We have reported that middle ear pressure changes influenced vestibular nerve activity. In the present study the influence of middle ear pressure on the lateral vestibular nucleus neurons was investigated in anesthetized cats. The activities of the lateral vestibular nucleus neurons, especially the lateral vestibulo-spinal tract neurons, were recorded extracellularly. Positive or negative pressure was applied to the middle ear cavity bilaterally through perforation of the tympanic membrane.
In most lateral vestibular nucleus neurons firings were increased with negative pressure and decreased with positive pressure. These effects were more prominent when pressure changes were applied to the contralateral middle ear cavity. These influences of middle ear pressure on the lateral vestibular nucleus neurons were opposite to those on the vestibular nerve, and the existence of inhibitory interneurons was considered.