Figure 1. Schematic experimental setup. CO₂ goes through the flowmeter into a device consisting of micro-valves controlled by a software and synchronized with image acquisition. When the valves open, CO₂ goes through a rubber tube into the magnetic resonance (MR) room, where it mixes with medical air. This gas mixture is delivered to the participant through a nasal cannula, which also has a connection with an MR-compatible vital sign monitor (capnography) to continuously check and record the physiological parameters (end-tidal CO₂, SpO₂, heart rate and respiration rate) during the experiments.