I selected the same file (imported raw) on both sides, then I click run --> Processes --> Connectivity --> Amplitude Envelope Correlation (AEC) AxB but then I had just one electrode to compute AEC 1x19. What I want to compute is interhemispheric AEC (I mean between electrode pairs: O1 with O2, T4 with T3, etc).
I know that if I compute NxN AEC I will get these values too, but I don't want a big connectivity matrix cause many variables can affect results and give no significant results, I would like to get a connectivity matrix with just interhemispheric electrode pairs, is that possible?
Ah indeed, AxB lets you do only 1xN across separate files, so not a solution for you.
Then I don't think there is any solution other than computing the full NxN matrix and keeping only the values that are interesting for you.
If you really don't want to see the other values, you can explicitly set them to zero in the matrix. You'd need to edit the TF field in the connectivity file manually: https://neuroimage.usc.edu/brainstorm/Tutorials/Scripting#Custom_processing