Functional Magnetic Resonance Imaging Phase Synchronization as a Measure of Dynamic Functional Connectivity
Functional Magnetic Resonance Imaging Phase Synchronization as a Measure of Dynamic Functional Connectivity
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DOI：
10.1089/brain.2011.0068
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发表时间：
2012-04-01
影响因子：
3.4
通讯作者：
Sams, Mikko
中科院分区：
文献类型：
--
作者：
Glerean, Enrico;Salmi, Juha;Sams, Mikko
功能性脑活动和连通性已经通过计算与功能性磁共振成像（fMRI）获得的血液动力学数据的受试者间和基于种子的相关性进行了研究。为了检查时间动态，这些相关性的措施已经计算过滑动时间窗口的时间窗口，妥协的时间分辨率的时间窗口的长度上的必要限制。在这里，我们表明，它是可能的，以提高时间分辨率，通过使用瞬时相位同步（PS）作为衡量动态（随时间变化）的功能连接。我们将PS应用于12名健康志愿者观看故事片时获得的fMRI数据集。在PS分析中使用窄频带（0.04-0.07 Hz），以避免人为结果。我们定义了三个指标，用于计算时变功能连接性和时变受试者间可靠性，这些指标基于对受试者间瞬时PS的估计：（1）基于种子的PS，（2）受试者间PS，以及（3）受试者间基于种子的PS。我们的研究结果表明，这些PS为基础的指标产生的结果一致的种子为基础的相关性和学科间的相关性的方法时，检查整个时间序列，但提供了一个重要的优势，最大的单TR时间分辨率。这些指标可以应用于具有复杂自然刺激的研究（例如，在MRI扫描仪中看电影或听音乐）和更受控制（例如，事件相关或阻塞设计）范例。MATLAB工具箱FUNPSY（http：//becs.aalto.fi/bml/software.html）可公开用于在fMRI数据分析中使用这些度量。
Functional brain activity and connectivity have been studied by calculating intersubject and seed-based correlations of hemodynamic data acquired with functional magnetic resonance imaging (fMRI). To inspect temporal dynamics, these correlation measures have been calculated over sliding time windows with necessary restrictions on the length of the temporal window that compromises the temporal resolution. Here, we show that it is possible to increase temporal resolution by using instantaneous phase synchronization (PS) as a measure of dynamic (time-varying) functional connectivity. We applied PS on an fMRI dataset obtained while 12 healthy volunteers watched a feature film. Narrow frequency band (0.04-0.07 Hz) was used in the PS analysis to avoid artifactual results. We defined three metrics for computing time-varying functional connectivity and time-varying intersubject reliability based on estimation of instantaneous PS across the subjects: (1) seed-based PS, (2) intersubject PS, and (3) intersubject seed-based PS. Our findings show that these PS-based metrics yield results consistent with both seed-based correlation and intersubject correlation methods when inspected over the whole time series, but provide an important advantage of maximal single-TR temporal resolution. These metrics can be applied both in studies with complex naturalistic stimuli (e.g., watching a movie or listening to music in the MRI scanner) and more controlled (e.g., event-related or blocked design) paradigms. A MATLAB toolbox FUNPSY (http://becs.aalto.fi/bml/software.html) is openly available for using these metrics in fMRI data analysis.