Effect of Temperature on Facilitation and Inhibition of Reflex Activity

Abstract

A study was made of the effects of cooling and warming the spinal cord on the reflex responses elicited from spinal and decerebrate cats. Cold increased and prolonged both facilitation and inhibition of monosynaptic reflexes, post-tetanic potentiation and the facilitation of antidromic potentials by conditioning orthodromic volleys. Warming the cord had the opposite effect. Cooling the cord produced a progressive increase in amplitude and duration of focally recorded synaptic potentials and antidromic potentials until a critical temperature was reached. Further reduction of cord temperature led to a diminution of these potentials. Interneuronal activity was augmented by cooling the cord and reflex activity produced by stimulation of group I muscle afferents showed a polysynaptic component when the cord was cooled. This late action was responsible for some of the modifications in the facilitation and inhibition curves obtained at low temperatures.