Ultrasonic vocalisation emitted by infant rodents: a tool for assessment of neurobehavioural development

Ultrasonic vocalisations (USVs) emitted by altricial rodent pups are whistl e-like sounds with frequencies between 30 and 90 kHz. These signals play an important communicative role in mother-offspring interaction since they el icit in the dam a prompt response concerning caregiving behaviours. Both ph ysical and social parameters modulate the USV emission in the infant rodent . Recently, a more detailed analysis of the ultrasonic vocalisation pattern , considering the spectrographic structure of sounds has allowed a deeper i nvestigation of this behaviour, In order to investigate neurobehavioural de velopment. the analysis of USVs presents several advantages, mainly: (i) US Vs are one of the few responses produced by very young mice that can be qua ntitatively analysed and elicited by quantifiable stimuli: (ii) USV product ion follows a clear ontogenetic profile from birth to PND 14-15. thus allow ing longitudinal neurobehavioural analysis during very early postnatal onto geny. The study of this ethologically-ecologically relevant behaviour repre sent a valid model to evaluate possible alterations in the neurobehavioural development of perinatally treated or genetically modified infant rodents. Furthermore., the role played by several receptor agonists and antagonists in modulating USV rate makes this measure particularly important when inve stigating the effects of anxiogenic and anxiolytic compounds, and emotional behaviour in general. (C) 2001 Elsevier Science B.V. All rights reserved.