Figure 5. 50–55 kHz FM USVs in High and Low USV Callers.
During access to self-administered cocaine, 50–55 kHz FM USVs were significantly greater in the High, compared to the Low USV Caller group. Data are daily mean (+SEM) 50–55 kHz USVs shown with a fourth degree polynomial fit. *, ** = significant difference between daily group means at p<0.05 and <0.01, respectively.