Delays conferred by escalating costs modulate dopamine release to rewards but not their predictors.
Delays conferred by escalating costs modulate dopamine release to rewards but not their predictors.
复制标题
DOI：
10.1523/jneurosci.2691-10.2010
复制
发表时间：
2010-09-08
期刊：
影响因子：
--
通讯作者：
Phillips PE
中科院分区：
文献类型：
--
作者：
Wanat MJ;Kuhnen CM;Phillips PE
有效的奖励寻求是生存的必要条件，并且总是需要克服成本，例如体力劳动和延迟，这些成本在自然环境中是不断变化的。多巴胺传递与权衡获得奖励的收益和成本的决策有关，但目前尚不清楚动态变化的努力和延迟成本如何影响多巴胺向奖励和相关刺激的信号。采用快速扫描循环伏安法，研究了大鼠寻求奖励行为中伏隔核（NAcc）核和壳的阶段性多巴胺释放。为了操纵获得奖励所需的努力和时间，我们使用了工具性任务，其中反应要求（按压杠杆的次数）在行为过程中是固定的（固定比率；FR），或者在一次又一次的试验中系统地增加（渐进比率；PR）。提示奖励可得性的多巴胺释放在这些条件下没有区别，表明对不断增加的努力或延迟成本不敏感。相比之下，多巴胺释放在NAcc核心和外壳的奖励传递在PR中增加，但在FR中没有增加。这种奖励诱发的多巴胺信号的增强也在反应要求固定但奖励传递延迟增加的会话中观察到，与PR会话的相应试验相关联。这些发现表明，延迟，而不是努力，是公关会议中奖励诱发的多巴胺释放增加的主要原因。综上所述，这些数据表明，NAcc多巴胺对奖励及其预测因子的释放是可分离的，并且受成本上升所带来的延迟的差异调节。
Efficient reward seeking is essential for survival and invariably requires overcoming costs, such as physical effort and delay, which are constantly changing in natural settings. Dopamine transmission has been implicated in decisions weighing the benefits and costs of obtaining a reward, but it is still unclear how dynamically changing effort and delay costs affect dopamine signaling to rewards and related stimuli. Using fast-scan cyclic voltammetry, we examined phasic dopamine release in the nucleus accumbens (NAcc) core and shell during reward-seeking behavior in rats. To manipulate the effort and time needed to earn a reward, we used instrumental tasks where the response requirements (number of lever presses) were either fixed throughout a behavioral session (fixed ratio; FR) or systematically increased from trial to trial (progressive ratio; PR). Dopamine release evoked by cues denoting reward availability was no different between these conditions, indicating insensitivity to escalating effort or delay costs. In contrast, dopamine release to reward delivery in both the NAcc core and shell increased in PR, but not in FR sessions. This enhancement of reward-evoked dopamine signaling was also observed in sessions where the response requirement was fixed but the delay to reward delivery increased, yoked to corresponding trials in PR sessions. These findings suggest that delay, and not effort, was principally responsible for the increased reward-evoked dopamine release in PR sessions. Together, these data demonstrate that NAcc dopamine release to rewards and their predictors are dissociable and differentially regulated by the delays conferred under escalating costs.