[Effects of acute high altitude hypoxia on EEG power in different emotional states]

Objective: To investigate the effects of acute high altitude hypoxia on EEG power in different emotional states. Methods: This study was two-factor within-subject design (2 levels of oxygen environment ×4 levels of emotion type). Twelve male subjects aged between 20 and 25 years old were induced to produce four different types of emotions by emotional picture evoked paradigm: low valence and low arousal(LVLA), high valence and low arousal(HVLA), low valence and high arousal(LVHA), high valence and high arousal(HVHA). Brain Products 32 was used to collect EEG signals under different emotional states. The next day, a constant depressed oxygen chamber was used to simulate a 4 300 m plateau hypoxia environment, and the same group of subjects used the same experimental paradigm to collect EEG signals 10h after hypoxia. The collected EEG signals were analyzed by power spectrum (FFT), and the five frequency bands (Delta, Theta, Alpha, beta, gamma) of the frontal lobe (F3\Fz\F4) were analyzed by variance analysis of two-factor repeated measurements. Results: FFT analysis found that before and after acute hypoxia, the whole brain distribution of alpha wave in four emotional states was mainly concentrated in frontal and parietal leaves; the distribution of alpha wave in the whole brain was the least in relaxed emotional state. The results of the two-factor repeated measurement ANOVA showed that: ①the power of delta\ beta band was significantly affected by the oxygen environment(P＜0.05), and the power was enhanced under hypoxia. ②The power index of theta\ alpha band showed a significant interaction between the oxygen environment and emotional types(P＜0.05). Except for the HVLA emotional state, the power of theta alpha band was significantly enhanced under hypoxia. ③ The two factors had no significant influence on the gamma band(P＞0.05). Conclusion: Under the four kinds of emotional states, the difference of the influence of oxygen environment on brain activity was mainly in the frontal lobe, parietal lobe and part of temporal lobe. Of the four types of emotions, the oxygen environment had the least significant effect on brain activity in HVLA emotional states, while the rest showed significant differences.