Infant rodents emit ultrasonic vocalizations (USVs) when isolated from the mother and littermates. While USVs reportedly promote maternal behavior, their communicatory role is still controversial. We performed a detailed behavioral characterization in 7-day-old CD-1 Swiss mice to describe (a) behavioral patterns accompanying or immediately preceding or following the USV and (b) how selected USV features are modulated according to the behavioral pattern being performed. The present results represent an ethogram of mouse pup behavior in close temporal proximity to USV, providing further information to evaluate the functional role of USVs in the framework of the mother-offspring relationship. A significant increase of head rising behavior immediately prior to the USV and a behavioral activation displayed by pups in conjunction with it suggest that pups behave in a way that may favor interaction with their mothers.
Copyright 2003 Wiley Periodicals, Inc. Dev Psychobiol 44: 37-44, 2004.