The effects of real vs simulated high altitude on associative memory for emotional stimuli

Introduction: This study aimed to investigate the effects of normobaric hypoxia (NH) and hypobaric hypoxia (HH) on associative memory performance for emotionally valenced stimuli. Methods: Two experiments were conducted. In Study 1, n = 18 undergraduates performed an associative memory task under three NH conditions (FiO(2)= 20.9%, 15.1 %, 13.6%) using a tent with a hypoxic generator. In Study 2, n = 20 participants were assessed in a field study at various altitudes on the Himalayan mountains, including the Pyramid Laboratory (5000 m above sea level), using functional Near-Infrared Spectroscopy (fNIRS) and behavioral assessments. Results: Study 1 revealed no significant differences in recognition accuracy across NH conditions. However, Study 2 showed a complex relationship between altitude and memory for emotionally valenced stimuli. At lower altitudes, participants more accurately recognized emotional stimuli compared to neutral ones, a trend that reversed at higher altitudes. Brain oxygenation varied with altitude, indicating adaptive cognitive processing, as revealed by fNIRS measurements. Conclusions: These findings suggest that hypoxia affects associative memory and emotional processing in an altitude-dependent manner, highlighting adaptive cognitive mechanisms. Understanding the effects of hypobaric hypoxia on cognition and memory can help develop strategies to mitigate its impact in high-altitude and hypoxic environments.