> When the SPMG1 function is used, ... I get the sub-briks under this names: S#0 and S#1. Which beta contain the effect
> of parametric modulation and which doesn't?
S#0 is the intercept while S#1 is the slope (modulation).
> When the SPMG2 function is used, ... I get the sub-briks under this names: S#0, S#1, S#2 and S#3. Which beta contain
> the effect of parametric modulation and which doesn't? Also, which beta is related with gamma variate and which beta is
> related with its derivatives?
S#0 is associated with the major component of the hemodynamic response while S#1 corresponds to the first-order derivative. S#2 and S#3 are their corresponding slope (modulation) effects.
> When I extract a contrast from my regressor (S-I = scenario - instruction), which beta is considered for the glt (S-I) regressor
If you want to obtain the contrast for the intercept, do this:
-gltsym 'SYM: S[0] -I[0]' \
You can extend this similarly to the other components.
Gang