Rats with hippocampal damage are impaired on place learning in the water task when overtrained under constrained...

To date, numerous investigations have been conducted on the mammalian hippocampus to determine its precise function. This research has implicated a fundamental role for the hippocampus in the formation of a spatial map that an animal can use to appropriately guide behavior in complex relational tasks. Despite substantial evidence to support this view, there have been challenges to this theory of hippocampal function. One alternative view suggests that the hippocampus is involved with the integration and updating of voluntary movement. Therefore, any impairments expressed by rats with hippocampal damage are not due to the inability to form or use a spatial map, but rather arise because they are unable to accurately control and monitor on-line movement. Accordingly, investigators, supporting the latter, claim that animals with hippocampal lesions are able to solve a spatial version of the water task if they are given explicit training on how to get to the hidden platform. In the present study we trained rodents with or without hippocampal damage on a cue/place water task for 40 days. In using behaviorally constraining procedures and by overtraining these animals, we provided them with knowledge of how to get to the hidden platform, and ensured enough time to learn the task. Our findings revealed that although rats with hippocampal lesions showed some place responses, they were significantly impaired on all measures of place learning compared to sham animals under these intensive procedures. Overall, the results of the present study do not support the idea that the hippocampus is not specifically involved in acquisition of place information in the water task.