Max-Planck Institute for Brain Research, 60528 Frankfurt am Main, Germany.
J Neurosci. 2012 Oct 24;32(43):14909-14. doi: 10.1523/JNEUROSCI.2051-12.2012.
Which neural processes underlie our conscious experience? One theoretical view argues that the neural correlates of consciousness (NCC) reside in local activity in sensory cortices. Accordingly, local category-specific gamma band responses in visual cortex correlate with conscious perception. However, as most studies manipulated conscious perception by altering the amount of sensory evidence, it is possible that they reflect prerequisites or consequences of consciousness rather than the actual NCC. Here we directly address this issue by developing a new experimental paradigm in which conscious perception is modulated either by sensory evidence or by previous exposure of the images while recording intracranial EEG from the higher-order visual cortex of human epilepsy patients. A clear prediction is that neural processes directly reflecting conscious perception should be present regardless of how it comes about. In contrast, we observed that although subjective reports were modulated both by sensory evidence and by previous exposure, gamma band responses solely reflected sensory evidence. This result contradicts the proposal that local gamma band responses in the higher-order visual cortex reflect conscious perception.
哪些神经过程是我们意识体验的基础？一种理论观点认为，意识的神经相关物（NCC）存在于感觉皮层的局部活动中。相应地，视觉皮层中的局部特定类别伽马波段反应与意识知觉相关。然而，由于大多数研究通过改变感觉证据的数量来操纵意识知觉，因此它们可能反映的是意识的前提条件或后果，而不是实际的 NCC。在这里，我们通过开发一种新的实验范式直接解决了这个问题，该范式通过记录人类癫痫患者高级视觉皮层的颅内 EEG，在调节意识知觉时可以通过感觉证据或图像的先前暴露来进行。一个明确的预测是，无论意识知觉是如何产生的，都应该存在直接反映意识知觉的神经过程。相比之下，我们观察到，尽管主观报告受到感觉证据和先前暴露的调节，但伽马波段反应仅反映感觉证据。这一结果与局部伽马波段反应在高级视觉皮层中反映意识知觉的提议相矛盾。
