MIT Professor Matt Wilson found that after running a maze, rats mentally replay the action - backwards!
... following a spatial experience such as running laps on a track, the awake animal replays the memory so precisely that its recorded brain activity corresponds exactly to the places it has just been. However, to the researchers' surprise, the episode is replayed in time-reverse order, with the most recent locations first, proceeding sequentially back to the beginning of the task.
This backward instant replay may play a significant role in reinforcing learning, Wilson said. "Understanding this replay is likely to be critical in understanding how animals - and humans - learn from experience. This phenomenon may constitute a general mechanism of learning and memory."