Help with dipole fitting

Ludwing Torres lumatobu2 at HOTMAIL.COM
Sun Jul 18 00:26:34 CEST 2010


Hi everyone. Im trying to make a forward computation of the dipole potentials measured in the scalp. I'm following this example:

http://fieldtrip.fcdonders.nl/example/compute_forward_simulated_data_and_apply_a_dipole_fit

but in the part that they describe the two dipole computations:
% create a dipole simulation with two dipoles and a custom timecourse

I dont understand why they take the dipole moments like this:

cfg.dip.mom = [      % each row represents [qx1 qy1 qz1 qx2 qy2 qz2]
   1 0 0 0 0 0       % this is how signal1 contributes to the 6 dipole components
   0 0 0 1 0 0       % this is how signal2 contributes to the 6 dipole components
   ]';               % note, it should be transposed

¿Does it mean that if I have three dipoles, the dipole moment should be like this? :

cfg.dip.mom = [
   1 0 0 0 0 0 0 0 0
   0 0 0 1 0 0 0 0 0
   0 0 0 0 0 0 1 0 0
]';

¿And to four dipoles, like this?

cfg.dip.mom = [
   1 0 0 0 0 0 0 0 0 0 0 0
   0 0 0 1 0 0 0 0 0 0 0 0
   0 0 0 0 0 0 1 0 0 0 0 0
   0 0 0 0 0 0 0 0 0 1 0 0
]';

¿ And what if I have 128 dipoles?

PLEASE HELP ME UNDERSTAND THIS, BECAUSE IM GETTING AN ERROR IF I FOLLOW THIS RULE TO 128 DIPOLES AND I THINK THIS IS A MISTAKE

OTHER THING IS HOW CAN I COMPUTE THE FORDWARD ELECTRODE POTENTIALS, NOT JUST THE POSITIONS.

PLEASE HELP ME !!!!!

 		 	   		  
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