Vestibular inputs to the lateral tegmental field of the cat: potential role in autonomic control.

The lateral tegmental field (LTF), which is comprised of the lateral reticular formation near the obex, is an important integrative area involved in cardiovascular control and the production of emesis. Using neuroanatomical and electrophysiological techniques, we tested the hypothesis that LTF neurons receive vestibular inputs; the neurons studied included those projecting into the subretrofacial rostral ventrolateral medulla (sRVLM), which contains cells that make direct connections with sympathetic preganglionic neurons. Injections of the anterograde tracer PHA-L into the medial and inferior vestibular nuclei produced labeled terminals in the LTF. Electrical stimulation of the vestibular nerve affected the firing rate of LTF neurons, including approximately one-third of those antidromically activated from the sRVLM. The response latencies ranged from 1.5 to 20 ms, suggesting that the neurons received both direct and polysynaptic vestibular inputs from the vestibular nuclei. The LTF may be involved in the production of vestibulosympathetic reflexes and vestibular-elicited vomiting.