Effect of Cerebellar Ablation on the H Reflex in the Cat

Abstract

Any ATTEMPT to evaluate pathological conditions characterized by disorders of movement or posture must take into account the physiological state of the spinal motoneuron pool. One means of obtaining information about the excitability of spinal motoneurons in man is to study the H wave which can be recorded from the calf muscles after stimulating the posterior tibial nerve in the popliteal fossa.^1,2 The determination of the time-course of changes in amplitude of the H reflex response to a test stimulus at intervals of time after a conditioning volley has been employed as a method of testing the excitability of the spinal motoneuron pool in patients with upper motor neuron lesions^3-5 and in those with Parkinson's disease.^6-8 However, the interpretation of the recovery curves so obtained has been rendered difficult because there has been no clear demonstration under experimental conditions of the various factors which influence the