sciencehabit writes: If you were a rat living in a completely virtual world like in the movie The Matrix, could you tell? Maybe not, but scientists studying your brain might be able to. Today, researchers report that certain cells in rat brains work differently when the animals are in virtual reality than when they are in the real world. In the experiment, rats anchored to the top of a ball ran in place as movielike images around them changed, creating the impression that they were running along a track. Their sense of place relied on visual cues from the projections and their self-motion cues, but they had to do without proximal cues like sound and smell. The rodents used half as many neurons to navigage the virtual world as they did the real one.