Division of Neuroscience & Experimental Psychology, School of Biological Sciences, The University of Manchester, UK; Faculty of Medicine and Surgery, University of Malta, Malta.
Division of Neuroscience & Experimental Psychology, School of Biological Sciences, The University of Manchester, UK.
Cortex. 2019 Nov;120:298-307. doi: 10.1016/j.cortex.2019.06.014. Epub 2019 Jul 11.
The hub-and-spoke model of semantic cognition seeks to reconcile embodied views of a fully distributed semantic network with patient evidence, primarily from semantic dementia, who demonstrate modality-independent conceptual deficits associated with atrophy centred on the ventrolateral anterior temporal lobe. The proponents of this model have recently suggested that the temporal cortex is a graded representational space where concepts become less linked to a specific modality as they are processed farther away from primary and secondary sensory cortices and towards the ventral anterior temporal lobe. To explore whether there is evidence that the connectivity patterns of the temporal lobe converge in its ventral anterior end the current study uses three dimensional Laplacian eigenmapping, a technique that allows visualisation of similarity in a low dimensional space. In this space similarity is encoded in terms of distances between data points. We found that the ventral and anterior temporal lobe is in a unique position of being at the centre of mass of the data points within the connective similarity space. This can be interpreted as the area where the connectivity profiles of all other temporal cortex voxels converge. This study is the first to explicitly investigate the pattern of connectivity and thus provides the missing link in the evidence that the ventral anterior temporal lobe can be considered a multi-modal graded hub.
语义认知的中心辐射模型试图调和具有充分分布式语义网络的体现观点与患者证据（主要来自语义性痴呆），后者表现出与腹外侧前颞叶萎缩相关的、与模态无关的概念缺陷。该模型的支持者最近提出，颞叶是一个渐变的表示空间，随着概念从初级和次级感觉皮层更远地向腹侧前颞叶移动，它们与特定模态的联系变得越来越不紧密。为了探索颞叶的连接模式是否在其腹侧前端会聚，本研究使用了三维拉普拉斯特征映射，这是一种可以在低维空间中可视化相似性的技术。在这个空间中，相似性用数据点之间的距离来表示。我们发现，腹侧和前颞叶处于连接相似性空间中数据点质心的独特位置。这可以解释为所有其他颞叶皮层体素的连接分布集中在该区域。这项研究首次明确地调查了连接模式，从而为腹侧前颞叶可以被视为多模态渐变中枢的证据提供了缺失的一环。
