Optimum and pessimum frequency of stimulation for the tetanic and tonic reflex apparatus

Summary

Experiments were performed on spinal frogs. It was demonstrated that in excessive increase of the frequency of stimulation of the afferent paths a condition of pessimal inhibition is developed in the nerve centers innervating the tonic muscular apparatus. Pessimal phenomena begin at the frequency of 60–70 stimulations per second. Complete depression of the reflex response takes place at the frequencies of 300–350 stimulations per second. As to the centers innervating the tetanic muscle fibers the pessimal phenomena commence only at the frequency of 100–150 per second. Inhibition in “tetanic centers” develops much quicker. Complete depression of the reflex response usually takes place at the frequencies of 150–200. These facts point to the lower lability of the nerve centers innervating the tonic muscular apparatus.