Vagal responses to vestibular stimulation in the cat.

The effects of vestibular stimuli on the vagal efferent complex were examined in cats under chloralose anasthesia. The results showed that two functionally distinct groups of vagal efferent fibres are excited by vestibular stimuli. The neural complex involved in the delayed vestibulo-vagal response (latency of 15-22 msec) lies at the orbital surface of the cerebral cortex. The early response (latency of 3-5 msec) originates in the medulla oblongata. The reaction of some vagal units to vestibular polarization is quite similar to that of vestibular units and suggests that primary vestibular fibres reach the ipsilateral vagal efferent neurons. The present experiments give further evidence that the vestibular complex exerts a controlling influence on the cardiovascular system.