THE INSPIRATORY AUGMENTATION OF PROPRIOCEPTIVE REFLEXES

Abstract

Experiments on men, dogs and cats demonstrate that with each inspiration in normal breathing the knee jerk and the Achilles reflex are augmented. The augmentation is not demonstrable in all subjects and animals, nor in the same ones at all times. The conditions, favorable and unfavorable, are discussed. The phenomenon is not a reflex from the respiratory tract or muscles, but is dependent upon the discharge of impulses from the respiratory center. There is no increase in the knee jerk during normal expiration, but during forced breathing there is some evidence of a slight increase. By forcing the respiratory effort the effects of inspiration are increased. The inspiratory augmentation is demonstrable through the whole range of intensity of stimulation, from threshold to maximal, but is best shown in the weak and medium range. Within the limits tested, the augmentation bears no relation to the rate of stimulation. The existence of a true refractory state is not essential for its production. The inspiratory augmentation of the reflexes studied is attributed to the irradiation of impulses from the respiratory center. The exact mechanism involved is not clear, but the possibilities have been stated, and the lines of work necessary for further clarification pointed out.