[Eeglablist] Interpolate 8 channel montage

[Makoto Miyakoshi]

Dear Brian and Zaeem,

My first data I analyzed had only seven electrodes.
Because these electrodes were placed symmetrically to both left-right and
anterior-posterior axes, it was like an extremely sparse full-scalp
recording (something like 20-40 system, instead of 10-20)

You can process such data normally except for the following points:

   - Electrode interpolation--could be very rough
   - Average referencing--Some people say no, but I think it is fine to go
   ahead if the electrode coverage is more or less uniform across the scalp.
   - Dipole fitting--the result accuracy (?) is naturally limited, though
   you tend to see smaller r.v. (why? Because less data needs to be
   approximated)

In any case, as long as you describe these limitations clearly in your
report, it is fine.

Makoto


On Thu, Jul 23, 2020 at 8:14 AM Kavanaugh, Brian <brian_kavanaugh at brown.edu>
wrote:

> Zaeem,
>
> This is quite useful, thank you very much!
>
> Brian
>
> On Mon, Jul 20, 2020 at 12:17 PM Zaeem Hadi <zaeemhadi at ymail.com> wrote:
>
> > Hi Brian,
> >
> > I have been working with 8 channel dataset. However, I have avoided using
> > the clean_rawdata plugin. The reason being the eye blinks, which are
> quite
> > high in amplitude and also present in other channels to some degree. And
> > thus clean_rawdata would almost always reject 2 or 3 channels. And
> > interpolating so much data on just 8 channels wouldn't make sense. But if
> > you have relatively clean data, you might be able to use it.
> >
> > To avoid that, I am using the pop_eegthresh(ALLEEG) function to
> > semi-automatically reject epochs based on amplitude thresholding. For
> some
> > reason, it is not available through GUI.
> >
> > That being said, I have interpolated some channels in my data due to
> > excessive noise at the Alpha frequency range, but then I reduced the
> number
> > of Independent components being determined using 'pca' option in infomax
> > ICA, as suggested by Makoto in his pre-processing pipeline.
> >
> > Kind Regards,
> >
> > Zaeem Hadi
> >
> > Brain and Vestibular Group
> > Imperial College London
> > On Monday, July 20, 2020, 10:40:00 AM GMT+1, Kavanaugh, Brian <
> > brian_kavanaugh at brown.edu> wrote:
> >
> >
> > Hi everyone,
> >
> > We are hoping to analyze a previously collected dataset that used an 8
> > channel montage. Does anyone have any experience analyzing such a small
> > amount of electrodes? We are specifically curious about channel
> > interpolation options if channels are removed via clean_rawdata. Can we
> > follow a similar approach that we use for 32/64 channel data? Thanks
> > everyone!
> >
> > Brian
> >
> > --
> > Brian Kavanaugh, PsyD.
> > Pediatric Neuropsychologist, E. P. Bradley Hospital/Rhode Island Hospital
> > Assistant Professor (Research), Warren Alpert Medical School of Brown
> > University
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>
>
> --
> Brian Kavanaugh, PsyD.
> Pediatric Neuropsychologist, E. P. Bradley Hospital/Rhode Island Hospital
> Assistant Professor (Research), Warren Alpert Medical School of Brown
> University
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