Bekhtereva Valeria, Craddock Matt, Müller Matthias M
Institute of Psychology, University of Leipzig, Leipzig, Germany.
Institute of Psychological Sciences, University of Leeds, Leeds, UK.
Neuroimage. 2015 May 15;112:254-266. doi: 10.1016/j.neuroimage.2015.03.052. Epub 2015 Mar 25.
Emotionally arousing stimuli are known to rapidly draw the brain's processing resources, even when they are task-irrelevant. The steady-state visual evoked potential (SSVEP) response, a neural response to a flickering stimulus which effectively allows measurement of the processing resources devoted to that stimulus, has been used to examine this process of attentional shifting. Previous studies have used a task in which participants detected periods of coherent motion in flickering random dot kinematograms (RDKs) which generate an SSVEP, and found that task-irrelevant emotional stimuli withdraw more attentional resources from the task-relevant RDKs than task-irrelevant neutral stimuli. However, it is not clear whether the emotion-related differences in the SSVEP response are conditional on higher-level extraction of emotional cues as indexed by well-known event-related potential (ERPs) components (N170, early posterior negativity, EPN), or if affective bias in competition for visual attention resources is a consequence of a time-invariant shifting process. In the present study, we used two different types of emotional distractors - IAPS pictures and facial expressions - for which emotional cue extraction occurs at different speeds, being typically earlier for faces (at 170ms, as indexed by the N170) than for IAPS images (220-280ms, EPN). We found that emotional modulation of attentional resources as measured by the SSVEP occurred earlier for faces (around 180ms) than for IAPS pictures (around 550ms), after the extraction of emotional cues as indexed by visual ERP components. This is consistent with emotion related re-allocation of attentional resources occurring after emotional cue extraction rather than being linked to a time-fixed shifting process.
已知情绪唤起性刺激会迅速吸引大脑的处理资源，即使它们与任务无关。稳态视觉诱发电位（SSVEP）反应是对闪烁刺激的神经反应，它能有效地测量分配给该刺激的处理资源，已被用于研究这种注意力转移过程。先前的研究使用了一项任务，参与者要在产生SSVEP的闪烁随机点运动图（RDK）中检测连贯运动的时间段，结果发现与任务无关的情绪刺激比与任务无关的中性刺激从与任务相关的RDK中吸引了更多的注意力资源。然而，尚不清楚SSVEP反应中与情绪相关的差异是否取决于由著名的事件相关电位（ERP）成分（N170、早期后负电位、EPN）所指示的情绪线索的高级提取，或者视觉注意力资源竞争中的情感偏差是否是一个时间不变的转移过程的结果。在本研究中，我们使用了两种不同类型的情绪干扰物——国际情感图片系统（IAPS）图片和面部表情，对于它们，情绪线索提取的速度不同，面部表情通常比IAPS图片更早（约170毫秒，由N170指示）（IAPS图片约220 - 280毫秒，EPN）。我们发现，在视觉ERP成分所指示的情绪线索提取之后，通过SSVEP测量的注意力资源的情绪调节对面部表情的发生时间（约180毫秒）早于IAPS图片（约550毫秒）。这与情绪线索提取后发生的与情绪相关的注意力资源重新分配一致，而不是与一个固定时间的转移过程相关。
