[Freesurfer] average p-value from an ROI

Dear all, I have a follow-up question to the previous discussion ("correction for behavioral varialbles in qdec" Tue, 04 Aug 2009.

Is there an option to extract the average p-value from a ROI? After a group analysis I specified ROIs at p < 0.001 and extracted the mean cortical thickness, the peak p-value, and mean ROI size. Now, I would like to report not the peak, but the average p-value of an ROI in the fsaverage space. Is there any flag to obtain this information? I did not use the mri_surfcluster command, but a matlab script to extract the information form the output of the mri_segstats command.

Thanks for help! Cheers, Aga