The change of attention network functions and physiological adaptation during high-altitude hypoxia and reoxygenation.

Previous studies have not reached a definitive conclusion regarding the effect of high-altitude hypoxia and reoxygenation on attention. To clarify the influence of altitude and exposure time on attention and the relations between physiological activity and attention, we conducted a longitudinal study to track attention network functions in 26 college students. The scores on the attention network test and physiological data, including heart rate, percutaneous arterial oxygen saturation (SpO2), blood pressure, and vital capacity in pulmonary function measurement, were collected at five time-points: two weeks before arriving at high altitude (baseline), within 3 days after arriving at high altitude (HA3), 21 days after arriving at high altitude (HA21), 7 days after returning to sea level (POST7) and 30 days after returning to sea level (POST30). The alerting scores at POST30 were significantly higher than those at baseline, HA3 and HA21; the orienting scores at HA3 were lower than those at POST7 and POST30; the executive control scores at POST7 were significantly lower than those at baseline, HA3, HA21, and POST30; and the executive control scores at HA3 were significantly higher than those at POST30. The change in SpO2 during high-altitude acclimatization (from HA3 to HA21) was positively correlated with the orienting score at HA21. Vital capacity changes during acute deacclimatization positively correlated with orienting scores at POST7. Attention network functions at the behavioral level did not decline after acute hypoxia exposure compared with baseline. Attention network functions after returning to sea level were improved compared with those during acute hypoxia; additionally, alerting and executive function scores were improved compared with those at baseline. Thus, the speed of physiological adaptation could facilitate the recovery of orienting function during acclimatization and deacclimatization.