Figure–ground modulation, i.e., the enhancement of neuronal responses evoked by the figure relative to the background, has three complementary components: edge modulation (boundary detection), center modulation (region filling), and background modulation (background suppression). However, the neuronal mechanisms mediating these three modulations and how they depend on awareness remain unclear. For each modulation, we compared both the cueing effect produced in a Posner paradigm and fMRI blood oxygen-level dependent (BOLD) signal in primary visual cortex (V1) evoked by visible relative to invisible orientation-defined figures. We found that edge modulation was independent of awareness, whereas both center and background modulations were strongly modulated by awareness, with greater modulations in the visible than the invisible condition. Effective-connectivity analysis further showed that the awareness-dependent region-filling and background-suppression processes in V1 were not derived through intracortical interactions within V1, but rather by feedback from the frontal eye field (FEF) and dorsolateral prefrontal cortex (DLPFC), respectively. These results indicate a source for an awareness-dependent figure–ground segregation in human prefrontal cortex.

图地调制，即由图引起的神经元反应相对于背景的增强，具有三个互补的组成部分：边缘调制（边界检测）、中心调制（区域填充）和背景调制（背景抑制）。然而，介导这三种调节的神经元机制以及它们如何依赖于意识仍不清楚。对于每个调制，我们比较了在 Posner 范式中产生的提示效应和初级视觉皮层 (V1) 中由可见相对于不可见方向定义的图形引起的 fMRI 血氧水平依赖 (BOLD) 信号。我们发现边缘调制与意识无关，而中心和背景调制都受到意识的强烈调制，可见的调制比不可见的调制更大。有效连接分析进一步表明，V1 中依赖于意识的区域填充和背景抑制过程不是通过 V1 内的皮层内相互作用产生的，而是来自额叶眼场 (FEF) 和背外侧前额叶皮层 (DLPFC) 的反馈，分别。这些结果表明人类前额叶皮层中依赖于意识的图形-地面分离的来源。