Fig. 2. Chronic fluoxetine increases hippocampal involvement during retrieval.

The graphs show percentage of freezing time expressed as mean ± SEM, and experimental design is shown at the top of each panel. a Examples of Nissl-stained sections and summary of microinjection cannula placements in the dorsal hippocampus. The numbers on the right side of the individual sections indicate the distances from bregma. b Although fluoxetine- and vehicle-treated animals were sensitive to intrahippocampal muscimol infusion (test vs. re-test comparison), fluoxetine-treated animals expressed a more robust impairment during retrieval (between-group comparison during test). No differences were detected during the re-test (*Differences between groups, ^#Differences within group. *p < 0.05, ^###p < 0.001, ^#p < 0.05, repeated-measures analysis of variance followed by Student–Newman–Keuls post hoc test—Vehicle n = 11, Fluoxetine n = 8)