preparing leadfield for Phantom

Jim Li megjim1 at GMAIL.COM
Thu May 7 02:08:47 CEST 2009


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

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