脑海科技数据分析服务之方案1

Introduction

After preprocessing, the time series for each voxel was filtered (bandpass, 0.01-0.08 Hz) to removethe effects of very-low-frequency drift and high frequency noise, e.g., respiratory and heart rhythms. Next, the filtered time series was transformedto a frequency domain with a fast Fourier transform (FFT) (parameters: taperpercent=0, FFT length=shortest) and the power spectrum was then obtained. Sincethe power of a given frequency is proportional to the square of the amplitudeof this frequency component of the original time series in the time domain, thesquare root was calculated at each frequency of the power spectrum and theaveraged square root was obtained across 0.01-0.08 Hz at each voxel. Thisaveraged square root was taken as the ALFF. (Zang et al., 2007)

Process Stream

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