Figure 2. Percentage of freezing (mean ± SEM) during the baseline (BL), extinction (EXT), and test (TEST) sessions in rats undergoing immediate (IMMED) or delayed (DELAY) extinction.

Freezing was significantly higher in IMMED rats compared to their DELAY controls prior to extinction (pre-period in EXT session) and during the retention test (p<0.05). Data were averaged across the 10-min pre-CS period or 10 CS trials (first and last 10 trials for early and late EXT periods).