A longitudinal study on the impact of high-altitude hypoxia on perceptual processes.

This study aimed to explore the neural mechanisms underlying high-altitude (HA) adaptation and deadaptation in perceptual processes in lowlanders. Eighteen healthy lowlanders were administered a facial S1-S2 matching task that included incomplete face (S1) and complete face (S2) photographs combined with ERP technology. Participants were tested at four time points: shortly before they departed the HA (Test 1), twenty-five days after entering the HA (Test 2), and one week (Test 3) and one month (Test 4) after returning to the lowlands. Compared with those at sea level (SL), shorter reaction times (RTs), shorter latencies of P1 and N170, and larger amplitudes of complete face N170 were found in HAs. After returning to SL, compared with that of HA, the amplitude of the incomplete face P1 was smaller after one week, and the complete face was smaller after one month. The right hemisphere N170 amplitude was greater after entering HA and one week after returning to SL than at baseline, but it returned to baseline after one month. Taken together, the current findings suggest that HA adaptation increases visual cortex excitation to accelerate perceptual processing. More mental resources are recruited during the configural encoding stage of complete faces after HA exposure. The perceptual processes affected by HA exposure are reversible after returning to SL, but the low-level processing stage differs between incomplete and complete faces due to neural compensation mechanisms. The configural encoding stage in the right hemisphere is affected by HA exposure and requires more than one week but less than one month to recover to baseline.

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.

Attention Network Changes of High-Altitude Migrants.

INTRODUCTION: The present study aimed to explore whether there are changes in the alerting, orienting, and executive network efficiencies of attention function between high altitude immigrants and low altitude residents.METHODS: Event-related potentials (ERP) were acquired during an attention network test (ANT). The high-altitude (HA) group comprised 22 college student immigrants who were born and raised at low altitudes and had lived at a HA (11,975 ft/3650 m) for 26 mo (tests were conducted when they returned to HA for 3 mo). The low-altitude (LA) group comprised 23 college students who had never visited HA areas before.RESULTS: Compared with the LA group, the HA group had a higher pulse rate, lower oxygen saturation level, and decreased alerting and orienting effects in the behavioral results. The ERP results of the HA group showed a smaller P1 in the occipital area, a larger N1 both in the parietal and occipital areas of the alerting network, and a smaller P1 and larger N1 in the orienting network than the LA group. In the executive control network, the N2 amplitude of the HA group was more negative and the P3 amplitude of the HA group decreased in incongruent conditions.DISCUSSION: Together, these findings suggest that high-altitude migrants are less effective at alerting and orienting than low-altitude residents. For executive control function, changes in the P3 amplitudes of incongruent conditions indicated a decrease in conflict inhibition underlying the executive-control network.An X, Tao G, Zhang X, Ma H, Wang Y. Attention network changes of high-altitude migrants. Aerosp Med Hum Perform. 2022; 93(11):791-799.