Hi Mingrui,

Thanks for your response. In order to merge the pial files of the two hemispheres from Merge Mesh tool in the menu bar, we need to load three files: 1) Left (lh.pial), 2) Right (rh.pial), and 3) New (.nv file). The pial files are provided in the surf folder of freesurfer. How about the New nv file?
Should I load the left and right pial files on one of template nv files that came with BrainNet Viewer package, e.g. ICBM152? Or do I just need to make an empty text file with extension .nv and load the pial files into it? Or do I somehow need to make this ASCII text *.nv file? (with vertex number, vertex coordinates, triangle faces number and index of vertex making up the triangles fields)

Thank you,
Afarin