Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, UK.
Department of Experimental Psychology, University of Oxford, Oxford, UK.
Nat Commun. 2017 Jun 9;8:15808. doi: 10.1038/ncomms15808.
Current computational accounts posit that, in simple binary choices, humans accumulate evidence in favour of the different alternatives before committing to a decision. Neural correlates of this accumulating activity have been found during perceptual decisions in parietal and prefrontal cortex; however the source of such activity in value-based choices remains unknown. Here we use simultaneous EEG-fMRI and computational modelling to identify EEG signals reflecting an accumulation process and demonstrate that the within- and across-trial variability in these signals explains fMRI responses in posterior-medial frontal cortex. Consistent with its role in integrating the evidence prior to reaching a decision, this region also exhibits task-dependent coupling with the ventromedial prefrontal cortex and the striatum, brain areas known to encode the subjective value of the decision alternatives. These results further endorse the proposition of an evidence accumulation process during value-based decisions in humans and implicate the posterior-medial frontal cortex in this process.
目前的计算模型假设，在简单的二元选择中，人类在做出决策之前会积累不同选择的证据。在顶叶和前额叶皮层的知觉决策中发现了这种累积活动的神经相关物；然而，基于价值的选择中这种活动的来源尚不清楚。在这里，我们使用同时进行的 EEG-fMRI 和计算建模来识别反映累积过程的 EEG 信号，并证明这些信号在试验内和试验间的可变性可以解释后内侧前额叶皮层的 fMRI 反应。与在做出决策之前整合证据的作用一致，该区域还表现出与腹内侧前额叶皮层和纹状体的任务相关耦合，这些脑区已知编码决策替代方案的主观价值。这些结果进一步支持了在人类基于价值的决策中存在证据积累过程的观点，并暗示后内侧前额叶皮层在这个过程中起作用。
