Brain Gets Rewired During Extended Space Travel

An international team of researchers has analyzed the structural connectivity changes that occur in the brain after long spaceflights, and the results may form a basis for future research into the full scope of brain changes during human space exploration.

Using a brain imaging technique called fiber tractography, the researchers found significant microstructural changes in several white matter tracts, which are the regions of the brain responsible for communication between gray matter and the body and between various gray matter regions. Gray matter is where information processing is done.

“Fiber tractography gives a sort of wiring scheme of the brain. Our study is the first to use this specific method to detect changes in brain structure after spaceflight,” says study lead Dr. Floris Wuyts of the University of Antwerp. Wuyts led the research, which was part of a collaborative project between the European Space Agency (ESA) and Roscosmos, a state corporation of the Russian Federation responsible for space flights, cosmonautics programs, and aerospace research.

Wuyts and his team also acquired the diffusion MRI (dMRI) scans of 12 male cosmonauts before and right after their spaceflights. The cosmonauts all engaged in long-duration missions of an average length of 172 days. The researchers also collected eight follow-up scans seven months after.

Previous research has shown that spaceflight has the potential to alter both the shape and function of an adult brain. The current study found proof of this neuroplasticity concept. “We found changes in the neural connections between several motor areas of the brain,” says coauthor Andrei Doroshin, of Drexel University. “Motor areas are brain centers where commands for movements are initiated. In weightlessness, an astronaut needs to adapt his or her movement strategies drastically, compared to Earth. Our study shows that their brain is rewired, so to speak.”

The authors also found an explanation for anatomical brain shifts observed after spaceflight. “We initially thought to have detected changes in the corpus callosum, which is the central highway connecting both hemispheres of the brain,” says Wuyts. The corpus callosum borders the brain ventricles, a communicating network of chambers filled with fluid that expands because of the physical effects of space. “The structural changes we initially found in the corpus callosum are actually caused by the dilation of the ventricles that induce anatomical shifts of the adjacent neural tissue,” he says.  “Where initially it was thought that there are real structural changes in the brain, we only observe shape changes. This puts the findings in a different perspective.” The follow-up scans revealed that the changes are still visible several months after the cosmonauts returned to earth.

The study illustrates a need to understand how spaceflight affects the human brain. Current countermeasures exist for muscle and bone loss, such as exercising for a minimum of two hours a day. Future research may provide evidence that countermeasures are necessary for the brain.

“These findings give us additional pieces of the entire puzzle… It is crucial to maintain this line of research, looking for spaceflight induced brain changes from different perspectives and using different techniques,” says Wuyts.

The work  was published in Frontiers in Neural Circuits.