afni.nimh.nih.gov

Yes. To be precise:

- Take the power spectrum of fMRI signal (FFT ==> 3dPeriodogram)
- Smooth it with a Hamming window of 15/11/7 (not sure which one to use yet)
- Plot it with their respective frequencies
- Take logarithms of power spectrum and the frequencies to make it more linear-ish
- Fit a linear regression line to the logarithms
- The slope of that line is power-law exponent.

Like this paper: [www.hindawi.com]