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A model of the feline medial gastrocnemius motoneuron-muscle system subjected to recurrent inhibition

Authors
  • Uchiyama, Takanori1
  • Johansson, Håkan2
  • Windhorst, Uwe2, 3, 4
  • 1 Keio University, Department of Applied Physics and Physico-Informatics, Faculty of Science and Technology, 3–14–1, Hiyoshi, Kohoku-ku, Yokohama, 223–8522, Japan , Yokohama
  • 2 National Institute for Working Life, Centre for Musculoskeletal Research, Petrus Laestadius väg, Umeå, Sweden , Umeå
  • 3 Universität Göttingen, Zentrum Physiologie und Pathophysiologie, Humboldtallee 23, Göttingen, D-37073, Germany , Göttingen
  • 4 University of Calgary, Department of Clinical Neurosciences, Department of Physiology and Biophysics, 3330 Hospital Dr. N.W., Calgary, Alberta, T2N 4N1, Canada
Type
Published Article
Journal
Biological Cybernetics
Publisher
Springer-Verlag
Publication Date
Jun 18, 2003
Volume
89
Issue
2
Pages
139–151
Identifiers
DOI: 10.1007/s00422-003-0413-y
Source
Springer Nature
Keywords
License
Yellow

Abstract

Recurrent inhibition in the mammalian spinal cord is complex, and its functions are not yet well understood. Skeletomotoneurons (α-MNs) excite, via recurrent axon collaterals, inhibitory Renshaw cells (RCs), which in turn inhibit α-MNs and other neurons. The anatomical and functional structure of the recurrent inhibitory network is nonhomogeneous, and the gain and filtering characteristics of RCs are modulated by inputs circumventing α-MNs. This complex organization is likely to play important roles for the discharge and recruitment properties of α-MNs. Modeling this system is a way of investigating hypothesized roles for normal functioning including muscle fatigue and different forms of physiological pathological tremor. In this paper, a detailed model including α-MNs, RCs, and the muscle fibers innervated by the α-MNs is presented. Outlines of the experimental data underlying the model and the modeling philosophy and procedure are presented. Then the behavior of a RC model is compared with experimental data reported in the literature. Model and experimental data agree well for burst responses elicited by synchronous single-pulse activation of different numbers of motor axons. In addition, the static relation between motor-axon activation rate and RC firing rate agree fairly well in model and experiment, and the same applies to the dynamic responses to step changes in motor-axon rate. The ultimate objective is to use this model in probing the role of recurrent inhibition in the control and stability of (isometric) muscular force under normal and altered conditions occurring during fatigue and muscle pain.

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