Montembeault Maxime, Miller Zachary A, Geraudie Amandine, Pressman Peter, Slegers Antoine, Millanski Carly, Licata Abigail, Ratnasiri Buddhika, Mandelli Maria Luisa, Henry Maya, Cobigo Yann, Rosen Howard J, Miller Bruce L, Brambati Simona M, Gorno-Tempini Maria Luisa, Battistella Giovanni
Memory and Aging Center, Department of Neurology, University of California in San Francisco, San Francisco, CA 94158, USA.
Douglas Mental Health University Institute, Montréal, QC H4H 1R3, Canada.
Brain Commun. 2023 Mar 16;5(2):fcad077. doi: 10.1093/braincomms/fcad077. eCollection 2023.
Semantic variant primary progressive aphasia is a clinical syndrome characterized by marked semantic deficits, anterior temporal lobe atrophy and reduced connectivity within a distributed set of regions belonging to the functional network associated with semantic processing. However, to fully depict the clinical signature of semantic variant primary progressive aphasia, it is necessary to also characterize preserved neural networks and linguistic abilities, such as those subserving speech production. In this case-control observational study, we employed whole-brain seed-based connectivity on task-free MRI data of 32 semantic variant primary progressive aphasia patients and 46 healthy controls to investigate the functional connectivity of the speech production network and its relationship with the underlying grey matter. We investigated brain-behaviour correlations with speech fluency measures collected through clinical tests (verbal agility) and connected speech (speech rate and articulation rate). As a control network, we also investigated functional connectivity within the affected semantic network. Patients presented with increased connectivity in the speech production network between left inferior frontal and supramarginal regions, independent of underlying grey matter volume. In semantic variant primary progressive aphasia patients, preserved (verbal agility) and increased (articulation rate) speech fluency measures correlated with increased connectivity between inferior frontal and supramarginal regions. As expected, patients demonstrated decreased functional connectivity in the semantic network (dependent on the underlying grey matter atrophy) associated with average nouns' age of acquisition during connected speech. Collectively, these results provide a compelling model for studying compensation mechanisms in response to disease that might inform the design of future rehabilitation strategies in semantic variant primary progressive aphasia.
语义变异型原发性进行性失语是一种临床综合征，其特征为明显的语义缺陷、颞叶前部萎缩以及在属于与语义处理相关的功能网络的一组分布式区域内连接性降低。然而，要全面描述语义变异型原发性进行性失语的临床特征，还必须对保留的神经网络和语言能力进行表征，例如那些支持言语产生的能力。在这项病例对照观察研究中，我们对32名语义变异型原发性进行性失语患者和46名健康对照的静息态MRI数据采用基于全脑种子点的连接性分析，以研究言语产生网络的功能连接性及其与潜在灰质的关系。我们通过临床测试（言语敏捷性）和连贯言语（语速和发音率）收集的言语流畅性测量指标来研究脑-行为相关性。作为对照网络，我们还研究了受影响的语义网络内的功能连接性。患者在左侧额下回和缘上回区域之间的言语产生网络中表现出连接性增加，这与潜在灰质体积无关。在语义变异型原发性进行性失语患者中，保留的（言语敏捷性）和增加的（发音率）言语流畅性测量指标与额下回和缘上回区域之间连接性增加相关。正如预期的那样，患者在连贯言语过程中与平均名词习得年龄相关的语义网络中表现出功能连接性降低（取决于潜在灰质萎缩）。总体而言，这些结果为研究针对疾病的代偿机制提供了一个有说服力的模型，这可能为未来语义变异型原发性进行性失语康复策略的设计提供参考。
