Temporal Effects of Hypoxia Exposure at High Altitudes on Compensatory Brain Function: Evidence from Functional Connectivity of Resting-State EEG Brain Networks.

Ren, Hong, Xi-Yue Yang, Rui Su, HaiLin Ma, and Hao Li. Temporal Effects of Hypoxia Exposure at High Altitudes on Compensatory Brain Function: Evidence from Functional Connectivity of Resting-State EEG Brain Networks. High Alt Med Biol. 00:00-00, 2024. Background: The aim of this study was to investigate the effects of prolonged exposure to hypobaric hypoxia at high altitude on changes in brain function measured by electroencephalography (EEG), focusing specifically on the resting-state brain network functional connectivity and compensatory adaptations in brain function among individuals with varying durations of high altitude residency. Methods: In study I, 64 participants were divided into high-altitude group (HG) and low-altitude group (LG). Ninety-six long-term migrants residing at an altitude of 3,650 m were recruited for studyII and categorized into three groups based on their duration of stay at high altitude: group A (1-2 years), group B (8-10 years), and group C (18-20 years). Resting-state EEG data were collected from each participant, and functional connectivity analysis was conducted using Phase Locking Value. Results: Study I showed that participants with HG had stronger functional connectivity in the occipital lobe than those with LG (p < 0.05). The study II findings indicate that there were significant differences in functional connectivity strength among the frontal and occipital lobes in groups A, B, and C across the α, β, δ, and θ frequency bands. Specifically, the functional connectivity strength of the frontal lobe was significantly higher in group A compared with group B, and in group B compared with group C (p < 0.05). Additionally, the functional connectivity of the occipital lobe was significantly higher in group C compared with group B, and in group B compared with group A (p < 0.05). Conclusions: The consistent results of the whole frequency band suggest that the individual's occipital lobe function is enhanced to compensate for the damage of frontal lobe function, so as to better adapt to the extreme environment at high altitude.