Simulated microgravity [bed rest] has little influence on taste, odor or trigeminal sensitivity

Area of Science:

• Spaceflight physiology
• Sensory science
• Human physiology

Background:

• Astronauts report altered food perception in space.
• Fluid shifts toward the head in microgravity may affect taste and smell sensitivity.
• Head-down bed rest (HDBR) simulates spaceflight-induced fluid shifts.

Purpose of the Study:

• To investigate if HDBR alters taste, odor, or trigeminal sensitivities.
• To determine the effect of simulated microgravity on sensory perception thresholds.

Main Methods:

• Six subjects underwent sensory testing before, during, and after HDBR.
• Thresholds for specific odors, tastants (including monosodium glutamate), and capsaicin were measured.
• A modified staircase procedure was used for threshold determination.

Main Results:

• Monosodium glutamate (MSG) taste thresholds were slightly elevated during HDBR.
• No significant changes were observed in odor, other taste, or capsaicin trigeminal sensation thresholds.
• Self-reported nasal congestion levels were also recorded.

Conclusions:

• HDBR, simulating spaceflight fluid shifts, did not broadly alter sensory perception.
• A slight increase in MSG taste threshold during HDBR suggests a potential, specific effect on umami taste.
• Further research is needed to fully understand sensory changes during spaceflight.