[Eeglablist] CTF275 MEG channel position from FieldTrip to EEGLAB

[Makoto Miyakoshi]

Dear Zhi,

I don't have the same experience but I remember I also had some
inconvenience with fieldtrip2eeglab for which I needed to modify it a bit.
Anyway, it sounds like a low-level technical problem, which I recommend you
post to eeglab github issues to let the developers know.

https://urldefense.com/v3/__https://github.com/sccn/eeglab/issues__;!!Mih3wA!HRaod6OUYqL-hkUByVAxKDaF2pcX-dMAj5PLM3GojfDQHahcgRqJsniv9KFx0NmwA77ZTh8104HADK8cKzMSSdefpRk$ 

It may take some time for the developers to take a look at it. Sorry for
the inconvenience.

Makoto

On Fri, Jul 1, 2022 at 2:01 PM Zhi Li <lizhi.psych at gmail.com> wrote:

> Hi,
>
> I would like to use ICA and IClabel in EEGLAB to detect artefacts in my MEG
> data. But no matter if I used *fieldtrip2eeglab* or *pop_fileio*, the
> gradiometer
> channel positions cannot be correctly extracted from the ctf275 .ds folder.
> The channel positions in eeglab format *EEG* are all empty.
>
> I tried to copy the channel information directly from the header of the
> ctf275 data folder but the MEG channels cannot be projected on the 2-D map
> appropriately. It seems like the channel position in the MEG data imported
> by FieldTrip are the real locations of the MEG helmet and their unit is cm.
> whereas the channel position in EEGLAB is based on the 10-10 system which
> is already on the scalp. Hence the projected channels on the scalp are all
> misplaced if I use the raw XYZ from the header of ctf275 data.
>
> May I ask how I could transform the MEG channel position from FieldTrip to
> EEGLAB appropriately, or is there any other solution? Many thanks.
>
> Best regards,
>
> Zhi Li
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