Autonomic response to real versus illusory motion (vection)

This study explored the cardiovascular responses to illusions of self-motion (vection) induced in normal subjects according to the hypothesis that vection may be a model for vertigo in vestibular disease. Responses were obtained from 10 men who were exposed to rapid tilts of 20 degrees and 30 degrees rolling from the upright position down to the right or left shoulder. These responses were compared with those evoked during the illusion of roll-tilt vection provoked by a torsionally rotating visual field. Comparisons were made between 10-second data epochs before and after stimulus onset. In response to vection, blood pressure (BP) in the radial artery rose consistently in six subjects, and in all of these, a pressor response to real tilt was also observed. The remaining four subjects consistently had decreased BP in response to vection, and their BPs were affected little by tilt. Subjects whose BP increased with vection and tilt may have been dominated by tendency to arousal, whereas those whose BP decreased may reveal the more appropriate response to tilt from the upright position, which is a decrease in BP. This may reflect individual stereotypes and differences in the relative contributions of somatosensory and vestibular control of autonomic regulation.