Parametric study of postrotatory nystagmus in normal squirrel monkeys.

In order to find the most consistent nystagmic parameter following rotation, 16 healthy young adult squirrel monkeys were rotated from 0 to 200 degrees/sec with 1 degrees/sec2 constant angular acceleration and then abruptly stopped. This centric horizontal rotation was performed in a dark room without the eyes being covered. Horizontal eye movement of the postrotatory nystagmic response was recorded: maximum slow and quick phase eye speeds, nystagmic duration, amplitude, number of beats, and maximum average frequencies were studied. The maximum frequency of the nystagmic beats was statistically confirmed at the least variable parameter among the seven parameters. The importance of baseline establishment in the animal nystagmus experiment was emphasized.