Influence of Exposure at Different Altitudes on the Executive Function of Plateau Soldiers—Evidence From ERPs and Neural Oscillations

Abstract

This study investigates the changes in soldiers' brain executive function at different altitude environments and their relationship with blood oxygen saturation. Stratified sampling was conducted in different altitude 133 active-duty soldiers who were stationed in Weinan (347 m, n = 34), Nyingchi (2,950 m, n = 32), Lhasa (3,860 m, n = 33), and Nagqu (4,890 m, n = 34) for 2 years. The Go/NoGo paradigm with event-related potentials (ERPs) and event-related oscillations (EROs) was used to explore the time and neural oscillation courses of response inhibition. Behavioral results revealed that at the 4,890-m altitude area, the soldiers had the highest false alarm rate, the longest reaction time, and the slowest information transmission rate. The electrophysiological results revealed that NoGo-N2 and N2d decreased with increasing altitude, with significant changes at 3,860 m; the amplitudes of NoGo-P3 and P3d in plateau groups were significantly more negative than the plain and changed significantly at 2,950 m. The results of correlation analysis showed that NoGo-P3 was negatively correlated with altitude (r = −0.358, p = 0.000), positively correlated with SpO2 (r = 0.197, p = 0.041) and information translation rate (ITR) (r = 0.202, p = 0.036). P3d was negatively correlated with altitude (r = −0.276, p = 0.004) and positively correlated with ITR (r = 0.228, p = 0.018). N2d was negatively correlated with ITR (r = 0.204, p = 0.034). The power spectrum analysis of NoGo-N2 and NoGo-P3 showed that the power of δ and θ bands at the plateau area was significantly lower than the plain area and showed a significant step-by-step decrease; the α-band power increases significantly only in the area of 4,890 m. The effect of chronic hypoxia exposure at different altitudes of the plateau on the response inhibition of soldiers was manifested: 3,860 m was the altitude at which the brain response inhibition function decreased during the conflict monitoring stage, and 2,950 m was the altitude at which it dropped during the response inhibition stage. In addition, the soldier's brain's executive function was closely related to SpO2, and a reduction in SpO2 may lead to a decline in response inhibition.

Sleep, short-term memory, and mood states of volunteers with increasing altitude

“…Headache (1) and transient cerebral ischemia (2) were also common neurological symptoms associated with HA. And the reasons why individuals from low to high altitudes can develop sleep-disordered breathing (SDB) involved not only the stimulation of peripheral chemoreceptors of the carotid body which adjust the frequency and depth of breathing by detecting changes in arterial O 2 -7 and CO 2 -pH but also the instability of feedback control system resulting from the high gain in the system and changes in the ventilatory recruitment threshold (3,4). In severe cases, people can develop mountain sickness, high-altitude cerebral edema, Abbreviations: stage 1, plain; stage 2, in the 3rd month at an altitude of 1,650 m; stage 3, in the 3rd month at an altitude of 4,000 m; stage 4, in the 9th month at an altitude of 4,000 m; AHI, apnea-hypopnea index; TST, total sleep time; TSA90, the duration of time with SaO 2 < 90%; LAT, the longest apnea time; MAT, the mean apnea time; MSpO 2 , the mean pulse oxygen saturation; LSpO 2 , the lowest pulse oxygen saturation; SpO 2 , pulse oxygen saturation; NM, negative mood; PM, positive mood; TMD, total mood disturbance; F+B score, forward+backward score; SAS, sleep apnea; OSA, obstructive sleep apnea syndrome; CSA, central sleep apnea.…”

Changes in CYP3A4 Enzyme Expression and Biochemical Markers Under Acute Hypoxia Affect the Pharmacokinetics of Sildenafil

“…This is one of the important reasons for the decreased clearance of sildenafil in rats after acute hypoxia, i.e ., changes in biochemical indicators mainly affect the distribution, clearance, and excretion of sildenafil. Several studies have shown that high-altitude environments have varying degrees of impact on human physiological functions and their circadian rhythms, brain functions, and behavioral functions ( Ma, 1988 ; Rostrup et al, 2005 ; Xie et al, 2020 ; Wei et al, 2021 ). Therefore, it is expected that similar results may be observed in humans in this study.…”

Effects of Long-Term Exposure to 2260 m Altitude on Working Memory and Resting-State Activity in the Prefrontal Cortex: A Large-Sample Cross-Sectional Study

“…This finding is in line with a previous study that showed that acute exposure to 2600 m altitude (simulated normobaric hypoxia) did not impair spatial working memory [ 15 ]. Moreover, another study on long-term exposure to moderate altitude showed that two years of exposure to 2950 m altitude did not affect response inhibition [ 19 ]. Our findings provide further evidence that there is no detectable influence of long-term exposure to moderate altitude on spatial working memory performance, whereas a study on high altitude showed that long-term (three years) exposure to 3650 m altitude decreased spatial working memory performance [ 40 ].…”

“…Our previous behavioral study showed that no significant changes were found in most cognitive functions (including new verbal learning and memory, working memory, long-term explicit memory, implicit procedural learning and short- and long-term visual memory) after six months of exposure to 2260 m altitude, except for visual perception [ 18 ]. In addition, a recent study using the Go/NoGo paradigm with event-related potential (ERP) showed that no changes were found in behavioral performance, while the amplitude of P3 was significantly decreased after two years of exposure to 2950 m [ 19 ]. Adaptation based on compensatory mechanisms may account for the preserved cognitive performance.…”

“…The present study focused on the prefrontal cortex (PFC) with a large sample size. This is because a large number of studies have consistently shown that long-term exposure to high altitude impairs the PFC functions [ 19 , 22 , 23 ]. The PFC plays an important role in executive function, which includes general cognitive control, task switching and working memory updating [ 24 ].…”