Center for Cognitive Neuroscience, Duke University, Durham, NC 27708, USA.
J Cogn Neurosci. 2012 May;24(5):1113-26. doi: 10.1162/jocn_a_00211. Epub 2012 Feb 23.
Attention is attracted exogenously by physically salient stimuli, but this effect can be dampened by endogenous attention settings, a phenomenon called "contingent capture." Emotionally salient stimuli are also thought to exert a strong exogenous influence on attention, especially in anxious individuals, but whether and how top-down attention can ameliorate bottom-up capture by affective stimuli is currently unknown. Here, we paired a novel spatial cueing task with fMRI to investigate contingent capture as a function of the affective salience of bottom-up cues (face stimuli) and individual differences in trait anxiety. In the absence of top-down cues, exogenous stimuli validly cueing targets facilitated attention in low-anxious participants, regardless of affective salience. However, although high-anxious participants exhibited similar facilitation following neutral exogenous cues, this facilitation was completely absent following affectively negative exogenous cues. Critically, these effects were contingent on endogenous attentional settings, such that explicit top-down cues presented before the appearance of exogenous stimuli removed anxious individuals' sensitivity to affectively salient stimuli. fMRI analyses revealed a network of brain regions underlying this variability in affective contingent capture across individuals, including the fusiform face area (FFA), posterior ventrolateral frontal cortex, and SMA. Importantly, activation in the posterior ventrolateral frontal cortex and the SMA fully mediated the effects observed in FFA, demonstrating a critical role for these frontal regions in mediating attentional orienting and interference resolution processes when engaged by affectively salient stimuli.
注意会被物理上显著的刺激物吸引，但是这种效应可以被内源性注意设置所抑制，这种现象被称为“条件性捕获”。情绪显著的刺激物也被认为会对注意力产生强烈的外源性影响，特别是在焦虑个体中，但是自上而下的注意力是否以及如何改善情绪刺激的自下而上捕获目前尚不清楚。在这里，我们将一项新的空间提示任务与 fMRI 结合起来，研究了作为自下而上提示（面部刺激）的情绪显著性和特质焦虑个体差异的函数的条件性捕获。在没有自上而下提示的情况下，有效地提示目标的外源性刺激促进了低焦虑参与者的注意力，而与情绪显著性无关。然而，尽管高焦虑参与者在中性外源性提示后表现出类似的促进作用，但在外源性负性情绪刺激后，这种促进作用完全消失。至关重要的是，这些效应取决于内源性注意力设置，例如，在出现外源性刺激之前呈现的明确的自上而下的提示消除了焦虑个体对情绪显著刺激的敏感性。fMRI 分析揭示了个体之间情感条件性捕获变化的大脑区域网络，包括梭状回面孔区（FFA）、后外侧额下皮质和 SMA。重要的是，后外侧额下皮质和 SMA 的激活完全介导了 FFA 中观察到的效应，表明这些额区在处理情绪显著刺激时，在介导注意力定向和干扰解决过程中起着关键作用。
