The effect of saccular ablation on vertical optokinetic after-nystagmus in squirrel monkeys.
The effect of bilateral saccular ablation on the asymmetry of vertical optokinetic after-nystagmus (OKAN) was studied in squirrel monkeys. No significant changes occurred in the initial slow-phase eye velocity (SPEV) or the time constant of the upward or downward OKAN first phase (OKAN-I) under various stimulus conditions. However, with a protracted downward stimulus, the maximum SPEV and the number of beats of the slow-phase-up OKAN second phase (OKAN-II) significantly increased. This increase should be the result from enhancement of the downward optokinetic input. In contrast, there was only minimal change in the slow-phase-down OKAN-II. Thus, the asymmetrical dominance of the vertical OKAN (dominance upward) remained the same after saccular deafferentation.
Igarashi
M
M
Department of Otorhinolaryngology and Communicative Sciences, Baylor College of Medicine, Houston, TX 77030.
Himi
T
T
MacDonald
S
S
Takeda
N
N
Kataura
A
A
D000818:Animals; D005133:Eye Movements / Q000502:physiology; D009760:Nystagmus, Physiologic / Q000502:physiology*; D012444:Saccule and Utricle / Q000502:physiology*; D012453:Saimiri; D013997:Time Factors