Thank you Anderson. I don't succeed to understand how can I get a 4D "clean" dataset (I need this for a spectral analysis).
I am running a GLM including 5 regressors for a task-based fMRI study.
My model is Y = x_stim*B_stim + x_c1*B_c1 + x_c2*B_c2 + x_r1*B_r1 + x_r2*B_r2 + e, where:
x_stim : stimulus time course convolved with HRF
x_c1 and x_c2: cardiac regressors
x_r1 and x_r2: respiratory regressors
I would like now to get the "clean" data, and what I mean is the data from which I removed the contribution of the cardiac and respiratory regressors. In order to do this I applied the following formula:
Yclean = Y - ( x_c1*.B_c1 + x_c2*.B_c2 + x_r1*.B_r1 + x_r2*.B_r2 )
Anyway, from the comparison between the clean data and the model fitting I'm convinced that there's something wrong. Could you please tell me how would you do to reach this purpose?
Thank you and sorry for bothering you!
|