Department of Psychology and Neuroscience, Duke University, Durham, NC 27708, USA.
Department of Psychological and Brain Sciences, Dartmouth College, Hanover, NH 03755, USA.
Neuropsychologia. 2019 May;128:73-77. doi: 10.1016/j.neuropsychologia.2017.10.034. Epub 2017 Oct 31.
Although backward masking is a powerful experimental tool in mitigating visual awareness of facial expressions of emotion, ~20% of participants consistently report being resistant to its effects. In our previous studies, we excluded these participants from analysis as we focused on neural data in individuals who were subjectively unaware of backward-masked facial features that were presented for a brief period of time (e.g., 17ms). Here, we shifted our focus to potential structural brain difference between aware and unaware participants. To achieve this, structural magnetic resonance imaging (sMRI) data were pooled from two recent backward masking studies of emotional faces or eye whites (Kim et al., 2016, 2010). Out of a total of 64 participants, 12 reported being subjectively aware of the masked faces or their facial features. Whole-brain, voxel-based morphometric analysis of structural MRI data yielded significantly greater volume of the posterior thalamus, including the bilateral pulvinar, for the subjectively aware versus unaware individuals. No other brain region showed significant volumetric differences between groups. The present findings offer a neuroanatomical basis for visual awareness of emotional content in the form of backward-masked facial features, which complements the known functional role of the pulvinar in such neurobehavioral processes.
尽管后向掩蔽是减轻人们对情绪面部表情的视觉意识的有力实验工具，但仍有约 20%的参与者始终对其效果有抵抗力。在我们之前的研究中，由于我们专注于那些主观上无法意识到短暂呈现的（例如 17 毫秒）后向掩蔽面部特征的个体的神经数据，因此将这些参与者排除在分析之外。在这里，我们将注意力转向有意识和无意识参与者之间潜在的结构脑差异。为此，我们汇集了两个最近的关于情绪面孔或眼白的后向掩蔽研究的结构磁共振成像 (sMRI) 数据（Kim 等人，2016 年，2010 年）。在总共 64 名参与者中，有 12 名报告主观上意识到了被掩蔽的面孔或其面部特征。对结构 MRI 数据的全脑体素形态计量学分析得出，与无意识个体相比，主观上有意识的个体的丘脑后部，包括双侧的丘脑枕体积更大。两组之间没有其他脑区显示出明显的体积差异。本研究结果为以向后掩蔽面部特征形式出现的情绪内容的视觉意识提供了神经解剖学基础，这补充了已知的丘脑枕在这些神经行为过程中的功能作用。
