Figure 6.

Evolution of freezing, respiration, and ultrasonic vocalizations (USV) during contextual fear conditioning in two groups of animals trained with different shock intensities: 0. 4 versus 0.8 mA. The three parameters were collected at different periods of the acquisition (left part) and retention (right part) sessions: beginning (first foot-shock delivery), middle (after 5 foot-shocks), and end (after 10 foot-shocks). (A) Freezing behavior (mean ± SEM). (B) Respiratory frequency (mean ± SEM). (C) USV response duration (mean ± SEM). *Significant difference between 0.4 and 0.8 mA animals, p < 0.05.