UiT The Arctic University of Norway
Question
Asked 29th Aug, 2016
EEG error: datasets missing channels. It's strange because they were recorded well, and faulty files are quite as heavy as the good ones. Any ideas?
Hi everyone,
If you could please give me a hand with this error, I would be very grateful. I have EEG from a psychological experiment, recorded with BrainVision Recorder, and being analyzed with BrainVision Analyzer 2. Most of the recordings are perfectly fine, but a few present a big error. Out of 64 original electrodes, only two appear. These are the right mastoid (RM) and the left eye sensor (LEOG). Both are bipolar electrodes. RM is to be re-referenced to the online reference electrode, while LEOG is to be re-referenced to the right eye electrode.
I just can't fathom the error because all electrodes worked fine during the recording. Also, the data sets with the error are quite as heavy in terms of bytes as those without the error. Further, why should the RM and LEOG channels remain perfectly well as they do?
This issue might seem like a simple zoom I've bypassed, or similar... But unfortunately the channels are just not there. I've confirmed it as I tried to copy the pipeline from the good data sets onto the faulty ones, where I got the error 'No channels enabled.' In case you had access to the BVA analysis software, please find the raw files for one of the faulty data sets here: https://www.dropbox.com/sh/2bpoh4coi2z5y6a/AAAaAipH2RuD2RXUlX6pRd5Ea?dl=0
Most recent answer
Update: Problem solved.
As Nikolay said, the error originated in Recorder (I had used the workspace from the previous experimenter), and the problem was solved by setting the label and position of each channel.
I tried editing the .vhdr file in raw (it seemed nice and quick to directly assign the channel names as labels) but i didn't quite find the way. Therefore, with a tip from the Brain Products team, I went about it within the program. First, I used the transform function 'Edit channels' to rename all labels and set each within their coordinates. I did that for just one subject (it doesn't take as long as it sounds). Afterwards, I created a 'History template' out of that process, and copied it to all other nodes.
At any rate, never getting out of the comfort workspace again... :D
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Popular answers (1)
The Chinese University of Hong Kong
Hi Pablo,
I have opened your data on my computer and all 64 channels can be seen (see the figure), but all except RM and LEOG lack labels. Is then the lack of labels that wories you or you don't see the waveforms either? The latter would suggest that your Analyzer somehow omits the channels without labels. This is very strange, but seems like in either case bringing back the labels should solve the problem.
The lack of labels must have originated in your Recorder workspace. The Name column in the amplifier setup should contain electrodes names and not numbers as it is now. The best is to upload the ready-made workspace for your cap from the manufacturer before experiment. You can also correct it after recording by editing your .vhdr file as ChXX=electrodelabel, but be careful with those and make sure you keep the backup of the data.
Greetings, Nikolay
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All Answers (4)
The Chinese University of Hong Kong
Hi Pablo,
I have opened your data on my computer and all 64 channels can be seen (see the figure), but all except RM and LEOG lack labels. Is then the lack of labels that wories you or you don't see the waveforms either? The latter would suggest that your Analyzer somehow omits the channels without labels. This is very strange, but seems like in either case bringing back the labels should solve the problem.
The lack of labels must have originated in your Recorder workspace. The Name column in the amplifier setup should contain electrodes names and not numbers as it is now. The best is to upload the ready-made workspace for your cap from the manufacturer before experiment. You can also correct it after recording by editing your .vhdr file as ChXX=electrodelabel, but be careful with those and make sure you keep the backup of the data.
Greetings, Nikolay
3 Recommendations
UiT The Arctic University of Norway
Hi Nikolay,
Thank you so much. That's a great relief. I cannot see those channels. Some setting must be hiding them because they're unlabeled, so I'll try and change that.
Best regards
UiT The Arctic University of Norway
Alright, I can see them now! It was about an edited montage (which strangely does work with the other datasets).
Thank you again!!
UiT The Arctic University of Norway
Update: Problem solved.
As Nikolay said, the error originated in Recorder (I had used the workspace from the previous experimenter), and the problem was solved by setting the label and position of each channel.
I tried editing the .vhdr file in raw (it seemed nice and quick to directly assign the channel names as labels) but i didn't quite find the way. Therefore, with a tip from the Brain Products team, I went about it within the program. First, I used the transform function 'Edit channels' to rename all labels and set each within their coordinates. I did that for just one subject (it doesn't take as long as it sounds). Afterwards, I created a 'History template' out of that process, and copied it to all other nodes.
At any rate, never getting out of the comfort workspace again... :D
2 Recommendations
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