Matchin William, Mollasaraei Zeinab K, Bonilha Leonardo, Rorden Christopher, Hickok Gregory, den Ouden Dirk, Fridriksson Julius
Department of Communication Sciences and Disorders, University of South Carolina, Columbia, SC 29208, USA.
Department of Pharmacology, Physiology, Neuroscience, University of South Carolina, Columbia, SC 29208, USA.
Brain Commun. 2024 Dec 11;6(6):fcae449. doi: 10.1093/braincomms/fcae449. eCollection 2024.
Syntactic processing and verbal working memory are both essential components to sentence comprehension. Nonetheless, the separability of these systems in the brain remains unclear. To address this issue, we performed causal-inference analyses based on lesion and connectome network mapping using MRI and behavioural testing in two groups of individuals with chronic post-stroke aphasia. We employed a rhyme judgement task with heavy working memory load without articulatory confounds, controlling for the overall ability to match auditory words to pictures and to perform a metalinguistic rhyme judgement, isolating the effect of working memory load (103 individuals). We assessed non-canonical sentence comprehension, isolating syntactic processing by incorporating residual rhyme judgement performance as a covariate for working memory load (78 individuals). Voxel-based lesion analyses and structural connectome-based lesion symptom mapping controlling for total lesion volume were performed, with permutation testing to correct for multiple comparisons (4000 permutations). We observed that effects of working memory load localized to dorsal stream damage: posterior temporal-parietal lesions and frontal-parietal white matter disconnections. These effects were differentiated from syntactic comprehension deficits, which were primarily associated with ventral stream damage: lesions to temporal lobe and temporal-parietal white matter disconnections, particularly when incorporating the residual measure of working memory load as a covariate. Our results support the conclusion that working memory and syntactic processing are associated with distinct brain networks, largely loading onto dorsal and ventral streams, respectively.
句法处理和言语工作记忆都是句子理解的重要组成部分。尽管如此，这些系统在大脑中的可分离性仍不明确。为了解决这个问题，我们对两组慢性中风后失语症患者进行了基于病变和连接组网络映射的因果推断分析，并结合了MRI和行为测试。我们采用了一个具有繁重工作记忆负荷且无发音混淆的韵律判断任务，控制了将听觉单词与图片匹配以及进行元语言韵律判断的整体能力，从而分离出工作记忆负荷的影响（103名个体）。我们评估了非规范句子理解，通过将残余韵律判断表现作为工作记忆负荷的协变量纳入，从而分离出句法处理的影响（78名个体）。进行了基于体素的病变分析和基于结构连接组的病变症状映射，并控制了总病变体积，采用排列检验来校正多重比较（4000次排列）。我们观察到，工作记忆负荷的影响定位于背侧流损伤：颞顶叶后部病变和额顶叶白质连接中断。这些影响与句法理解缺陷不同，句法理解缺陷主要与腹侧流损伤有关：颞叶病变和颞顶叶白质连接中断，特别是在将工作记忆负荷的残余测量作为协变量纳入时。我们的结果支持这样的结论，即工作记忆和句法处理与不同的脑网络相关，在很大程度上分别加载到背侧流和腹侧流上。
