Semantic retrieval during overt picture description: Left anterior temporal or the parietal lobe?
Semantic retrieval during overt picture description: Left anterior temporal or the parietal lobe?
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DOI：
10.1016/j.neuropsychologia.2014.12.012
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发表时间：
2015-09
期刊：
影响因子：
2.6
通讯作者：
Wise RJ
中科院分区：
文献类型：
--
作者：
Geranmayeh F;Leech R;Wise RJ
语义表征的提取是显性言语产生的核心过程。越来越多的人达成共识，认为必须存在一个非模态的语义‘中枢’，将特定于通道的概念表示结合在一起。根据额叶退行性变患者萎缩的分布和行为缺陷，提出该中枢定位于双侧前颞叶(ATL)，并通过左侧ATL与言语输出系统进行功能联系。另一种观点可以追溯到Geschind于1965年提出的观点，即角回(AG)是基于对象的语义表征的核心。在这项fMRI研究中，我们检查了左侧ATL和顶叶(PL)与已知在显性图片描述过程中激活的全脑网络的连接性。我们使用独立成分分析将这两个大脑体积分别分解为15个感兴趣区域(ROI)。使用双重回归分析来建立每个ROI与整个脑网络的连接。左侧前上颞沟(AntSTS)内的ROI在功能上与左侧ATL的其他部分相连，包括前腹内侧左侧颞叶皮质(因易感性伪影而信号部分减弱)、大的左侧背外侧前额叶区域(包括经典的Broca区)、广泛的双侧感觉-运动皮质以及双侧颞上回的长度。这个功能连接的网络的时间进程与图片描述有关，但与非语义基线任务无关。该系统具有预期的分布，以产生具有适当语义内容的显性语音，并对显性语音输出进行听觉监控。相比之下，唯一显示出与大脑系统的连接的PL ROI被图片描述任务最强烈地激活，这是在顶上叶(SUPL)。这一区域显示了与图像刺激视觉处理所需的主要后部皮质区域的连接，另外还有与左侧AG背侧和左额下回的一小部分的连接。包括左侧AG的一部分在内的其他PL ROI都不是仅由言语激活的。对这些结果的最好解释是，左侧的antSTS连接了所提出的语义中枢(根据临床神经心理学研究，特别是定位于前颞叶腹侧皮质)到负责公开产生语音的额后区和感觉-运动皮质。语义认知依赖于语义中枢与输入/输出系统的连接。我们在语音过程中检测了左侧ATL和PL亚区的连接性。在语言过程中，ATL亚区与Broca区和感觉-运动皮质相连。一个PL亚区与主要参与图片刺激知觉加工的系统有关。左边的ATL将建议的语义中枢连接到输出系统，以生成公开的语音。
Retrieval of semantic representations is a central process during overt speech production. There is an increasing consensus that an amodal semantic ‘hub’ must exist that draws together modality-specific representations of concepts. Based on the distribution of atrophy and the behavioral deficit of patients with the semantic variant of fronto-temporal lobar degeneration, it has been proposed that this hub is localized within both anterior temporal lobes (ATL), and is functionally connected with verbal ‘output’ systems via the left ATL. An alternative view, dating from Geschwind's proposal in 1965, is that the angular gyrus (AG) is central to object-based semantic representations. In this fMRI study we examined the connectivity of the left ATL and parietal lobe (PL) with whole brain networks known to be activated during overt picture description. We decomposed each of these two brain volumes into 15 regions of interest (ROIs), using independent component analysis. A dual regression analysis was used to establish the connectivity of each ROI with whole brain-networks. An ROI within the left anterior superior temporal sulcus (antSTS) was functionally connected to other parts of the left ATL, including anterior ventromedial left temporal cortex (partially attenuated by signal loss due to susceptibility artifact), a large left dorsolateral prefrontal region (including ‘classic’ Broca's area), extensive bilateral sensory-motor cortices, and the length of both superior temporal gyri. The time-course of this functionally connected network was associated with picture description but not with non-semantic baseline tasks. This system has the distribution expected for the production of overt speech with appropriate semantic content, and the auditory monitoring of the overt speech output. In contrast, the only left PL ROI that showed connectivity with brain systems most strongly activated by the picture-description task, was in the superior parietal lobe (supPL). This region showed connectivity with predominantly posterior cortical regions required for the visual processing of the pictorial stimuli, with additional connectivity to the dorsal left AG and a small component of the left inferior frontal gyrus. None of the other PL ROIs that included part of the left AG were activated by Speech alone. The best interpretation of these results is that the left antSTS connects the proposed semantic hub (specifically localized to ventral anterior temporal cortex based on clinical neuropsychological studies) to posterior frontal regions and sensory-motor cortices responsible for the overt production of speech. Semantic cognition depends on connectivity of semantic hub with input/output systems. We examined the connectivity of the left ATL and PL sub-regions during speech. An ATL sub-region was linked to Broca's area and sensory-motor cortices during Speech. A PL subregion was linked to systems involved in predominantly perceptual processing of picture stimuli. The left ATL connects the proposed semantic hub to output systems for overt speech production.