Hi!

 I am trying to use the gppi toolbox (PPPI Version: 13.1.4-17-2014 with SPM25) but have come across issues related to the timeseries extraction function  (y=spm_filter(SPM.xX.K,SPM.xX.W*y)). In our study, we have 6 runs per subject and individualized ROIs already created using retinotopy data. Everything is in MNI space and has the same voxel dimensions. 

 For the first level model, I included each run as an independent regressor. I wasn't sure how to create the one VOI.mat file/subject as the model contains 6 runs, so instead I used the nii file for the VOI parameter (P.VOI= VOI.nii). I also included P.ConcatR = 1; % Enables concatenation of sessions so that the 6 sessions are concatenated at this level of analysis. I also included P.equalroi=0; and P.FLmask=1 to offset an error related to "VOI larger than dataset". 

When running the PPI, I get the following outputs: VOI has 670 voxels in 1.500000e+00x1.500000e+00x1.500000e+00 space. This is in the the same space as the input data and functional mask. But then receive the error message: Error using  *  multiplication. Error in timeseries_extract (line 355) y=spm_filter(SPM.xX.K,SPM.xX.W*y);

Please advise on how to setup the proper first-level GLM, VOI extraction and gPPI setup to help solve this problem!

Thanks!

Madeline