Provocation of Labyrinthine Reflex by Visual Stimuli: Evaluation of the Theory of Subliminal Rotation

Abstract

Recently, a new method of examination on the labyrinthine function called the subliminal rotation (Egmond, Arslan) has been universally put into practice in the place of Barany's method. This method is based upon the theory which establishes a threshold of angular acceleration about the labyrinthine function when a man or an animal is rotated. The cupulometry is also founded on this theory. It insists that the labyrinth remains unstimulated if the subject is rotated at such a low angular acceleration below a certain limit as to cause no perrotatoric nystagmus. The purpose of this paper is to criticize this theory, producing counter-evidence especially in regard to the optic condition of the subliminal rotation.

The labyrinth never remains unstimulated at the so-called subliminal rotation; the perrotatoric nystagmus is not induced only because the subject is under a special visual condition. The fact is that the labyrinth is stimulated and reacts in promoting the optokinetic nystagmus.

The labyrinth favours the optokinetic nystagmus by making a subject catch separately optokinetic stimuli.

Nystagmus rises originally from the optokinetic stimuli, and the labyrinth plays its physiological part secondarily, thereby favouring the optokinetic nystagmus.