How Glitter Relates to Gold: Similarity-Dependent Reward Prediction Errors in the Human Striatum
How Glitter Relates to Gold: Similarity-Dependent Reward Prediction Errors in the Human Striatum
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DOI：
10.1523/jneurosci.2383-12.2012
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发表时间：
2012-11-14
影响因子：
5.3
通讯作者：
Tobler, Philippe N.
中科院分区：
文献类型：
--
作者：
Kahnt, Thorsten;Park, Soyoung Q.;Tobler, Philippe N.
最佳选择得益于先前的学习。然而，目前尚不清楚以前学习的刺激如何影响行为的新的，但类似的刺激。一种可能性是基于学习和当前刺激之间的相似性进行概括。在这里，我们使用神经科学的方法和一种新的计算模型来告知刺激泛化如何在人脑中实现的问题。行为反应在维内歧视任务表现出相似性依赖的泛化。此外，发生了峰移，即，行为泛化梯度的峰值在远离未奖励条件刺激的方向上从奖励条件刺激移位。为了解释行为反应，我们设计了一个基于相似性的强化学习模型，其中预测误差在相似的刺激中泛化并更新它们的值。我们发现，该模型预测了纹状体中的相似性依赖的神经泛化梯度以及在灭绝过程中响应的变化。此外，在所有受试者中，概括的宽度与纹状体和海马体之间的功能连接呈负相关。这一结果表明，海马-纹状体连接有助于通过控制泛化的宽度来更新刺激特异性值。总之，我们的研究结果揭示了一个基本的神经生物学，相似性依赖的学习原则，允许学习从未遇到过的刺激的价值。
Optimal choices benefit from previous learning. However, it is not clear how previously learned stimuli influence behavior to novel but similar stimuli. One possibility is to generalize based on the similarity between learned and current stimuli. Here, we use neuroscientific methods and a novel computational model to inform the question of how stimulus generalization is implemented in the human brain. Behavioral responses during an intradimensional discrimination task showed similarity-dependent generalization. Moreover, a peak shift occurred, i.e., the peak of the behavioral generalization gradient was displaced from the rewarded conditioned stimulus in the direction away from the unrewarded conditioned stimulus. To account for the behavioral responses, we designed a similarity-based reinforcement learning model wherein prediction errors generalize across similar stimuli and update their value. We show that this model predicts a similarity-dependent neural generalization gradient in the striatum as well as changes in responding during extinction. Moreover, across subjects, the width of generalization was negatively correlated with functional connectivity between the striatum and the hippocampus. This result suggests that hippocampus-striatal connections contribute to stimulus-specific value updating by controlling the width of generalization. In summary, our results shed light onto the neurobiology of a fundamental, similarity-dependent learning principle that allows learning the value of stimuli that have never been encountered.