It’s not hard to be captivated by the wonders of space travel – being able to see your home planet among the stars, realizing how small you are compared to the vastness of the universe, marveling at the uncanny effects of weightlessness as you float through space. There is, however, a darker side to it. Despite the phenomenon of space travel being about six decades old, we have yet to come up with a sustainable, much less commercially viable means of space travel. Deep interplanetary or even interstellar exploration would take years – and would-be travelers would face the prospect of spending that time in confinement, outliving all their loved ones as they made their journey.
With the very real prospect that one day in the near future, humans will be able to travel to Mars, there is a growing body of literature that explores how well the human body can accommodate space travel in various ways – with only a handful of studies looking at how it affects the brain, both physiologically and psychologically. A recent study published by the journal Frontiers in Neural Circuits marks the first attempt to analyze the brain’s changes in structural connectivity that occur following a long flight through space. The experiment’s results demonstrate how considerable microstructural changes occur among several tracts of white matter – namely the sensorimotor tracts, which act as the brain’s switchboard. This new study could offer a basis for how neurobiologists in the future will model the myriad of brain changes that occur in humans as they explore the far reaches of space.
Our brains are able to constantly alter in structure and adapt to unique environments all throughout our lives, being more malleable than was once thought possible. Research in the past has shown that the last great frontier, space travel, has the ability to alter not only the shape but also the function of the adult brain. Subsequent research, which has relatively small sample sizes to work with, has sought to better understand those patterns taking place.
A collaborative effort between the European Space Agency (ESA) and the international research team Roscosmos, set out to carry out this latest effort, led by Dr Floris Wuyts of the University of Antwerp in Belgium, where he leads the lab of equilibrium investigations and aerospace. Wuyts, a physicist who studied blood vessel elasticity, along with his team of researchers has managed, for the first time, to see the brain’s structural changes following spaceflight within the white matter tracts of the deep-brain.
White matter refers to those regions of the brain sheathed in myelin fibers that relay messages between the brain’s gray matter – those regions of the brain responsible for information processing – and the rest of the body.
The educated brain
In order to monitor the shaping of brain structure and function following spaceflight, the research team made use of a brain imaging technique known as fiber tractography.
“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 Wuyts.
Wuyts and his fellow researchers gathered diffusion MRI (dMRI) scans from 12 male cosmonauts that were taken right before and immediately after their time in outer space – prolonged missions aboard the International Space Station. The team also carried out eight subsequent follow-up scans on the cosmonauts, seven months after their spaceflight. Each of the cosmonauts involved in the study participated in missions of long-duration – spending an average length of 172 days away from planet Earth.
The researchers made a surprising discovery: proof of ‘the learned brain’ concept in their test subjects. In order to adjust to spaceflight, the brain’s levels of neuroplasticity need to realign, much in the way that astronauts need to exercise more rigorously in space to keep their muscles intact than they do at home. “We found changes in the neural connections between several motor areas of the brain,” said the paper’s first author, 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.”
From the follow-up scans, Wuyts’ team discovered that even seven months after the cosmonauts returned to Earth, the neuroplastic changes could still be seen in their brains.
“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,” Wuyts added.
The authors have also found an explanation for why these anatomical brain shifts occur following a sojourn in space.
“We initially thought to have detected changes in the corpus callosum, which is the central highway connecting both hemispheres of the brain,” Wuyts explains. The corpus callosum is a structure situated next to the brain ventricles, which are themselves a communication network with fluid filled chambers. Gravitational pull from spaceflight puts pressure on these chambers and affects their ebb and flow.
“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,” says 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.”
Looking to the future
The new study emphasizes a need to understand just how the many facets of spaceflight can affect the body, particularly by way of long-term research on the effects it may have on the human brain. At present, we have countermeasures that astronauts can take to reverse muscle and bone loss from long dormant periods – things that can be averted by exercising for at least two hours per day. Future research may provide evidence that countermeasures are necessary for the brain.
“These findings give us additional pieces of the entire puzzle. Since this research is so pioneering, we don’t know how the whole puzzle will look yet. These results contribute to our overall understanding of what’s going on in the brains of space travelers. It is crucial to maintain this line of research, looking for spaceflight induced brain changes from different perspectives and using different techniques,” Wuyts explains.
An inevitable result of spaceflight happening more frequently in the future – with travelers spending longer durations among the cosmos. While these individuals give up much of their own lives back on planet Earth, they’re paving the way to help us not only chart great discoveries, but to learn new things about ourselves. The neuroplasticity that occurs in space could perhaps lead us one day to relief from post-traumatic stress disorder and the state of fear its sufferers are constantly under.
The most significant episodes of space travel in the last five decades, such as the moon landing, have already brought about significant strides in medical technology. Researchers like Wuyts who have studied the mechanics of the brain – the relationship of how it functions at a molecular level to its impact on our mental health, are sure to break new ground that will inevitably benefit all of humanity.
