Research on rats exposed to heavy particle radiation performed poorly in navigating mazes and were easily distracted. They also had difficulty learning food pellet retrieval. These experiments suggest that radiation encountered on trips to Moon/Mars could harm astronauts brains.
I think that is very important for long-duration spaceflight. Once you know how much radiation is acceptable, you can design the mission and spacecraft to keep within those limits. [Bernard Rabin of the University of Maryland in Baltimore, US.]
