Koivisto Mika, Revonsuo Antti, Lehtonen Minna
Centre for Cognitive Neuroscience, University of Turku, FIN-20014 Turku, Finland.
Cereb Cortex. 2006 Mar;16(3):415-24. doi: 10.1093/cercor/bhi121. Epub 2005 Jun 15.
Recent brain imaging studies have revealed that increased neural activity along the ventral visual stream and parietal and frontal areas is associated with visual awareness. In order to study the time-course and temporal aspects of awareness, we examined electrophysiological correlates of conscious vision in two masking experiments. The differences in event-related potentials (ERPs) between unmasked (consciously recognized) and masked (unrecognized) stimuli were considered to be electrophysiological correlates of awareness. Two attentional conditions (global, local) were included to examine the relationship between the scope of attention and awareness. Two ERP-deflections were found to correlate with awareness. First, awareness was associated with a posterior negative amplitude shift 130-320 ms after the stimulus. This effect was present in both attention conditions, suggesting that it emerges independent of the scope of attention. Second, ERPs to unmasked stimuli became more positive as compared with masked stimuli around 400 ms, peaking at parietal sites. This effect was attenuated in the local attention condition, although the participants were aware of the stimuli, suggesting that the late positivity does not directly correlate with visual awareness. The results imply that the earlier negativity is the earliest and most direct correlate of visual awareness.
最近的脑成像研究表明，腹侧视觉通路以及顶叶和额叶区域神经活动的增加与视觉意识相关。为了研究意识的时间进程和时间特征，我们在两项掩蔽实验中检测了有意识视觉的电生理相关指标。未被掩蔽（被有意识识别）和被掩蔽（未被识别）刺激之间的事件相关电位（ERP）差异被视为意识的电生理相关指标。实验纳入了两种注意力条件（整体、局部），以检验注意力范围与意识之间的关系。结果发现有两种ERP偏转与意识相关。首先，意识与刺激后130 - 320毫秒出现的后部负向振幅偏移有关。这种效应在两种注意力条件下均存在，表明它的出现与注意力范围无关。其次，与被掩蔽刺激相比，未被掩蔽刺激在约400毫秒时ERP变得更正，在顶叶部位达到峰值。尽管参与者意识到了刺激，但在局部注意力条件下这种效应减弱了，这表明晚期正性波与视觉意识没有直接关联。结果表明，较早出现的负向波是视觉意识最早且最直接的相关指标。
