pre/post connectivity

Hi,
I have a pre/post study and I'm trying to calculate connectivity (pearson correlation) between pre and post phases in some pre-defined ROIs.
However I don't know how to set up the batch. I think I need to create two conditions (pre and post), but how can I link the pre_study.nii scan with the pre condition, and the post_study.nii scan with the post condition?

I tried the following batch for one subject but it gives an error, and it doesn't associate the scans with the conditions anyway...
batch.filename='conn_prepost.mat';
batch.Setup.isnew = 1;
batch.Setup.functionals = {'/home/bba/group/pre_study.nii', '/home/bba/group/post_study.nii'};
batch.Setup.conditions.names={'pre','post'};
batch.Setup.conditions.onsets = {0};
batch.Setup.conditions.durations = {inf};
batch.Setup.nsubjects=1;
batch.Setup.RT=2;
batch.Setup.done = 1;

Thanks!
ben