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Intracranial Fluid Redistribution But No White Matter Microstructural Changes During a Spaceflight Analog
Vincent Koppelmans1, Ofer Pasternak2, Jacob J Bloomberg3
1School of Kinesiology, University of Michigan, Ann Arbor, MI, United States.
Scientific Reports
|June 11, 2017
Summary
Head down-tilt bed rest alters brain fluid distribution, particularly in fronto-temporal and posterior-parietal regions, impacting sensorimotor function. These fluid shifts largely recover post-bed rest, unlike white matter microstructure.
Area of Science:
- Neuroscience
- Space Physiology
- Biomedical Engineering
Background:
- Spaceflight causes sensorimotor impairments, but neural correlates are unknown.
- Head down-tilt bed rest (HDBR) simulates microgravity's fluid shifts and unloading.
- Understanding brain changes during HDBR is crucial for astronaut health.
Purpose of the Study:
- Investigate brain white matter (WM) and fluid shifts during HDBR.
- Correlate these changes with sensorimotor and balance impairments.
- Identify potential neuroplasticity mechanisms.
Main Methods:
- 16 subjects underwent 70 days of 6° HDBR with repeated Diffusion MRI and Free-Water Imaging.
- Control group (n=12) assessed over 90 days.
- WM microstructure, intracranial extracellular free water (FW), and functional mobility/balance were measured.
Main Results:
- HDBR caused significant FW increases in fronto-temporal and decreases in posterior-parietal regions.
- These FW changes largely recovered within two weeks post-HDBR.
- WM microstructure remained unaffected; FW decreases correlated with balance impairment.
Conclusions:
- HDBR induces reversible brain fluid shifts, not white matter microstructural changes.
- Brain fluid shifts correlate with sensorimotor and balance deficits.
- Findings suggest adaptive neuroplasticity, warranting further mechanistic studies.
