Navajas Joaquin, Nitka Aleksander W, Quian Quiroga Rodrigo
Centre for Systems Neuroscience, University of Leicester, Leicester, United Kingdom.
Institute of Cognitive Neuroscience, University College London, London, United Kingdom.
Psychophysiology. 2017 Aug;54(8):1138-1150. doi: 10.1111/psyp.12873. Epub 2017 Apr 26.
Given the higher chance to recognize attended compared to unattended stimuli, the specific neural correlates of these two processes, attention and awareness, tend to be intermingled in experimental designs. In this study, we dissociated the neural correlates of conscious face perception from the effects of visual attention. To do this, we presented faces at the threshold of awareness and manipulated attention through the use of exogenous prestimulus cues. We show that the N170 component, a scalp EEG marker of face perception, was modulated independently by attention and by awareness. An earlier P1 component was not modulated by either of the two effects and a later P3 component was indicative of awareness but not of attention. These claims are supported by converging evidence from (a) modulations observed in the average evoked potentials, (b) correlations between neural and behavioral data at the single-subject level, and (c) single-trial analyses. Overall, our results show a clear dissociation between the neural substrates of attention and awareness. Based on these results, we argue that conscious face perception is triggered by a boost in face-selective cortical ensembles that can be modulated by, but are still independent from, visual attention.
与未被注意的刺激相比，由于识别被注意到的刺激的可能性更高，在实验设计中，注意力和意识这两个过程的特定神经关联往往相互交织。在本研究中，我们将有意识的面部感知的神经关联与视觉注意力的影响区分开来。为此，我们在意识阈值下呈现面部，并通过使用外部预刺激线索来操纵注意力。我们发现，N170成分作为面部感知的头皮脑电图标记物，受注意力和意识的独立调节。较早的P1成分不受这两种效应的调节，而较晚的P3成分表明有意识但与注意力无关。这些结论得到了以下几方面的汇聚证据支持：(a) 在平均诱发电位中观察到的调节；(b) 单受试者水平上神经数据与行为数据之间的相关性；(c) 单次试验分析。总体而言，我们的结果表明注意力和意识的神经基础之间存在明显的分离。基于这些结果，我们认为有意识的面部感知是由面部选择性皮层集合的增强触发的，这种增强可受视觉注意力调节，但仍独立于视觉注意力。
