Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, United Kingdom.
Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, United Kingdom
Proc Natl Acad Sci U S A. 2021 Jul 27;118(30). doi: 10.1073/pnas.2022650118.
Sensitivity to satiety constitutes a basic requirement for neuronal coding of subjective reward value. Satiety from natural ongoing consumption affects reward functions in learning and approach behavior. More specifically, satiety reduces the subjective economic value of individual rewards during choice between options that typically contain multiple reward components. The unconfounded assessment of economic reward value requires tests at choice indifference between two options, which is difficult to achieve with sated rewards. By conceptualizing choices between options with multiple reward components ("bundles"), Revealed Preference Theory may offer a solution. Despite satiety, choices against an unaltered reference bundle may remain indifferent when the reduced value of a sated bundle reward is compensated by larger amounts of an unsated reward of the same bundle, and then the value loss of the sated reward is indicated by the amount of the added unsated reward. Here, we show psychophysically titrated choice indifference in monkeys between bundles of differently sated rewards. Neuronal chosen value signals in the orbitofrontal cortex (OFC) followed closely the subjective value change within recording periods of individual neurons. A neuronal classifier distinguishing the bundles and predicting choice substantiated the subjective value change. The choice between conventional single rewards confirmed the neuronal changes seen with two-reward bundles. Thus, reward-specific satiety reduces subjective reward value signals in OFC. With satiety being an important factor of subjective reward value, these results extend the notion of subjective economic reward value coding in OFC neurons.
饱腹感的敏感性构成了神经元对主观奖励价值进行编码的基本要求。自然持续消费产生的饱腹感会影响学习和接近行为中的奖励功能。更具体地说，饱腹感会降低在选择具有多个奖励成分的选项之间的个体奖励的主观经济价值。在两种选择之间进行无混淆的经济奖励价值评估需要在选择无差异的条件下进行测试，而这对于饱腹感的奖励来说是很难实现的。通过将具有多个奖励成分的选项进行概念化（“捆绑”），揭示偏好理论可能提供一种解决方案。尽管有饱腹感，但当一个饱腹感的捆绑奖励的价值降低被相同捆绑的更大数量的未饱腹感奖励所补偿时，针对未改变的参考捆绑的选择可能仍然保持无差异，然后，饱腹感奖励的价值损失由添加的未饱腹感奖励的数量来表示。在这里，我们在猴子身上展示了通过心理物理滴定法在不同饱腹感的捆绑奖励之间进行的选择无差异。眶额皮质（OFC）中的神经元选择价值信号密切跟随单个神经元的记录期间内的主观价值变化。一个能够区分捆绑和预测选择的神经元分类器证实了主观价值的变化。对传统的单一奖励的选择证实了与两奖励捆绑相关的神经元变化。因此，奖励特异性饱腹感会降低 OFC 中的主观奖励价值信号。由于饱腹感是主观奖励价值的一个重要因素，这些结果扩展了 OFC 神经元中主观经济奖励价值编码的概念。
