I would like to know if there is a easy way in BS to flip left-right MEG sensor or source data. I see a related post (link below) from 2014, but not sure if anything has been done.
You can find information to flip left-right EEG channels:
In the case of MEG, you should not do any source modeling after flipping the sensors left-right.
For source data: what would you do with this exactly?
Thanks. I understand the issues with flipping the MEG data. I have a set of subjects for whom stimulus was delivered to either the right or left extremity. Consequentially, predominant MEG activity is recorded on the contralateral hemisphere, left hemi for right extremity stimulation and right hemi for left extremity stimulation. I cannot do group analysis unless, all the data is aligned to one side. Whats the best approach to deal with such situations?
In source space, you can define scouts that define the ROIs in each condition.
Depending on the participant, these scouts would be on the left or the right.
Extract and average the scouts time series.
Thanks. However, scouts reduce the spatial specificity of activity. Assuming each source is a tiny scout by itself, isn't it possible to just flip the source times series from one hemisphere to another? I understand the possible implications of head position changes, in that case.
Brains are not symmetrical, neither anatomically nor functionally.
Theoretically: Mapping one-to-one vertices in the two hemispheres for MEG source-level analysis is an abstraction that has little chance of making sense physiologically.
Practically: We haven't implemented this in Brainstorm.
Working at the ROI level, especially if designed in a data-driven way, gives an option to work around both problems.