[Identification of Differences in Brain Functions at Varied Degrees of Acclimatization to High Altitudes Based on...

To explore the differences in brain functions between individuals with good acclimatization to high altitudes and those with poor acclimatization based on microstate and functional connectivity analysis of resting-state electroencephalogram (EEG) activities.

A total of 44 residents exposed to the high-altitude environment of 3650 m above sea level were enrolled. They were divided into two groups according to their findings for the high-altitude acclimatization index (AAI), with 22 in the good acclimatization group and 22 in the poor acclimatization group. The good acclimatization group had 10 males and 12 females of the mean age of (20.48±2.09) years. Among them, 10 were Tibetans, and 12 were Han Chinese. The poor acclimatization group consisted of 18 males and 4 females, with a mean age of (18.90±1.25) years. Among them, 7 were Tibetans, and 15 were Han Chinese. The K-means clustering algorithm was used to classify EEG microstates into four categories of A, B, C, and D. The average duration, coverage, occurrence frequency, and transition probabilities between microstates were compared. Coherence analysis (COH) was performed to assess the strength of brain network connectivity.

Compared to the good acclimatization group, the poor acclimatization group exhibited a longer duration, higher occurrence frequency, and coverage of microstate C. The coverage of microstate D was also higher, while the occurrence frequency and coverage of microstate B were lower. The poor acclimatization group showed a decrease in transitions from microstate B to A or D, while transitions from C to B or D, and those from D to A or C increased, showing statistically significant differences between the groups (P<0.05). In the α, β, δ, and θ frequency bands, the poor acclimatization group had higher COH strength in regions such as the frontal and occipital lobes, showing symmetrical functional connectivity between the left and right hemispheres.

The good and poor high-altitude acclimatization groups exhibit different neural mechanisms in terms of microstates and functional connectivity. There are significant differences between individuals with good acclimatization and those with poor acclimatization regarding visual information processing, interference resistance, brain network stability, and coherence.