Dopamine encoding of Pavlovian incentive stimuli diminishes with extended training.
Dopamine encoding of Pavlovian incentive stimuli diminishes with extended training.
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DOI：
10.1523/jneurosci.5119-12.2013
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发表时间：
2013-02-20
期刊：
影响因子：
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通讯作者：
Phillips PE
中科院分区：
文献类型：
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作者：
Clark JJ;Collins AL;Sanford CA;Phillips PE
多巴胺作为强化学习中的教学信号和获得奖励的激励行动密切相关。然而，多巴胺神经元的时间编码特性与其释放的行为后果之间仍然存在理论上的脱节。在这里，我们在大鼠中证明，巴甫洛夫线索诱发的多巴胺在获取过程中增加，但随着长时间训练该信号返回到预处理水平，与稳定的条件食欲行为分离。对行为范式统计参数的实验操作表明，渐近后时期线索诱发的多巴胺释放的减弱可归因于获得的任务时间结构的知识。与此同时，长期训练后，条件行为对多巴胺的依赖程度降低。因此，当前的工作表明，随着通过任务信息的获取来预期奖励预测刺激的呈现，调节这些激励刺激的动机特性的神经生物学基质发生了变化。
Dopamine is highly implicated both as a teaching signal in reinforcement learning and in motivating actions to obtain rewards. However, theoretical disconnects remain between the temporal encoding properties of dopamine neurons and the behavioral consequences of its release. Here, we demonstrate in rats that dopamine evoked by Pavlovian cues increases during acquisition, but dissociates from stable conditioned appetitive behavior as this signal returns to pre-conditioning levels with extended training. Experimental manipulation of the statistical parameters of the behavioral paradigm revealed that this attenuation of cue-evoked dopamine release during the post-asymptotic period was attributable to acquired knowledge of the temporal structure of the task. In parallel, conditioned behavior became less dopamine dependent after extended training. Thus, the current work demonstrates that as the presentation of reward-predictive stimuli becomes anticipated through the acquisition of task information, there is a shift in the neurobiological substrates that mediate the motivational properties of these incentive stimuli.