University of Oregon, Eugene, OR, USA.
Cereb Cortex. 2012 Dec;22(12):2733-44. doi: 10.1093/cercor/bhr346. Epub 2011 Dec 12.
As demonstrated by the attentional blink (AB) phenomenon, awareness for attended stimuli is governed by sharp capacity limits. We used a linguistic AB task to investigate the neural mechanisms that underlie failures of awareness, examining both event-related potentials and oscillatory brain activity to correctly reported and missed second targets (T2s) presented after a correctly reported first target (T1) in a rapid visual stream of distractors. Correctly reported targets occurring at a short lag (250 ms) after T1-within the classic AB period-elicited enhanced late gamma activity relative to incorrectly reported targets but showed no P300 modulation relative to missed targets. In contrast, correctly reported targets presented at a long lag (830 ms)-outside the classic AB period-elicited a greater P300 component but did not significantly modulate oscillatory activity. This double dissociation suggests that there are multiple neural mechanisms supporting awareness that may operate in parallel. Either the P300 or the gamma can index impairment in the cascade of processing leading to a target's entry into awareness. We conclude that the P300 and gamma activity reflect functionally distinct neural mechanisms, each of which plays an independent role in awareness.
正如注意瞬脱（AB）现象所表明的，对注意刺激的意识受到敏锐的容量限制的控制。我们使用语言 AB 任务来研究意识失败的神经机制，同时检查事件相关电位和振荡脑活动，以正确报告和错过在快速视觉流中呈现的第二个目标（T2）后呈现的第一个目标（T1）。在 T1 后短时间（250 毫秒）出现的正确报告的目标——在经典 AB 期间内——相对于错误报告的目标引起了增强的后期伽马活动，但相对于错过的目标没有 P300 调制。相比之下，在经典 AB 期间之外的长时间（830 毫秒）出现的正确报告的目标引起了更大的 P300 成分，但对振荡活动没有显著调制。这种双重分离表明，有多种支持意识的神经机制可能并行运作。要么是 P300，要么是伽马可以指示导致目标进入意识的处理级联中的损伤。我们得出结论，P300 和伽马活动反映了功能上不同的神经机制，每个机制在意识中都起着独立的作用。
