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 rete ntion phase of a delayed-foraging task disrupted performance different ially; rats with PL lesions visited arms in a random manner, whereas r ats with AC lesions revisited previously baited arms preferentially. R ats with AC lesions were also impaired on a single-trial foraging task ; they made numerous revisits to previously baited arms. PL lesions ha d 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 stra tegy after a PL lesion, when they were switched unexpectedly to the si ngle-trial foraging task. These data demonstrate functional heterogene ity within the rat mPFC and suggest that the PL is involved in process es through which recently acquired information is used to organize and modify foraging behavior, whereas the AC may play an important role i n response flexibility.