Fear conditioning. The first part of fear conditioning (Training) was carried out approximately 1–1/2 to 2 h after the startle and pre-pulse inhibition test. Animals were placed in the fear conditioning chambers (24.13 cm × 22.86 cm, with a grid floor) and allowed to habituate for 2.5 min. Animals were then presented with three pairings of an 85 dB tone and 0.36 mA footshock. The tone was 30 seconds in duration, and the shock was presented during the last 2 seconds of the tone. There was a 2.5 min interval between each of the tone plus shock pairings.
