Contribution of the retrosplenial cortex to route selection in a complex maze

The retrosplenial cortex (RSC) is a region involved in navigation. In this study, we investigated the role of the RSC in navigation in a large-scale environment where the destination is not visible from the current location. We used a large maze where the routes could be freely designed by inserting and removing plates. In Experiment 1, rats learned a specific route in the maze and then were tested with a shortcut route in addition to the learned route. The rats with RSC lesions utilized the shortcut faster than those in the control group. In Experiment 2, rats were initially trained to follow a specific route, and subsequently, we tested the effects of a small change in the environment on their route-following behavior. In the test, the rats with RSC lesions demonstrated more errors than those in the control group. This suggests that lesions in the RSC make navigation to a goal unstable. These findings suggest that the RSC may be involved in the ability to perform appropriate behavior at a segment on a learned route in a large-scale environment, which drives habitually following the learned route.