The latest MIT new release reveals new information about how a rat's brain learns during rest or sleep by replaying recent events in reverse. "The animal's hippocampal cells fired in order, corresponding with the animal's position on the track. When the animal stopped, many of the same cells fired again, but the sequence of cell activation was in reverse order and spanned the entire track." Meanwhile, researchers at the CMU Robotics Institute have released a new paper on rat brains with the impressive sounding title, "Firing Fields of Dorsocaudal Medial Entorhinal Cortex as a Context-Independent Spatial Map" (PDF format). The CMU folks are getting close to understanding the neural network used by the rat's brain to store position and navigation information. Using "place cells" in the hippocampus, the rat is able to "find its direction, position, and distance from a self-selected 'home base'". This type of research has a lot of potential uses in robot navigation.