Ultrasonic Vocalizations in Mice

Mice were isolated for 3 days in their home cage prior to USV test day. Each subject mouse’s home cage was placed into the USV chamber. Age-matched female mice (C57BL/6 J) were randomly introduced to each subject male mice’s cage. Subject male mice and intruder female mice freely interacted for 5 min. For the pup USV test, each pup (postnatal day 7) was isolated from the dam. The USV calls were recorded in the USV chamber for 3 min. Avisoft SASLab Pro software was used to analyze USVs. The number of USV calls and the mean duration of each call were analyzed. Signals were filtered from 1 Hz to 100 kHz and digitized with a sampling frequency of 250 kHz, 16 bits per sample (Avisoft UltraSoundGate 116H). To generate spectrograms, the following parameters were used (FFT length: 256, frame size: 100, window: FlatTop, overlap: 75%), resulting in a frequency resolution of 977 Hz and a temporal resolution of 0.256 msec. Frequencies lower than 25 kHz were filtered out to reduce background white noises [82 (link)].