[Eeglablist] Question regarding reference channel (Makoto's Preprocessing Pipeline)

[Clement Lee]

If 'REF' is only on your cap and not in your data, you need to account for
this 'missing' channel for your data to be full rank. The ground truth is
based on the amplifier acquisition, not whether or not the channel shows up
on your data recording/processing software. The moment you re-reference to
another montage, this 'REF' channel becomes non-zero.  Use the full rank
average referencing plug-in.

Best,
Clement Lee
Applications Programmer
Swartz Center for Computational Neuroscience
Institute for Neural Computation, UC San Diego
858-822-7535


On Fri, Apr 3, 2020 at 3:59 PM Mahjabeen Rahman <
mahjabeen.rahman at knights.ucf.edu> wrote:

> Quoting you, "but REF is only 0 when you are actually referenced to it "
>
>  As there's no reference channel, neither during recording nor when I
> import data to EEGLAB. The REF channel is only on the cap. So in my case,
> the reference channel should be actually 0 then, if I understand your point
> correctly.
>
> I am computing average reference by going edit => rereference => compute
> average. Or should I do something else for full rank average ?
>
>
> Thanks much.
> Mahjabeen
> ------------------------------
> *From:* Clement Lee <cll008 at eng.ucsd.edu>
> *Sent:* Thursday, March 12, 2020 1:21 PM
> *To:* Mahjabeen Rahman <mahjabeen.rahman at Knights.ucf.edu>
> *Cc:* eeglablist at sccn.ucsd.edu <eeglablist at sccn.ucsd.edu>
> *Subject:* Re: [Eeglablist] Question regarding reference channel
> (Makoto's Preprocessing Pipeline)
>
> Hi Mahjabeen,
>
> It's 64 for built-in EEGLAB processing and 65 for full rank average
> referencing. GND is always 0 (even if you rereference), but REF is only 0
> when you are actually referenced to it (and becomes non-zero if you
> rereference to any other montage).
>
> Best,
> Clement Lee
> Applications Programmer
> Swartz Center for Computational Neuroscience
> Institute for Neural Computation, UC San Diego
> 858-822-7535
>
>
> On Thu, Mar 12, 2020 at 12:32 AM Mahjabeen Rahman <
> mahjabeen.rahman at knights.ucf.edu> wrote:
>
> Hi everyone,
>
> I am confused about one issue regarding my reference channel. I am
> recording data with Cognionics Mobile 64 channel device. So there are two
> zero-filled channels on the cap I am using called "REF" and "GND" near the
> mastoid region which never show up during the recording. When I import the
> raw data to eeglab, it shows no reference channel, only 64 channels show
> up. I am not sure, how I will apply average referencing here. Should I have
> to worry about the denominator here? Should it be 64 or 66 (considering the
> two zero-filled channels).
>
> Would appreciate any help on this.
>
> Thanks,
> Mahjabeen Rahman
> PhD Student
> Industrial Engineering & Management Systems
> University of Central Florida
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