Dear Freesurfer experts,

I am doing a thickness-age correlation group difference study (patients versus controls. I would like to know if:

1) my contrast vector defined as 0 0 0.5 0.5 is correct in order to test the change in thickness with age
2)what is the best iteration number for the simulation? Should be 5000 or 1000 or greater?
3)why when I run the simulation for 5 iterations I've got zero clusters?
4)can I derive the thickness from the significant clusters of glm analysis? Do I need to run QDEC after GLM?

 Thanks for any enlightenment.
Antonella