The influence of middle ear pressure on the vestibular nerve activity in cats.

The influence of middle ear pressure on the vestibular nerve activities was investigated in anesthetized cats. The vestibular nerve activities were recorded intraaxonally and positive or negative pressure was applied to the middle ear cavity through a tympanic membrane perforation. The firing of vestibular nerve fibers, especially the regular type nerve that responded to horizontal semicircular canal stimulation, increased with positive pressure and decreased with negative pressure. Most vestibular nerves that responded to anterior or posterior semicircular canal stimulation were not influenced by changes in the middle ear pressure. These results indicate that middle ear pressure load is transmitted to the vestibular end organs and then to vestibular nerve.