How does the brain react to virtual reality? Completely different pattern of activity in brain

http://www.sciencedaily.com/releases/2014/11/141124162926.htm

UCLA neurophysicists have found that space-mapping neurons in the brain react differently to virtual reality than they do to real-world environments. Their findings could be significant for people who use virtual reality for gaming, military, commercial, scientific or other purposes

Virtual Reality Affects Brain’s ‘GPS Cells’

http://www.livescience.com/49021-virtual-reality-brain-maps.html
a new study in rats shows that the virtual world affects the brain differently than real-world environments, which could offer clues for how the technology could be used to restore navigating ability and memory in humans.

Per Google Scholar:
http://scholar.google.com/scholar?q=brain+and+virtual+reality&hl=en&as_sdt=0&as_vis=1&oi=scholart&sa=X&ei=KvCMVKrHPIaayATNjYKADA&ved=0CB0QgQMwAA