Ishai Alumit, Pessoa Luiz, Bikle Philip C, Ungerleider Leslie G
Laboratory of Brain and Cognition, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA.
Proc Natl Acad Sci U S A. 2004 Jun 29;101(26):9827-32. doi: 10.1073/pnas.0403559101. Epub 2004 Jun 21.
Single-unit recordings and functional brain imaging studies have shown reduced neural responses to repeated stimuli in the visual cortex. By using event-related functional MRI, we compared the activation evoked by repetitions of neutral and fearful faces, which were either task relevant (targets) or irrelevant (distracters). We found that within the inferior occipital gyri, lateral fusiform gyri, superior temporal sulci, amygdala, and the inferior frontal gyri/insula, targets evoked stronger responses than distracters and their repetition was associated with significantly reduced responses. Repetition suppression, as manifested by the difference in response amplitude between the first and third repetitions of a target, was stronger for fearful than neutral faces. Distracter faces, regardless of their repetition or valence, evoked negligible activation, indicating top-down attenuation of behaviorally irrelevant stimuli. Our findings demonstrate a three-way interaction between emotional valence, repetition, and task relevance and suggest that repetition suppression is influenced by high-level cognitive processes in the human brain.
单神经元记录和功能性脑成像研究表明，视觉皮层对重复刺激的神经反应有所减少。通过使用事件相关功能磁共振成像，我们比较了中性和恐惧面孔重复呈现时所诱发的激活情况，这些面孔要么与任务相关（目标），要么与任务无关（干扰物）。我们发现，在枕下回、外侧梭状回、颞上沟、杏仁核以及额下回/脑岛中，目标诱发的反应比干扰物更强，并且目标的重复与反应显著减少有关。重复抑制表现为目标第一次和第三次重复时反应幅度的差异，恐惧面孔的重复抑制比中性面孔更强。无论干扰面孔的重复情况或效价如何，其诱发的激活都可忽略不计，这表明行为上无关刺激存在自上而下的衰减。我们的研究结果证明了情绪效价、重复和任务相关性之间的三向相互作用，并表明重复抑制受人类大脑高级认知过程的影响。
