Dear SPM experts,
I have a question regarding the Unweighted Graph Laplacian matrix in SPM12. By assuming a 2d slice, my question is, when the voxel is located on the boundary of the mask, which has fewer than 4 neighbors, what is the form of the UGL like?
According to "Penny et al 2005", the UGL matrix will still have 4 on the diagonal component, and -1 on the edges that are inside the mask, and 0 on the edges that are outside the mask. Can anyone help me confirm this? Thanks a lot!
Sincerely,Ming