Lead Field

Cristiano Micheli michelic72 at GMAIL.COM
Fri Jun 20 16:34:43 CEST 2008

Hi everybody
I tested the leadfield routine (compute_leadfield.m) for current dipole in
MEG forward solution.
How are the units expressed?
I expect the current dipole to be expressed in nA.m according to CTF
convention (i am using a 275 channels MEG CTF system), the gradiometers'
positions in cm and the lead field in Tesla.
Nevertheless i compared it with CTF software and there is quite a high
mismatch in the scaling factor, and the field is not perfectly distributed
as in CTF software forward solution.
In the Fieldtrip documentation it is mentioned a leadfield computation
method from Lütkenhöner, Habilschrift '92 which i could not find. How do i
get to the article?
I attach the code:

dip_pos = [2 2 10]; % cm
dip_mom = [10 0 0]; % 10 nA*m
% grad: gradiometers structure
% vol:  conductive sphere model
lf = compute_leadfield(dip_pos, grad, vol, 'singlesphere','yes')*dip_mom';

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