easycap M43-V2 (63 equidistant electrodes) lookup table (standard montage coordinates)

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1

Hi all,

I am wondering if someone has a standard lookup table of easycap M43-V2 system (63 equidistant electrodes).
Currently, its not available in MNE.

Here how it looks like,

Screenshot from 2023-06-14 16-04-52
Screenshot from 2023-06-14 16-04-52750×864 127 KB

thanks,

2

I have never seen coordinates for this layout (neither in MNE-Python, nor in FieldTrip) … If I were in your position, I’d:

  1. do a thorough search whether you can find it in EEGLAB or Brainstorm, or some other analysis software
  2. contact Easycap to provide coordinates
  3. try to “create” the coordinates from scratch

Option 3 might be easier than it looks:

  1. set a circle to some radius (for example 1) → this is the outer circle
  2. create 5 “inner circles” at equal distances from 0 (the origin) to 1 (the radius … outer circle)
  3. count the number of electrodes to be placed on each of the inner circles (and the outer circle)
  4. for each inner circle, place the number of electrodes at equal distances (note: for the outer circle and the largest inner circle you’d need to “imagine” the electrodes towards the nose were still there … and then delete them from the data later – this should be reasonably simple to eyeball)
  5. place the ref electrode at (0, 0) of the coordinate system
  6. place the gnd electrode at x=0 and y=“halfway between first inner and fourth inner circle”
  7. finally, play around with your data and this function to get the layout you need: mne.channels.Layout — MNE 1.5.0.dev25+g959d2b64d documentation
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3

@sappelhoff Many thanks for the suggestions.

I have created a PR.

This should fix the issue.

best,
Dip

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