Macro- and microstructural changes in cosmonauts’ brains after long-duration spaceflight
Steven Jillings, Angelique Van Ombergen, Elena Tomilovskaya, Alena Rumshiskaya, Liudmila Litvinova, Inna Nosikova, Ekaterina Pechenkova, Ilya Rukavishnikov, Inessa B. Kozlovskaya, Olga Manko, S. N. Danilichev, Stefan Sunaert, Paul M. Parizel, В. Е. Синицын, Victor Petrovichev, Steven Laureys, Peter zu Eulenburg, Jan Sijbers, Floris L. Wuyts, Ben Jeurissen
Abstract
Long-duration spaceflight causes widespread physiological changes, although its effect on brain structure remains poorly understood. In this work, we acquired diffusion magnetic resonance imaging to investigate alterations of white matter (WM), gray matter (GM), and cerebrospinal fluid (CSF) compositions in each voxel, before, shortly after, and 7 months after long-duration spaceflight. We found increased WM in the cerebellum after spaceflight, providing the first clear evidence of sensorimotor neuroplasticity. At the region of interest level, this increase persisted 7 months after return to Earth. We also observe a widespread redistribution of CSF, with concomitant changes in the voxel fractions of adjacent GM. We show that these GM changes are the result of morphological changes rather than net tissue loss, which remained unclear from previous studies. Our study provides evidence of spaceflight-induced neuroplasticity to adapt motor strategies in space and evidence of fluid shift-induced mechanical changes in the brain.