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Hello Peter, I'm not sure if I undestood your problem correctly. However I think that if you want to do is "regress out" all nuissance factors while extracting ts from a VOI (using spm). In this case what you need to do while setting up your F-contrast is assigns ones only to your affects of interest (zeros to nuissance regressors). In your case it would be: matrix=[eye(n) zeros(n,11)] n=number of task conditions (regressor of interest) 11: regressors of no interest. While doing so you restrict the variance of ts to the effects attributable to the task conditions and not to signal from WM, CSF, global signal, movement residuals etc. Did I understand you correctly? Iwo On Aug 27 2011, Peter Michalsky wrote: >Hello SPM experts, > > I want to estimate the connectivity between two VOIs and use the VOI > batch to extract the time-series from the first-level model. The > first-level model has covariates for task, movement, WM, CSF and a global > signal. The global signal seems to explain a large share of the variance. > Hence, the complete model consists of 11 covariates plus the constant. I > want to extract the time-course after adjusting for the variance that is > explained by all the covariates together. First I thought I needed to set > up the f-contrast as eye(11) but the resulting time-series is almost > perfectly correlated with the non-adjusted time-series so that can't be > it, right? I tried to only adjust for the global signal (third regressor > in design matrix, f-contrast: 0 0 1), which resulted in a time-series > that is much weaker correlated (0.6) with the non-adjusted time series. > Hence, I figured if I wanted to eliminate the total variance that is > explained by the covariates of no interest I have to set up a f-contrast > like this: 1 1 1 1 1 1 1 1 1 1 1 0. The results seem quite plausible but > I really want to make sure that I'm doing everything right here. I would > highly appreciate if anybody could help me out here! Thanks! > >Peter > -- Iwo Bohr, PhD (Torun) University of Cambridge Department of English and Applied Linguistics 9 West Road Cambridge CB3 9DP UK Tel: +44 1223 767 354 Fax: +44 1223 767 398 http://www.rceal.cam.ac.uk/People/Staffpages/ijb25.html