The action of knee joint afferents and the concomitant influence of cutaneous (sural) afferents on the discharge of triceps surae gamma-motoneurones in the cat.
Electrical stimulation of group II joint afferents of the posterior articular nerve (PAN) to the knee evoked short-latency facilitation and/or inhibition of the background discharge of gastrocnemius-soleus (GS) gamma-motoneurones in decerebrated spinal cats. The latencies of these responses were consistent with mediation via segmental oligosynaptic spinal pathways. In addition, a longer-latency facilitation was frequently observed. Mechanical non-noxious stimulation of the skin within the field of innervation of the sural nerve, on the lateral aspect of the heel, suppressed the short-latency facilitation, but not the inhibition or long-latency facilitation. Brief mechanical indentation of the posterior aspect of the knee joint capsule could elicit facilitation or inhibition of gamma-motoneurones. Facilitation, but not inhibition, was blocked by anaesthesia or section of the PAN. Both actions could be suppressed by mechanical stimulation of the heel. We conclude that GS gamma-motoneurones receive both facilitatory and inhibitory segmental inputs from group II articular afferents arising in the knee joint. Cutaneous afferents from the sural field exert a selective inhibitory influence over the facilitation of fusimotor discharge by articular afferents.
Ellaway
P H
PH
Department of Physiology, Charing Cross and Westminster Medical School, London, UK.
Davey
N J
NJ
Ferrell
W R
WR
Baxendale
R H
RH
D000818:Animals; D002415:Cats; D003213:Conditioning, Psychological; D004558:Electric Stimulation; D005260:Female; D006614:Hindlimb; D007719:Knee Joint / Q000294:innervation*; D008297:Male; D009047:Motor Neurons, Gamma / Q000502:physiology*; D009132:Muscles / Q000294:innervation*; D009424:Nervous System Physiological Phenomena; D009475:Neurons, Afferent / Q000502:physiology*; D010812:Physical Stimulation; D012867:Skin / Q000294:innervation*; D012879:Skin Physiological Phenomena; D013497:Sural Nerve / Q000166:cytology / Q000502:physiology*