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.



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