Both whole-body rotation and visual flow induce cardiovascular autonomic response in human, but visual response is overridden by vestibular stimulation

While the influence of the vestibular and extra-vestibular gravity signals on the cardiovascular system has been demonstrated, there is little evidence that visual stimuli can trigger cardiovascular responses. Furthermore, there is no evidence of interaction between visual and vestibular signals in autonomic control, as would be expected since they are highly integrated. The present study explored the cardiovascular responses to vestibular and visual stimuli in normal subjects. We hypothesized that the visual stimuli would modify the cardiovascular response to vestibular stimulation, especially when the latter is ambiguous with respect to gravity. Off-Vertical-Axis-Rotation (OVAR) was used to stimulate vestibular and extra-vestibular receptors of gravity in 36 healthy young adults while virtual reality was used for visual stimulation. Arterial pressure (AP), respiratory rate and ECG were measured. The analysis accounted for the respiratory modulation of AP and heart rate (HR). Vestibular stimulation by OVAR was shown to modulate both mean arterial pressure (MAP) and HR, while the visual stimulation was significantly affecting HR modulation, but not MAP. Moreover, the specific visual effect was present only when the subjects were not in rotation. Therefore, visual stimulation is able to modulate the heart rate, but is overridden by vestibular stimulation due to real movement.