Abstract
The vestibular system is sensing posture or direction of the gravity. It has been known that it is playing important roles not only posture control, but also cardiovascular dynamics via the autonomic nervous system as output. The control system is playing important roles for controlling arterial pressure during posture change in human subjects. Changing the posture from supine to standing, body fluid shifts footward, and venous return or cardiac output is decreased. Without any control, arterial pressure should be decreased, but it is not changed largely in healthy subjects. However, arterial pressure is decreased when vestibular input is confused with galvanic vestibular stimulation (GVS). Thus, vestibular system is playing an important role for arterial at the onset of this standing. The change in arterial pressure at the onset of standing is correlated with balance of otolith function. Furthermore, GVS increases high frequency component which is a marker of parasympathetic nerve activity in heart rate variability. The increase is also correlated with change in arterial pressure at the onset of standing. The results suggest a presence of vestibulo-parasympathetic pathway.
