Social deprivation weakens sender-receiver coupling in mother-infant acoustic communication by altering pup vocal development in Mongolian gerbils (Meriones unguiculatus).

In rodent pups, ultrasonic vocalizations (USVs) are thought to function as contact signals in mother-infant communication, but it remains unclear whether early disruption of the social environment alters their communicative effectiveness. Using the Mongolian gerbils (Meriones unguiculatus), we examined whether early social deprivation (SD), consisting of 24-h individual isolation of a subset of pups from each litter from the dam and from physical interaction with littermates, alters pup USVs and maternal responses to them. Isolation-induced USVs were recorded longitudinally from 54 pups from 9 litters at postnatal days P7, P9, and P10, and acoustic features based on peak-frequency trajectories were quantified. In addition, a two-choice playback experiment was conducted in lactating dams using stimuli derived from P10 control and SD pups. SD affected both the quantity and acoustic structure of pup USVs. In particular, group differences became most evident at P10, when SD pups emitted fewer calls and showed reduced frequency-modulation related acoustic features. In the playback test, maternal approach-related responses were stronger to control-derived stimuli than to SD-derived stimuli. These findings suggest that early social deprivation alters pup vocal development and reduces the effectiveness of pup USVs in eliciting maternal responses, supporting the presence of experience-dependent plasticity in sender-receiver coupling in mammalian acoustic communication.