Presynaptic and Disynaptic Inhibition Induced by Group I Muscle Afferents

  • Annie Schmied
  • Jean-Marc Aimonetti
  • Jean-Pierre Vedel
Part of the Advances in Experimental Medicine and Biology book series (AEMB, volume 508)


The task related changes in the GpIinputs were investigated in type-identified motor units in the wrist extensor muscles. During wrist extension, the monosynaptic inputs generated by applying radial nerve stimulation were distributed among the motoneurone pool in line with the size principle. Their effectiveness was enhanced in the same way during hand clenching and during wrist extension combined with stimulation of the palm and finger cutaneous receptors. The orderly distribution of the monosynaptic Gp I inputs was reversed by the presynaptic inhibition induced by stimulating the Gp I flexor afferents. The effects of the presynaptic inhibition were partially released by applying cutaneous stimulation. During wrist extension, the Gp I flexor afferents generated disynaptic excitatory inputs acting specifically on high-threshold motor units together with disynaptic inhibitory inputs distributed in line with the size principle among the wrist extensor motor nucleus. During hand clenching, their effectiveness was differentially modulated depending on the motor unit type.


Motor Unit Presynaptic Inhibition Wrist Extension Wrist Extensor Firing Probability 
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Copyright information

© Springer Science+Business Media New York 2002

Authors and Affiliations

  • Annie Schmied
    • 1
  • Jean-Marc Aimonetti
  • Jean-Pierre Vedel
    • 1
  1. 1.DPM-CNRS 31 chemin Joseph AiguierMarseille cedex 20France

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