Habituation, Efference and Vestibular Interplay II.: Combined Calorie Habituation

Abstract

Following an initial caloric test in each of five subjects, the right ear was habituated by repeated irrigation tests at 44°C. The result was checked by a further caloric test. Four of the subjects then underwent secondary habituation of the right ear with water at 30°C, and the fifth, of the left ear at 44°C. The outcome was studied by means of a final caloric test.

Primary habituation elicited directional preponderance to the left; secondary habituation involved a reversal, with preponderance to the right, whether the right ear was habituated to cold water or the left ear to hot water. The initial habituation was associated with secondary nystagmus to the left, but on secondary habituation its direction was reversed. The nystagmograms showed concurrent characteristic dysrhythmia, which was also altered by secondary habituation. These results are attributed to regular changes in the efferent activity of the two labyrinths.