Vassena Eliana, Krebs Ruth M, Silvetti Massimo, Fias Wim, Verguts Tom
Department of Experimental Psychology, Ghent University, Henri Dunantlaan 2, B-9000 Ghent, Belgium; GIfMI, Ghent Institute for Functional and Metabolic Imaging, Ghent University Hospital, De Pintelaan 185B, B-9000 Ghent, Belgium.
Department of Experimental Psychology, Ghent University, Henri Dunantlaan 2, B-9000 Ghent, Belgium.
Neuropsychologia. 2014 Jul;59:112-23. doi: 10.1016/j.neuropsychologia.2014.04.019. Epub 2014 May 9.
Acting in an uncertain environment requires estimating the probability and the value of potential outcomes. These computations are typically ascribed to various parts of the medial prefrontal cortex (mPFC), but the functional architecture of this region remains debated. The anterior cingulate cortex (ACC) encodes reward prediction and outcome (i.e. win vs lose, Silvetti, Seurinck, & Verguts, 2013. Cortex, 49(6), 1627-35. doi:10.1016/j.cortex.2012.05.008). An outcome-related value signal has also been reported in the ventromedial Prefrontal Cortex (vmPFC, Rangel & Hare, 2010. Current Opinion in Neurobiology, 20(2), 262-70. doi:10.1016/j.conb.2010.03.001). Whether a functional dissociation can be traced in these regions with respect to reward prediction and outcome has been suggested but not rigorously tested. Hence an fMRI study was designed to systematically examine the contribution of ACC and vmPFC to reward prediction and outcome. A striking dissociation was identified, with ACC coding for positive prediction errors and vmPFC responding to outcome, irrespective of probability. Moreover, ACC has been assigned a crucial role in the selection of intentional actions (decision-making) and computing the value associated to these actions (action-based value). Conversely, vmPFC seems to implement stimulus-based value processing (Rudebeck et al., 2008. Journal of Neuroscience, 28(51), 13775-85. doi:10.1523/JNEUROSCI.3541-08.2008; Rushworth, Behrens, Rudebeck, & Walton, 2007. Trends in Cognitive Sciences, 11(4), 168-76. doi:10.1016/j.tics.2007.01.004). Therefore, a decision-making factor (choice vs. no choice condition) was also implemented in the present paradigm to distinguish stimulus-based versus action-based value coding in the mPFC during both decision and outcome phase. We found that vmPFC was more activated during the outcome phase in the no-choice than in the choice condition, potentially confirming the role of this area in stimulus-based (more than action-based) value processing.
在不确定的环境中行动需要估计潜在结果的概率和价值。这些计算通常归因于内侧前额叶皮质（mPFC）的各个部分，但该区域的功能结构仍存在争议。前扣带回皮质（ACC）对奖励预测和结果进行编码（即赢与输，Silvetti、Seurinck和Verguts，2013年。《皮质》，49(6)，1627 - 35。doi:10.1016/j.cortex.2012.05.008）。腹内侧前额叶皮质（vmPFC）也有与结果相关的价值信号的报道（Rangel和Hare，2010年。《神经生物学当前观点》，20(2)，262 - 70。doi:10.1016/j.conb.2010.03.001）。关于奖励预测和结果，这些区域是否存在功能分离已被提出，但尚未经过严格测试。因此，设计了一项功能磁共振成像（fMRI）研究，以系统地研究ACC和vmPFC对奖励预测和结果的贡献。研究发现了一个显著的分离现象，ACC编码正预测误差，而vmPFC对结果做出反应，与概率无关。此外，ACC在有意行动的选择（决策）以及计算与这些行动相关的价值（基于行动的价值）方面被赋予了关键作用。相反，vmPFC似乎执行基于刺激的价值处理（Rudebeck等人，2008年。《神经科学杂志》，28(51)，13775 - 85。doi:10.1523/JNEUROSCI.3541 - 08.2008；Rushworth、Behrens、Rudebeck和Walton，2007年。《认知科学趋势》，11(4)，168 - 76。doi:10.1016/j.tics.2007.01.004）。因此，在当前范式中还引入了一个决策因素（选择与无选择条件），以区分在决策和结果阶段mPFC中基于刺激的价值编码与基于行动的价值编码。我们发现，在无选择条件下，vmPFC在结果阶段比在选择条件下更活跃，这可能证实了该区域在基于刺激（而非基于行动）的价值处理中的作用。
