FIGURE 5.

Quantitative analysis of the ultrasonic vocalizations (USVs) emitted during the social interaction test in adult and old mice (3 and 18 months of age). USVs were recorded during the direct social interaction test. Male experimental subjects were habituated to the testing cage for 30 min prior to testing; an unfamiliar adult stimulus female mouse was then introduced and left there for 3 min. Previous studies have shown that in these experimental settings USVs are emitted only by the male mouse in the male-female interaction (Whitney et al., 1973; Maggio and Whitney, 1985). The number (A,C) and mean duration (B,D) of USVs were automatically measured using the software Sonotrack. Data are expressed as mean ± SEM. N for each group are indicated as (N) in each graph.