Studies on the Correlation between the Optokinetic Stimulus and Induced Nystagmus

Publisher Website
Google Scholar
Abstract
In order to investigate the correlation between the optokinetic (OK) stimulus and induced optokinetic nystagmus (OKN), 2 different types of OK stimuli subtending large and small angles were used for this study. Narrow-angle OK stimulation was carried out by means of a small Barany-type drum (BTD) and wide-angle stimulation by means of a large Jung-type projector screen (JTPS) in a series of 15 healthy individuals. A striking difference between OKN elicited by narrow and wide angle stimuli could be demonstrated. Within the low-speed range of target movements, the pattern of OKN elicited by narrow-angle stimuli was irregular, whereas the pattern of OKN induced by wide angle stimuli was uniform. Within this speed range, the velocity of the slow phase of OKN elicited by narrow-angle stimuli was smaller than the target velocity. However, the speed of the slow phase of OKN induced by wide-angle stimuli was nearly equal to that of the target movement. Within the high-speed range of target movements, however, the eye speed of the slow phase of OKN elicited by wide-angle stimuli was inferior to that of the target velocity. In order to study the influence of repeated OK stimuli upon the OK and vestibulospinal responses, 10 persons were trained by repetitive wide-angle stimuli and 5 persons by repeated narrow-angle stimuli. In both groups a definite increase of the OK responses could be demonstrated. This response increment was more evident in subjects trained by narrow-angle OK stimuli. In subjects trained by repeated wide-angle stimuli, the stepping test revealed a very marked tendency to rotate or deviate in a direction opposite to that of the target movement. This modification of a vestibulospinal mechanism could not be observed in test subjects trained by repeated narrow-angle stimuli.

This publication has 0 references indexed in Scilit: