The Mind Research Network, Lovelace Biomedical and Environmental Research Institute, Albuquerque, New Mexico.
Department of Electrical and Computer Engineering, University of New Mexico, Albuquerque, New Mexico.
Hum Brain Mapp. 2019 May;40(7):2089-2103. doi: 10.1002/hbm.24509. Epub 2019 Jan 19.
Sliding window correlation (SWC) is utilized in many studies to analyze the temporal characteristics of brain connectivity. However, spurious artifacts have been reported in simulated data using this technique. Several suggestions have been made through the development of the SWC technique. Recently, it has been proposed to utilize a SWC window length of 100 s given that the lowest nominal fMRI frequency is 0.01 Hz. The main pitfall is the loss of temporal resolution due to a large window length. In this work, we propose an average sliding window correlation (ASWC) approach that presents several advantages over the SWC. One advantage is the requirement for a smaller window length. This is important because shorter lengths allow for a more accurate estimation of transient dynamicity of functional connectivity. Another advantage is the behavior of ASWC as a tunable high pass filter. We demonstrate the advantages of ASWC over SWC using simulated signals with configurable functional connectivity dynamics. We present analytical models explaining the behavior of ASWC and SWC for several dynamic connectivity cases. We also include a real data example to demonstrate the application of the new method. In summary, ASWC shows lower artifacts and resolves faster transient connectivity fluctuations, resulting in a lower mean square error than in SWC.
滑动窗口相关（SWC）被广泛应用于许多研究中，用于分析大脑连接的时间特征。然而，在使用该技术模拟数据时，已经报道了虚假的伪影。通过 SWC 技术的发展，提出了一些建议。最近，有人建议使用 100 秒的 SWC 窗口长度，因为最低的名义 fMRI 频率为 0.01 Hz。主要的缺陷是由于窗口长度较大而导致时间分辨率的损失。在这项工作中，我们提出了一种平均滑动窗口相关（ASWC）方法，与 SWC 相比具有几个优势。一个优势是需要较小的窗口长度。这一点很重要，因为较短的长度可以更准确地估计功能连接的瞬态动态性。另一个优势是 ASWC 作为可调高通滤波器的行为。我们使用具有可配置功能连接动态性的模拟信号来展示 ASWC 相对于 SWC 的优势。我们提出了解释 ASWC 和 SWC 在几种动态连接情况下行为的分析模型。我们还包括一个真实数据示例，以演示新方法的应用。总之，ASWC 显示出较低的伪影，并能更快地解决瞬态连接波动，导致均方误差低于 SWC。
