This is Your Brain on Spaceflight

When you go to space, it’s going to change your brain. Count on it. That’s because space travelers enter microgravity, and that challenges everything the brain knows about gravity. The experience alters their brain functions and “connectivity” between different regions. It’s all part of the ability of our brains and nervous systems to change in response to changes in the environment, or because of traumatic brain stress or injuries.

We’ve long known about physical changes in astronauts who spend long a long time in space. For example, their circulatory systems adapt, their metabolisms shift, and their bodies have to learn to exist in near-weightless conditions. But, the effect on the brain is still a relatively new area of study although we’ve known of some changes from NASA studies. Some of the changes persist for months after people return to Earth. Understanding what they are and how they affect people is important for future space exploration.

That’s why a recent long-term study of cosmonauts by scientists at the University of Antwerp and the University of Liege, in cooperation with the European Space Agency, is so crucial. If people are going to live and work in orbit or travel between planets, their mental capacity has to be top-notch. Raphaël Liégeois, soon to be the third Belgian in space, acknowledges the importance of the research, “to prepare the new generation of astronauts for longer missions.”

In addition to the implications for long-term space habitation, the current work also holds out hope for research into conditions suffered by people on Earth.

Probing the Brain before and After Flight

So, what happens to a brain when it goes into space? Obviously, it’s not isolated—it depends on information from the rest of the body. Suddenly, it’s in a place where all the cues about gravity are wrong. Some signals, like from the inner ear, tell the brain one thing (I’m falling!) while the eyes show that nothing is moving (whoa!). Day-night signals are all wonky, too. An astronaut might feel tired after working on a project and watch the sunset as a way to relax. But, there are 16 sunsets and sunrises per 24 hours at the International Space Station. The brain begins to wonder, when’s bedtime? When’s it time to get up? With mixed signals like that, the neural connections have to rewire themselves. It’s a stressful environment.

To understand how brains adapt, the Belgian research teams did magnetic resonance imaging (MRI) scans of 16 cosmonauts’ brains. Some were taken before the missions while they were “at rest”. That is, they didn’t do any tasks at all during the scans. Then, after their time in space, the team took several more scans to see what changes existed and how long they persisted. The “resting-state functional MRI” technique enabled the researchers to investigate the brain’s default and “post-flight” states.

What Does the Brain Do in Space?

The results showed that the brain’s functional connectivity was definitely different after the flights. That describes a state where activity in some areas correlates with activities in other parts. According to the two study leaders, Steven Jillings and Floris Wuyts (University of Antwerp), space traveler brains showed marked differences in pre- and post-flight scans. “We found that connectivity was altered after spaceflight in regions which support the integration of different types of information, rather than dealing with only one type each time, such as visual, auditory, or movement information’, they said. “Moreover, we found that some of these altered communication patterns were retained throughout eight months of being back on Earth. At the same time, some brain changes returned to the level of how the areas were functioning before the space mission.”

The regions of the brain and associated functions that are affected by space flight.  Credit: UAntwerpen.
The regions of the brain and associated functions that are affected by space flight. Credit: UAntwerpen.

The good news: in the long run, the brain adapted. The space travelers got used to the changes. In fact, after a short time, it was like they’d been born “in orbit”. In the longer run, however, some changes lasted a long time, and some became permanent. It’s almost like the space travelers came home as different people in fundamental ways.

It’s important to understand both the physical and neurological changes astronauts face as they plan for long visits to space. The next steps are to study what effects these changes have on behavior. Could these changes help astronaut selection? Could people with greater “plasticity” in their neural connections be more suited to long-duration flight? All good questions that merit further research.

Earth-bound Implications

The study of astronaut brain changes also has some interesting implications for people on Earth whose brains don’t adapt to signals coming from their bodies. Obviously, this is a difficult area to study, since researchers can’t just dig into people’s heads to find out why they have problems after a trauma or with a disease. But, the MRI-based study offers a starting point for medical research. Fluyts points out that it’s an ethical way to look at people’s brains before and after a stressful experience.

“Ideally, we would have brain scans of people when they were healthy and after they started suffering from a disorder because then we can see where the changes have taken place,” he said. “But such an ideal situation does not exist, and neither can we give subjects a traumatic experience on purpose, of course.”

So, this controlled study using advanced MRI methods on astronauts is showing researchers where to look in the brain’s complex neural network to target areas for further study and cures. “The scans from the astronauts are like lighthouses, illuminating points where problems can be in patients on Earth,” said Floris.

For More Information

Prolonged microgravity induces reversible and persistent changes on human cerebral connectivity
Space travel influences the way the brain works
Cortical reorganization in an astronaut’s brain after long-duration spaceflight
Astronaut brains as beacons for researchers