Unchanged cerebrovascular CO reactivity and hypercapnic ventilatory response during strict head-down tilt bed rest in a mild hypercapnic environment.

Key Points: Carbon dioxide levels are mildly elevated on the International Space Station and it is unknown whether this chronic exposure causes physiological changes to astronauts. We combined ∼4 mmHg ambient with the strict head-down tilt bed rest model of spaceflight and this led to the development of optic disc oedema in one-half of the subjects. We demonstrate no change in arterialized , cerebrovascular reactivity to CO or the hypercapnic ventilatory response.

Static monocular visual cues can decrease the vestibular-evoked balance response at low frequencies.

Background: The balance system continually integrates and processes diverse sensorimotor cues to maintain upright posture. Yet, little is known about how monocular visual cues may modulate the vestibular control of standing balance.

Research Question: To determine how visual cues, specifically monocular vision, modulate the vestibular-evoked myogenic and whole-body balance response.