Stable Representations of Decision Variables for Flexible Behavior
Stable Representations of Decision Variables for Flexible Behavior
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DOI：
10.1016/j.neuron.2019.06.001
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发表时间：
2019-09-04
期刊：
影响因子：
16.2
通讯作者：
Cohen, Jeremiah Y.
中科院分区：
文献类型：
--
作者：
Bari, Bilal A.;Grossman, Cooper D.;Cohen, Jeremiah Y.
决策发生在动态的环境中。在强化学习框架中，执行动作的概率受决策变量的影响。预测和获得的奖励之间的差异(奖励预测误差)更新了这些变量，但在其他方面，它们在决策之间是稳定的。尽管奖励预测错误已经被映射到中脑多巴胺神经元，但尚不清楚大脑如何代表决策变量本身。我们训练小鼠进行动态觅食任务，让它们在不同概率提供奖励的备选方案中进行选择。内侧前额叶皮质的神经元，包括向背内侧纹状体的投射，在很长的时间尺度上保持持续的放电率变化。这些变化稳定地代表了相对动作值(对偏向选择)和总动作值(对偏向反应时间)，并具有缓慢的衰减。相比之下，决策变量在前外侧运动皮质中的表现较弱，这是产生选择所必需的区域。因此，我们定义了一种稳定的神经机制来驱动灵活的行为。
Decisions occur in dynamic environments. In the framework of reinforcement learning, the probability of performing an action is influenced by decision variables. Discrepancies between predicted and obtained rewards (reward prediction errors) update these variables, but they are otherwise stable between decisions. Although reward prediction errors have been mapped to midbrain dopamine neurons, it is unclear how the brain represents decision variables themselves. We trained mice on a dynamic foraging task in which they chose between alternatives that delivered reward with changing probabilities. Neurons in the medial prefrontal cortex, including projections to the dorsomedial striatum, maintained persistent firing rate changes over long timescales. These changes stably represented relative action values (to bias choices) and total action values (to bias response times) with slow decay. In contrast, decision variables were weakly represented in the anterolateral motor cortex, a region necessary for generating choices. Thus, we define a stable neural mechanism to drive flexible behavior.