Ant writes "A Nature News article explains that, after running a maze, rats mentally replay their actions backwards." From the article: "As the rats ran along the track, the nerve cells fired in a very specific sequence. This is not surprising, because certain cells in this region are known to be triggered when an animal passes through a particular spot in a space. But the researchers were taken aback by what they saw when the rats were resting. Then, the same brain cells replayed the sequence of electrical firing over and over, but in reverse and speeded up. 'It's absolutely original; no one has ever seen this before at all,' says Edvard Moser, who studies memory at the Norwegian University of Science and Technology in Trondheim."