[Mne_analysis] Estimates using mne_volume_source_space
Matti Hamalainen
msh at nmr.mgh.harvard.edu
Fri May 22 22:02:17 EDT 2009
Hi Andrés,
On May 22, 2009, at 6:14 PM, Andres Felipe Salazar Gomez wrote:
> Hi MNE users,
>
> I have used the mne_volume_source_space command to get a source
> space of 6
> dipoles. After getting my estimates I get a total of 18 sources
> orientations. I would like to know which sources correspond to what
> dipoles.
>
> If I have 18 sources, are they arrange so that the first 3 elements
> are
> for the first dipole, the second third for the second dipole and so
> on?
>
> I think it is so but I want to confirm it.
>
> Thank you very much for your comments and suggestions.
The data are arranged exactly as you describe. The forward matrix A =
(a_1 a_2 a_3 .... a_3N) where N is the number of sources and column
a_1 is the the field of the dipole oriented in the x direction at
location 1, a_2 is the field of the dipole oriented in the y direction
at location 1, a_3 is the field of the dipole oriented in the z
direction etc.
If the --mricoord option was specified when the forward solution was
computed, the x, y, and z axes are those of the MRI (RAS) coordinate
system. In the absense of this option, the orientations are defined by
the MEG head coordinate system.
I hope this helps
- Matti
---------
Matti Hamalainen, Ph.D.
Athinoula A. Martinos Center for Biomedical Imaging
Massachusetts General Hospital
msh at nmr.mgh.harvard.edu
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