[Study on vomiting and the vestibulo-autonomic reflex]

When vestibular organs are abnormally stimulated, autonomic reactions such as nausea, vomiting, palpitation, etc., occur, indicating the existence of fiber connections from the vestibular organs to the autonomic centers. The relationship between the "vomiting center" in the medulla oblongata as described by Borison and Wang and the vestibular nucleus remains obscure. To investigate the central mechanism of vomiting caused by vestibular stimulation, the intragastric pressure, gastric peristalsis and respiration during electric stimulation of the medullary vomiting center and the semicircular canal nerve were recorded in 12 adult cats. Evoked potential was also recorded while electrically stimulating the semicircular canal nerve. When the peripheral labyrinth was stimulated, a conflicting result was founded, namely, that the pressure in the stomach increased or decreased. Retching or vomiting-like behavior was observed in several sites when the dorsolateral portion of the reticular formation of the medulla was stimulated. It was found that neural structures in the dorsolateral portion of the reticular formation of the medulla were associated with the semicircular canal nerve, but retching or vomiting-like behavior was not always observed during stimulation there.