Pourtois Gilles, Schwartz Sophie, Seghier Mohamed L, Lazeyras François, Vuilleumier Patrik
Neurology and Imaging of Cognition, Clinic of Neurology, University Hospital and Department of Neurosciences, University Medical Center, Switzerland.
Neuroimage. 2006 Jun;31(2):920-33. doi: 10.1016/j.neuroimage.2005.12.034. Epub 2006 Feb 17.
Attention may reflexively shift towards the location of perceived threats, but it is still unclear how these spatial biases recruit the distributed fronto-parietal cortical networks involved in other aspects of selective attention. We used event-related fMRI to determine how brain responses to a neutral visual target are influenced by the emotional expression of faces appearing at the same location during a covert orienting task. On each trial, two faces were briefly presented, one in each upper visual field (one neutral and one emotional, fearful or happy), followed by a unilateral target (a small horizontal or vertical bar) replacing one of the faces. Participants had to discriminate the target orientation, shown on the same (valid) or opposite (invalid) side as the emotional face. Trials with faces but no subsequent target (cue-only trials) were included to disentangle activation due to emotional cues from their effects on target detection. We found increased responses in bilateral temporo-parietal areas and right occipito-parietal cortex for fearful faces relative to happy faces, unrelated to the subsequent target and cueing validity. More critically, we found a selective modulation of intraparietal and orbitofrontal cortex for targets following an invalid fearful face, as well as an increased visual response in right lateral occipital cortex for targets following a valid fearful face. No such effects were observed with happy faces. These results demonstrate that fearful faces can act as exogenous cues by increasing sensory processing in extrastriate cortex for a subsequent target presented at the same location, but also produce a cost in disengaging towards another location by altering the response of IPS to invalidly cued targets. Neural mechanisms responsible for orienting attention towards emotional vs. non-emotional stimuli are thus partly shared in parietal and visual areas, but also partly distinct.
注意力可能会反射性地转向感知到的威胁所在位置，但目前仍不清楚这些空间偏差是如何招募参与选择性注意其他方面的分布式额顶叶皮层网络的。我们使用事件相关功能磁共振成像来确定在隐蔽定向任务期间，大脑对中性视觉目标的反应如何受到出现在同一位置的面部情绪表达的影响。在每次试验中，会短暂呈现两张面孔，分别位于每个上视野（一张中性面孔和一张情绪面孔，恐惧或开心），随后是一个单侧目标（一个小的水平或垂直条）取代其中一张面孔。参与者必须辨别目标方向，目标显示在与情绪面孔相同（有效）或相反（无效）的一侧。包含有面孔但随后没有目标的试验（仅提示试验），以区分由情绪提示引起的激活与其对目标检测的影响。我们发现，相对于开心面孔，恐惧面孔在双侧颞顶叶区域和右侧枕顶叶皮层引发的反应增强，这与随后的目标和提示有效性无关。更关键的是，我们发现对于无效恐惧面孔之后的目标，顶内沟和眶额皮层有选择性调制，对于有效恐惧面孔之后的目标，右侧枕叶外侧皮层的视觉反应增强。开心面孔未观察到此类效应。这些结果表明，恐惧面孔可以通过增加对随后出现在同一位置的目标的纹外皮层感觉处理，充当外部提示，但也会通过改变顶内沟对无效提示目标的反应，在转向另一个位置时产生代价。因此，负责将注意力导向情绪与非情绪刺激的神经机制在顶叶和视觉区域部分共享，但也部分不同。
