Hi Freesurfers

I have a few questions about gammafit flag in mkanalysis-sess command and I appreciate if you could respond whenever you had time.

-How should we decide which function is best to apply on hemodynamic response signal? I have used both spmhrf and gammafit and I see slightly different results. 

-Does Freesurfer has a default function that applies on hemodynamic response signal if I don't use these flags?

-Where should I get gfdelta and gftau from?

Thanks

Mona