The mean proportion of USV types produced by males and females across exposure conditions.

<p>The left column is females and the right column is males. The top row is the isolated condition, the middle row is the same sex exposure condition, and the bottom row is the opposite sex exposure condition. The different colors/shadings represent the mean proportion of each of the nine different categories of ultrasonic vocalizations.</p

Number of vocalizations across exposure conditions.

<p><b>(a)</b> Box plot showing the range of vocalizations produced across exposure conditions, the median (line in the box), and 95% confidence intervals. The black dots represent data points that lie outside the 10^th and 90^th percentiles. The isolate condition is shown in black, the same-sex condition is shown in gray, and the opposite sex condition is shown in white. The * represent significantly different conditions. <b>(b)</b> Box plot showing the range of vocalizations produced across exposure conditions, the median (line in the box), and 95% confidence intervals. The black dots represent data points that lie outside the 10^th and 90^th percentiles. The left half of the figure is females and the right half of the figure is males. The isolated condition is shown in black, the same-sex exposure condition is shown in gray, and the opposite-sex exposure condition is shown in white.</p

Exposure apparatus.

<p>The exposure apparatus was a standard mouse cage lined with wood shavings, divided in half with a metal mesh divider fixed to the cage. Mice were placed in this cage for one hour prior to recordings.</p

Number of vocalizations across the sexes.

<p>Box plot showing the range of vocalizations produced by males and females, the median (line in the box), and 95% confidence intervals. The black dots represent data points that lie outside the 10^th and 90^th percentiles. Males are gray, females are black.</p

Recording chamber.

<p>The recording chamber was a standard mouse cage lined with a paper towel to reduce noise. The recording cage was placed into a homemade double walled sound attenuated booth lined with anechoic foam. An ultrasonic condenser microphone was placed above the recording cage pointing downwards. Mice were recorded in this chamber in acoustic isolation for five minutes.</p

CBA/CaJ mouse ultrasonic vocalizations depend on prior social experience

<div><p>Mouse ultrasonic vocalizations (USVs) have variable spectrotemporal features, which researchers use to parse them into different categories. USVs may be important for communication, but it is unclear whether the categories that researchers have developed are relevant to the mice. Instead, other properties such as the number, rate, peak frequency, or bandwidth of the vocalizations may be important cues that the mice are using to interpret the nature of the social interaction. To investigate this, a comprehensive catalog of the USVs that mice are producing across different social contexts must be created. Forty male and female adult CBA/CaJ mice were recorded in isolation for five minutes following either a one-hour period of isolation or an exposure to a same- or opposite-sex mouse. Vocalizations were separated into nine categories based on the frequency composition of each USV. Additionally, USVs were quantified based on the bandwidth, duration, peak frequency, total number, and proportion of vocalizations produced. Results indicate that mice differentially produce their vocalizations across social encounters. There were significant differences in the number of USVs that mice produce across exposure conditions, the proportional probability of producing the different categories of USVs across sex and conditions, and the features of the USVs across conditions. In sum, there are sex-specific differences in production of USVs by laboratory mice, and prior social experiences matter for vocalization production. Furthermore, this study provides critical evidence that female mice probably produce vocalizations in opposite-sex interactions, which is important because this is an often overlooked variable in mouse communication research.</p></div