Figure 3

Effects of single-CS exposure prior to extinction training. (A) One day after conditioning, mice received either one CS presentation or no CS/context only 1 hour prior to extinction training. All mice then received equivalent extinction training. One day later, mice received unsignaled US presentations, and we then tested for fear the following day. (B) S1 mice significantly increased freezing across conditioning trials. During CS pre-exposure, freezing was higher during the 1xCS presentation than the no CS condition. Freezing did not change during across extinction trial-blocks regardless of CS pre-exposure. Freezing was also no different between groups during the post-reinstatement test (n = 10). (C) In B6 mice, freezing significantly increased across conditioning trials. During CS pre-exposure, freezing was higher to the CS presentation relative to the no CS condition. Freezing significantly decreased across extinction trial-blocks regardless of CS pre-exposure. Freezing did not differ between groups during the post-reinstatement test (n = 10). Data are means ± SEM. #P < .05 Lst vs. Fst conditioning trial, *P < .05 CS vs. no CS at same point in testing.