[The facilitation and inhibition of monosynaptic reflexes in the upper extremity of nursing infants].

Abstract

The upper extremity H-reflex was investigated in healthy children, aged from 3 to 15 months. The electromyographic reflex responses of m. abduct or digiti min. and m. flexor carpi uln. were registered after electric stimulation of n. ulnaris. We constructed the curve of restoration of H-reflex after application of a couple of stimuli with equal duration and intensity, but over increasing intervals. We established changes in the excitation of H-reflex, obtained from m. flexor carpi uln., by increasing of the interval between the conditional and test stimuli. In the interval of 5 ms maximal facilitation was registered, while in the interval of 20 and 30 ms-maximal inhibition. In children aged from 3 to 9 months with persisting H-reflex in m. abductor digit min. we established possibility for its complete inhibition after application of a couple of stimuli with interval of 20 ms. In children aged from 9 to 15 months with vanished H-reflex in m. abductor digiti min. possibility for its obtaining was established after application of a couple of stimuli with interval of 5 ms. Quotation is made of evidences in favour of the hypothesis for the functional character of the disappearance of H-reflex in the small muscles of the arm in the first year of life of the children.