[Eeglablist] Help with EEG channel location import, channel numbers incorrect

Maria Fini mfini at asu.edu
Fri Sep 27 11:50:30 PDT 2019


Oh could I just shuffle the order of the data rows in the EEG.data matrix
after importing the channels? Is there a better way to do it, or any other
components of the data I would have to change?

On Fri, Sep 27, 2019 at 11:47 AM Maria Fini <mfini at asu.edu> wrote:

> Hi Clement, thank you for getting back to me so quickly!
>
> I don't think problem 2 can be avoided. For problem 1 though, is your
> EEG.data being shuffled, or are your EEG.chanlocs.labels?
> As far as I can tell, it is the EEG.chanlocs.labels that are being
> shuffled, the data still stays in the same order (see 3.png in my first
> email), but the channels now have new labels.
>
> Does the captrack .sfp contain the same channel labels as your
> EEG.chanlocs.labels before importing channel locations?
> I'm assuming you mean the 1020 labels? Ie 'AFz', 'Cz', etc. Yes, with the
> exception of the electrode I removed, the labels should be the same in the
> .sfp and EEG.chanlocs.labels
>
> If you know these things and your data is consistently collected in the
> same way, you can add any corrections in a preprocessing script.
> This is great news! Any tips or tricks to point me in the right direction?
>
> On Fri, Sep 27, 2019 at 9:46 AM Clement Lee <cll008 at eng.ucsd.edu> wrote:
>
>> Hi Maria,
>>
>> I don't think problem 2 can be avoided. For problem 1 though, is your
>> EEG.data being shuffled, or are your EEG.chanlocs.labels? Does the captrack
>> .sfp contain the same channel labels as your EEG.chanlocs.labels before
>> importing channel locations? If you know these things and your data is
>> consistently collected in the same way, you can add any corrections in a
>> preprocessing script.
>>
>> Best,
>> Clement Lee
>> Applications Programmer
>> Swartz Center for Computational Neuroscience
>> Institute for Neural Computation, UC San Diego
>> 858-822-7535
>>
>>
>> On Fri, Sep 27, 2019 at 1:03 AM Maria Fini <mfini at asu.edu> wrote:
>>
>>> Hello Community,
>>> I am new to eeglab and having some trouble with importing my recorded
>>> electrode locations.
>>> I recorded 64 channels of data using the brainvision EEG recording
>>> system,
>>> with electrodes in the standard 10-20 locations, except 1 electrode,
>>> which
>>> I removed to do ultrasound stimulation, and placed on the chest to record
>>> HR.
>>> Electrode montage matches that of the template file
>>> ('[eeglabPath]/plugins/dipfit2.3/standard_BEM/elec/standard_1005.elc')
>>> with the reference at the left mastoid and the ground front and center on
>>> the cap.
>>>
>>> I recorded each subjects' electrode locations using the brainvision
>>> captrack system.
>>> When I go into the gui edit>channel locations> then click 'Read
>>> locations'
>>> to bring in the.spf file, the 3d plot of the electrode locations looks
>>> correct, but I am running into a couple of problems: (an pointers would
>>> be
>>> greatly appreciated)!
>>>
>>> 1) Main problem I'm having is that the channel locations look correct in
>>> space, but are registering with different channel numbers than the
>>> default
>>> locations, which I am 99% sure is how my data was recorded. Ie electrode
>>> Fp1 in the default template, and I believe also in my recording, is
>>> registered as channel 1 in the EEG data, but when I load in my recorded
>>> locations, it shows up as channel 43, so the data and electrode
>>> assignments
>>> are getting shuffled into wrong positions in the eeg data matrix (see
>>> attached photo 3: template locations on the right, left is data after
>>> .spf
>>> channel location file loaded). I think the program is assigning them
>>> numbers 1-64 based on what order the electrodes were detected by the cap
>>> track system, because usually the algorithm starts by the left ear. Yet,
>>> the locations in 3d space are correct.
>>>
>>> 2) Secondary problem is that the electrode which I removed from the cap
>>> for
>>> the ultrasound and used to record the heart rate, was also removed from
>>> the
>>> captrack file. I don't really want this electrode included in the global
>>> scalp calculations because it was used to record HR, not EEG. It seems I
>>> have to manually enter it back in to prevent an error in the system from
>>> having less electrode locations than recorded channels. I can manually do
>>> this using the coordinates of the reference, but it's a pain.  This
>>> channel
>>> seems to get rejected in cleanline, so I guess it isn't too much of a
>>> problem.
>>>
>>>
>>>  I suppose I could just go forward on my data processing with the default
>>> locations, but I figured since I recorded the actual electrode
>>> locations, I
>>> might as well use them. Any suggestions on how to still use the recorded
>>> locations, but not screw up the channel numbers would be wonderful!
>>> Thanks for your time.
>>>
>>>
>>> --
>>> Maria Fini
>>> Arizona State University
>>> Tyler Neuroperformance Lab, Dept. of Biomedical Engineering
>>> PhD Student
>>> *703.989.9650*
>>> *mfini at asu.edu <mfini at asu.edu>*
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>>
>
> --
> Maria Fini
> Arizona State University
> Tyler Neuroperformance Lab, Dept. of Biomedical Engineering
> PhD Student
> *703.989.9650*
> *mfini at asu.edu <mfini at asu.edu>*
>


-- 
Maria Fini
Arizona State University
Tyler Neuroperformance Lab, Dept. of Biomedical Engineering
PhD Student
*703.989.9650*
*mfini at asu.edu <mfini at asu.edu>*


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