Department of Psychology, McGill University, Montreal, QC, Canada.
Eur J Neurosci. 2013 Feb;37(4):640-7. doi: 10.1111/ejn.12071. Epub 2012 Nov 28.
In this study, we examined how risk and delay influence rats' decision-making, and the role of the ventral hippocampus (VHC) and orbitofrontal cortex (OFC) in the valuation of these two factors. We used a touchscreen testing method in which rats with VHC lesions, OFC lesions and sham control surgery made choices in two decision-making tasks. In the delay discounting task, rats chose between two visual stimuli, one of which indicated a small, immediate reward, and the other of which indicated a large, delayed reward. In the probability discounting task, two stimuli indicated, instead, a small, certain reward or a large, uncertain reward. The two lesion groups showed a double dissociation with respect to the two tasks. Rats with VHC lesions were intolerant of delay, and were strongly biased towards the small, immediate reward. However, the same rats were indistinguishable from sham controls in the probability discounting task. The opposite pattern was observed for rats with OFC lesions; they performed normally in the delay discounting task, but showed a reduced tolerance for uncertainty as compared with sham-operated controls. These data support the conclusion that the VHC and OFC contribute differentially to decision-making that involves delayed or uncertain outcomes. This provides a means for understanding the neural basis of a range of neurological and psychiatric patients who show impaired decision-making and executive dysfunction.
在这项研究中，我们研究了风险和延迟如何影响大鼠的决策，以及腹侧海马体（VHC）和眶额皮质（OFC）在评估这两个因素中的作用。我们使用了一种触摸屏测试方法，其中 VHC 损伤、OFC 损伤和假手术大鼠在两个决策任务中进行选择。在延迟折扣任务中，大鼠在两个视觉刺激之间进行选择，其中一个表示小的、即时奖励，另一个表示大的、延迟奖励。在概率折扣任务中，两个刺激表示小的、确定的奖励或大的、不确定的奖励。两个损伤组在两个任务上表现出双重分离。VHC 损伤的大鼠对延迟不宽容，强烈偏向于小的、即时奖励。然而，同样的大鼠在概率折扣任务中与假手术对照组没有区别。OFC 损伤的大鼠则表现出相反的模式；它们在延迟折扣任务中表现正常，但与假手术对照组相比，对不确定性的容忍度降低。这些数据支持了这样的结论，即 VHC 和 OFC 对涉及延迟或不确定结果的决策有不同的贡献。这为理解一系列表现出决策和执行功能障碍的神经和精神疾病患者的神经基础提供了一种手段。
