Vestibular Mechanisms of Facilitation and Inhibition of Cord Reflexes

Abstract

The facilitatory effect of the spontaneous impulse discharge in the 8th nerve on oscillographically recorded peripheral nerve to ventral root reflexes has been investigated. The facilitatory action is chiefly transmitted over the reticulo-spinal tract and the vestibulo-spinal tract seems to play a subordinate part. A facilitatory or inhibitory effect of adequate vestibular stimulation depending on the deflection of the cupulae in the ampullae of the horizontal semicircular canals can be demonstrated on the monosynaptic test response, the latter being elicited from the nerve to the anterior tibial muscle or the gastrocnemius nerve. The results show that there is a reciprocal action which may be initiated from the reticular level.