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Understanding the neural basis of episodic amnesia in logopenic progressive aphasia: A multimodal neuroimaging study.
Cortex ( IF 3.6 ) Pub Date : 2020-01-22 , DOI: 10.1016/j.cortex.2019.12.026
Siddharth Ramanan 1 , Lars Marstaller 2 , John R Hodges 3 , Olivier Piguet 1 , Muireann Irish 1
Affiliation  

Logopenic progressive aphasia (LPA) is a neurodegenerative disorder characterised by profound naming and sentence repetition disturbances, attributable to disproportionately left-sided temporo-parietal atrophy. Accumulating evidence suggests, in addition to language impairments, the presence of stark verbal and nonverbal episodic memory dysfunction in LPA. The neurocognitive bases of such impairments, however, remain to be clarified. Here, we characterised episodic memory disruption and its corresponding grey and white matter correlates in the LPA syndrome. Nineteen LPA patients were contrasted with 23 matched typical Alzheimer's disease (AD) patients and 31 healthy Controls on standardized verbal and nonverbal episodic delayed recall measures. Participants further underwent structural magnetic resonance and diffusion-weighted imaging. Significant verbal memory deficits were evident in both patient groups, with LPA patients performing at an intermediate level to AD and Controls. For nonverbal memory, however, LPA performance was indistinguishable from that of AD, with both groups displaying marked impairments relative to Controls. Whole-brain voxel-based morphometry analyses revealed significant left temporo-parietal and left hippocampal atrophy in the LPA group. Covariate analyses showed that verbal and nonverbal amnesia in LPA correlated with grey matter integrity of bilateral frontoparietal and left medial temporal lobe regions. Notably, the common regions underpinning verbal and nonverbal memory dysfunction in LPA were the left orbitofrontal cortex and bilateral angular gyri in the inferior parietal cortex. The bilateral angular gyri, along with prefrontal and hippocampal regions further emerged as disease-general correlates of verbal and nonverbal memory performance. Alterations in mean diffusivity in structural connections between the left angular gyrus and medial temporal lobes were further associated with verbal memory performance in all participants. Our findings reveal, for the first time, the presence of pervasive memory impairments in LPA mediated by degeneration of a distributed prefrontal-hippocampal-parietal network, and disrupted parieto-hippocampal structural connectivity.

中文翻译:

了解渐进性失语症发作性健忘症的神经基础:多模式神经影像学研究。

对开性进行性失语症(LPA)是一种神经退行性疾病,其特征是命名严重和句子重复障碍,可归因于左侧颞顶顶萎缩。越来越多的证据表明,除了语言障碍外,LPA中还存在明显的言语和非言语情节性记忆功能障碍。然而,此类损伤的神经认知基础尚待阐明。在这里,我们表征了情节性记忆破坏及其在LPA综合征中的对应的灰色和白色物质。在标准的言语和非言语情节性延迟回忆方法上,将19例LPA患者与23例匹配的典型阿尔茨海默病(AD)患者和31例健康对照者进行了对比。参与者进一步进行了结构磁共振和弥散加权成像。在两个患者组中,明显的言语记忆障碍均很明显,LPA患者的表现中等至AD和对照组。然而,对于非语言记忆,LPA的表现与AD的没有区别,两组相对于对照组均显示出明显的损伤。基于全脑体素的形态学分析显示,LPA组的左颞顶叶和左海马萎缩明显。协变量分析显示,LPA中的言语和非言语性失忆与双侧额叶额叶和左侧颞叶内侧区域的灰质完整性相关。值得注意的是,LPA的言语和非言语记忆功能障碍的常见区域是左顶额叶皮层和下顶叶皮层的双侧角回。双边角回,随着额叶和非语言记忆表现的疾病-一般相关性,前额叶和海马区进一步出现。在所有参与者中,左角回和内侧颞叶之间的结构连接的平均扩散率的改变还与言语记忆表现有关。我们的发现首次揭示了由分布式前额-海马-顶叶网络的变性介导的LPA中普遍存在的记忆障碍,并破坏了顶叶-海马结构连接性。
更新日期:2020-01-22
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