1 Department of Biomedical Engineering, Marquette University and the Medical College of Wisconsin, Milwaukee, Wisconsin.
2 Department of Physical Therapy, Marquette University, Milwaukee, Wisconsin.
Brain Connect. 2019 May;9(4):365-377. doi: 10.1089/brain.2018.0640. Epub 2019 Mar 23.
The goal of this work was to examine task-dependent functional connectivity of the brain in people with stroke. The work was motivated by prior observations indicating that, during pedaling, cortical activation volume is lower in people with stroke than controls. During paretic foot tapping, activation volume tends to be higher in people with stroke than controls. This study asked whether these differences could be explained by altered network function of the brain. Functional magnetic resonance imaging was used to examine local and global network function of the brain during tapping and pedaling in 15 stroke and 8 control participants. Independent component analysis was used to identify six task regions of interest (ROIs) in the primary sensorimotor cortex (M1S1), anterior lobe of cerebellum (AlCb), and secondary sensory cortex (S2) on the lesioned and non-lesioned sides of the brain (left, right for controls). Global connectivity was calculated as the correlation between mean time series for each ROI. Local connectivity was calculated as the mean correlation between voxels within each ROI. Local efficiency, weighted sum, and clustering coefficient were also calculated. Results suggested that local and global networks of the brain were altered in stroke, but not in the same direction. Detection of both global and local network changes was task-dependent. We found that global network function of the brain was reduced in stroke participants as compared with controls. This effect was detected during pedaling and nonparetic tapping, but not during paretic tapping. Local network function of the brain was elevated in stroke participants during paretic tapping and reduced during pedaling. No between-group differences in local connectivity were seen during nonparetic tapping. Connections involving S2, M1S1, and AlCb were significantly affected. Reduced global connectivity of the brain might contribute to reduced brain activation volume during pedaling poststroke.
这项工作的目的是研究脑卒中患者大脑的任务相关功能连接。这项工作的动机是先前的观察结果表明，在蹬踏时，脑卒中患者的皮质激活体积低于对照组。在瘫痪足敲击时，脑卒中患者的激活体积往往高于对照组。本研究旨在探讨这些差异是否可以用大脑网络功能的改变来解释。在 15 名脑卒中患者和 8 名对照组参与者进行蹬踏和足敲击时，使用功能磁共振成像来检查大脑的局部和全局网络功能。独立成分分析用于在大脑受损和未受损侧（左侧和右侧为对照组）的初级感觉运动皮层（M1S1）、小脑前叶（AlCb）和次级感觉皮层（S2）上识别六个任务感兴趣区（ROI）。全局连接性作为每个 ROI 的平均时间序列之间的相关性来计算。局部连接性作为每个 ROI 内体素之间的平均相关性来计算。局部效率、加权和聚类系数也进行了计算。结果表明，脑卒中患者大脑的局部和全局网络都发生了改变，但改变的方向并不相同。大脑全局和局部网络的变化是任务依赖的。我们发现，与对照组相比，脑卒中患者大脑的全局网络功能降低。这种效应在蹬踏和非瘫痪敲击时检测到，但在瘫痪敲击时没有检测到。在瘫痪敲击时，脑卒中患者大脑的局部网络功能升高，在蹬踏时降低。在非瘫痪敲击时，未观察到两组间的局部连接性差异。涉及 S2、M1S1 和 AlCb 的连接受到显著影响。大脑全局连接性降低可能导致脑卒中后蹬踏时大脑激活体积减少。
