RATS WITH FIMBRIA-FORNIX LESIONS DISPLAY A PLACE RESPONSE IN A SWIMMING POOL - A DISSOCIATION BETWEEN GETTING THERE AND KNOWING WHERE

Some theories of hippocampal formation function postulate that it is i nvolved in using the relationships between distal cues for spatial nav igation. That rats with damage to the hippocampal formation are impair ed in learning place responses of escaping to a platform hidden just b elow the surface of the water of a swimming pool, supports this view. Using rats with fimbria-fornix (FF) lesions, we examined whether their impairment is related to an inability to learn how to reach the platf orm as opposed to learning its location. In a first experiment, the FF rats were impaired in learning to swim to a hidden platform but could swim to a visible platform. In a second experiment, after being pretr ained to swim to a visible platform, the FF rats swam to, paused, and searched the vicinity of the platform's previous location when it was removed. This finding showed that the FF rats expected to find the pla tform at that location. Additional tests confirmed that they had learn ed a place response. Despite having acquired a place response, they st ill could not acquire new place responses when only the hidden platfor m training procedure was used. Thus, these results in dissociating the processes of ''getting there'' and ''knowing where'' suggest that the FF rats' impairment may be in some process of motoric control, such a s path integration, rather than in learning the location of the platfo rm in relation to ambient cues. The results are discussed in relation to relevant theories of hippocampal function.