Perception and Cognition Lab, European Neuroscience Institute Goettingen - A Joint Initiative of the University Medical Center Goettingen and the Max-Planck-Society, Goettingen, Germany.
School of Artificial Intelligence & Data Science, Indian Institute of Technology Jodhpur, Jodhpur, India.
Commun Biol. 2024 Nov 21;7(1):1550. doi: 10.1038/s42003-024-07253-8.
Neuroeconomics theories propose that the value associated with diverse rewards or reward-predicting stimuli is encoded along a common reference scale, irrespective of their sensory properties. However, in a dynamic environment with changing stimulus-reward pairings, the brain must also represent the sensory features of rewarding stimuli. The mechanism by which the brain balances these needs-deriving a common reference scale for valuation while maintaining sensitivity to sensory contexts-remains unclear. To investigate this, we conducted an fMRI study with human participants engaged in a dynamic foraging task, which required integrating the reward history of auditory or visual choice options and updating the subjective value for each sensory modality. Univariate fMRI analysis revealed modality-specific value representations in the orbitofrontal cortex (OFC) and modality-general value representations in the ventromedial prefrontal cortex (vmPFC), confirmed by an exploratory multivariate pattern classification approach. Crucially, modality-specific value representations were absent when the task involved instruction-based rather than value-based choices. Effective connectivity analysis showed that modality-specific value representations emerged from selective bidirectional interactions across the auditory and visual sensory cortices, the corresponding OFC clusters, and the vmPFC. These results illustrate how the brain enables a valuation process that is sensitive to the sensory context of rewarding stimuli.
神经经济学理论提出，不同奖励或奖励预测刺激物的价值是沿着共同的参照尺度编码的，而与它们的感觉特性无关。然而，在一个刺激-奖励配对不断变化的动态环境中，大脑还必须表示奖励刺激物的感觉特征。大脑如何平衡这些需求——为评估得出一个共同的参照尺度，同时保持对感觉环境的敏感性——仍然不清楚。为了研究这一点，我们进行了一项 fMRI 研究，参与者参与了一项动态觅食任务，该任务要求整合听觉或视觉选择选项的奖励历史，并为每种感觉模式更新主观价值。单变量 fMRI 分析显示，眶额皮层（OFC）中存在特定于模态的价值表示，腹内侧前额叶皮层（vmPFC）中存在模态通用的价值表示，通过探索性多变量模式分类方法得到证实。至关重要的是，当任务涉及基于指令而不是基于价值的选择时，特定于模态的价值表示就不存在了。有效连通性分析表明，特定于模态的价值表示来自听觉和视觉感觉皮层、相应的 OFC 簇以及 vmPFC 之间的选择性双向相互作用。这些结果说明了大脑如何使价值评估过程对奖励刺激的感觉环境敏感。
