Dissociating effects on encoding versus access in visual masking

两个互补的过程在调节视觉刺激是否到达人的意识中起着作用。首先，刺激必须在视觉系统中进行编码。其次，大脑必须提供在视觉皮质中表示刺激的途径。目前尚不清楚哪些大脑过程分别调节编码和信息获取。重要的是，表征、编码和获取之间的区别并不遵循视觉和前额叶皮质区域之间的简单区别。这是因为视觉脑区参与调节通路(例如，通过V4中的注意功能)，而前额叶区域可以参与对刺激的编码。在这里，我们提出了一个项目，将使用基于多变量解码和功能磁共振的信息论框架来研究编码和获取的大脑皮层机制。我们将研究在不同形式的掩蔽下，可见刺激和不可见刺激之间的渐变转换如何导致视觉大脑区域以及传统视觉系统以外的区域(包括前额叶皮质)刺激特征编码的变化。这将有助于揭示受视觉感知调节的大脑区域在多大程度上确实参与了特定刺激特征的编码。

Two complementary processes play a role in regulating whether a visual stimulus reaches a person's awareness. First, the stimulus has to be encoded in the visual system. Second, the brain has to provide access to a representation of the stimulus in visual cortex. Currently it is unclear which brain processes mediate encoding and access respectively. Importantly, the distinction between representation or encoding and access does not follow a simple distinction between visual and prefrontal cortical regions. This is because visual brain regions take place in regulating access (for example via attentional functions in V4), and prefrontal regions can take part in encoding of stimuli. Here we propose a project that will investigate the cortical mechanisms of encoding and access using an information-theoretic framework based on multivariate decoding in combination with fMRI. We will investigate how graded transitions between visible and invisible stimuli under different forms of masking lead to changes in the encoding of stimulus features in visual brain regions, but also in regions outside the traditional visual system including prefrontal cortex. This will help reveal to which degree brain regions that are modulated by visual awareness are indeed involved in encoding of specific stimulus features.