preparing leadfield for Phantom

[Jim Li]

Hi all,

Actually I just observed something: "hdr.grad.pnt" doesn't contain the 
coordinates of digitization points, but instead seems to be sensor coil-related. 

My question regarding how to prepare the lead field using the 
single shell modeling still remains. Any suggestion will be greatly appreciated!

Thanks,

Jim

On Thu, 7 May 2009 02:08:47 +0200, Jim Li <megjim1 at GMAIL.COM> wrote:

>Dear FTer:
>
>I'm trying to test a localization algorithm with some epoch data collected on 
>our phantom. Can anyone suggest a way to prepare the lead field using the 
>single shell modeling? I'm using 4D's system right now.
>
>While playing with "prepare_singleshell" and  "prepare_leadfield", I 
encountered 
>two questions:
>
>1) How can I get my headshape points in head coordinate system? 
>
>I can run 
>--------
>hdr = read_fcdc_header(FileName);
>cfg.headshape = hdr.grad.pnt;
>[vol] = prepare_singleshell(cfg);
>-------
>but that doesn't seem to give me headshape points in head coordinate 
system 
>and it'll crash "prepare_leadfield" later on.
>
>2) Do I need to define "cfg.vol.r = 7.5; cfg.vol.o = [0,0,0];" before 
>running "prepare_leadfield"? If not, I'll get weird stuff like "1 dipoles inside, 26 
>dipoles outside brain".
>
>I'd appreciate it if anyone can show me your complete script of preparing 
lead 
>field from beginning to end.
>
>Cheers,
>
>Jim
>
>----------------------------------
>The aim of this list is to facilitate the discussion between users of the 
FieldTrip  toolbox, to share experiences and to discuss new ideas for MEG and 
EEG analysis. See also http://listserv.surfnet.nl/archives/fieldtrip.html and 
http://www.ru.nl/neuroimaging/fieldtrip.

----------------------------------
The aim of this list is to facilitate the discussion between users of the FieldTrip  toolbox, to share experiences and to discuss new ideas for MEG and EEG analysis. See also http://listserv.surfnet.nl/archives/fieldtrip.html and http://www.ru.nl/neuroimaging/fieldtrip.