Rotman Research Institute of Baycrest, Canada.
Neuroimage. 2010 May 15;51(1):83-90. doi: 10.1016/j.neuroimage.2010.01.100. Epub 2010 Feb 2.
Using the notion of complexity and synchrony, this study presents a data-driven pipeline of nonlinear analysis of neuromagnetic sources reconstructed from human magnetoencephalographic (MEG) data collected in reaction to vibrostimulation of the right index finger. The dynamics of MEG source activity was reconstructed with synthetic aperture magnetometry (SAM) beam-forming technique. Considering brain as a complex system, we applied complexity-based tools to identify brain areas with dynamic patterns that remain regular across repeated stimulus presentations, and to characterize their synchronized behavior. Volumetric maps of brain activation were calculated using sample entropy as a measure of signal complexity. The complexity analysis identified activity in the primary somatosensory (SI) area contralateral to stimuli and bilaterally in the posterior parietal cortex (PPC) as regions with decreased complexity, consistently expressed in a group of subjects. Seeding an activated source with low complexity in the SI area, cross-sample entropy was used to generate synchrony maps. Cross-sample entropy analysis confirmed the synchronized dynamics of neuromagnetic activity between areas SI and PPC, robustly expressed across subjects. Our results extend the understanding of synchronization between co-activated brain regions, focusing on temporal coordination between events in terms of synchronized multidimensional signal patterns.
本研究运用复杂性和同步性的概念，提出了一种从人体脑磁图（MEG）数据中重建神经磁源的非线性分析数据驱动管道，这些数据是对右食指振动刺激的反应而采集的。MEG 源活动的动力学通过合成孔径磁力计（SAM）波束形成技术进行重建。考虑到大脑是一个复杂的系统，我们应用基于复杂性的工具来识别具有动态模式的大脑区域，这些模式在重复刺激呈现时保持规则，并对其同步行为进行特征描述。使用样本熵作为信号复杂性的度量，计算大脑激活的体绘制图。复杂性分析确定了与刺激相对侧的初级体感（SI）区域以及后顶叶皮层（PPC）双侧的活动为具有降低复杂性的区域，在一组受试者中一致表达。在 SI 区域中用低复杂性的激活源播种，使用交叉样本熵生成同步图。交叉样本熵分析证实了 SI 区和 PPC 之间的神经磁活动的同步动力学，在受试者中具有稳健的表达。我们的结果扩展了对共同激活的脑区之间同步性的理解，重点关注事件在同步多维信号模式方面的时间协调。
