Thanks Gang for your quick and clear answer! It really helps me a lot!

I have few other questions please:

1. Now is clear to me that for SPMG1: S#0 will give me the intercept (and is associated with the major component of the hemodynamic response, as the first component from SPMG2, right? ) and S#1 will give me the slope, or the signal modulated by the parametric modulation of the function component (please correct me if I am wrong). I still don't know what will represent the output for which I ask just the regular glt (S-I) regressor, without specifically mentioning which contrast (intercept = 0 or slope =1) to provide? It will provide kind of an average between those contrasts (intercept/slope)?

2. Also, for SPMG2, I understand that S#0 and S#1 will provide the intercepts (S#0 representing the major component of the hemodynamic response while S#1 representing the first-order derivative), while S#2 and S#3 are the corresponding slope/modulation effects of the two components of the SPMG2 function (again, please correct me if I am wrong). Similar for SPMG1, what significance will have the output for which I ask just the regular glt (S-I) regressor, without specifically mentioning which contrast to provide (0/1=intercept/slope without modulation and 2/3=intercept/slope with modulation)?

Thanks in advance for your help!

P.S. I had some issues with accessing my AFNI Message Board account, therefore I come back to this topic a little bit late.