Hippocampus, delay discounting, and vicarious XXXX .

@entity35 @entity75 @entity2246
UNASSIGNED: In decision-making, an immediate reward is usually preferred to a delayed reward, even if the latter is larger. We tested whether the hippocampus is necessary for this form of temporal discounting, and for vicarious @entity2246 at the decision point. @entity35 were trained on a recently developed, adjustable delay-discounting task (Papale et al. (2012) Cogn Affect Behav Neurosci 12:513-526), which featured a choice between a small, nearly immediate reward, and a larger, delayed reward. @entity35 then received either hippocampus or sham lesions. Animals with @entity75 adjusted the delay for the larger reward to a level similar to that of sham-lesioned animals, suggesting a similar valuation capacity. However, the hippocampus lesion group spent significantly longer investigating the small and large rewards in the first part of the sessions, and were less sensitive to changes in the amount of reward in the large reward maze arm. Both sham- and hippocampus-lesioned @entity35 showed a greater amount of vicarious @entity2246 on trials in which the delay was adjusted. In a nonadjusting version of the delay discounting task, animals with @entity75 showed more variability in their preference for a larger reward that was delayed by 10 s compared with sham-lesioned animals. To verify the lesion behaviorally, @entity35 were subsequently trained on a water maze task, and @entity35 with @entity75 were significantly impaired compared with sham-lesioned animals. The findings on the delay discounting tasks suggest that damage to the hippocampus may impair the detection of reward magnitude.    2014 Wiley Periodicals, Inc.
