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. Author manuscript; available in PMC: 2013 May 1.
Published in final edited form as: Hippocampus. 2011 May 26;22(5):1096–1106. doi: 10.1002/hipo.20954

FIGURE 2.

FIGURE 2

Design and behavioral results for pre-training lesion experiment. A: Rats were given pre-training lesions of the dorsal hippocampus (DH) or sham lesions. Following a ~12 day recovery period, rats were fear conditioned (4 tone-shock trials) in context A and extinguished for 2 days (30 tone alone presentations) in context A or B (AAA and ABA groups, respectively). On each extinction day, animals also received context exposure to the alternate context for an equivalent amount of time. One day later, they were tested for tone fear in context A using either 4 discrete tones (Disc) or 1 continuous tone (Cont). B: Mean (± SEM) freezing during the baseline period (BL) and to each tone presentation comprising a tone-shock trial. All animals acquired fear regardless of whether they received sham surgery (squares) or DH lesions (circles). C: Mean (± SEM) freezing during the baseline period (BL) and during the 6, 5-tone bins that comprised the first extinction session. Animals extinguished in A (open shapes) froze more to the context (BL freezing) compared to animals extinguished in a novel context, B (filled shapes). All animals displayed significant tone fear extinction regardless of group. D: Mean (± SEM) freezing during the baseline period (BL) and to tone bins during the second extinction session. All animals displayed significant tone fear extinction and low levels of baseline fear. E: Mean (± SEM) freezing during the initial 30 seconds of tone testing (collapsed across test type) represents our measure of “Early” fear. Significant early renewal was seen in ABA groups (black bars) when freezing was compared to their respective AAA control group (white bars), regardless of lesion condition. F: Mean (± SEM) freezing averaged across either four discrete tone presentations (left panels) or one continuous tone presentation (right panels) represents our “Sustained” fear measure. DH-lesioned, continuous tone-tested rats failed to show renewal compared to all other groups. Statistically significant renewal (AAA vs. ABA comparison) for each respective surgical condition is signified as follows: *P < .05, **P < .01, ***P < .001. Comparisons between AAA and ABA trained animals collapsed across surgical condition are signified as follows: #P < .05, ##P < .01, ###P < .001.