  Olfaction is the first sensory modality to develop during fetal life in
mammals, and plays a key role in the various behaviors of neonates such as
feeding and social interaction. Odorant cues (i.e., mother or predator scents)
can trigger potentiation or inhibition of ultrasonic vocalizations (USV)
emitted by pups following their isolation. Here, we report how USV are
inhibited by olfactory cues using a sono-olfactometer that has been designed to
quantify precisely olfaction in pups congenitally infected by cytomegalovirus.
This olfactory-driven behavioral test assesses the USV emitted in presence of
unfamiliar odorants such as citral scent or adult male mouse scent. We measure
the number of USV emitted as an index of odorant detection during the three
periods of the 5-min isolation time of the pup into the sono-olfactometer:
first period without any odorant, second period with odorant exposure and last
period with exhaust odorant. This protocol can be easily used to reveal
olfactory deficits in pups with altered olfactory system due to toxic lesions
or infectious diseases.
