Thanks Doug! I also found another solution from you in this post:

https://mail.nmr.mgh.harvard.edu/pipermail//freesurfer/2013-July/031726.html

Reza

One way is to create a surface overlay with the target vertex = 1 and 
other vertices 0 (mri_volsynth, use delta, works for surface overlays 
too). Then smooth by a certain FWHM (mri_surf2surf or mris_fwhm). This 
will create a circle. If you divide all vertices by the value of the 
vertex after smoothing and then threshold at 0.5, then you should have a 
circle of radius approximately FWHM/2.

Hi,

I want to draw a circle around a vertex on the smoothwm or pial surface, with a particular radius (e.g. 10 mm), fill the circular region and save it as a label file, then repeat this for all the vertices on the surface. I need this for doing a searchlight analysis. Does anyone have a script/code for it?

I know that mris_pmake (using Dijkstra's algorithm) can be used for this purpose, but I don't know exactly how to make it to work in a script for drawing circular ROIs.

Thanks for any help!

Reza