State Key Laboratory of Cognitive Neuroscience and Learning, IDG/McGovern Institute for Brain Research, Beijing Normal University, 100875, China; College of Biomedical Engineering and Instrument Sciences, Zhejiang University, 310027, China.
Department of Neurology, Huashan Hospital, Fudan University, 200040, China.
Cortex. 2019 Nov;120:78-91. doi: 10.1016/j.cortex.2019.05.014. Epub 2019 Jun 12.
Although the human temporal lobe has been documented to participate in semantic processing of both verbal and nonverbal stimuli, the exact neural basis underlying the common and unique processing of the two modalities is unclear. Semantic dementia (SD), a disease with a semantic-selective deficit due to predominant temporal lobe atrophy is an ideal lesion model to address this issue. However, many previous studies of SD used an impure patient sample or did not appropriately control for common components between tasks. To overcome these limitations, the present study aims to identify amodal semantic hubs and modality-specific regions in the temporal lobe by investigating behavioral performance on a verbal modality task (word associative matching) and a nonverbal modality task (picture associative matching) and neuroimaging data in 33 SD patients. We found that the left anterior fusiform gyrus was an amodal semantic hub whose gray matter volume correlated significantly with both modalities. We also observed two verbal modality-specific regions (the left posterior inferior temporal gyrus and the left middle superior temporal gyrus) and a nonverbal modality-specific region (the right lateral anterior middle temporal gyrus) whose gray matter volume correlated significantly with one modality when performance on the other modality was partialled out. The results remained significant when we excluded a wide range of potential confounding variables. Furthermore, to confirm the observed effects, we compared the performance of left- and right-hemispheric-predominant atrophic patients on the verbal and nonverbal tasks. The left-predominant patients showed more severe deficits in performance of the verbal task than the right-predominant patients, whereas the two groups of patients presented comparable deficits in the performance of the nonverbal task. These findings refined the structure of semantic network in the temporal lobe, deepening our understanding of the critical role of the temporal lobe in semantic processing.
尽管人类颞叶已被证明参与了言语和非言语刺激的语义处理，但两种模态共同和独特处理的精确神经基础尚不清楚。语义性痴呆（Semantic Dementia，SD）是一种由于颞叶主要萎缩导致的语义选择性缺陷的疾病，是解决这一问题的理想病变模型。然而，许多以前的 SD 研究使用了不纯的患者样本，或者没有适当控制任务之间的共同成分。为了克服这些限制，本研究旨在通过研究 33 名 SD 患者的言语模态任务（词联想匹配）和非言语模态任务（图片联想匹配）的行为表现和神经影像学数据，来确定颞叶中的无模态语义枢纽和模态特异性区域。我们发现，左侧前梭状回是一个无模态语义枢纽，其灰质体积与两种模态均显著相关。我们还观察到两个言语模态特异性区域（左侧后下颞叶和左侧中颞上回）和一个非言语模态特异性区域（右侧外侧前中颞叶），当排除另一种模态的表现时，其灰质体积与一种模态显著相关。当排除广泛的潜在混杂变量时，结果仍然显著。此外，为了确认观察到的效应，我们比较了左半球和右半球优势萎缩患者在言语和非言语任务上的表现。左优势患者在言语任务上的表现比右优势患者更严重，而两组患者在非言语任务上的表现则相当。这些发现细化了颞叶语义网络的结构，加深了我们对颞叶在语义处理中关键作用的理解。
