The goal of this study is to investigate whether prospective memory, i.e., memory for delayed intentions, is impaired at moderate altitude (4,000m).

It will also allow to study the effect of air and oxygen administration during hypoxia exposure.

The main questions it aims to answer are:

• Does moderate acute hypoxia impair prospective memory ?
• If so, does air or oxygen adminsitration induce a restoration of prospective memory? Researchers will compare cognitive performance during normobaric hypoxia exposure to cognitive performance during normoxia (control situation).

Participants will:

• Session S0. Perform a battery of neuropsychological tests and questionnaires). EEG will be recorded during tests. A cheek swab will be performed.
• Sessions S1 and S2. Perform several cognitive tasks while exposed to hypoxia and to normoxia (2 different sessions, randomized order) in a normobaric chamber. These are standardized cognitive tests administered on a computer and cognitive tests embedded in a flight simulator scenario. Various questionnaires will be performed on a regular basis. Several physiological measurements will be performed continuously: EEG, ECG, SpO2 and breathing rate. Blood pressure will be measured at the beginning and at the end of hypoxia/normoxia exposure. A blood sample will also be performed. At last, participants will inhale air or oxygen through a mask while making a cognitive task in the chamber.

Flight crew operate in a dynamic, complex, and uncertain environment that requires them to process a large amount of information from multiple sources under time pressure. To successfully carry out their mission, flight crews must therefore constantly sort, prioritize, and analyze relevant information based on the situation, which requires them to manage their cognitive resources simultaneously-at the risk of experiencing a decline in performance that could significantly compromise aviation safety.

With recent changes in the geostrategic context, the flight profiles of operational missions expose military aircraft crews and onboard operators to a greater risk of in-flight hypoxia. During an acute hypoxic episode, physiological cardiac and respiratory responses are triggered to protect the body-and particularly the brain-from oxygen deprivation. However, these mechanisms are effective only for a limited time. If normoxia is not restored, symptoms will manifest as hypoxemia worsens.

Among flight crew members, impairments in cognitive functions-particularly prospective memory-such as failing to report one's position to other aircraft or failing to retract the flaps before takeoff, are common and can lead to serious accidents. To our knowledge, the effects of hypoxic exposure on this form of memory have not yet been investigated.

Inclusion Criteria:

• Healthy volunteer
• Has provided informed consent

Exclusion Criteria:

• Individuals who do not understand French
• Pregnant or breastfeeding women
• Cardiovascular risk factor
• Infectious disease within the last 4 weeks
• Chronic cardiovascular, respiratory, hematological, neurological, psychiatric, or metabolic disease
• History of epileptic seizures, convulsions, or loss of consciousness
• Individuals with migraines
• History of a bleeding disorder
• History of high blood pressure
• Current medication use (excluding contraception)
• History of episodes of altitude intolerance
• Stay at high altitude (> 3,500 m) within the last 3 months
• Anxiety score on the Hospital Anxiety and Depression (HAD) scale > 7
• Depression score on the HAD scale > 7
• Uncontrollable claustrophobia or a history of panic attacks