"In 2015, Mayank Mehta, a neuroscientist at the University of California, Los Angeles, reported that hippocampal neurons fired differently — and to a lesser extent — when rats explored a 2D VR system, compared with when the rodents walked around a real-world replica room7. (Mehta printed patterns on the curtains of the room to recreate his VR set-up.) In the real world, says Mehta, the synchronized changing of tactile, smell and sound cues, together with the rat’s ability to move its head and body naturally, engages the animal’s navigational system in a different way from in the simulation. But Mehta’s points haven’t significantly dented interest in VR. As he and others have shown, VR and real-world set-ups generate similar neural firing patterns when rodents move in a straight line down a corridor. And in newer 2D VR systems that allow rodents’ bodies to rotate on a spherical treadmill, creating naturalistic balance and movement signals, researchers do see similar neural representations of space in virtual and real worlds.
These experiments are helping researchers to ask at what point virtual reality is so real that the brain can’t tell the difference, Mehta says."