Primary progressive aphasia (PPA) is a neurodegenerative syndrome with three main variants (nonfluent, logopenic, semantic) that are identified primarily based on language deficit profiles and are associated with neurotopographically distinct atrophic patterns. We used a graph-theoretic analytic approach to examine changes in functional network properties measured with resting-state fMRI in all three PPA variants compared with age-matched healthy controls. All three variants showed a more segregated network organization than controls. To better understand the changes underlying the increased segregation, we examined the distribution of functional "hubs". We found that while all variants lost hubs in the left superior frontal and parietal regions, new hubs were recruited in different areas across the variants. In particular, both logopenic and semantic variants recruited significant numbers of hubs in the right hemisphere. Importantly, these functional characteristics could not be fully explained by local volume changes. These findings indicate that patterns of functional connectivity can serve as further evidence to distinguish the PPA variants, and provide a basis for longitudinal studies and for investigating treatment effects. This study also highlights the utility of graph-theoretic approaches in understanding the brain's functional reorganization in response to neurodegenerative disease.

中文翻译：

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原发性进行性失语症变体中功能网络重组的不同模式：图论分析

原发性进行性失语症 (PPA) 是一种神经退行性综合征，具有三种主要变异（非流利、语言减少、语义），主要根据语言缺陷特征进行识别，并与神经拓扑学上不同的萎缩模式相关。我们使用图论分析方法来检查与年龄匹配的健康对照相比，在所有三种 PPA 变体中使用静息状态 fMRI 测量的功能网络特性的变化。所有三个变体都显示出比对照更隔离的网络组织。为了更好地理解隔离加剧背后的变化，我们检查了功能“中心”的分布。我们发现，虽然所有变体都在左上额叶和顶叶区域失去了中枢，但在变种的不同区域招募了新中枢。特别是，logopenic 和语义变体都在右半球招募了大量的中枢。重要的是，这些功能特征不能完全用局部体积变化来解释。这些发现表明，功能连接的模式可以作为区分 PPA 变体的进一步证据，并为纵向研究和调查治疗效果提供基础。这项研究还强调了图论方法在理解大脑对神经退行性疾病做出反应的功能重组方面的效用。这些发现表明，功能连接的模式可以作为区分 PPA 变体的进一步证据，并为纵向研究和调查治疗效果提供基础。这项研究还强调了图论方法在理解大脑对神经退行性疾病做出反应的功能重组方面的效用。这些发现表明，功能连接的模式可以作为区分 PPA 变体的进一步证据，并为纵向研究和调查治疗效果提供基础。这项研究还强调了图论方法在理解大脑对神经退行性疾病做出反应的功能重组方面的效用。