PREFRONTAL CORTICAL MEDIATION OF RATS PLACE LEARNING IN A MODIFIED WATER MAZE

The acquisition of a place learning task in a water maze modified from the ''standard'' set-up by restriction of distal cues and addition of ''proximal'' cues (ping-pong balls in fixed positions on the surface of the water) was tested in three groups of rats: (I) animals subjecte d to bilateral ablation of the anteromedial prefrontal cortex, (II) ra ts in which the parietal ''association'' cortex had been removed bilat erally, and (III) a sham operated control group. The task acquisition of the prefrontally ablated group was significantly impaired, whereas the animals in which the parietal cortex had been removed acquired the task as quickly as the control group. Upon reaching criterion level p erformance all animals were tested on ''challenge'' sessions on which the cues were manipulated. Such ''challenges'' demonstrated that the a nimals of all three groups discriminated between the distal cues and u tilized such a discrimination for navigational purposes.