Selective damage to the hippocampal region blocks long-term retention of a natural and nonspatial stimulus-stimulus association.

Normal rats rapidly acquire and remember associations between nonspatial stimuli as expressed in the social transmission of food preferences. In the present study, rats with selective neurotoxic lesions including all subdivisions of the hippocampal region (hippocampus proper, dentate gyrus, and subiculum) normally acquired and briefly retained the food odor association as demonstrated by intact memory immediately after social training. However, long-term memory in these animals was severely impaired in contrast to strong 24-h retention by intact rats. More selective lesions to the hippocampus proper plus dentate gyrus alone, or the subiculum alone had no effect on memory at either test interval. These findings indicate that the hippocampal region is required for long-term retention of a nonspatial form of natural memory.