EFFECTS OF FIMBRIA-FORNIX LESIONS ON RATS USE OF INTRAMAZE STIMULI INTHE WATER MAZE

In order to examine the role of the hippocampus in spatial learning, f imbria-fornix-lesioned (FF) rats and control rats were trained in a wa ter maze enclosed in black curtains. In the condition with stimuli, tw o objects of different appearance were hung on the water surface as in tramaze stimuli. The hidden goal and two objects formed a triangle, an d their spatial relationship was kept constant throughout the training . For the condition without stimuli, the two stimuli were removed. In the condition with stimuli, the control group solved the task faster t han the FF group. Analysis of navigational strategy indicated that the control group used both the place strategy and the response strategy, whereas the FF group used only the response strategy. In the conditio n without stimuli, the performance of both groups was similar, with bo th groups solving the task using only the response strategy. These res ults suggest that the hippocampus plays an important role in utilizati on of the spatial relationships among intramaze stimuli.