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A New Way of Using Modelling to Estimate the Size of a Motoneurone’s EPSP

  • Peter B. C. Matthews
Chapter
Part of the Advances in Experimental Medicine and Biology book series (AEMB, volume 508)

Abstract

Earlier modelling of a noisy motoneurone has been extended to provide a new measure of excitability. The distance-to-threshold estimate of an MN’s AHP, derived from its interval histogram, is used to create a simplified daughter model to mimic the behaviour of its parent and determine a new measure of an MN’s response to a stimulus. This Estimated Potential (EP) provides a linear measure of the size of the parent’s underlying EPSP, irrespective of its firing rate, and thereby improves on the classic firing index from which it is derived. The EP is applicable with both random and spike-triggered stimulation. It is emphasized that in the presence of noise a tonically firing MN’s average responsiveness at a given time during its AHP depends upon what may be termed the “survivor’s mean trajectory”, rather than upon the “distance to threshold” AHP found in the absence of noise; these differ because noise-induced spiking eliminates individual trajectories when they reach threshold.

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References

  1. Matthews, P. B. C., 1996, Relationship of firing intervals of human motor units to the trajectory of post-spike afterhyperpolarisation and synaptic noise, Journal of Physiology, 492, 597–628.PubMedGoogle Scholar
  2. Matthews, P. B. C., 1999, The effect of firing on a model motoneurone and its implications for cortical stimulation, Journal of Physiology, 518, 867–882.PubMedCrossRefGoogle Scholar
  3. Matthews, P. B. C., 2000, Modelling the tonic firing elicited by noisy inputs, Appendix pp. 145–149 in Powers and Binder, op. cit.Google Scholar
  4. Powers, R. K., and Binder, M. D., 1996, Experimental evaluation of input-output models of motoneuron discharge, Journal of Neurophysiology, 79, 367–379.Google Scholar
  5. Powers, R. K., and Binder, M. D., 2000, Relationship between the time course of the afterhyperpolarisation and discharge variability in cat spinal motoneurones, Journal of Physiology, 528, 131–150.PubMedCrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media New York 2002

Authors and Affiliations

  • Peter B. C. Matthews
    • 1
  1. 1.University Laboratory of PhysiologyOxfordUK

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