Habituation, Efference and Vestibular Interplay:III. Unidirectional rotatory habituation

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Abstract
Fourteen vestibularly normal human subjects were subjected to unidirectional rotatory habituation. Before and after the habituation a caloric test was carried out and the results of these tests were compared in order to establish whether the habituation had produced changes in the mode of reaction of the two labyrinths in the same way as had been shown earlier through monaural caloric habituation. This proved to be the case. In nine persons there was a directional preponderance to the right, whereas five showed generally diminished vestibular reactions. In one subject a spontaneous nystagmus to the right appeared. Ten persons showed a secondary nystagmus to the right after irrigations which produced nystagmus to the left. Nine cases presented, after the habituation, a characteristic dysrhythmia, mainly in connection with nystagmus to the right. The two groups seem to be extreme cases with all gradations between them, depending partly on the mode of reaction of the subjects and partly on the strength of the stimulus used. The results suggest that the reaction changes are not a consequence of a given method of stimulation, but are a real expression of the way in which a habituation is developed within the vestibular organ.