Ontogeny of Ultrasonic and Locomotor Responses to Nest Odors in Rodents

Abstract

SYNOPSIS. Rodents discriminate and prefer familiar odors early in life. Almost from birth young rats suckle in response to maternal odor, but suckle less when nipples are cleaned with organic solvents. In two-choice tests, young prefer familiar nest odors, whether naturally occurring or artificially presented, and can even be made to tolerate odors normally aversive or to avoid odors normally pleasant. Variations in maternal diet can alter odor preferences of theyoung. Nest odors can affect vocalization of young rodents. In contrast to the consistent effects of cold temperature and handling in the many rodents studied, nest odors may affect vocalization differently in different species. For example, familiar odors reduce calling in rats, but increase calling in pine voles. Nest odor also alters spontaneous activity in young rats, whichlocomote less when maternal odor is present. In this paper I report that home nest odors enhanced locomotion in rodents of three species (pine voles, Microtus pinetorum ; white-footed mice, Peromyscus leucopus ; and wild house mice, Mus musculus ), but that the age at which this pattern occurred and the relationships of nest odors to vocalizations differed among the species.