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. 1990 Oct;429:511–528. doi: 10.1113/jphysiol.1990.sp018270

Afferent inhibition and facilitation of transmission through the spinocervical tract in the anaesthetized cat.

A D Short 1, A G Brown 1, D J Maxwell 1
PMCID: PMC1181713  PMID: 2277356

Abstract

1. Extracellular microelectrode recordings were made from single spinocervical tract (SCT) neurones in the lumbosacral spinal cord of cats anaesthetized with chloralose and paralysed with gallamine triethiodide. 2. Pairs of air-jet stimuli, 60 ms in duration, were used to investigate in-field afferent inhibition in SCT cells. One jet was used to condition the responses to another jet located at a different position within the excitatory receptive field and occurring at times from 100 to 1800 ms later. Fifteen neurones were tested and significant in-field inhibition was observed in all of them. 3. The in-field afferent inhibition was organized spatially in the sense that inhibition was generally strongest when conditioning and testing stimuli were close together and became weaker as they were moved apart. There was also a weak effect due to the strength of the conditioning response; when conditioning produced a strong response, from near the most excitable part of the receptive field, there was often a weak reduction in the test response from distant sites. The inhibitory areas defined in these experiments were generally less than 100 mm in length in units with excitatory receptive fields much longer than this. 4. The in-field afferent inhibition had a time course that lasted from 300 to about 1000 ms. 5. Afferent inhibition was also evoked by applying either air-jet stimuli to hairy skin outside, but close to, the excitatory receptive field or by applying a vibratory stimulus from a piezoelectric transducer (200 Hz) to glabrous skin of the toe pads or the central foot pad. These conditioning stimuli had durations of 20 or 60 ms. For convenience we call this inhibition 'out-of-field' afferent inhibition. 6. Out-of-field afferent inhibition was evoked from both glabrous and hairy skin areas outside the excitatory receptive field. It was common in neurones with receptive fields on the toes and of twenty-eight such neurones tested it was observed in twenty-four. This inhibition had a short latency (usually about 10 ms or less but occasionally up to 30 ms) and lasted for about the duration of the test stimulus (30 or 80 ms when the test stimulus was 20 or 60 ms respectively). It was often followed by a further period of inhibition, with a latency of between 50 and 100 ms and lasting for 60 up to 130 ms. 7. In thirteen SCT neurones more complex effects were seen.(ABSTRACT TRUNCATED AT 400 WORDS)

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Selected References

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  1. Brown A. G. Effects of descending impulses on transmission through the spinocervical tract. J Physiol. 1971 Dec;219(1):103–125. doi: 10.1113/jphysiol.1971.sp009652. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Brown A. G., Iggo A. A quantitative study of cutaneous receptors and afferent fibres in the cat and rabbit. J Physiol. 1967 Dec;193(3):707–733. doi: 10.1113/jphysiol.1967.sp008390. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Brown A. G., Kirk E. J., Martin H. F., 3rd Descending and segmental inhibition of transmission through the spinocervical tract. J Physiol. 1973 May;230(3):689–705. doi: 10.1113/jphysiol.1973.sp010212. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Brown A. G., Koerber H. R., Noble R. Actions of trains and pairs of impulses from single primary afferent fibres on single spinocervical tract cells in cat. J Physiol. 1987 Jan;382:313–329. doi: 10.1113/jphysiol.1987.sp016369. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Brown A. G., Koerber H. R., Noble R. An intracellular study of spinocervical tract cell responses to natural stimuli and single hair afferent fibres in cats. J Physiol. 1987 Jan;382:331–354. doi: 10.1113/jphysiol.1987.sp016370. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Brown A. G., Maxwell D. J., Short A. D. Receptive fields and in-field afferent inhibition of neurones in the cat's lateral cervical nucleus. J Physiol. 1989 Jun;413:119–137. doi: 10.1113/jphysiol.1989.sp017645. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Brown A. G., Noble R., Rowe M. J. Receptive field profiles and integrative properties of spinocervical tract cells in the cat. J Physiol. 1986 May;374:335–348. doi: 10.1113/jphysiol.1986.sp016082. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Harrison P. J., Jankowska E. An intracellular study of descending and non-cutaneous afferent input to spinocervical tract neurones in the cat. J Physiol. 1984 Nov;356:245–261. doi: 10.1113/jphysiol.1984.sp015462. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Hongo T., Jankowska E., Lundberg A. Post-synaptic excitation and inhibition from primary afferents in neurones of the spinocervical tract. J Physiol. 1968 Dec;199(3):569–592. doi: 10.1113/jphysiol.1968.sp008669. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Jänig W., Schoultz T., Spencer W. A. Temporal and spatial parameters of excitation and afferent inhibition in cuneothalamic relay neurons. J Neurophysiol. 1977 Jul;40(4):822–835. doi: 10.1152/jn.1977.40.4.822. [DOI] [PubMed] [Google Scholar]
  11. Jänig W., Spencer W. A., Younkin S. G. Spatial and temporal features of afferent inhibition of thalamocortical relay cells. J Neurophysiol. 1979 Sep;42(5):1450–1460. doi: 10.1152/jn.1979.42.5.1450. [DOI] [PubMed] [Google Scholar]
  12. Laskin S. E., Spencer W. A. Cutaneous masking. II. Geometry of excitatory andinhibitory receptive fields of single units in somatosensory cortex of the cat. J Neurophysiol. 1979 Jul;42(4):1061–1082. doi: 10.1152/jn.1979.42.4.1061. [DOI] [PubMed] [Google Scholar]
  13. Noble R., Short A. D. Spatial spread of in-field afferent inhibition in the cat's spinocervical tract. J Physiol. 1989 Jun;413:107–118. doi: 10.1113/jphysiol.1989.sp017644. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Tapper D. N., Wiesenfeld Z., Craig A. D., Jr A dorsal spinal neural network in cat. II. Changes in responsiveness initiated by single conditioning impulses in single type 1 cutaneous input fibers. J Neurophysiol. 1983 Feb;49(2):534–547. doi: 10.1152/jn.1983.49.2.534. [DOI] [PubMed] [Google Scholar]
  15. Zieglgänsberger W., Herz A. Changes of cutaneous receptive fields of spino-cervical-tract neurones and other dorsal horn neurones by microelectrophoretically administered amino acids. Exp Brain Res. 1971;13(2):111–126. doi: 10.1007/BF00234080. [DOI] [PubMed] [Google Scholar]

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