Implicit motivational value and salience are processed in distinct areas of orbitofrontal cortex
Implicit motivational value and salience are processed in distinct areas of orbitofrontal cortex
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DOI：
10.1016/j.neuroimage.2012.06.016
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发表时间：
2012-09-01
期刊：
影响因子：
5.7
通讯作者：
Sterzer, Philipp
中科院分区：
文献类型：
--
作者：
Rothkirch, Marcus;Schmack, Katharina;Sterzer, Philipp
最近的研究表明，即使在个人没有积极参与刺激评估的情况下，动机刺激信息也会在大脑中表现出来。然而，它仍然不清楚是否神经表征这种内隐的动机信息反映的动机价值或动机的显着性刺激。虽然动机值对应于刺激的愿望，但动机显著性与刺激引起的唤醒有关。在这里，我们的目标是解开两个动机维度的神经表征。在第一部分中，参与者学习了面部刺激与金钱奖励和惩罚的联系。在随后的fMRI实验中，同样的面部刺激，在此期间，参与者要么进行性别歧视任务的面孔或方向歧视任务的两个同时提出的酒吧。重要的是，面孔只是在先前的学习任务中获得的内隐动机信息方面有所不同，因为参与者在fMRI实验中既没有接受货币强化，也没有被要求明确判断他们的面孔偏好。我们发现，内隐激励值对外侧眶额皮层的神经反应有调制作用，而面孔的内隐激励显著性则编码在内侧眶额皮层。外侧眶额皮层的内隐激励值相关反应随着时间的推移而减弱，而内侧眶额皮层的内隐激励显著性相关反应在整个fMRI实验过程中保持稳定。两个动机维度的神经反应被观察到独立的参与者的注意力是否被定向到面孔或周围的酒吧，这表明一个自动处理的隐含的动机价值和显着性。内的眶额皮层的功能分离表明，这一地区是至关重要的参与不同的动机相关的过程：在内侧OK，一个代表性的显着项目可能会保持，以促进对行为相关的刺激在未来的反应;相反，在外侧眶额皮层的临时价值效应可能会反映在没有明确的动机刺激差异的刺激价值下降。(c)2012 Elsevier Inc. All rights reserved.
Recent studies have shown that motivational stimulus information is represented in the brain even in situations where the individual is not actively engaged in stimulus evaluation. However, it has remained unclear whether neural representations of such implicit motivational information reflect the motivational value or motivational salience of stimuli. While motivational values correspond to the desirability of stimuli, motivational salience is related to the arousal elicited by the stimulus. Here we aimed at disentangling the neural representation of both motivational dimensions. In the first part, participants learned the association of face stimuli with monetary reward and punishment. The same face stimuli were presented in a subsequent fMRI experiment, during which participants either performed a gender discrimination task on the faces or an orientation discrimination task on two simultaneously presented bars. Importantly, faces only differed regarding their implicit motivational information as acquired in the previous learning task, as participants neither received monetary reinforcement during the fMRI experiment nor were they asked to explicitly judge their face preferences. We found that neural responses in lateral OFC were modulated by implicit motivational value, whereas the faces' implicit motivational salience was coded in medial OFC While the value-related responses in lateral OFC decreased over time, the salience-related modulation of medial OFC activity remained stable over the duration of the fMRI experiment. Neural responses to both motivational dimensions were observed independent of whether participants' attention was directed to the faces or to the surrounding bars, suggesting an automatic processing of implicit motivational value and salience. The functional dissociation within the OFC suggests that this region is critically involved in distinct motivation-related processes: In medial OK, a representation of salient items may be maintained in order to facilitate responses towards behaviourally relevant stimuli in the future; in contrast the temporary value effect in lateral OFC might reflect decreasing stimulus valuation in the absence of explicit motivational stimulus differences. (c) 2012 Elsevier Inc. All rights reserved.