Dear Adeel:
I enjoyed reading your recent paper about large-scale DCMs for resting-state fMRI (Razi et al., Network Neurosci 2017) and have two questions about the paper. (1) Is the 20 min per iteration reported for spectral DCM without any constraints on the prior covariance matrix or with functional connectivity priors? I tried to invert a 36-node DCM using spectral approach (using the routine spm_dcm_fmri_csd.m) and it took more than 3 hours for each iteration. Maybe I missed it, it seems you did not mention how efficient it will be under functional connectivity priors (i.e., running time difference with and without prior constraints). (2) Is the MATLAB code of the example available in SPM12 (as indicated in the paper)? If yes, what is the name of the routine and where can I find it? I think I can understand the approach better when I take a look at the code.
Sorry to bother you again and thank you very much for your help!
Best regards,
Guoshi Li
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