Background:Olfactory dysfunction (OD) is a frequent symptom of Parkinson’s disease (PD) that appears years prior to diagnosis. Previous studies suggest that PD-related OD is different from non-parkinsonian forms of olfactory dysfunction (NPOD) as PD patients maintain trigeminal sensitivity as opposed to patients with NPOD who typically exhibit reduced trigeminal sensitivity. We hypothesize the presence of a specific alteration of functional connectivity between trigeminal and olfactory processing areas in PD. Objective:We aimed to assess potential differences in functional connectivity within the chemosensory network in 15 PD patients and compared them to 15 NPOD patients, and to 15 controls. Methods:Functional MRI scanning session included resting-state and task-related scans where participants carried out an olfactory and a trigeminal task. We compared functional connectivity, using a seed-based correlation approach, and brain network modularity of the chemosensory network. Results:PD patients had impaired functional connectivity within the chemosensory network while no such changes were observed for NPOD patients. No group differences we found in modularity of the identified networks. Both patient groups exhibited impaired connectivity when executing an olfactory task, while network modularity was significantly weaker for PD patients than both other groups. When performing a trigeminal task, no changes were found for PD patients, but NPOD patients exhibited impaired connectivity. Conversely, PD patients exhibited a significantly higher network modularity than both other groups. Conclusion:In summary, the specific pattern of functional connectivity and chemosensory network recruitment in PD-related OD may explain distinct behavioral chemosensory features in PD when compared to NPOD patients and healthy controls.

中文翻译：

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帕金森氏病影响嗅觉-三叉神经网络内的功能连接。

背景：嗅觉功能障碍 (OD) 是帕金森病 (PD) 的常见症状，在诊断前数年出现。先前的研究表明，PD 相关 OD 与非帕金森形式的嗅觉功能障碍 (NPOD) 不同，因为 PD 患者保持三叉神经敏感性，而 NPOD 患者通常表现出三叉神经敏感性降低。我们假设 PD 中三叉神经和嗅觉处理区域之间存在功能连接的特定改变。目的：我们旨在评估 15 名 PD 患者化学感应网络内功能连接的潜在差异，并将其与 15 名 NPOD 患者和 15 名对照组进行比较。方法：功能性 MRI 扫描会话包括静息状态和与任务相关的扫描，参与者执行嗅觉和三叉神经任务。我们使用基于种子的相关方法和化学感应网络的大脑网络模块性比较了功能连接。结果：PD 患者在化学感应网络内的功能连接受损，而 NPOD 患者未观察到此类变化。我们在已识别网络的模块化中没有发现组差异。在执行嗅觉任务时，两个患者组都表现出连通性受损，而 PD 患者的网络模块性明显弱于其他两组。在执行三叉神经任务时，PD 患者没有发现任何变化，但 NPOD 患者表现出连通性受损。相反，PD 患者表现出明显高于其他两组的网络模块性。结论：综上所述，