National Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, Beijing, China, 100875.
IDG/McGovern Institute for Brain Research, Beijing Normal University, Beijing, China, 100875.
J Neurosci. 2018 Mar 28;38(13):3303-3317. doi: 10.1523/JNEUROSCI.2562-17.2018. Epub 2018 Feb 23.
Concepts can be related in many ways. They can belong to the same taxonomic category (e.g., "doctor" and "teacher," both in the category of people) or be associated with the same event context (e.g., "doctor" and "stethoscope," both associated with medical scenarios). How are these two major types of semantic relations coded in the brain? We constructed stimuli from three taxonomic categories (people, manmade objects, and locations) and three thematic categories (school, medicine, and sports) and investigated the neural representations of these two dimensions using representational similarity analyses in human participants (10 men and nine women). In specific regions of interest, the left anterior temporal lobe (ATL) and the left temporoparietal junction (TPJ), we found that, whereas both areas had significant effects of taxonomic information, the taxonomic relations had stronger effects in the ATL than in the TPJ ("doctor" and "teacher" closer in ATL neural activity), with the reverse being true for thematic relations ("doctor" and "stethoscope" closer in TPJ neural activity). A whole-brain searchlight analysis revealed that widely distributed regions, mainly in the left hemisphere, represented the taxonomic dimension. Interestingly, the significant effects of the thematic relations were only observed after the taxonomic differences were controlled for in the left TPJ, the right superior lateral occipital cortex, and other frontal, temporal, and parietal regions. In summary, taxonomic grouping is a primary organizational dimension across distributed brain regions, with thematic grouping further embedded within such taxonomic structures. How are concepts organized in the brain? It is well established that concepts belonging to the same taxonomic categories (e.g., "doctor" and "teacher") share neural representations in specific brain regions. How concepts are associated in other manners (e.g., "doctor" and "stethoscope," which are thematically related) remains poorly understood. We used representational similarity analyses to unravel the neural representations of these different types of semantic relations by testing the same set of words that could be differently grouped by taxonomic categories or by thematic categories. We found that widely distributed brain areas primarily represented taxonomic categories, with the thematic categories further embedded within the taxonomic structure.
概念可以通过多种方式联系在一起。它们可以属于同一分类范畴（例如，“医生”和“教师”都属于“人”这一范畴），或者与同一事件背景相关联（例如，“医生”和“听诊器”都与医疗场景相关联）。这两种主要类型的语义关系在大脑中是如何编码的？我们从三个分类范畴（人、人造物品和地点）和三个主题范畴（学校、医学和运动）构建刺激，并在人类参与者中使用代表性相似性分析来研究这两个维度的神经表示（10 名男性和 9 名女性）。在特定的感兴趣区域，左前颞叶（ATL）和左颞顶联合区（TPJ），我们发现，虽然这两个区域都有显著的分类信息效应，但在 ATL 中，分类关系的效应比在 TPJ 中更强（在 ATL 神经活动中，“医生”和“教师”更接近），而主题关系则相反（在 TPJ 神经活动中，“医生”和“听诊器”更接近）。一个全脑搜索光分析显示，广泛分布的区域，主要在左半球，代表了分类维度。有趣的是，只有在控制了左 TPJ、右上外侧枕叶和其他额叶、颞叶和顶叶区域的分类差异后，主题关系的显著效应才会出现。总之，分类分组是分布在大脑中的主要组织维度，主题分组进一步嵌入在这种分类结构中。概念在大脑中是如何组织的？众所周知，属于同一分类范畴的概念（例如，“医生”和“教师”）在特定的大脑区域共享神经表示。概念以其他方式（例如，“医生”和“听诊器”，它们在主题上相关）如何相关联仍知之甚少。我们使用代表性相似性分析来揭示这些不同类型语义关系的神经表示，方法是测试同一组可以通过分类范畴或主题范畴进行不同分组的单词。我们发现，广泛分布的大脑区域主要代表分类范畴，主题范畴进一步嵌入在分类结构中。
