Tivarus Madalina E, Pester Britta, Schmidt Christoph, Lehmann Thomas, Zhu Tong, Zhong Jianhui, Leistritz Lutz, Schifitto Giovanni
Department of Imaging Sciences, University of Rochester Medical Center, Rochester, New York, United States of America.
Institute of Medical Statistics, Computer Sciences and Documentation, Jena University Hospital, Friedrich Schiller University, Jena, Germany.
PLoS One. 2015 Oct 5;10(10):e0139118. doi: 10.1371/journal.pone.0139118. eCollection 2015.
Lithium therapy has been shown to affect imaging measures of brain function and microstructure in human immunodeficiency virus (HIV)-infected subjects with cognitive impairment. The aim of this proof-of-concept study was to explore whether changes in brain microstructure also entail changes in functional connectivity. Functional MRI data of seven cognitively impaired HIV infected individuals enrolled in an open-label lithium study were included in the connectivity analysis. Seven regions of interest (ROI) were defined based on previously observed lithium induced microstructural changes measured by Diffusion Tensor Imaging. Generalized partial directed coherence (gPDC), based on time-variant multivariate autoregressive models, was used to quantify the degree of connectivity between the selected ROIs. Statistical analyses using a linear mixed model showed significant differences in the average node strength between pre and post lithium therapy conditions. Specifically, we found that lithium treatment in this population induced changes suggestive of increased strength in functional connectivity. Therefore, by exploiting the information about the strength of functional interactions provided by gPDC we can quantify the connectivity changes observed in relation to a given intervention. Furthermore, in conditions where the intervention is associated with clinical changes, we suggest that this methodology could enable an interpretation of such changes in the context of disease or treatment induced modulations in functional networks.
锂疗法已被证明会影响人类免疫缺陷病毒（HIV）感染且有认知障碍的受试者的脑功能和微观结构的成像指标。本概念验证研究的目的是探讨脑微观结构的变化是否也会导致功能连接的变化。一项开放标签锂研究中纳入的7名认知受损的HIV感染者的功能磁共振成像数据被纳入连接性分析。基于先前通过扩散张量成像观察到的锂诱导的微观结构变化，定义了7个感兴趣区域（ROI）。基于时变多元自回归模型的广义偏相干（gPDC）用于量化所选ROI之间的连接程度。使用线性混合模型的统计分析显示，锂治疗前后条件下的平均节点强度存在显著差异。具体而言，我们发现该人群中的锂治疗引起了功能连接强度增加的变化。因此，通过利用gPDC提供的功能相互作用强度信息，我们可以量化与给定干预相关的连接性变化。此外，在干预与临床变化相关的情况下，我们建议这种方法能够在疾病或治疗引起的功能网络调制的背景下解释此类变化。
