Timeline of behavioral procedures. (A) In Experiment 1, two groups of rats received CS-US pairings in Context A. One group had a 27 day retention interval (Remote group) and one group had a 1 day retention interval (Recent group) prior to extinction training. Extinction (CS alone) for all groups occurred in Context B. On each extinction day, rats were given equivalent exposure to the renewal context (no CS/US). At the completion of extinction, groups underwent renewal testing in Contexts A and B. Following renewal testing, a new cue was paired with shock in Context C, prior to summation testing in B and A. (B) Experiment 2 was similar to Experiment 1, with the following exceptions. There were 3 days of pre-exposure, 6 days of extinction training, renewal and summation testing occurred in B and C, and click conditioning occurred in Context A.
