Azab Habiba, Hayden Benjamin Y
Department of Brain and Cognitive Sciences and Center for Visual Sciences, University of Rochester, Rochester, New York, United States of America.
Department of Neuroscience and Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, Minnesota, United States of America.
PLoS Biol. 2017 Nov 15;15(11):e2003091. doi: 10.1371/journal.pbio.2003091. eCollection 2017 Nov.
We hypothesized that during binary economic choice, decision makers use the first option they attend as a default to which they compare the second. To test this idea, we recorded activity of neurons in the dorsal anterior cingulate cortex (dACC) of macaques choosing between gambles presented asynchronously. We find that ensemble encoding of the value of the first offer includes both choice-dependent and choice-independent aspects, as if reflecting a partial decision. That is, its responses are neither entirely pre- nor post-decisional. In contrast, coding of the value of the second offer is entirely decision dependent (i.e., post-decisional). This result holds even when offer-value encodings are compared within the same time period. Additionally, we see no evidence for 2 pools of neurons linked to the 2 offers; instead, all comparison appears to occur within a single functionally homogenous pool of task-selective neurons. These observations suggest that economic choices reflect a context-dependent evaluation of attended options. Moreover, they raise the possibility that value representations reflect, to some extent, a tentative commitment to a choice.
我们假设，在二元经济选择过程中，决策者会将他们首先关注的选项作为默认选项，并以此为参照来比较第二个选项。为了验证这一想法，我们记录了猕猴在异步呈现的赌博选项之间进行选择时，其背侧前扣带回皮层（dACC）中神经元的活动。我们发现，对第一个选项价值的整体编码包括与选择相关和与选择无关的方面，就好像反映了一个部分决策。也就是说，其反应既不完全是决策前的，也不完全是决策后的。相比之下，对第二个选项价值的编码则完全取决于决策（即决策后）。即使在同一时间段内比较选项价值编码，这一结果依然成立。此外，我们没有发现与这两个选项相关的两类神经元的证据；相反，所有比较似乎都发生在一个功能上同质的任务选择性神经元池中。这些观察结果表明，经济选择反映了对所关注选项的情境依赖评估。此外，它们还提出了一种可能性，即价值表征在某种程度上反映了对某个选择的初步承诺。
