The polynomial is one way to do highpass filtering (ie, removing low frequency components). The bandwidth of the filter changes depending on the order, the TR, and the number of time points. If you want to select the order based on cutoff frequency, you can run fast_polyorder(ntp,TR,fCutOffHz) in matlab to give you the order. At some point I will just include this as an option in mkanalysis-sess. You can specify the cuttoff frequency with -hpf CuttoffHz in mkanalysis-sess (this uses cosine bases instead of polynomial).

On 6/6/18 12:41 PM, Piero Chiacchiaretta wrote:

Hi list, FS-FAST guidelines reports this example for seed-based FC analayis:

mkanalysis-sess -analysis fc.lpccseed.surf.lh -surface fsaverage lh -fwhm 5 -notask -taskreg L_Posteriorcingulate.dat 1 -nuisreg vcsf.dat 5 -nuisreg wm.dat 5 -mcextreg -polyfit 5 -nskip 4 -fsd bold -TR <TR>

You suggest a 5th order polynomial. Thus, I wonder to know which is the rationale to use this option and which is the advatage to use it then defaut option (1st or 2nd order). Thanks

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