Reciprocal Interaction of Antagonistic Muscles in the Flexion Reflex of the Intact Hindlimb of the Decerebrate Cat (original) (raw)

Twenty cats were decerebrated by intercollicular section to produce hyperactive stretch reflexes similar to those found in patients with spasticity. Simultaneous recordings were made of electrical activity from the soleus and tibialis anterior muscles and of ankle joint movement during the flexion response elicited by cutaneous stimulation. Three types of responses were recorded from the antagonistic soleus muscle: I) a short latency twitch elicited by the mechanical stretch from dorsiflexion; 2) a long latency tetanic rebound (120-240 msec post stimulation) initiated by cutaneous afferents, and 3) a twitch coincident with that of the tibialis anterior, for which contributing factors were not delineated. Changing ankle joint position modified these responses. When soleus electrical activity was continuous and intense, the periods of evoked inhibition were markedly reduced. Olinical observation of patients with hyperactive stretch reflexes has raised the question of the influence of these reflexes on voluntary motion. In the patient with spasticity, the lower threshold of the motoneuron may alter reciprocal interaction, Miss Sahrmann is a Ph.D. candidate,