I am attempting to run DCM model specification on fMRI data, using SPM8, using two blocks of trials which are different lengths. I have run the blocks separately but would like to run them together to ensure that the findings from the separate blocks are accurate. I extracted VOIs for the same regions for each block in order to run this. When I try to run it this way, I encounter this error.
??? Subscripted assignment dimension mismatch.
Error in ==> spm_dcm_specify at 287
Y.y(:,i) = xY(i).u;
Error in ==> spm_dcm_ui at 106
spm_dcm_specify;
From what I was able to gather from looking into the error, it seems like the problem comes with the different lengths of the blocks, which results in it trying to assign an N length array to a matrix that's already set to length M. So I have two questions:
1) Is there a way to set up the VOIs so that instead of being in two blocks, they are through the whole run? Since my SPM runs have two sessions it is always asking for me to specify a block. A VOI for the full run would bypass this problem entirely, but I have not found a way to do this.
2) If the above cannot be done, is there a way to allow data for runs of different lengths to be read into the same model?
