Accession Number : AD0622841

Title :   EFFECTS OF PROLONGED CALORIC STIMULATION UPON OCULOMOTOR, VESTIBULOSPINAL, AND SEGMENTAL SPINAL ACTIVITY.

Descriptive Note : Research rept. no. 2,

Corporate Author : NAVAL SCHOOL OF AVIATION MEDICINE PENSACOLA FLA

Personal Author(s) : Gernandt,Bo E. ; Igarashi,Makoto ; ades,Harlow W.

Report Date : 24 JUN 1965

Pagination or Media Count : 21

Abstract : The effects of prolonged caloric stimulation with hot (45C) or ice water have been studied upon eye movements, vestibulospinal, and segmental spinal activity. The results obtained under this variety of test conditions demonstrate that continuous irrigation with water of extreme temperatures evokes, in addition to the effects upon the position of the cupula by endolymphatic convection currents according to the theory of Barany, an initial excitatory thermal effect giving rise to an increased afferent firing which is followed by a paralyzing effect upon the vestibular sensori-neural structures. In order to localize more specifically the site of action of thermal stimulation, experiments were carried out upon labyrinthectomized squirrel monkeys and monkeys with the three semicircular canals plugged. These results, and those obtained by recording the cochlear microphonic and neural components to click stimulation during maximal cold and warm irrigation of the ear, indicate that the effect is upon the peripheral nerve fibers somewhere along their course from the ampulla to the internal auditory meatus. Earlier theories which have predicted this direct effect on the nerves are mentioned, but, for the present, without comment as to their respective importance in explaining paradoxical caloric reactions. (Author)

Descriptors :   (*VESTIBULAR APPARATUS, STIMULATION(PHYSIOLOGY)), EAR, SEMICIRCULAR CANALS, PERIPHERAL NERVOUS SYSTEM, EYE, MOTION, SPINAL COLUMN, NERVES, NERVE FIBERS, TEMPERATURE, MONKEYS

Distribution Statement : APPROVED FOR PUBLIC RELEASE