Relation Between Strength of Acceleration and Duration of Postacceleratory Nystagmus

Abstract

Altogether 22 clinically healthy subjects were rotated at acceleration strengths of 1, 2, 4 and 8°/sec². After each acceleration, the duration was measured of postacceleratory nystagmus, denoted as the after-discharge. The after-discharge showed a distinct tendency to be longer with increasing strength of stimulus, although a relatively small increase was noted in the acceleration range 4-8°/sec². On the average, the after-discharge was approximately the same in clockwise and in counterclockwise acceleration. When a difference was present, it was generally greater after weaker stimuli, but large individual variations exist in normal subjects, and their borderlines were therefore calculated. The investigation also disclosed that the results are not in agreement with those found in movement of a damped pendulum. After stronger stimuli, a shorter after-discharge was recorded than that one would have expected had this applied.