Progress in understanding the neural bases of cognitive control has been supported by the paradigmatic color-word Stroop task, in which a target response (color name) must be selected over a more automatic, yet potentially incongruent, distractor response (word). For this paradigm, models have postulated complementary coding schemes: dorsomedial frontal cortex (DMFC) is proposed to evaluate the demand for control via incongruency-related coding, whereas dorsolateral PFC (DLPFC) is proposed to implement control via goal and target-related coding. Yet, mapping these theorized schemes to measured neural activity within this task has been challenging. Here, we tested for these coding schemes relatively directly, by decomposing an event-related color-word Stroop task via representational similarity analysis. Three neural coding models were fit to the similarity structure of multivoxel patterns of human fMRI activity, acquired from 65 healthy, young-adult males and females. Incongruency coding was predominant in DMFC, whereas both target and incongruency coding were present with indistinguishable strength in DLPFC. In contrast, distractor information was strongly encoded within early visual cortex. Further, these coding schemes were differentially related to behavior: individuals with stronger DLPFC (and lateral posterior parietal cortex) target coding, but weaker DMFC incongruency coding, exhibited less behavioral Stroop interference. These results highlight the utility of the representational similarity analysis framework for investigating neural mechanisms of cognitive control and point to several promising directions to extend the Stroop paradigm.

SIGNIFICANCE STATEMENT How the human brain enables cognitive control — the ability to override behavioral habits to pursue internal goals — has been a major focus of neuroscience research. This ability has been frequently investigated by using the Stroop color-word naming task. With the Stroop as a test-bed, many theories have proposed specific neuroanatomical dissociations, in which medial and lateral frontal brain regions underlie cognitive control by encoding distinct types of information. Yet providing a direct confirmation of these claims has been challenging. Here, we demonstrate that representational similarity analysis, which estimates and models the similarity structure of brain activity patterns, can successfully establish the hypothesized functional dissociations within the Stroop task. Representational similarity analysis may provide a useful approach for investigating cognitive control mechanisms.

典型的颜色词斯特鲁普任务支持了理解认知控制神经基础的进展，其中必须选择目标响应（颜色名称）而不是更自动但可能不一致的干扰响应（单词）。对于这种范式，模型假设了互补的编码方案：背内侧额叶皮层（DMFC）被提议通过不一致相关编码来评估控制需求，而背外侧 PFC（DLPFC）被提议通过目标和目标相关编码来实现控制。然而，将这些理论方案映射到该任务中测量的神经活动一直具有挑战性。在这里，我们通过表征相似性分析分解与事件相关的颜色词 Stroop 任务，相对直接地测试了这些编码方案。三种神经编码模型适合从 65 名健康年轻成年男性和女性获得的人类功能磁共振成像活动多体素模式的相似结构。不一致编码在 DMFC 中占主导地位，而目标编码和不一致编码在 DLPFC 中都存在，强度无法区分。相比之下，干扰信息在早期视觉皮层中被强烈编码。此外，这些编码方案与行为有不同的相关性：具有较强 DLPFC（和外侧后顶叶皮层）目标编码但较弱 DMFC 不一致编码的个体表现出较少的行为 Stroop 干扰。这些结果强调了表征相似性分析框架在研究认知控制神经机制方面的实用性，并指出了扩展斯特鲁普范式的几个有希望的方向。

意义陈述人脑如何实现认知控制（即超越行为习惯以追求内部目标的能力）一直是神经科学研究的主要焦点。人们经常通过使用斯特鲁普颜色词命名任务来研究这种能力。以斯特鲁普为试验台，许多理论提出了特定的神经解剖学分离，其中额叶内侧和外侧大脑区域通过编码不同类型的信息而成为认知控制的基础。然而，直接证实这些说法一直具有挑战性。在这里，我们证明表征相似性分析（估计和建模大脑活动模式的相似性结构）可以成功地在 Stroop 任务中建立假设的功能分离。表征相似性分析可能为研究认知控制机制提供有用的方法。