Railo Henry, Revonsuo Antti, Koivisto Mika
Department of Psychology, University of Turku, 20014, Finland.
Centre for Cognitive Neuroscience, University of Turku, 20014, Finland.
Neurosci Conscious. 2015 Jan;2015(1):niv004. doi: 10.1093/nc/niv004. Epub 2015 Jul 30.
A fundamental unsettled dispute concerns how fast the brain generates subjective visual experiences. Both early visual cortical activation and later activity in fronto-parietal global neuronal workspace correlate with conscious vision, but resolving which of the correlates causally triggers conscious vision has proved a methodological impasse. We show that participants can report whether or not they consciously perceived a stimulus in just over 200 ms. These fast consciousness reports were extremely reliable, and did not include reflexive, unconscious responses. The neural events that causally generate conscious vision must have occurred before these behavioral reports. Analyses on single-trial neural correlates of consciousness revealed that the late cortical processing in fronto-parietal global neuronal workspace (∼300 ms) started after the fastest consciousness reports, ruling out the possibility that this late activity directly reflects the emergence of visual consciousness. The consciousness reports were preceded by a negative amplitude difference (∼160-220 ms) that spread from occipital to frontal cortex, suggesting that this correlate underlies the emergence of conscious vision.
一个尚未解决的基本争议涉及大脑产生主观视觉体验的速度有多快。早期视觉皮层激活以及额叶 - 顶叶全局神经元工作空间中较晚的活动都与有意识视觉相关，但要确定这些相关因素中哪一个能因果性地触发有意识视觉，已证明是一个方法上的僵局。我们发现，参与者能够在略超过200毫秒的时间内报告他们是否有意识地感知到了一个刺激。这些快速的意识报告极其可靠，且不包括反射性的无意识反应。因果性地产生有意识视觉的神经事件必定发生在这些行为报告之前。对意识的单次试验神经相关因素的分析表明，额叶 - 顶叶全局神经元工作空间中的晚期皮层处理（约300毫秒）在最快的意识报告之后才开始，排除了这种晚期活动直接反映视觉意识出现的可能性。意识报告之前存在一个从枕叶扩散到额叶皮层的负向振幅差异（约160 - 220毫秒），这表明这种相关因素是有意识视觉出现的基础。
