Determining within-cluster mean FC values

Hello,
I have been working on interpreting results from an ANCOVA using resting-state functional connectivity data, and after applying AlphaSim cluster-extent thresholds, I have several clusters of voxels that reach significance.  What I would like to do, but what I have so far been unable to determine how to do, is to calculate the mean functional connectivity values within each cluster (for each of my two groups, at each of two scanning sessions) so that I can plot out the mean values graphically.  I am aware of the "Extract ROI signal" utility, but I have been unsuccessful at computing these cluster-wise mean FC values using this.  I also want to be able to extract these means for each subject.

I have tried to "Save Clusters" within the REST slice viewer, and then to use that as a predefined ROI in the "Extract ROI Signal" utility, but when I try to calculate something like "mean(i1)" I get an error.  How should I go about calculating within-cluster FC values at the individual subject level?

Any thoughts regarding this issue would be much appreciated, thank you.

- Ben Mooneyham
Graduate Student
Department of Psychological & Brain Sciences
University of California, Santa Barbara 

Dear Ben,
I suggest you should use 'Save cluster' instead of 'Save clusters' to save one significant region as a predefied ROI (because you want to get the mean correlation within each cluster), then try again to extract the ROI signal as you did before.

Best regardes,
Bin-Ke