Dear FreeSurfer experts,

I need help trying to understand how the white matter gets parcellated. I have a clinical dataset, which means that the resolution is not as research images, but it ran without a problem. I would like to measure the volume of the basal ganglia and looking at wmparc.mgz I am not sure how Freesurfer decides where a structure ends and the other one begins. I am attaching two images to show what I mean.

I would really appreciate some clarification. I am using FreeSurfer 7.1.1

Thanks in advance.

José