Brains of astronauts may undergo changes in shape, compressing and expanding during spaceflight, according to a new study that may pave the way for treating related health conditions. The study, believed to be the first to examine structural changes that take place in astronauts' brains during spaceflight, found that the volume of grey matter increased or decreased, and the extent of the alteration depended on the length of time spent in space.
Scientists at University of Michigan (UM) in the US examined structural MRIs in 12 astronauts who spent two weeks as shuttle crew members and 14 who spent six months on the International Space Station (ISS). All experienced increases and decreases in grey matter in different parts of the brain, with more pronounced changes the longer the astronauts spent in space.
"We found large regions of grey matter volume decreases, which could be related to redistribution of cerebrospinal fluid in space," said Rachael Seidler, professor at UM.
"Gravity is not available to pull fluids down in the body, resulting in so-called puffy face in space. This may result in a shift of brain position or compression," said Seidler.
The researchers also found increases in grey matter volume in regions that control leg movement and process sensory information from legs, which may reflect changes related to the brain learning how to move in microgravity. These changes were greater in space station astronauts because their brains were learning and adapting 24/7. "It's interesting because even if you love something you won't practice more than an hour a day," Seidler said. However, the brain changes researchers observed were equivalent to someone practicing a new skill round-the-clock.
"In space, it's an extreme example of neuroplasticity in the brain because you're in a microgravity environment 24 hours a day," Seidler said. Though they have not pinpointed the exact nature of the changes yet, the findings may lead to new ways of thinking about certain health conditions. For example, people on long-duration bed rest or people who have normal pressure hydrocephalus, a condition in which cerebrospinal spinal fluid accumulates in ventricles in the brain and causes pressure.
The study was published in the journal Nature Microgravity.
