Startle and fear conditioning system

The fear conditioning test was performed as described with modification [23 (link)]. Mice were placed into a shock chamber and allowed to explore for 2 min. Then, a white noise tone (87 dB) sounded for 30 s (conditional stimulus or “CS”). During the last 1.5 s of the tone, mice received a mild footshock (0.5 mA) (unconditioned stimulus or “US”). 2 min later, the same tone-footshock (CS-US) combination was delivered again. This cycle was presented a total of three times with a 60-s interval. The context test was performed 24 h after the training. During the test, mice were placed back into the same training chamber, and monitored by an overhead camera in the chamber for 5 min. No stimuli were applied. Two-hours after the context test, the cue test was performed, in which colored plexiglass inserts were placed into the training chamber to hide the shock grid and to change the “context” of the chamber. Mice were then placed in the chamber and monitored by the overhead camera for 6 min, during which two CS (spaced the same way as in the training session) were given. In the fear conditioning test, all events were programmed and all data were recorded through the Startle and Fear conditioning system (Panlab) and Packwin software (V2.0.05).

The fear conditioning test was performed as described^{32 (link)}. Mice were habituated to a shock chamber for 2 min and then received a mild footshock (0.5 mA) (unconditioned stimulus or “US”) during the last 1.5 s of a 30-s white noise tone (87 dB) (conditional stimulus or “CS”). Two minutes later, mice received the same tone-footshock pairing (CS–US). The cycle was performed three times. After 24 h, the context test was performed by placing the mice back into the same chamber and monitoring them for 5 min. The cue test was performed 2 h later, in which colored plexiglass inserts were used to change the chamber surrounding. Mice were placed in and monitored for 6 min with two CS (administered in the same way as in the training session) given in the meantime. All events were programmed in the fear conditioning test, and the data were recorded using the Startle and Fear conditioning system (Panlab) and Packwin software (V2.0.05).