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Sci Rep. 2017 Jun 9;7(1):3154. doi: 10.1038/s41598-017-03311-w.

Intracranial Fluid Redistribution But No White Matter Microstructural Changes During a Spaceflight Analog.

Author information

1
School of Kinesiology, University of Michigan, Ann Arbor, MI, United States.
2
Departments of Psychiatry and Radiology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, United States.
3
NASA Johnson Space Center, Houston, TX, United States.
4
KBRwyle, Houston, TX, United States.
5
Azusa Pacific University, Azusa, CA, United States.
6
The University of Texas Health Science Center, Houston, TX, United States.
7
Department of Psychology, University of Michigan, Ann Arbor, MI, United States.
8
School of Kinesiology, University of Michigan, Ann Arbor, MI, United States. rseidler@umich.edu.
9
Department of Psychology, University of Michigan, Ann Arbor, MI, United States. rseidler@umich.edu.
10
Neuroscience Program, University of Michigan, Ann Arbor, MI, United States. rseidler@umich.edu.

Abstract

The neural correlates of spaceflight-induced sensorimotor impairments are unknown. Head down-tilt bed rest (HDBR) serves as a microgravity analog because it mimics the headward fluid shift and axial body unloading of spaceflight. We investigated focal brain white matter (WM) changes and fluid shifts during 70 days of 6° HDBR in 16 subjects who were assessed pre (2x), during (3x), and post-HDBR (2x). Changes over time were compared to those in control subjects (n = 12) assessed four times over 90 days. Diffusion MRI was used to assess WM microstructure and fluid shifts. Free-Water Imaging was used to quantify distribution of intracranial extracellular free water (FW). Additionally, we tested whether WM and FW changes correlated with changes in functional mobility and balance measures. HDBR resulted in FW increases in fronto-temporal regions and decreases in posterior-parietal regions that largely recovered by two weeks post-HDBR. WM microstructure was unaffected by HDBR. FW decreases in the post-central gyrus and precuneus correlated negatively with balance changes. We previously reported that gray matter increases in these regions were associated with less HDBR-induced balance impairment, suggesting adaptive structural neuroplasticity. Future studies are warranted to determine causality and underlying mechanisms.

PMID:
28600534
PMCID:
PMC5466616
DOI:
10.1038/s41598-017-03311-w
[Indexed for MEDLINE]
Free PMC Article

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