Damage to the anterior arcuate fasciculus predicts non-fluent speech production in aphasia
Damage to the anterior arcuate fasciculus predicts non-fluent speech production in aphasia
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DOI：
10.1093/brain/awt267
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发表时间：
2013-11-01
期刊：
影响因子：
14.5
通讯作者：
Rorden, Chris
中科院分区：
文献类型：
--
作者：
Fridriksson, Julius;Guo, Dazhou;Rorden, Chris
不流利的失语症意味着一种相对简单的神经疾病，其特征是言语输出有限。然而，它是影响言语产生的不同潜在损害的总称。一些研究已经寻找了导致非流利性失语的关键病变位置。结果好坏参半，但通常累及前部皮质区域，如Broca区、左前脑岛和深部白质区域。为了更清楚地了解非流利性失语症患者的大脑皮质损伤，目前的研究检查了对失语症患者的语言流畅性产生负面影响的大脑损伤。它控制了一些基本的语音和语言理解因素，以便更好地区分不同机制对流利性的贡献，或缺乏流利性。在慢性左半球卒中患者中，皮层损害与总体语言流畅性有关，通过使用西方失语症成套语言流畅度量表、诊断运动率、基本听觉语言理解和执行功能(矩阵推理测试的分数)进行临床判断来评估。一项包括通常涉及语音和语言处理的大脑区域的感兴趣区分析显示，失语症中的不流利主要是通过左侧弓状束前段的损伤来预测的。一个改进的预测模型还包括左钩状束，即连接中、前颞叶和额叶区域的白质束，包括三角部。控制心动率、图文再认或执行功能的模型也揭示了前段受累与语言流畅性之间的密切关系。全脑分析证实了感兴趣区分析的结果。另一项探索性分析显示，在Broca‘s和全面性失语这两种最常见的非流利性失语之间，钩状神经束的参与被判定为失语。综上所述，目前的结果表明，左侧弓状束的前段是位于Broca区和感觉-运动皮质后部深处的白质束，是失语症患者言语流畅性受损的有力预测指标，即使将运动语言、词汇处理和执行功能作为辅助因素也是如此。简单地说，这些区域的损伤会导致不流利的失语症；如果它们没有受损，就会导致流畅的失语症。
Non-fluent aphasia implies a relatively straightforward neurological condition characterized by limited speech output. However, it is an umbrella term for different underlying impairments affecting speech production. Several studies have sought the critical lesion location that gives rise to non-fluent aphasia. The results have been mixed but typically implicate anterior cortical regions such as Broca's area, the left anterior insula, and deep white matter regions. To provide a clearer picture of cortical damage in non-fluent aphasia, the current study examined brain damage that negatively influences speech fluency in patients with aphasia. It controlled for some basic speech and language comprehension factors in order to better isolate the contribution of different mechanisms to fluency, or its lack. Cortical damage was related to overall speech fluency, as estimated by clinical judgements using the Western Aphasia Battery speech fluency scale, diadochokinetic rate, rudimentary auditory language comprehension, and executive functioning (scores on a matrix reasoning test) in 64 patients with chronic left hemisphere stroke. A region of interest analysis that included brain regions typically implicated in speech and language processing revealed that non-fluency in aphasia is primarily predicted by damage to the anterior segment of the left arcuate fasciculus. An improved prediction model also included the left uncinate fasciculus, a white matter tract connecting the middle and anterior temporal lobe with frontal lobe regions, including the pars triangularis. Models that controlled for diadochokinetic rate, picture-word recognition, or executive functioning also revealed a strong relationship between anterior segment involvement and speech fluency. Whole brain analyses corroborated the findings from the region of interest analyses. An additional exploratory analysis revealed that involvement of the uncinate fasciculus adjudicated between Broca's and global aphasia, the two most common kinds of non-fluent aphasia. In summary, the current results suggest that the anterior segment of the left arcuate fasciculus, a white matter tract that lies deep to posterior portions of Broca's area and the sensory-motor cortex, is a robust predictor of impaired speech fluency in aphasic patients, even when motor speech, lexical processing, and executive functioning are included as co-factors. Simply put, damage to those regions results in non-fluent aphasic speech; when they are undamaged, fluent aphasias result.