Sterzer Philipp, Jalkanen Lauri, Rees Geraint
Wellcome Trust Centre for Neuroimaging, Institute of Neurology, University College London, UK.
Neuroimage. 2009 Jul 1;46(3):803-8. doi: 10.1016/j.neuroimage.2009.02.046. Epub 2009 Mar 10.
When two incompatible monocular images compete for perceptual dominance, one can dominate awareness while the other is suppressed and invisible. It has been suggested that binocular suppression of this kind involves competitive neuronal interactions at multiple levels of the visual processing hierarchy. Here we asked whether in such situations, complex stimulus information is still preserved at advanced visual processing stages despite competitive interactions at early levels of the visual system. We tested whether face stimuli made invisible through binocular suppression would evoke category-specific responses in the human brain, using magnetoencephalography. During scanning participants were presented with face or house stimuli that were either visible or rendered invisible using continuous flash suppression (CFS). Online behavioural assessment with a two-alternative forced choice task confirmed that participants were neither able to detect target stimuli on CFS trials nor to correctly classify the stimuli as faces or houses. Even though the amplitude of the M170, a well-established face-specific signal, was strongly reduced by CFS, there was still a significantly greater signal in response to invisible face compared to invisible house stimuli at the latency and the location of the M170 to visible stimuli. Thus, visual object stimuli undergo category-specific processing in the ventral visual pathway even when profoundly suppressed from awareness by binocular competition.
当两个不兼容的单眼图像争夺感知主导权时，一个可以主导意识，而另一个则被抑制且不可见。有人认为，这种双眼抑制涉及视觉处理层次结构多个层面上的竞争性神经元相互作用。在这里，我们探讨了在这种情况下，尽管视觉系统早期存在竞争性相互作用，但复杂的刺激信息在高级视觉处理阶段是否仍然得以保留。我们使用脑磁图测试了通过双眼抑制变得不可见的面部刺激是否会在人脑中引发特定类别的反应。在扫描过程中，向参与者呈现面部或房屋刺激，这些刺激要么是可见的，要么使用连续闪光抑制（CFS）使其变得不可见。通过二选一强制选择任务进行的在线行为评估证实，参与者在CFS试验中既无法检测到目标刺激，也无法正确将刺激分类为面部或房屋。尽管CFS强烈降低了M170（一种公认的面部特异性信号）的幅度，但在M170对可见刺激的潜伏期和位置上，与不可见房屋刺激相比，对不可见面部的反应仍有显著更强的信号。因此，即使视觉对象刺激因双眼竞争而从意识中被深度抑制，它们在腹侧视觉通路中仍会经历特定类别的处理。
