Studies on Habituation of Vestibular Reflexes: VI. Habituation in darkness of calorically induced nystagmus, laterotorsion and vertigo in man

Abstract

Fifteen normal subjects received 12 consecutive caloric irrigations, all in darkness, with water of 30°C in the right ear. For each calorization nystagmus and laterotorsion were recorded and maximum vertigo was indicated by the subject. Four qualities were compared; (1) eye-velocity, (2) duration of nystagmus, (3) laterotorsion, and (4) vertigo.

There was a response decline of these four qualities. The order of habituation rate from the greatest to the slightest was: (1) vertigo, (2) eye-velocity, (3) duration of nystagmus equal to laterotorsion. At the end of the irrigations vertigo had usually disappeared with nystagmus and laterotorsion still present.

The mode of response decline of each of the four qualities showed considerable individual differences.

There was a growing dysrhythmia of nystagmus with increasing habituation.