Playback of female rat ultrasonic vocalizations during sexual behavior.

Both male and female rats emit ultrasonic vocalizations during mating. In an earlier study, female vocalizations were shown to be associated with female darting: when the female was devocalized, she increased her rate of darting. In a preliminary playback study, tape-recorded female ultrasounds were presented to devocalized females paired with intact males. Darting was reduced towards presurgical control levels. In this study, the playback experiment was replicated using a refined procedure to present female ultrasounds to the mating rats. Taped vocalizations were obtained from females, and were presented in a manner which more closely approximated the patterning of ultrasound production seen in the intact female. Each rat pair was tested three times: once prior to the devocalization of the female, and twice afterwards. In one postsurgical test, taped ultrasounds were presented during mating; in the other, tape hiss was presented. Several patterns of behavior increased in frequency when the female was devocalized relative to the control condition, but decreased when tape recorded ultrasounds were presented. These patterns included female darting and approaches towards the partner by both males and females. The darting results confirm and extend the findings of our earlier paper. Changes in approach behavior were not observed previously because the male was confined in the earlier study. This study contains the first direct evidence that female vocalizations affect the socio-sexual behavior of the male.