Representational similarity analysis reveals commonalities and differences in the semantic processing of words and objects.
Representational similarity analysis reveals commonalities and differences in the semantic processing of words and objects.
复制标题
DOI：
10.1523/jneurosci.3809-13.2013
复制
发表时间：
2013-11-27
期刊：
影响因子：
--
通讯作者：
Tyler LK
中科院分区：
文献类型：
--
作者：
Devereux BJ;Clarke A;Marouchos A;Tyler LK
理解单词和物体的含义需要激活潜在的概念表征。语义表示通常被假定为被编码，使得无论输入模态如何都能唤起意义。然而，在多大程度上意义编码在模态独立或非模态系统仍然存在争议。我们解决这个问题，在人类功能磁共振成像研究调查的神经处理的概念，分别提出书面文字和图片。每个单词和图片的激活图被用作基于探照灯的多体素模式分析的输入。表征相似性分析被用来识别与词和对象的低层次视觉模型相关的区域以及两者共同的语义类别结构。两种模式的共同语义类别效应被发现在左侧化的网络，包括左后颞中回（LpMTG），左角回，左顶内沟（LIPS），除了对象和单词特定的语义处理在腹侧颞叶皮层和更前MTG，分别。为了探索不同区域和模式的代表性内容的差异，我们开发了新的数据驱动分析，基于探照灯相异性矩阵的k均值聚类和种子相关性分析。这些揭示了语义敏感区域中的表征的细微差异，LIPS中的表征相对于刺激模态不变，LpMTG中的表征在模态之间不相关。这些结果表明，虽然LpMTG和LIPS都参与语义处理，只有LIPS的功能作用是相同的，无论视觉输入，而LpMTG的功能作用不同的单词和对象。
Understanding the meanings of words and objects requires the activation of underlying conceptual representations. Semantic representations are often assumed to be coded such that meaning is evoked regardless of the input modality. However, the extent to which meaning is coded in modality-independent or amodal systems remains controversial. We address this issue in a human fMRI study investigating the neural processing of concepts, presented separately as written words and pictures. Activation maps for each individual word and picture were used as input for searchlight-based multivoxel pattern analyses. Representational similarity analysis was used to identify regions correlating with low-level visual models of the words and objects and the semantic category structure common to both. Common semantic category effects for both modalities were found in a left-lateralized network, including left posterior middle temporal gyrus (LpMTG), left angular gyrus, and left intraparietal sulcus (LIPS), in addition to object- and word-specific semantic processing in ventral temporal cortex and more anterior MTG, respectively. To explore differences in representational content across regions and modalities, we developed novel data-driven analyses, based on k-means clustering of searchlight dissimilarity matrices and seeded correlation analysis. These revealed subtle differences in the representations in semantic-sensitive regions, with representations in LIPS being relatively invariant to stimulus modality and representations in LpMTG being uncorrelated across modality. These results suggest that, although both LpMTG and LIPS are involved in semantic processing, only the functional role of LIPS is the same regardless of the visual input, whereas the functional role of LpMTG differs for words and objects.