ROI Connectivity Analysis Electrode Numbers

In doing ROI connectivity using (wPLI ISPC), is it necessary to have the same or close to the same electrode number within ROI’s? Resting state. Connectivity is calculated by taking electrode to electrode connectivity between each electrode in each roi then averaging.

Moreover, is there a minimum number of electrodes to use for an ROI? I have, at minimum, 6 in one ROI.

I have 4 rois, Frontal Right, Frontal Left, Parietal Right, Parietal Left. Though, I am missing electrodes from Frontal Left due to a hole in my cap related to my experimental paradigm. Should I restrict the frontal right electrodes to the same ones remaining in frontal left? I am comparing connectivity between conditions, not assessing differences between ROI’s alone.

Hi Josh. Good question. What’s important is to have the SNR roughly similar. So how can you match SNR between channels? Grouping could be one way.

My concern would be more about how well those electrodes actually form a “group” than whether the number per group were exactly matched.

So I guess my answer to your question is that I wouldn’t worry about it too much unless the numbers really differed, e.g., 6 vs. 1.

Thank you very much sir!