Interhemispheric interactions during sentence comprehension in patients with aphasia
Interhemispheric interactions during sentence comprehension in patients with aphasia
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DOI：
10.1016/j.cortex.2018.08.022
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发表时间：
2018-12-01
期刊：
影响因子：
3.6
通讯作者：
Bitan, Tali
中科院分区：
文献类型：
--
作者：
Chu, Ronald;Meltzer, Jed A.;Bitan, Tali
左脑损伤后右脑参与语言加工可能反映了代偿过程，也可能反映了同位经胼胝体抑制的释放，从而导致过度的从右向左抑制，从而导致语言表现不适应。使用功能磁共振成像，我们评估了15名中风后失语症患者的大脑半球有效连通性，以及年龄匹配和更年轻的对照组在句子理解任务中。动态因果模型应用于包括额下回（IFG）和初级听觉皮质（A1）在内的四个双侧区域。尽管存在病变，但9/15的患者获得了满意的模型拟合。在年轻的对照组中，唯一显著的同位连接（RA1-LA1）是兴奋性的，而抑制性连接来自LIFG到左侧和右侧A1。有趣的是，这些联系也与患者的语言理解得分相关。同调连接的结果表明，从ra1到la1的兴奋性连接和从la1到ra1的抑制性连接与一般听觉言语理解有关。此外，句子理解与自上而下耦合在异位连接（LIFG-to-RA1）和半球内连接（LIFG-to-LA1）之间均呈负相关。这些结果并不表明患者出现了新的从右到左的代偿性兴奋，也不支持对照组存在从左到右的经胼胝体抑制。然而，与患者表现的相关性与代偿模型和经胼胝体抑制解释RH作用的某些方面是一致的。总之，我们的研究结果表明，LH损伤引起的兴奋性和抑制性同位和异位连接的变化可能是不适应的，因为它们破坏了正常的半球间协调和交流。(C) 2018 Elsevier Ltd.版权所有。
Right-hemisphere involvement in language processing following left-hemisphere damage may reflect either compensatory processes, or a release from homotopic transcallosal inhibition, resulting in excessive right-to-left suppression that is maladaptive for language performance. Using fMRI, we assessed inter-hemispheric effective connectivity in fifteen patients with post-stroke aphasia, along with age-matched and younger controls during a sentence comprehension task. Dynamic Causal Modeling was used with four bilateral regions including inferior frontal gyri (IFG) and primary auditory cortices (A1). Despite the presence of lesions, satisfactory model fit was obtained in 9/15 patients. In young controls, the only significant homotopic connection (RA1-LA1), was excitatory, while inhibitory connections emanated from LIFG to both left and right A1's. Interestingly, these connections were also correlated with language comprehension scores in patients. The results for homotopic connections show that excitatory connectivity from RA1-to-LA1 and inhibitory connectivity from LA1-to-RA1 are associated with general auditory verbal comprehension. Moreover, negative correlations were found between sentence comprehension and top down coupling for both heterotopic (LIFG-to-RA1) and intra-hemispheric (LIFG-to-LA1) connections. These results do not show an emergence of a new compensatory right to left excitation in patients nor do they support the existence of left to right transcallosal suppression in controls. Nevertheless, the correlations with performance in patients are consistent with some aspects of both the compensation model, and the transcallosal suppression account for the role of the RH. Altogether our results suggest that changes to both excitatory and inhibitory homotopic and heterotopic connections due to LH damage may be maladaptive, as they disrupt the normal inter-hemispheric coordination and communication. (C) 2018 Elsevier Ltd. All rights reserved.