[Effects of simulated weightlessness on EEG frequency fluctuation characteristics]

Objective. To develop a method of EEG monitoring under special environment, which is of value for astronauts selection and training. Method. Weightlessness was simulated by means of -6 degrees head down bed rest (HDBR). Rest EEG was recorded in 12 male subjects (aged 18-22) with eyes-closed and then analyzed by means of EEG frequency-fluctuation analysis system. Result. Before HDBR, the dominant order at parietal and occiput was 10, 9, 11 Hz; At frontal and temporal regions 9 Hz competed with 10 Hz for the main dominant component, while the third was 7 Hz. During HDBR, reversible changes of position and interrelation between 7, 8, 9, 10, 11 and 12 Hz appeared, and the frequency components and their regions involved spread gradually. The probability of 7 Hz and 8 Hz dominance increased, while 10 Hz and 11 Hz dominance decreased. At parietal, occiput and post-temporal regions, 9 Hz competed with 10 Hz for the main dominant component, the third was 7 Hz. At frontal and pre-temporal regions, 9 Hz occupied the main dominant position, while the second was 7 Hz (at right-frontal regions, it even occupied the main dominant position), the third was 10 Hz. Conclusion. Simulated weightlessness cause change of EEG dominant-frequency fluctuation competitive structure significantly. Brain adaptation function decrease, and headache can be easily induced. There exists a potential influence on brain function.