[Simnibs-discuss] Using Captrak coordinates for the optimization

Hyoungkyu Kim kim.hyoungkyu at gmail.com
Fri Jul 29 10:42:51 CEST 2022

Hi Jesper,

Thank you so much for your reply.
The positions of EEG channels are scanned by the Captrak device after
wearing EEG cap and we can know the actual coordinates of EEG channels.
The anatomical references of the Captrak system are  Nz, Cz, LPA, and RPA.

I thought I need to consider and fit the reference points properly when I
transfer the Captrak coordinates to the MNI Coordinate to use in SimNIBS
against than simple transforming of coordinates.
I wonder if my concern makes sense to you?

Thank you!


2022년 7월 29일 (금) 오후 5:09, Jesper Duemose Nielsen <jesperdn at drcmr.dk>님이 작성:

> Hi Hyoungkyu Kim
> Let me first apologize for the late reply!
> I assume you (perhaps as part of the Captrak system?) have a way of
> coregistering between captrak coordinates and MRI coordinates (e.g., based
> on fiducials)? If so, and you want the coordinates in MNI space, then you
> could use the function `subject2mni_coords` once you have created a
> headmodel using headreco (simnibs 3) or charm (simnibs 4 beta). By default,
> `subject2mni_coords` will apply the nonlinear deformation obtained during
> the segmentation. Does this do what you want?
> Best,
> Jesper
> On 7/1/2022 6:39, 김형규[ 교수 / 뇌공학연구소 ] wrote:
> To whom it may concern,
> Hello, I am Hyoungkyu Kim, a research professor in the brain engineering
> department at Korea University. First of all, I really appreciate using
> your great program, SimNIBS, for my research. The completion of the program
> is amazing and the tutorials are easy to understand.
> Our team is planning to measure EEG and fMRI during the memory task
> (sternberg test) under the tES stimulation, and I think SimNIBS is a
> perfect solution to optimize the stimulation by using a personal T1 image.
> I checked I can use personalized coordinates in the calculation of the
> leadfield, and I have the coordinates of Captrak (
> https://brainvision.com/products/captrak/). *I wonder if I can have the
> codes or information transforming Captrak coordinates to MNI coordinates
> (or to other coordinates) because I have not much experience with the
> registration between two different coordinates properly.  *
> It will be really helpful to me if I can have any advice from you.
> Thank you so much and have a great day!
> Best,
> Hyoungkyu Kim
> _______________________________________________
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