Thanks! That makes sense!
I noticed that when I compute unconstrained head model using defined source grid template, I got warning messages:
Some dipoles are outside the BEM layers, The leadfield for these dipoles is probably incorrect.
The number of dipoles vary among subjects. For the two subjects I tried so far, the number for one subject is 56 dipoles, and the number for the other subject is 655 dipoles...
How much will this affect future analysis? and is there a way I can avoid this warning from happening?
Thank you very much!