Visualize head/helmet coregistration after coregistering MEG runs

1

Hello,

I have 6 runs per subject collected with Neuromag Elekta, the headpoints were collected once at the beginning of the experiment and the data was MaxFiltered, and I want to compute one head model per subject (not per run), so I use the process_megreg function:

sFiles = bst_process('CallProcess', 'process_megreg', sFiles, [], ...
    'targetchan', 1, ...  % Average of all the runs
    'sharechan',  1, ...  % Yes, share the same channel file between runs
    'epsilon',    0.0001);

Before doing that, I first imported the raw file for each run and refined with head point. I could visualize for each run if the MRI/MEG coregistration was OK by double-clicking on the 'Neuromag channels' inside each run. It was all good/corrected.

After using process_megreg however, the 'Neuromag channels' file only appears in the Common files (which is what we want!) but when I double click on it the head is completely outside of the helmet.

I am wondering if it's the visualization that is not able to correctly display MRI/MEG coregistration after the process_megreg, or if there is something deeper that is wrong (which would impact the computation of my inverse kernel).

Thanks!

2

Hello again!
the problem actually comes from the fact that after importing the 6 runs and averaging between them, I import empty room recordings and it replaces the 'Neuromag channels' file! I saw the option 'channelreplace', I will correct my script, sorry for bothering you!
julie

2 Likes