Prolonged exposure to microgravity can cause an astronaut’s brain to shift upward, stretch and compress within the skull, according to new research.
A team led by Rachael Seidler of the University of Florida analysed MRI scans from 26 astronauts taken before and after missions to the International Space Station, and compared them with scans from 24 volunteers who spent 60 days in a head-down tilt to simulate microgravity.
The results, published in Proceedings of the National Academy of Sciences, show that without Earth’s gravity to anchor it, the brain does more than simply rise – it undergoes non-linear deformation, with areas stretching and compressing in different directions.
More human spaceflight
Notably, the supplementary motor cortex – a region of the brain involved in controlling movement – shifted upward by about 2.5mm (0.09 inches) in astronauts who spent up to a year in space.
Such shifts have been linked with temporary balance and coordination problems after astronauts return to Earth, as areas involved in sensorimotor control become displaced.
Earlier research also observed increases in ventricular volume (the cerebrospinal-fluid-filled spaces within the brain) that can persist for months after astronauts land.
While most astronauts’ brains recovered within six months of returning, as human spaceflight moves towards more far-flung missions and longer times spent in microgravity, the researchers emphasise the need to understand and mitigate these changes: "The health and human performance implications require further study to pave the way for safer human space exploration."
As humanity seeks to spend more time in space, and for longer periods at a time, the research could have implications for long-duration missions on space stations around the Moon, or crewed journeys to Mars.
