A Role for Dorsal and Ventral Hippocampus in Inter-Temporal Choice Cost-Benefit Decision Making

model: Group₄ × (Stage 2 × Block₂ × S₃₉)]. The analysis revealed a main effect of testing stage, F(1, 35) = 21.78; p < .001, and block, F(1, 35) = 11.80; p < .005, but no main effect of group, F(3, 35) = 2.30; p = .1. In addition, there was a stage × group interaction, F(3, 35) = 3.01; p < .05. Analysis of simple main effects revealed that there was only an effect of lesion group in the first stage of testing (blocks 3 & 4), F(3, 35) = 2.87; p < .05, but not the second stage, F(3, 35) = 1.54; p = .22. Analysis of simple main effects also revealed an effect of stage within the cHPC lesion group F(1, 35) = 23.1; p < .001, who made significantly more HR choices in stage 2.

In stage 3 of testing (Figure 1d), the original parameters were reinstated (HR = 10s delay; LR = 0s delay). After 3 blocks (30 trials), the majority of rats continued to select the HR arm and therefore had received very little exposure to the new contingencies in the LR arm (i.e., that the delay had been removed from this arm). The rats were therefore given only forced trials for two days (20 forced trials in total, 10 to HR arm, 10 to LR arm) to expose them fully to the change in delay/reward contingencies in the LR arm. Thereafter, a further 6 blocks (60 trials) of choice trials were run. Over the nine blocks of stage 3, all animals reduced their preference for the HR but this reduction was more apparent in all three of the lesion groups compared to the shams. The nine blocks were collapsed into three `triple-blocks' and analyzed with a repeated-measures ANOVA