Previous studies suggest a preferential role for dorsal hippocampus (dHPC) in spatial memory tasks, whereas ventral hippocampus (vHPC) has been implicated in aspects of fear and/or anxiety. In this study, we tested the hypothesis that vHPC may be a critical subregion for performance on a delay-based, cost-benefit decision making task. Rats chose between the two goal arms of a T maze, one containing an immediately available small reward, the other containing a larger reward that was only accessible after a delay. dHPC, vHPC, and complete hippocampal (cHPC) lesions all reduced choice of the delayed high reward (HR) in favor of the immediately available low reward (LR). The deficits were not due to a complete inability to remember which reward size was associated with which arm of the maze. When an equivalent 10-s delay was introduced in both goal arms, all rats chose the HR arm on nearly all trials. The deficit was, however, reinstated when the inequality was reintroduced. Our results suggest an important role for both dHPC and vHPC in the extended neural circuitry that underlies intertemporal choice.

Three studies are reported showing that emotional responses to stress can be modified by systematic prior practice in adopting particular processing modes. Participants were induced to think about positive and negative scenarios in a mode either characteristic of or inconsistent with the abstract-evaluative mind-set observed in depressive rumination, via explicit instructions (Experiments 1 and 2) and via implicit induction of interpretative biases (Experiment 3), before being exposed to a failure experience. In all three studies, participants trained into the mode antithetical to depressive rumination demonstrated less emotional reactivity following failure than participants trained into the mode consistent with depressive rumination. These findings provide evidence consistent with the hypothesis that processing mode modifies emotional reactivity and support the processing-mode theory of rumination.

Enhanced sensitivity to information of negative (compared to positive) valence has an adaptive value, for example, by expediting the correct choice of avoidance behavior. However, previous evidence for such enhanced sensitivity has been inconclusive. Here we report a clear advantage for negative over positive words in categorizing them as emotional. In 3 experiments, participants classified briefly presented (33 ms or 22 ms) masked words as emotional or neutral. Categorization accuracy and valence-detection sensitivity were both higher for negative than for positive words. The results were not due to differences between emotion categories in either lexical frequency, extremeness of valence ratings, or arousal. These results conclusively establish enhanced sensitivity for negative over positive words, supporting the hypothesis that negative stimuli enjoy preferential access to perceptual processing.