Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, USA.
Russell H Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, USA.
Sci Rep. 2023 Jun 8;13(1):7878. doi: 10.1038/s41598-023-33331-8.
Spaceflight induces widespread changes in human brain morphology. It is unclear if these brain changes differ with varying mission duration or spaceflight experience history (i.e., novice or experienced, number of prior missions, time between missions). Here we addressed this issue by quantifying regional voxelwise changes in brain gray matter volume, white matter microstructure, extracellular free water (FW) distribution, and ventricular volume from pre- to post-flight in a sample of 30 astronauts. We found that longer missions were associated with greater expansion of the right lateral and third ventricles, with the majority of expansion occurring during the first 6 months in space then appearing to taper off for longer missions. Longer inter-mission intervals were associated with greater expansion of the ventricles following flight; crew with less than 3 years of time to recover between successive flights showed little to no enlargement of the lateral and third ventricles. These findings demonstrate that ventricle expansion continues with spaceflight with increasing mission duration, and inter-mission intervals less than 3 years may not allow sufficient time for the ventricles to fully recover their compensatory capacity. These findings illustrate some potential plateaus in and boundaries of human brain changes with spaceflight.
太空飞行会引起人类大脑形态的广泛变化。目前尚不清楚这些大脑变化是否因任务持续时间或太空飞行经验史（即新手或有经验者、飞行任务次数、飞行任务之间的时间间隔）而异。在这里，我们通过定量分析 30 名宇航员飞行前后大脑灰质体积、白质微观结构、细胞外游离水（FW）分布和脑室体积的区域体素变化来解决这个问题。我们发现，飞行任务时间越长，右侧侧脑室和第三脑室扩张越大，大多数扩张发生在太空的前 6 个月，然后对于更长的任务似乎逐渐减少。飞行后，两次飞行之间的任务间隔时间越长，脑室扩张越大；在连续飞行之间恢复时间少于 3 年的机组人员，侧脑室和第三脑室几乎没有或没有扩大。这些发现表明，随着任务持续时间的增加，脑室扩张会继续发生，而两次飞行之间的任务间隔时间少于 3 年可能不足以让脑室完全恢复其代偿能力。这些发现说明了与太空飞行相关的人脑变化的一些潜在极限和界限。
