Boehler C N, Schoenfeld M A, Heinze H-J, Hopf J-M
Leibniz Institute for Neurobiology, D-39118 Magdeburg, Germany.
Proc Natl Acad Sci U S A. 2008 Jun 24;105(25):8742-7. doi: 10.1073/pnas.0801999105. Epub 2008 Jun 12.
Visual awareness has been proposed to depend on recurrent processing in early visual cortex areas including the primary visual cortex (V1). Here, we address this hypothesis with high spatiotemporal resolution magnetoencephalographic recordings in subjects performing a substitution masking paradigm. Neural activity reflecting awareness is assessed by directly comparing the neuromagnetic response elicited by effectively and ineffectively masked targets after the proportion of trials leading to masking was individually adjusted to match the proportion of trials without masking. This revealed a modulation of recurrent activity in the primary visual cortex rapidly after the onset of the feedforward sweep of processing in striate and extrastriate areas but significantly before the onset of attention-dependent recurrent modulations in V1. Our data provide direct support for the notion that (i) recurrent processing in V1 correlates with visual awareness and (ii) that attention and awareness involve distinct recurrent processing operations.
视觉意识被认为依赖于早期视觉皮层区域（包括初级视觉皮层V1）中的循环处理。在此，我们通过对执行替代掩蔽范式的受试者进行高时空分辨率的脑磁图记录来验证这一假设。通过在个体调整导致掩蔽的试验比例以匹配无掩蔽试验比例后，直接比较有效和无效掩蔽目标引发的神经磁反应，来评估反映意识的神经活动。这揭示了在纹状和纹外区域前馈处理扫描开始后不久，但在V1中注意力依赖的循环调制开始之前，初级视觉皮层中循环活动的调制。我们的数据为以下观点提供了直接支持：（i）V1中的循环处理与视觉意识相关；（ii）注意力和意识涉及不同的循环处理操作。
