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

[Mahjabeen Rahman]

Thank you so much for the clarification.

-Mahjabeen
________________________________
From: Clement Lee <cll008 at eng.ucsd.edu>
Sent: Friday, April 3, 2020 7:07 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)

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<mailto: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<mailto:cll008 at eng.ucsd.edu>>
Sent: Thursday, March 12, 2020 1:21 PM
To: Mahjabeen Rahman <mahjabeen.rahman at Knights.ucf.edu<mailto:mahjabeen.rahman at Knights.ucf.edu>>
Cc: eeglablist at sccn.ucsd.edu<mailto:eeglablist at sccn.ucsd.edu> <eeglablist at sccn.ucsd.edu<mailto: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<mailto: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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