STUDIES ON CENTRAL NYSTAGMUS INDUCED BY ELECTRICAL STIMULATION OF MESO-DIENCEPHALON IN RABBITS

Abstract

Since Blohmke and Toda described it, the fact has been known that the horizontal nystagmus of the eyes can be induced by electrical stimulation of the meso-diencephalon in rabbits. According to the method described by Lachmann et al, who did a great deal of research in this field, “the nystagmogenic area” was electrically stimulated in 26 rabbits. In addition to the electrical stimulation, they were given optokinetic and labyrinthine stimulations (1°/sec2 in 90see), simultaneously or independently.It was evaluated how the central nystagmus, which was induced by electrical stimulation to this area, interacted with the optokinetic and labyrinthine nystagmus and, furthermore, how the nystagmogenic area related to the physiological cooperation of the visual organ and the vestibular organ i.e. the so-called “optic-vestibular coordination”, in development of nystagmus. Following conclusions were obtained.1. Central nystagmus is always facillitated by optokinetic stimulation irrespective of the direction of the optokinetic stimulation.2. Central nystagmus is sometimes facillitated and sometimes inhibited by the labyrinthine stimulation depending on the direction of the stimulus. The effect is observed even if the subliminal rotation, which does not provoke nystagmus by itself, is applied.3. Central nystagmus is markedly facillitated by simultaneous aprication of the optokinetic and labyrinthine stimulations.4. The nystagmogenic area relates closely to the neural pathway of the optokinetic nystagmus. and plays an important role in the optic-vestibular coordination in development of nystagmus.