It is well documented that a few days stay in space induces a change in the vestibular-ocular reflex reflecting a reinterpretation of sensory inputs following the disappearance of gravity. If the change of eye reflexes actually the result of a reinterpretation of sensory input, the investigators should also expect to see an alteration of the vestibular-cardiovascular reflexes. The modification of these reflexes may modulate the carotid baroreflex and thus participate in the post-flight cardiovascular deconditioning.

The first objective of this project is to study the carotid baroreflex under different supine (dorsal, ventral and lateral) inducing different otolith stimulation in normal-gravity.

Inclusion Criteria:

• Healthy volunteers, male and / or female aged 18-30 years
• subject affiliated to a social security scheme, agreeing to participate in the study and who provided informed consent.

Exclusion Criteria:

• who participated in a clinical trial within less than the period of exclusion from this project
• with a past or present history of heart disease, vascular, neurological, respiratory, rheumatological, metabolic or otologic.
• pregnant women (dosage beta HCG)
• having taken any medication heart, vascular, neurological, respiratory, rheumatological, metabolic or might interfere on vestibular test results during the two years preceding the experiment.
• smoking or smoking more than 5 cigarettes / day, 1 cigarette / day or 1 pipe / day