanical pulses or taps evoked responses from many Purkyně cells which were pure excitatory, pure inhibitory or admixtures thereof. The latencies of onset were usually in the range of 12–20 msec from the onset of the tap, which tends to be a little longer than the observed latencies for mossy fiber responses described in the preceding paper. There was often a considerable difference in the sizes of the responses evoked from different pads of the same foot, and the usual threshold for response was below 0.2 mm amplitude. Durations of responses were usually 10–20 msec for excitation and 50–100 msec for inhibition. Pressure pulses to the central foot pads of 2 sec duration evoked a wide variety of responses: brief phasic at “on” and “off” that could be admixtures of excitation and inhibition; almost pure tonic excitations or inhibitions that were well maintained during the 2 sec; phasic-tonic responses in various relative degrees. Usually 500 g was maximally effective and the threshold was below 100 g. Hair receptors were stimulated preferentially by brief air jets, there being brief excitatory or inhibitory responses much as with taps, but with rather longer latency. The effective area was usually fairly extensive over the hairy skin of the foot. In general the effects on Purkyně cells by cutaneous mechanoreceptors acting via mossy fibers were in accord with the mossy fiber responses reported in the preceding paper and with the well-known excitatory and inhibitory effects that are exerted by mossy fiber inputs on Purkyně cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00235911
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