Brain power comparison between microgravity and head-down tilt bed rest: an electroencephalography approach

This study examines neurophysiological changes in microgravity by comparing EEG data from two ground analog 60-day head-down tilt bed rest (HDBR) experiments (ESA/DLR "Cocktail" and "RSL") and the NEUROSPAT experiment in space. The primary objective was to determine whether HDBR could effectively model spaceflight's impact on the human brain's EEG signal. In the HDBR dataset, increases in relative delta (2-4 Hz) (p < 0.01) and theta (4-8 Hz) (p < 0.001) power bands were observed during a two-month HDBR experiment, predominantly in the left temporal and parieto-occipital regions. Conversely, the NEUROSPAT dataset showed a significant increase in beta (12-30 Hz) (p < 0.05) power in the left somatosensory cortex during in-flight conditions, suggesting a potential adaptation to disrupted proprioceptive input and motor control in microgravity. The contrasting findings between the two datasets indicate that while HDBR can simulate some aspects of microgravity, it may not serve as a model for all central nervous system changes, especially those related to proprioception and motor functions. This highlights the need for further research, including larger sample sizes, consistent EEG recording conditions, and integration of additional physiological and cognitive markers to fully understand the effects of prolonged microgravity.