Changes in EEG pattern during acclimatization to high altitude (3500 m) in man

Area of Science:

• Neuroscience
• Altitude Physiology

Background:

• High altitude exposure presents physiological challenges to the human body.
• Understanding cerebral cortical adaptation to altitude is crucial for health and performance.

Purpose of the Study:

• To investigate electroencephalogram (EEG) changes during high-altitude acclimatization in healthy soldiers.
• To compare EEG patterns between lowlanders, acclimatized lowlanders, and high-altitude natives.

Main Methods:

• EEG recordings using the 10-20 international system were performed on 30 soldiers (10 lowlanders, 10 acclimatized lowlanders, 10 high-altitude natives).
• Lowlanders were studied at sea level and at 3500m over 4 weeks; acclimatized lowlanders and natives were studied at altitude.
• Quantitative EEG analysis focused on alpha index (AI) and average amplitude, including during hyperventilation (HV).

Main Results:

• Lowlanders showed initial cerebral cortical depression, followed by desynchronization, with EEG alpha index and amplitude changing over 4 weeks at altitude.
• EEG alpha index increased from 25.5% at sea level to a peak of 45.7% on day 2, then fluctuated.
• Average amplitude varied, decreasing initially before gradually increasing; AL and HAN exhibited significantly higher AI and amplitude than LL.

Conclusions:

• High-altitude acclimatization involves an initial phase of cerebral cortical depression followed by desynchronization and a gradual buildup of EEG activity.
• Acclimatized individuals and high-altitude natives demonstrate distinct, more robust EEG patterns indicative of successful adaptation.