Deciding When to Decide: Time-Variant Sequential Sampling Models Explain the Emergence of Value-Based Decisions in the Human Brain
Deciding When to Decide: Time-Variant Sequential Sampling Models Explain the Emergence of Value-Based Decisions in the Human Brain
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DOI：
10.1523/jneurosci.0727-12.2012
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发表时间：
2012-08-01
影响因子：
5.3
通讯作者：
Buechel, Christian
中科院分区：
文献类型：
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作者：
Gluth, Sebastian;Rieskamp, Joerg;Buechel, Christian
知觉决策的认知和神经机制已经成功地与序贯抽样模型联系起来。这些模型将决策过程描述为随着时间的推移感官证据的逐渐积累。然而，经济选择的时间演变在很大程度上仍未得到探索。我们测试了序贯抽样模型是否有助于理解行为和大脑反应方面基于价值的决策的形成。我们使用功能性磁共振成像（fMRI）来测量大脑活动，而人类参与者则执行一项购买任务，在这项任务中，他们自由决定如何以及何时选择。通过时变序贯抽样模型准确预测行为，该模型使用递减而不是固定的决策阈值来估计决策的时间点。随着时间的推移，前辅助运动区、尾状核和前额叶激活与证据的积累有关。此外，在决策过程开始时，这些区域的fMRI信号解释了与行为模型预测的逐个试验偏差：相对较高的激活先于相对较早的反应。价值信息的更新与腹内侧前额叶皮层、左右眶额皮层和腹侧纹状体的信号相关，而且在初级运动皮层中也与反应本身相关。我们的研究结果支持一种观点，即基于价值的决策是从连续的证据抽样中产生的，并表明当人们在任何时候都可以自由反应时，运动系统中的积累过程和活动之间存在密切联系。
The cognitive and neuronal mechanisms of perceptual decision making have been successfully linked to sequential sampling models. These models describe the decision process as a gradual accumulation of sensory evidence over time. The temporal evolution of economic choices, however, remains largely unexplored. We tested whether sequential sampling models help to understand the formation of value-based decisions in terms of behavior and brain responses. We used functional magnetic resonance imaging (fMRI) to measure brain activity while human participants performed a buying task in which they freely decided upon how and when to choose. Behavior was accurately predicted by a time-variant sequential sampling model that uses a decreasing rather than fixed decision threshold to estimate the time point of the decision. Presupplementary motor area, caudate nucleus, and anterior insula activation was associated with the accumulation of evidence over time. Furthermore, at the beginning of the decision process the fMRI signal in these regions accounted for trial-by-trial deviations from behavioral model predictions: relatively high activation preceded relatively early responses. The updating of value information was correlated with signals in the ventromedial prefrontal cortex, left and right orbitofrontal cortex, and ventral striatum but also in the primary motor cortex well before the response itself. Our results support a view of value-based decisions as emerging from sequential sampling of evidence and suggest a close link between the accumulation process and activity in the motor system when people are free to respond at any time.