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

We evaluated the role of the medial prefrontal cortex (mPFC) in the elabora tion of egocentric navigation strategies in a water maze (WM). Lesions of m PFC cell bodies was achieved in 21 rats using bilateral injections of ibote nic acid (IA): 13 control rats were injected with saline. After 17 days, ra ts had to learn an allocentric (using external cues: 10 lesioned, 7 saline rats) or an egocentric WM (using internal/kinetic cues: 10 lesioned, 6 sali ne rats) over six trials in a same session. Thr initial trajectory on the. sixth trial was used as an index of the elaboration of a navigation strateg y. In the egocentric test, lesioned rats were more rarely located in thr ta rget quadrant than control rats. No differences vr ere found between lesion ed and control rats: in the allocentric test. These results show that lesio ns of the mPFC impairs the capacity to elaborate an egocentric navigation s trategy. (C) 2001 Academic Press.