Frontal White Matter Tracts Sustaining Speech Production in Primary Progressive Aphasia
Frontal White Matter Tracts Sustaining Speech Production in Primary Progressive Aphasia
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DOI：
10.1523/jneurosci.3464-13.2014
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发表时间：
2014-07-16
影响因子：
5.3
通讯作者：
Gorno-Tempini, Maria Luisa
中科院分区：
文献类型：
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作者：
Mandelli, Maria Luisa;Caverzasi, Eduardo;Gorno-Tempini, Maria Luisa
在原发性进行性失语症（PPA）中，言语和语言困难是由特定大脑网络的神经变性引起的。在nonfluent/agrammatic变体（nfvPPA），运动语言和语法缺陷与萎缩的左额-岛-纹状体网络先前涉及的语音生产。在体内解剖的交叉白色物质（WM）束内的这个“语音生产网络”是复杂的，很少进行健康或PPA。我们假设这些神经束的损伤是nfvPPA特有的，并且与患者流畅能力的不同方面相关。我们前瞻性研究了25名PPA和21名健康个体，他们接受了广泛的认知测试和3 T MRI。在高角分辨率弥散加权成像（HARDI）上使用残余引导Q球概率纤维束成像，我们重建了连接后下额叶、下运动前区、小脑、辅助运动区（SMA）复合体、纹状体和标准腹侧和背侧语言通路的通路。我们提取了特定的弥散张量成像（DTI）指标，以评估PPA变体的变化并进行脑行为相关性。在nfvPPA中发现了左额内和额纹状体通路的显著WM变化，但在语义或逻辑变异中没有发现。特定的DTI指标与认知评分之间的相关性证实了这一前背网络在流畅性方面的具体参与，并建议后运动前SMA通路在运动言语中的优先作用。这项研究表明，左WM通路连接的语音生产网络选择性损害nfvPPA，并表明，在这个系统中的不同道参与流畅性的子组件。这些发现强调了扩散成像在神经退行性疾病鉴别诊断中的新作用。
In primary progressive aphasia (PPA), speech and language difficulties are caused by neurodegeneration of specific brain networks. In the nonfluent/agrammatic variant (nfvPPA), motor speech and grammatical deficits are associated with atrophy in a left fronto-insular-striatal network previously implicated in speech production. In vivo dissection of the crossing white matter (WM) tracts within this "speech production network" is complex and has rarely been performed in health or in PPA. We hypothesized that damage to these tracts would be specific to nfvPPA and would correlate with differential aspects of the patients' fluency abilities. We prospectively studied 25 PPA and 21 healthy individuals who underwent extensive cognitive testing and 3 T MRI. Using residual bootstrap Q-ball probabilistic tractography on high angular resolution diffusion-weighted imaging (HARDI), we reconstructed pathways connecting posterior inferior frontal, inferior premotor, insula, supplementary motor area (SMA) complex, striatum, and standard ventral and dorsal language pathways. We extracted tract-specific diffusion tensor imaging (DTI) metrics to assess changes across PPA variants and perform brain-behavioral correlations. Significant WM changes in the left intrafrontal and frontostriatal pathways were found in nfvPPA, but not in the semantic or logopenic variants. Correlations between tract-specific DTI metrics with cognitive scores confirmed the specific involvement of this anterior-dorsal network in fluency and suggested a preferential role of a posterior premotor-SMA pathway in motor speech. This study shows that left WM pathways connecting the speech production network are selectively damaged in nfvPPA and suggests that different tracts within this system are involved in subcomponents of fluency. These findings emphasize the emerging role of diffusion imaging in the differential diagnosis of neurodegenerative diseases.