Neural mechanisms underlying the clasp-knife reflex in the cat. I. Characteristics of the reflex

• DOI: 10.1152/jn.1990.64.4.1303
• Publication Date: 2017-12-24T20:52:10Z
• Authors: C. L. Cleland; W. Z. Rymer
• Keywords: Presynaptic inhibition; Reciprocal inhibition

1. The goal of this study was to characterize the clasp-knife reflex by use stretch and isometric contraction ankle extensor flexor muscles in decerebrated cats with bilateral dorsal hemisections their spinal cords at segment T12. 2. Stretch an muscle evoked inhibition both homonymous synergistic muscles. similarities between suggest that similar neural mechanisms were responsible. 3. Homonymous showed several characteristic features: 1) only large stretches produced significant force. Short did not produce forces excitation; 2) magnitude increased increasing initial motor output, as reflected level rectified EMG; 3) time course ramp-and-hold characterized segmentation EMG during ramp stretch, dynamic overshoot end-of-ramp slow but usually complete decay maintained stretch; 4) persisted beyond termination 5) adaptation repeated stretch. 4. Isometric soleus or medial gastrocnemius, electrical stimulation nerve, also powerful synergistic-reflex via stretch-evoked, inhibition. a greater degree than contraction, indicating receptors responsive contribute 5. effects stretching gastrocnemius confined close Extensor inhibited excited throughout hindlimb, which paralleled pattern flexion-withdrawal cutaneous stimulation. 6. muscle, tibialis anterior, same spatial action muscle--inhibition excitation including anterior. 7. We conclude neither Golgi tendon organs nor secondary spindle afferents are likely significantly because responses differ from actions contraction.(ABSTRACT TRUNCATED AT 400 WORDS)