快速傅里叶变换
同步(交流)
窗口(计算)
窗口函数
虚假关系
光谱密度
航程(航空)
频谱泄漏
计算机科学
工件(错误)
脑电图
傅里叶变换
算法
数学
人工智能
工程类
电信
数学分析
频道(广播)
航空航天工程
操作系统
心理学
机器学习
精神科
作者
Thomas Rusterholz,Peter Achermann,Roland Dürr,Thomas Koenig,Leila Tarokh
标识
DOI:10.1016/j.jneumeth.2017.04.002
摘要
Investigating functional connectivity between brain networks has become an area of interest in neuroscience. Several methods for investigating connectivity have recently been developed, however, these techniques need to be applied with care. We demonstrate that global field synchronization (GFS), a global measure of phase alignment in the EEG as a function of frequency, must be applied considering signal processing principles in order to yield valid results. Multichannel EEG (27 derivations) was analyzed for GFS based on the complex spectrum derived by the fast Fourier transform (FFT). We examined the effect of window functions on GFS, in particular of non-rectangular windows. Applying a rectangular window when calculating the FFT revealed high GFS values for high frequencies (>15 Hz) that were highly correlated (r = 0.9) with spectral power in the lower frequency range (0.75–4.5 Hz) and tracked the depth of sleep. This turned out to be spurious synchronization. With a non-rectangular window (Tukey or Hanning window) these high frequency synchronization vanished. Both, GFS and power density spectra significantly differed for rectangular and non-rectangular windows. Previous papers using GFS typically did not specify the applied window and may have used a rectangular window function. However, the demonstrated impact of the window function raises the question of the validity of some previous findings at higher frequencies. We demonstrated that it is crucial to apply an appropriate window function for determining synchronization measures based on a spectral approach to avoid spurious synchronization in the beta/gamma range.
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