Olfactory stimulation induces filial preferences for huddling in rat pups.

Abstract

Rat [Rattus norvegicus] pups of all ages huddle with conspecifics but the sensory control of contact behavior changes ontogenetically. Thermal cues control huddling until about day 15, at which time species'' odors become the dominant stimulus. The filial response to conspecific is probably dependent on olfactory experience. A synthetic chemical scent was added to the smells of the dam from day 1 to day 20 postpartum. Standardized videographic tests were used to assess the development of huddling preference. Preferences for nest-typical smells emerged by day 15 in pups fom both scented and nonscented litters. Pups from scented nests prefered to huddle with a scented stimulus rat; control pups preferred a nonadulterated rat stimulus. Additional testing showed that the affiliative preferences were specific to rearing odor and were not based on decreased aversion to test scents or on disrupted olfactory discrimination. The ontogeny of species-typical contact behavior is discussed in terms of the induction of a perceptual preference that is based on early odor stimulation.