Montage easycap 128 - Electrodes outside head circle

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Hi,

I’m working with EEG data and I’m using the standard 128ch actiCap montage from easyCap. Some of the electrodes appear outside the head circle. My code for loading the montage is:

name_Montage = ‘CACS-128_NO_REF.bvef’
montage=mne.channels.read_custom_montage(name_Montage)

and when I plot this montage I get this:
image

I wanted to know if there is a way to see the electrodes inside the head circle. I already tried using sphere=‘eeglab’, as mentioned in other discussions, but I get the exact same figure. You don’t see all the 128 channels because recorded less electrodes, but used that montage.

  • MNE version: 1.4.2_0
  • operating system: Ubuntu 22.04.3
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You can play with the sphere argument by setting it to a number, e.g.

montage.plot(sphere=0.1)

Try several different values until you’re happy with the result.

BTW, why do you want to have all electrodes inside the circle? In your current plot, the head circle is defined by electrodes Oz and Fz (among others), which just means that everything outside of the circle is below that circumference on the 3D head (so e.g. Iz is below that line).

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I’d also agree that the above plot looks correct and is what I’d desire most of the time.

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4

Thanks for your help. I agree that this looks correct. I’m just trying different things for visualization purposes and was interested on knowing how to do so. Thanks again :slight_smile:

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