To take or not to take the shortcut: Flexible spatial behaviour of rats based on cognitive map in a lattice maze.

To examine the flexibility of rats' spatial behaviour, we required rats to navigate to one of four boxes on the corners of a lattice maze. The maze consisted of five vertical and five horizontal corridors on a plane parallel to the ground and allowed us to design diverse routes. One box was set as goal and the other three were set as starting points. Both the time to arrive at the goal and the number of errors at the intersections on the route decreased, suggesting that the rats learned the route. As the goal boxes were successively changed, the decrease in the errors and the time to reach the goal became faster. This suggests that the rats learned the spatial layout of the maze, i.e., developed a cognitive map. We then carried out a shortcut test by removing one wall located near the centre of the maze. The rats took the shortcut route when passing through the location around the removed wall made the entire route shorter, but did not pass through the location when passing through the location made the entire route longer. These suggest that rats can flexibly utilize their internal representation of a spatial structure to respond to a change in a learned environment.