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. 1996 May 15;493(Pt 1):55–66. doi: 10.1113/jphysiol.1996.sp021364

Burst-generating neurones in the dorsal horn in an in vitro preparation of the turtle spinal cord.

R E Russo 1, J Hounsgaard 1
PMCID: PMC1158950  PMID: 8735694

Abstract

1. In transverse slices of the spinal cord of the turtle, intracellular recordings were used to characterize and analyse the responses to injected current and activation of primary afferents in dorsal horn neurones. 2. A subpopulation of neurones, with cell bodies located centrally in the dorsal horn, was distinguished by the ability to generate a burst response following a hyperpolarization from rest or during a depolarization from a hyperpolarized holding potential. The burst response was inactivated at the resting membrane potential. 3. The burst response was mediated by a low threshold Ca2+ spike assumed to be mediated by T-type Ca2+ channels since it resisted tetrodotoxin and was blocked by 3 mM Co2+ or 100-300 microM Ni2+ and resembled the low threshold spike (LTS) described elsewhere. 4. Some burst-generating cells also displayed plateau potentials mediated by L-type Ca2+ channels. In these cells the burst following a hyperpolarizing current pulse, applied from the resting membrane potential, facilitated the activation of the plateau potential. Wind-up of the plateau potential was produced when the hyperpolarizing pulse generating the burst was repeated at 0.1-0.3 Hz or faster. 5. The burst response and the underlying low threshold Ca2+ spike were activated synaptically by primary afferent stimuli in a voltage range hyperpolarized from the resting membrane potential. 6. Cells with bursts were morphologically distinguishable from cells with bursts and plateau properties. 7. Our findings in this and the preceding paper show that the intrinsic response properties of particular subtypes of neurones in the dorsal horn have a profound influence on the amplitude and time course of the responses mediated by primary afferent fibres. We predict that these postsynaptic properties are probable targets for synaptic modulation.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Alonso A., Llinás R. R. Electrophysiology of the mammillary complex in vitro. II. Medial mammillary neurons. J Neurophysiol. 1992 Oct;68(4):1321–1331. doi: 10.1152/jn.1992.68.4.1321. [DOI] [PubMed] [Google Scholar]
  2. Coulter D. A., Huguenard J. R., Prince D. A. Calcium currents in rat thalamocortical relay neurones: kinetic properties of the transient, low-threshold current. J Physiol. 1989 Jul;414:587–604. doi: 10.1113/jphysiol.1989.sp017705. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Crunelli V., Lightowler S., Pollard C. E. A T-type Ca2+ current underlies low-threshold Ca2+ potentials in cells of the cat and rat lateral geniculate nucleus. J Physiol. 1989 Jun;413:543–561. doi: 10.1113/jphysiol.1989.sp017668. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Fox A. P., Nowycky M. C., Tsien R. W. Kinetic and pharmacological properties distinguishing three types of calcium currents in chick sensory neurones. J Physiol. 1987 Dec;394:149–172. doi: 10.1113/jphysiol.1987.sp016864. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. 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]
  6. Huang L. Y. Calcium channels in isolated rat dorsal horn neurones, including labelled spinothalamic and trigeminothalamic cells. J Physiol. 1989 Apr;411:161–177. doi: 10.1113/jphysiol.1989.sp017566. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Huguenard J. R., Prince D. A. A novel T-type current underlies prolonged Ca(2+)-dependent burst firing in GABAergic neurons of rat thalamic reticular nucleus. J Neurosci. 1992 Oct;12(10):3804–3817. doi: 10.1523/JNEUROSCI.12-10-03804.1992. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Jahnsen H., Llinás R. Electrophysiological properties of guinea-pig thalamic neurones: an in vitro study. J Physiol. 1984 Apr;349:205–226. doi: 10.1113/jphysiol.1984.sp015153. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Llinás R., Yarom Y. Electrophysiology of mammalian inferior olivary neurones in vitro. Different types of voltage-dependent ionic conductances. J Physiol. 1981 Jun;315:549–567. doi: 10.1113/jphysiol.1981.sp013763. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Lopez-Garcia J. A., King A. E. Membrane properties of physiologically classified rat dorsal horn neurons in vitro: correlation with cutaneous sensory afferent input. Eur J Neurosci. 1994 Jun 1;6(6):998–1007. doi: 10.1111/j.1460-9568.1994.tb00594.x. [DOI] [PubMed] [Google Scholar]
  11. Markram H., Sakmann B. Calcium transients in dendrites of neocortical neurons evoked by single subthreshold excitatory postsynaptic potentials via low-voltage-activated calcium channels. Proc Natl Acad Sci U S A. 1994 May 24;91(11):5207–5211. doi: 10.1073/pnas.91.11.5207. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. McCormick D. A., Feeser H. R. Functional implications of burst firing and single spike activity in lateral geniculate relay neurons. Neuroscience. 1990;39(1):103–113. doi: 10.1016/0306-4522(90)90225-s. [DOI] [PubMed] [Google Scholar]
  13. Nowycky M. C., Fox A. P., Tsien R. W. Three types of neuronal calcium channel with different calcium agonist sensitivity. Nature. 1985 Aug 1;316(6027):440–443. doi: 10.1038/316440a0. [DOI] [PubMed] [Google Scholar]
  14. Russo R. E., Hounsgaard J. Plateau-generating neurones in the dorsal horn in an in vitro preparation of the turtle spinal cord. J Physiol. 1996 May 15;493(Pt 1):39–54. doi: 10.1113/jphysiol.1996.sp021363. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Russo R. E., Hounsgaard J. Short-term plasticity in turtle dorsal horn neurons mediated by L-type Ca2+ channels. Neuroscience. 1994 Jul;61(2):191–197. doi: 10.1016/0306-4522(94)90222-4. [DOI] [PubMed] [Google Scholar]
  16. Ryu P. D., Randic M. Low- and high-voltage-activated calcium currents in rat spinal dorsal horn neurons. J Neurophysiol. 1990 Feb;63(2):273–285. doi: 10.1152/jn.1990.63.2.273. [DOI] [PubMed] [Google Scholar]
  17. Sahara Y., Xie Y. K., Bennett G. J. Intracellular records of the effects of primary afferent input in lumbar spinoreticular tract neurons in the cat. J Neurophysiol. 1990 Dec;64(6):1791–1800. doi: 10.1152/jn.1990.64.6.1791. [DOI] [PubMed] [Google Scholar]
  18. Sandkühler J., Eblen-Zajjur A. A. Identification and characterization of rhythmic nociceptive and non-nociceptive spinal dorsal horn neurons in the rat. Neuroscience. 1994 Aug;61(4):991–1006. doi: 10.1016/0306-4522(94)90419-7. [DOI] [PubMed] [Google Scholar]
  19. Yoshimura M., Jessell T. M. Membrane properties of rat substantia gelatinosa neurons in vitro. J Neurophysiol. 1989 Jul;62(1):109–118. doi: 10.1152/jn.1989.62.1.109. [DOI] [PubMed] [Google Scholar]

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