Interaction Between the Utricles and the Vertical Semicircular Canals

Abstract

Selective bilateral sectioning of the anterior ampullar nerves was performed in 29 cats. This procedure resulted in a spontaneous nystagmus upwards. If the animals were tilted around their bitemporal axis, nose downwards, nystagmus was inhibited. Tilting nose upwards increased the nystagmus frequency. Selective bilateral sectioning of the posterior ampullar nerves caused a spontaneous nystagmus downwards. Tilting nose downwards increased the nystagmus, whereas tilting in the opposite direction caused its inhibition. Selective unilateral sectioning of the anterior and posterior ampullar nerves was followed by a rotatory nystagmus, which increased if the animals were tilted around their longitudinal axis towards the non-operated ear, and which was totally inhibited if they were tilted in the opposite direction. The cause of this phenomenon is discussed.