BACKGROUND In healthy subjects (HS), transcranial magnetic stimulation (TMS) demonstrated an increase in motor-evoked potential (MEP) amplitudes during specific linguistic tasks. This finding indicates functional connections between speech-related cortical areas and the dominant primary motor cortex (M1). OBJECTIVE To investigate M1 function with TMS and the speech-related cortical network with neuroimaging measures in frontotemporal dementia (FTD), including the non-fluent variant of primary progressive aphasia (nfv-PPA) and the behavioral variant of FTD (bv-FTD). METHODS M1 excitability changes during specific linguistc tasks were examined using TMS in 24 patients (15 with nfv-PPA and 9 with bv-FTD) and in 18 age-matched HS. In the same patients neuroimaging was used to assess changes in specific white matter (WM) bundles and grey matter (GM) regions involved in language processing, with diffusion tensor imaging (DTI) and voxel-based morphometry (VBM). RESULTS During the linguistic task, M1 excitability increased in HS, whereas in FTD patients it did not. M1 excitability changes were comparable in nfv-PPA and bv-FTD. DTI revealed decreased fractional anisotropy in the superior and inferior longitudinal and uncinate fasciculi. Moreover, VBM disclosed GM volume loss in the left frontal operculum though not in the parietal operculum or precentral gyrus. Furthermore, WM and GM changes were comparable in nfv-PPA and bv-FTD. There was no correlation between neurophysiological and neuroimaging changes in FTD. Atrophy in the left frontal operculum correlated with linguistic dysfunction, assessed by semantic and phonemic fluency tests. CONCLUSION We provide converging neurophysiological and neuroimaging evidence of abnormal speech-related cortical network activation in FTD.

中文翻译：

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额颞叶痴呆中言语相关皮质网络的改变

背景在健康受试者 (HS) 中，经颅磁刺激 (TMS) 在特定语言任务期间表现出运动诱发电位 (MEP) 振幅的增加。这一发现表明与语音相关的皮层区域和占主导地位的初级运动皮层 (M1) 之间的功能联系。目的通过额颞叶痴呆（FTD），包括原发性进行性失语症（nfv-PPA）的非流利变体（nfv-PPA）和FTD的行为变体（bv-FTD），研究TMS和言语相关皮层网络与神经影像学测量的M1功能. 方法 使用 TMS 在 24 名患者（15 名使用 nfv-PPA 和 9 名使用 bv-FTD）和 18 名年龄匹配的 HS 中检查特定语言学任务期间 M1 兴奋性的变化。在同一患者中，神经影像学用于评估参与语言处理的特定白质 (WM) 束和灰质 (GM) 区域的变化，使用扩散张量成像 (DTI) 和基于体素的形态测量学 (VBM)。结果 在语言任务中，HS 患者的 M1 兴奋性增加，而 FTD 患者则没有。M1 兴奋性变化在 nfv-PPA 和 bv-FTD 中具有可比性。DTI 显示上下纵束和钩状束的各向异性分数降低。此外，VBM 显示左额叶盖的 GM 体积损失，但在顶叶盖或中央前回没有。此外，WM 和 GM 的变化在 nfv-PPA 和 bv-FTD 中具有可比性。FTD 的神经生理学和神经影像学变化之间没有相关性。通过语义和音素流畅性测试评估的左额叶盖萎缩与语言功能障碍相关。结论 我们提供了 FTD 中异常语音相关皮层网络激活的融合神经生理学和神经影像学证据。