THE EFFECTS OF STIMULATING OPTIC TECTUM ON THE SPINAL ACTIVITY IN BULLFROG / 西安交通大学学报(医学版)

ABSTRACT

By using dorsal root patientials (DRP) and ventral root patientials (VRP) as in dexes, the effects of descending volleys originating from the optic tectum on spinal activity were observed in bullfrogs. The experimental results obtained were as follows; 1.DRP was evoked by stimulation of the optic rectum. 2. VRP evoked by stimulation of the siatic nerve comsisted of two components. The early conponent was evoked chiefly by type Ⅰ and Ⅱ afferent fibers and also contributed by type Ⅲ fibers; the late one was evoked by type Ⅳ afferent fibers. 3. VRP evoked by stimulation of the siatic nerve was inhibited by stimulation of the optic tectum. The duration of inhibition of the early component was related to that of DRP. Thus, the results indicate that the optic tectum takes part in the centrifugal control of somatosensory afferent activity, affects the spinal reflex, and involves in the mechanism of analgesia by way of presynaptic inhibition.