Independence of fusimotor and skeletomotor systems during voluntary movement

  • A. Prochazka
  • P. Wand


Variations in the sensitivities of primary and secondary muscle spindle afferents were observed in cats performing voluntary movements. The time course of fusimotor action was deduced from these variations. In unobstructed movements, there was evidence of steady, relatively low levels of both static and dynamic action. In imposed movements involving slight to moderate resistance, eight of the nine primary endings studied showed evidence of increased, steady, dynamic action. This may therefore represent a class of movement which is most often associated with a known change in spindle sensitivity in the normal animal. In imposed movements involving substantial resistance, further fusimotor action of both types was implicated. Although there was some evidence for e.m.g.-linked increases in fusimotor action in two of the primaries, it was not possible to decide whether or not these were examples of α–γ linkage. We conclude that much of the functionally important fusimotor action occurring during normal movements in cats is independent of skeletomotor activity.


Voluntary Movement Linear Filter Moderate Resistance Ankle Extensor Sensitivity Plot 
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Copyright information

© The contributors 1981

Authors and Affiliations

  • A. Prochazka
    • 1
  • P. Wand
    • 2
  1. 1.Sherrington School of PhysiologySt Thomas’s Hospital Medical SchoolLondonUK
  2. 2.Max Planck Institut für Experimentelle MedizinGöttingenGermany

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