Department of Psychology, University of Toronto, 100 St. George Street, Room 4020, Toronto, Ontario M5S 3G3, Canada.
Psychon Bull Rev. 2012 Jun;19(3):429-35. doi: 10.3758/s13423-012-0220-3.
Although significant advances in our understanding of the cognitive and neural processes involved in conscious awareness have occurred in recent years, the precise mechanisms that support consciousness remain elusive. Examining the neural correlates associated with the moment a stimulus enters or exits conscious awareness is one way to potentially identify the neural mechanisms that give rise to consciousness. In the present study, we recorded neural activity using electroencephalography (EEG) while participants observed a bilateral shape-from-motion (SFM) display. While the display is in motion, the observer perceives an object that is immediately segregated from a noisy background. After the motion stops, the observer's experience of the object remains momentarily in awareness, before it eventually fades out of consciousness back into the noisy background. Consistent with subjective reports of perceptual experience, we observed a prominent sustained posterior contralateral negativity known as the contralateral delay activity (CDA). This activity was sustained only in conditions associated with sustained awareness. Interestingly, the amplitude of the CDA was correlated with individual differences in visual awareness, suggesting that this activity plays a significant role in the maintenance of objects in consciousness. The CDA is typically associated with visual short-term memory (VSTM), suggesting that conscious visual awareness may be mediated by the same neural and cognitive mechanisms that support VSTM. Our results demonstrate that the CDA may reflect the contents of conscious awareness, and therefore can provide a measure to track when information moves in and out of consciousness.
尽管近年来我们对意识相关的认知和神经过程有了更深入的了解，但支持意识的确切机制仍然难以捉摸。检查与刺激进入或退出意识时刻相关的神经相关性，是确定产生意识的神经机制的一种方法。在本研究中，我们使用脑电图（EEG）记录参与者观察双边运动形状（SFM）显示时的神经活动。当显示处于运动状态时，观察者感知到一个立即与嘈杂背景分离的物体。运动停止后，观察者对物体的体验会在意识中暂时保持，然后最终从意识中淡出，回到嘈杂的背景中。与主观感知体验的报告一致，我们观察到了一种显著的持续后对侧负性，称为对侧延迟活动（CDA）。这种活动仅在与持续意识相关的条件下持续存在。有趣的是，CDA 的振幅与视觉意识的个体差异相关，表明这种活动在维持意识中的物体方面起着重要作用。CDA 通常与视觉短期记忆（VSTM）相关，这表明意识视觉可能由支持 VSTM 的相同神经和认知机制介导。我们的结果表明，CDA 可能反映了意识的内容，因此可以提供一种衡量标准，以跟踪信息何时进入和退出意识。
