[FieldTrip] Elekta Neuromag head positions indicators

[Casper Kerren]

Hi Gianpaolo,

Thank you for your reply. I will come back to you if I decide to do it.

Best,

Casper

-----Original Message-----
From: fieldtrip [mailto:fieldtrip-bounces at science.ru.nl] On Behalf Of gianpaolo.demarchi at gmail.com
Sent: 01 April 2019 13:58
To: FieldTrip discussion list
Subject: Re: [FieldTrip] Elekta Neuromag head positions indicators

Dear Casper,
sadly the Elekta machines don’t spit out the continuous head movement positions in the raw data files. It’s Maxfilter that, off-line, has to be summoned to “fit” the positions from the currents that are constantly injected in the head positions coils … and then either correct directly for those movements (standard Maxfilter approach) or get out the “quaternions” of the roto-traslations and get rid of the movements by yourself (e.g. via ft_regressconfound)
There is not theoretical reason why you wouldn’t be able to fit the positions by yourself (e.g. with many dipoles …), without having to necessarily go via Matrixfilter,  but we tried few years ago (find the story on bugzilla …) and failed … but you are welcome if you want to give it another spin :-)
Best luck,
Gianpaolo




Dr. Gianpaolo Demarchi
FB Psychologie - Universität Salzburg
Hellbrunnerstr, 34  5020 Salzburg (A)
gianpaolo.demarchi at sbg.ac.at

> On 01.04.2019, at 09:56, Casper Kerren <C.Kerren at pgr.bham.ac.uk> wrote:
> 
> Hi,
>  
> I have recorded MEG using Elekta Neuromag 306. I would like to correct for/incorporate head movement using the HPI coils. However, I am not sure what they are labelled as when reading the data? In the tutorial I can see that they are named HLC for the CTF system, but nothing on the labelling for Neuromag.
> Would someone be able to help me on this?
>  
> Thank you,
>  
>  
> Casper Kerrén, PhD student
> School of Psychology 
> College of Life and Environmental Sciences 
> University of Birmingham 
> Edgbaston 
> Birmingham B15 2TT
> e-mail: cxk699 at student.bham.ac.uk 
> tel:+46(0) 732 189595
>  
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> https://doi.org/10.1371/journal.pcbi.1002202




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