Research Interest: Vestibular Influences on Autonomic Control.A key role of the nervous system is to provide for homeostasis. One profound challenge to homeostasis can occur during changes posture. In particular, some movements, such as standing in humans or nose-up body pitch in quadrupeds, can threaten the maintenance of stable blood pressure and blood oxygenation. Unless compensation takes place quickly, these movements produce (1) blood pooling in the lower body that results in orthostatic hypotension and (2) a change in the resting length of the respiratory muscles that results in decreased air flow through the lungs. Many body sensors, including arterial baroreceptors, receptors in the heart, receptors in limb veins, receptors in the lungs, stretch receptors in respiratory muscles, and central and peripheral chemoreceptors, detect disturbances in homeostasis and trigger appropriate compensatory responses. However, effective maintenance of homeostasis would seem to require that compensation for the effects of movement on circulation and respiration begin even before the internal environment has been affected. One mechanism for accomplishing this would be through the actions of the vestibular system, which detects head position and head movements, and could thus provide “feed-forward” information to the brainstem autonomic centers, resulting in corrections in blood pressure and ventilation during changes in body position. The major research in our laboratory looks at the role of the vestibular system in adjusting blood pressure and respiration during movement and changes in posture. We are also determining the neural pathways through which vestibular signals influence the sympathetic nervous system (which controls blood pressure) and respiratory motoneurons. Finally, we are interested in determining which neural pathways are responsible for producing an aberrant autonomic effect that can result from vestibular stimulation: motion sickness.