Spatial strategy elaboration in egocentric and allocentric tasks following medial prefrontal cortex lesions in the rat

We evaluated the role of the medial prefrontal cortex (mPFC) in the elaboration of egocentric navigation strategies in a water maze (WM). Lesions of mPFC cell bodies was achieved in 21 rats using bilateral injections of ibotenic acid (IA); 13 control rats were injected with saline. After 17 days, rats had to learn an allocentric (using external cues: 10 lesioned, 7 saline rats) or an egocentric WM (using internal/kinetic cues: 10 lesioned, 6 saline rats) over six trials in a same session. The initial trajectory on the sixth trial was used as an index of the elaboration of a navigation strategy. In the egocentric test, lesioned rats were more rarely located in the target quadrant than control rats. No differences were found between lesioned and control rats in the allocentric test. These results show that lesions of the mPFC impairs the capacity to elaborate an egocentric navigation strategy.