Establishment and maintenance of preference for natural and artificial olfactory stimuli in juvenile rats.

The role of sensory-affective bias and of two types of experience (simple exposure to an odor and exposure to an odor in association with conspecifics) in the establishment and maintenance of preference of rat pups for odorants was investigated. (a) Simple exposure of pups to a mildly aversive odorant (peppermint extract) from birth to 21 days of age was sufficient to establish a preference for that odorant in 21-day-olds as strong as their normal preference for maternal excreta. (b) Simple exposure of pups to peppermint extract for 33 days following birth was not sufficient to maintain preference for peppermint extract to 33 days of age. (c) Exposure of pups to peppermint extract painted on the dam for 33 days following birth was sufficient to maintain pup preference for peppermint extract to 33 days of age. (d) Pups reared artificially with very limited contact with conspecificies, exhibited robust preferences for conspecific odors. Taken together, the data suggest that a variety of mechanisms play complementary roles in the development and maintenance of preference for olfactory stimuli.