Hello Francois!
Actually I'm working an eeg dataset which has CPz reference channel. Can you please tell me how to recompute this reference channel from the recording. As the channel file given is in BIDS format i.e..tsv format. It doesnt have X, Y, Z for CPz. I tried using custom montage but its not working. The cap used by them is a 64-Ag-AgCl electrodes stretch lycra cap, Brain Vision system.Could you please direct how to retrieve this channel back, as im confused about the coordinates, using brainstorm. It doesnt match with the read locs. File in EEGLAB which gives the coordinates for refe. Channel via pop.ref_m function.
Dear Francois!
I tried using the steps given, actually the .tsv file given doesn't have any locs for the reference electrode CPz. When I'm doing using the custom montage it automatically sets the value corresponding to CPz to be blank. Please suggest how should I do this.
Same question as in the other thread: why do you need to add the reference electrode to the dataset?
I tried using the steps given, actually the .tsv file given doesn't have any locs for the reference electrode CPz.
After adding it to the data file, you would need to set the position of this electrode somewhat manually.
Right-click on the channel file > Edit, add in the Loc field the average position between two electrodes on each side of CPz.
Then right-click on the channel file > MRI registration > Edit > Move the electrode CPz to where you think it should be.
When I'm doing using the custom montage it automatically sets the value corresponding to CPz to be blank.
I'm not sure I understand what this means.
Can you include screen captures?
I got the following raw file after following through all the steps mentioned in the forum, standardize> Apply Montage.
Although the retrieved file has no recording for CPz , which was the reference electrode.
I am able to retrieve CPz information when I'm using eeglab, but could not retrieve it using brainstorm. Kindly suggest me how should I pursue this now.
If you manage to obtain an extra flat CPz channel, you've done all the work.
Now change the reference to another electrode or an average reference, and you should see a non-zero signal in CPz. If it remains flat when displaying the recordings in average reference, it means that the recordings are already saved in average reference.
Can you please elaborate on why you are trying to do this?
In most cases this is not very useful to add the reference back, and in some cases it can even be detrimental to the data analysis.
I wanted to plot ERPs for Central electrodes, that's why I am trying to recompute it. As the ERPs for the task, I am interested in are localized to Central electrodes.
