Modulation of Behavior by Expected Reward Magnitude Depends on Dopamine in the Dorsomedial Striatum
Modulation of Behavior by Expected Reward Magnitude Depends on Dopamine in the Dorsomedial Striatum
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DOI：
10.1007/s12640-009-9009-1
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发表时间：
2009-02-01
影响因子：
3.7
通讯作者：
Hauber, Wolfgang
中科院分区：
文献类型：
--
作者：
Calaminus, Carsten;Hauber, Wolfgang
奖励预测线索对于指导行为反应很重要。在一系列实验中，我们试图表征背内侧纹状体中的多巴胺在视觉线索调节奖赏定向反应中的作用。将6-羟基多巴胺或赋形剂注入大鼠背内侧纹状体(PDMS)后部的不同组大鼠进行了三次实验。在实验1中，对大鼠进行了要求杠杆释放反应的可操作性任务。在完整的大鼠中，线索大奖赏试验的反应时间可靠地短于线索小奖赏试验。结果表明，如果视觉线索预测大的或小的奖励，则PDMS多巴胺耗竭会削弱依赖于奖励的反应时的调制，但如果视觉线索预测奖励或没有奖励，则不会。这些观察表明，PDMS中的多巴胺信号有助于一个过程，通过这个过程，奖赏定向反应变得由与不同奖赏大小相关的线索引导。实验2显示，PDMS多巴胺缺乏并不影响在操作盒中获得条件性视觉辨别任务，该任务要求学习一种类型的规则：如果提示灯亮，则按左杆奖励，如果暗淡，则按右杆。此外，实验3表明，PDMS多巴胺耗竭不会损害对跨迷宫任务的获得，该任务需要学习视觉线索辨别策略来获得食物奖励。实验2和实验3的共同结果表明，PDMS中的多巴胺信号并不有助于刺激辨别本身和刺激反应学习。
Reward-predictive cues are important to guide behavioral responding. In a series of experiments, we sought to characterize the role of dopamine in the dorsomedial striatum in modulation of reward-directed responding by visual cues. Different groups of rats subjected to infusion of 6-hydroxydopamine or vehicle into the posterior part of the dorsomedial striatum (pDMS) were tested in three experiments. In experiment 1, rats were examined in an operant task demanding a lever release response. In intact rats, reaction times of responding were reliably shorter on cued large reward trials than on cued small reward trials. Results showed that pDMS dopamine depletion impaired reward-dependent modulation of reaction times, if visual cues predict large versus small reward, but not if visual cues predict reward versus no reward. These observations suggest that dopamine signaling in the pDMS contributes to a process through which reward-directed responses become guided by cues associated with distinct reward magnitudes. Experiment 2 revealed that pDMS dopamine depletion did not compromise the acquisition of a conditional visual discrimination task in an operant box that required learning a rule of the type "if the cue light is bright press left lever for reward, if dim press right lever". Furthermore, experiment 3 showed that pDMS dopamine depletion did not impair the acquisition of a cross maze task that required learning a visual cue discrimination strategy to obtain food reward. Together results of experiments 2 and 3 indicate that dopamine signaling in the pDMS does not subserve stimulus discrimination per se and stimulus-response learning.