NASA is studying how prolonged exposure to conditions associated with space travel, like gravity, can affect the human brain, according to Science Daily.

Using data from astronauts, NASA has scanned the brains of its space explorers before they leave on a mission and after they've returned and found interesting affects from prolonged exposure to space travel.

"We are looking at the volume of different structures in the brain and whether they change in size or shape during spaceflight," said Rachael D. Seidler, chief researcher for the study and director of the Neuromotor Behaviour Laboratory at University of Michigan.

In the published study, NASA also ran tests mid-mission to measure the effects firsthand. They found that in instances where there was no gravity or much less of it than on Earth, the astronauts had a harder time getting control of their bodies and completing tasks laid out before them that required some degree of concentration.

They also reported that the astronauts had trouble with their balance and would sometimes suffer from "perceptual illusions," which are defined as the sensation of feeling as if you are toggling between being right-side-up and upside-down even though you are completely still, according to the Daily Mail.

"On Earth, your vestibular, or balance, system tells you how your head moves relative to gravity, but in space, the gravity reference is gone," said Seidler.