PLEASE HELP !!!!!

Ludwing Torres lumatobu2 at HOTMAIL.COM
Mon Jul 19 04:47:31 CEST 2010




Date: Sat, 17 Jul 2010 17:26:34 -0500
From: lumatobu2 at HOTMAIL.COM
Subject: [FIELDTRIP] Help with dipole fitting
To: FIELDTRIP at NIC.SURFNET.NL








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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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.
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