Ewbank Michael P, Lawrence Andrew D, Passamonti Luca, Keane Jill, Peers Polly V, Calder Andrew J
MRC Cognition and Brain Sciences Unit, Cambridge, UK.
Neuroimage. 2009 Feb 1;44(3):1144-51. doi: 10.1016/j.neuroimage.2008.09.056. Epub 2008 Oct 19.
Behavioural evidence indicates that individual differences in anxiety influence the response to facial signals of threat. Angry and fearful faces represent qualitatively different forms of threat. Fearful faces are thought to signal the presence of a significant, yet undetermined source of danger within the environment, referred to as 'ambiguous threat'. In contrast, angry faces represent a more direct form of threat, often used in face-to-face encounters to exert dominance. Given the inherent differences between anger and fear, we hypothesised that anxiety would modulate the amygdala response to angry faces to a greater extent when attended. Following previous research, we expected anxiety to show a stronger relationship with the amygdala response to unattended fearful faces. In an event-related fMRI study, we presented images of two houses and two faces (consisting of fearful, angry or neutral expressions) in horizontal and vertical pairs around a central fixation cross, with participants instructed to attend to either the face or house stimuli. The results showed that higher anxiety levels produced an increased right amygdala response to viewer directed angry facial expressions (versus neutral or fearful faces) only when attended. By contrast, increased anxiety was associated with a greater left amygdala response to fearful faces (versus neutral or angry faces) in the unattended condition, with only borderline evidence for attended fear (relative to neutral). Our findings demonstrate the striking effects of personality in a non-clinical population, and show how this can distinguish the neural coding of anger and fear faces.
行为学证据表明，焦虑的个体差异会影响对威胁性面部信号的反应。愤怒和恐惧的面孔代表了性质不同的威胁形式。恐惧的面孔被认为表明环境中存在重大但尚未确定的危险来源，即“模糊威胁”。相比之下，愤怒的面孔代表了一种更直接的威胁形式，常用于面对面的遭遇中以施加支配地位。鉴于愤怒和恐惧之间的内在差异，我们假设焦虑在被关注时会更大程度地调节杏仁核对愤怒面孔的反应。根据先前的研究，我们预计焦虑与杏仁核对未被关注的恐惧面孔的反应之间会有更强的关联。在一项事件相关功能磁共振成像研究中，我们在围绕中央注视点十字的水平和垂直对中呈现两所房子和两张面孔（包括恐惧、愤怒或中性表情）的图像，要求参与者关注面部或房子刺激。结果表明，只有在被关注时，较高的焦虑水平才会使右侧杏仁核对面向观察者的愤怒面部表情（相对于中性或恐惧面孔）的反应增强。相比之下，在未被关注的情况下，焦虑增加与左侧杏仁核对恐惧面孔（相对于中性或愤怒面孔）的反应增强有关，而对于被关注的恐惧面孔（相对于中性面孔）只有边缘证据。我们的研究结果证明了人格在非临床人群中的显著影响，并展示了其如何区分愤怒和恐惧面孔的神经编码。
