Recently there were two article published regarding clusterwise simulations for volumetric fmri analyses and potential errors for underestimating clusterwise extent thresholds.

1) http://www.pnas.org/content/113/28/7900.full.pdf?with-ds=yes

2) biorxiv.org/content/early/2016/07/26/065862

One issue pointed out from these articles seems software specific, however the second issue is determining the proper clustersize.  The heavy-tail nature of spatial smoothness seems to be ignored and a gaussian shape is generally assumed, leading to an underestimation of the spatial smoothness which can affect cluster size calculations.  The issues are highlighted in the second article above.  

I created my own monte carlo simulation in Freesurfer for a specific brain template and I wanted to find out if these concerns also apply to my surface based simulations?  I am not sure if it does since the monte carlo tool is a GRF simulation as opposed to an analytic equation, however given that these articles were highlighted very recently, I wanted to ensure I am running things appropriately for surface based cortical thickness/dti analyses.  

Thanks,

Ajay