Maybe I'd remember my reading better if I read it backwards...

New Scientist: Play it again, brain, but in reverse:

While the rats ran and then paused after reaching the food, the neurobiologists directly measured the animals’ brain cell activity using carefully placed electrodes. They focused on the hippocampus, a region of the brain believed to handle learning and memory.

The recordings revealed that, as the rats ran along each track, the cells in their hippocampus would fire in a particular sequence. But when the animals stopped for food at end of the new track, the same cells would also fire in the opposite order. This reverse-replay did not occur as often when they rested on either end of the familiar track.

The researchers suggest that the reverse signalling etches information into the brains of the rats as part of the learning process.