OLFACTORY-BASED SOCIAL-LEARNING VARIES AS A FUNCTION OF PARITY IN FEMALE RATS

New mother rats, under the influence of parturitional hormones, are nu rturant as soon as their pups are born. Maternal experiences acquired under the influence of these hormones are retained for a considerable period beyond parturition. This effect is more robust in the postpartu m animal than in a nulliparous animal that has been induced to become maternal nonhormonally through daily exposure to pups. The present exp eriments were designed to determine whether the parity difference in r obustness of a maternal experience reflects a parity difference in the ease of acquiring any task, or whether the learning must be specific to pups and the maternal context. In the first experiment, primiparous and nulliparous female rats were compared in their performance on a s ocially conditioned food preference task. Each animal was exposed to a conspecific that had previously eaten a new food and was then tested for amount consumed of the preexposed as opposed to nonpreexposed new food. The animals were exposed to their conspecifics for 5, 15, or 30 min and were tested 7 days later. Both parity groups and all three exp osure groups exhibited a significant preference for the preexposed die t, but a higher proportion of the postpartum animals did so. In the se cond experiment, postpartum and nulliparous animals were compared in t heir ability to recognize juvenile animals to whom they had been preex posed. Exposures lasted 30 min and exposure test intervals were 1, 3, or 5 days. Again, although both groups recognized the juveniles, the p ostpartum group showed a stronger recognition effect (reflected in cha nge in investigation scores from exposure to reexposure). Thus, althou gh the effects found were small, both experiments indicate that parity influences the robustness of social learning in a direction favoring the postpartum animal.