How does virtual reality affect the brain?

virtual-reality Nature Neuroscience, advance online publication: 24 November 2014.
UCLA Newsroom, 24 November 2014.

“Put rats in an IMAX-like surround virtual world limited to vision only, and the neurons in their hippocampi seem to fire completely randomly — and more than half of those neurons shut down — as if the neurons had no idea where the rat was, UCLA neurophysicists found in a recent experiment. Put another group of rats in a real room (with sounds and odors) designed to look like the virtual room, and they were just fine.” Kurzweil Accelerating Intelligence, November 25, 2014.

This raises many interesting questions: What happens when humans hear or read spatial descriptions or look at maps? Are their hippocampi building maps? Partial maps? No maps at all? How does this relate to the results reported in Benjamin Bergen’s book? How does the brain distinguish reality and fiction?