Interaction between the saccules and the vertical semicircular canals.
For the experiments 39 cats were used. Selective sectioning of either the anterior or the posterior vertical ampullar nerves was performed bilaterally. Additionally in some cats the utricular nerves were cut, or the saccule extirpated on one or both sides. The otolith organs were stimulated by tilting around the bitemporal axis of the animals. Bilateral sectioning of the anterior ampullar nerve induced vertical nystagmus upwards, which disappeared, if the animals were tilted upside down. When the posterior ampullar nerves were cut bilaterally a vertical nystagmus downwards was obtained, and if the animals were tilted upside down there was a large increase in nystagmus frequency. After unilateral extirpation of the saccule, vertical nystagmus downwards was observed in 50 percent of these experiments. This nystagmus was modulated by tilting. However, if the saccules on both sides were extirpated, no nystagmus could be elicited. The cause of these results is discussed.
D000818:Animals; D002415:Cats; D007758:Ear, Inner / Q000502:physiology*; D004558:Electric Stimulation; D004584:Electronystagmography; D011187:Posture; D012444:Saccule and Utricle / Q000502:physiology*; D012665:Semicircular Canals / Q000502:physiology*; D014725:Vestibular Nerve / Q000502:physiology