What’s going on in the brains of long-duration space travelers?

Understanding the consequences of spaceflight on human brains is critical as human space exploration expands to new heights. Previous studies have revealed that spaceflight has the ability to change the shape and function of an adult brain.

The first study to look at the structural connectivity changes in the brain following long-duration spaceflight was published in Frontiers in Neural Circuits.

Several white matter tracts, such as the sensorimotor tracts, show considerable microstructural changes, according to the findings. 

A team of international researchers led by Dr. Floris Wuyts of the University of Antwerp has been investigating structural alterations in the brain after spaceflight at the level of deep-brain white matter tracts.

The components of the brain responsible for communication between gray matter and the body, as well as between gray matter areas, are referred to as white matter. In summary, white matter is the brain’s communication route, whereas gray matter is where information is processed.

The researchers employed a brain imaging technique known as fiber tractography to examine the structure and function of the brain following spaceflight.

“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,” explains the author.

Before and after their spaceflights, the team obtained diffusion MRI (dMRI) images of 12 male cosmonauts. Seven months following the mission, they gathered eight follow-up scans. All of the cosmonauts were on missions that lasted an average of 172 days.

The researchers discovered evidence for the concept of ‘the learned brain,’ or the extent of neuroplasticity required by the brain to adapt to spaceflight.

“We found changes in the neural connections between several motor areas of the brain,” adds first author Dr Andrei Doroshin.

“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.”

Follow-up scans confirmed that these alterations were still present seven months following their return to Earth.

“From previous studies, we know that these motor areas show signs of adaptation after spaceflight. Now, we have a first indication that it is also reflected at the level of connections between those regions,” adds Wuyts.

Anatomical brain alterations found following spaceflight are also explained by the authors.

“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 surrounds the brain ventricles, a network of fluid-filled chambers that enlarge as a result of spaceflight.

“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,” explains Wuyts. “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.”

“These results contribute to our overall understanding of what’s going on in the brains of space travelers,” concludes Wuyts.

Source: 10.3389/fncir.2022.815838

Image Credit: Getty

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