Henry Maya L, Wilson Stephen M, Babiak Miranda C, Mandelli Maria Luisa, Beeson Pelagie M, Miller Zachary A, Gorno-Tempini Maria Luisa
University of Texas at Austin.
University of California, San Francisco.
J Cogn Neurosci. 2016 Feb;28(2):210-22. doi: 10.1162/jocn_a_00901. Epub 2015 Nov 6.
Individuals with primary progressive aphasia (PPA) show selective breakdown in regions within the proposed dorsal (articulatory-phonological) and ventral (lexical-semantic) pathways involved in language processing. Phonological STM impairment, which has been attributed to selective damage to dorsal pathway structures, is considered to be a distinctive feature of the logopenic variant of PPA. By contrast, phonological abilities are considered to be relatively spared in the semantic variant and are largely unexplored in the nonfluent/agrammatic variant. Comprehensive assessment of phonological ability in the three variants of PPA has not been undertaken. We investigated phonological processing skills in a group of participants with PPA as well as healthy controls, with the goal of identifying whether patterns of performance support the dorsal versus ventral functional-anatomical framework and to discern whether phonological ability differs among PPA subtypes. We also explored the neural bases of phonological performance using voxel-based morphometry. Phonological performance was impaired in patients with damage to dorsal pathway structures (nonfluent/agrammatic and logopenic variants), with logopenic participants demonstrating particular difficulty on tasks involving nonwords. Binary logistic regression revealed that select phonological tasks predicted diagnostic group membership in the less fluent variants of PPA with a high degree of accuracy, particularly in conjunction with a motor speech measure. Brain-behavior correlations indicated a significant association between the integrity of gray matter in frontal and temporoparietal regions of the left hemisphere and phonological skill. Findings confirm the critical role of dorsal stream structures in phonological processing and demonstrate unique patterns of impaired phonological processing in logopenic and nonfluent/agrammatic variants of PPA.
患有原发性进行性失语症（PPA）的个体在参与语言处理的拟议背侧（发音-音韵）和腹侧（词汇-语义）通路内的区域表现出选择性破坏。音韵短时记忆损害被认为是PPA的语音变异型的一个显著特征，这归因于背侧通路结构的选择性损伤。相比之下，音韵能力在语义变异型中被认为相对保留，并且在非流利/语法缺失变异型中很大程度上未被探索。尚未对PPA的三种变异型的音韵能力进行全面评估。我们调查了一组PPA患者以及健康对照的音韵处理技能，目的是确定表现模式是否支持背侧与腹侧功能-解剖框架，并辨别PPA各亚型之间的音韵能力是否存在差异。我们还使用基于体素的形态学方法探索了音韵表现的神经基础。背侧通路结构受损的患者（非流利/语法缺失和语音变异型）的音韵表现受损，语音变异型参与者在涉及非单词的任务上表现出特别的困难。二元逻辑回归显示，特定的音韵任务能够高度准确地预测PPA较不流利变异型的诊断组成员身份，特别是与一项运动言语测量相结合时。脑-行为相关性表明，左半球额叶和颞顶叶区域灰质的完整性与音韵技能之间存在显著关联。研究结果证实了背侧流结构在音韵处理中的关键作用，并证明了PPA的语音变异型和非流利/语法缺失变异型中音韵处理受损的独特模式。
