Pourtois Gilles, Grandjean Didier, Sander David, Vuilleumier Patrik
Neurology & Imaging of Cognition, University of Geneva, Switzerland.
Cereb Cortex. 2004 Jun;14(6):619-33. doi: 10.1093/cercor/bhh023. Epub 2004 Mar 28.
We investigated the spatio-temporal dynamic of attentional bias towards fearful faces. Twelve participants performed a covert spatial orienting task while recording visual event-related brain potentials (VEPs). Each trial consisted of a pair of faces (one emotional and one neutral) briefly presented in the upper visual field, followed by a unilateral bar presented at the location of one of the faces. Participants had to judge the orientation of the bar. Comparing VEPs to bars shown at the location of an emotional (valid) versus neutral (invalid) face revealed an early effect of spatial validity: the lateral occipital P1 component (approximately 130 ms post-stimulus) was selectively increased when a bar replaced a fearful face compared to when the same bar replaced a neutral face. This effect was not found with upright happy faces or inverted fearful faces. A similar amplification of P1 has previously been observed in electrophysiological studies of spatial attention using non-emotional cues. In a behavioural control experiment, participants were also better at discriminating the orientation of the bar when it replaced a fearful rather than a neutral face. In addition, VEPs time-locked to the face-pair onset revealed a C1 component (approximately 90 ms) that was greater for fearful than happy faces. Source localization (LORETA) confirmed an extrastriate origin of the P1 response showing a spatial validity effect, and a striate origin of the C1 response showing an emotional valence effect. These data suggest that activity in primary visual cortex might be enhanced by fear cues as early as 90 ms post-stimulus, and that such effects might result in a subsequent facilitation of sensory processing for a stimulus appearing at the same location. These results provide evidence for neural mechanisms allowing rapid, exogenous spatial orienting of attention towards fear stimuli.
我们研究了对恐惧面孔的注意偏向的时空动态。12名参与者在记录视觉事件相关脑电位（VEP）的同时执行了一项隐蔽的空间定向任务。每个试验包括一对面孔（一张情绪面孔和一张中性面孔）短暂呈现于上视野，随后在其中一张面孔的位置呈现一个单侧条。参与者必须判断条的方向。将VEP与呈现于情绪面孔（有效）与中性面孔（无效）位置的条进行比较，揭示了空间有效性的早期效应：与条替代中性面孔时相比，当条替代恐惧面孔时，枕外侧P1成分（刺激后约130毫秒）有选择性地增强。对于直立的快乐面孔或倒置的恐惧面孔未发现这种效应。先前在使用非情绪线索的空间注意的电生理研究中也观察到了P1的类似增强。在一项行为控制实验中，当条替代恐惧面孔而非中性面孔时，参与者在辨别条的方向方面也表现得更好。此外，与面孔对开始时间锁定的VEP显示，恐惧面孔的C1成分（约90毫秒）比快乐面孔的更大。源定位（LORETA）证实了显示空间有效性效应的P1反应起源于纹外区域，以及显示情绪效价效应的C1反应起源于纹状区域。这些数据表明，在刺激后90毫秒，初级视觉皮层的活动可能就会因恐惧线索而增强，并且这种效应可能会导致随后对出现在同一位置的刺激的感觉加工得到促进。这些结果为允许对恐惧刺激进行快速、外源性空间注意定向的神经机制提供了证据。
