Editing group level neighbourhood matrix
As explained on the Channel Neighbourhood page, you need to define which channels are neighbours to compute clusters. If using the EEGLAB STUDY interface, a default distance is used, or you had to enter a distance yourself if you called the LIMO tool. You might still want to edit this!
The distance selected reflects which channels should be pooled together, and unless this is done for 1 subject for which you have the exact locations, this distance might be inaccurate for some electrodes. This is particularly true with low-density arrays.
LIMO tools --> 'Create or edit an expected chanloc file' Two figures pop out, one showing the channel locations and the other the neighbourhood matrix (in white, this indicates what goes together). Simply click the channel pairs you want to edit (add or remove). Note this is a symmetric matrix and thus, whichever part you edit, it's symmetric value gets edited too automatically.
Simply right-click or click outside the matrix (on the figure) to exist. A 'edited_filename.mat' file is created.