Figure 4. Behavioral changes in response to playback of 50- and 22-kHz ultrasonic vocalizations (USV). Induction of exploratory behavior by playback of 50-kHz USV (white circles; N = 12) and induction of behavioral inhibition by playback of 22-kHz USV (black circles; N = 12), shown as distance traveled in centimeters (cm). USV were played back for 1 min (highlighted in gray). Behavioral activity in the minute before playback of USV was used as baseline. Male Wistar rats at the age of 25 days were used. Data are taken from Wöhr and Schwarting (PLoS One 2007; 2: e1365).