Functional differences between the prelimbic and anterior cingulate regions of the rat prefrontal cortex.

The effects of reversible lidocaine-induced lesions of 2 subregions of the rat medial prefrontal cortex (mPFC) were examined on a series of cognitively based foraging behaviors on a radial-arm maze. Lesions of the prelimbic (PL) or anterior cingulate (AC) cortex prior to the retention phase of a delayed-foraging task disrupted performance differentially; rats with PL lesions visited arms in a random manner, whereas rats with AC lesions revisited previously baited arms preferentially. Rats with AC lesions were also impaired on a single-trial foraging task; they made numerous revisits to previously baited arms. PL lesions had no effect on performance of this task in well-trained rats. However, rats trained on the 2-phase task did not adapt to a new foraging strategy after a PL lesions, when they were switched unexpectedly to the single-trial foraging task. These data demonstrate functional heterogeneity within the rat mPFC and suggest that the PL is involved in processes through which recently acquired information is used to organize and modify foraging behavior, whereas the AC may play an important role in response flexibility.