I wonder if the following procedure of normalization of coherence is acceptable.
- Get coherence for each ROI pair for each time window for each subject in Brainstorm.
- Get coherences among all Desikan-Killiany scouts for the entire epoch time window for each subject in Brainstorm. Compute mean and SD of these coherences.
- Normalize the ROI coherence (#1) with the mean and SD (#2) for each subject.
This is to minimize inter-subject variations, inspired by the paper by Nicolo 2015 Brain:
“Between-subject variation in synchronization magnitude can be due to variations in signal-to-noise ratios of the recordings. To avoid this potential confound in our analyses of the association between variations in [coherence] and clinical improvement, we normalized [coherence] map. This was achieved by subtracting, for each subject, the mean [coherence] across all voxels of the subject and by dividing by the standard deviation, hence yielding z-scores.”