first steps using lcmv

Nathan Weisz weisz at LYON.INSERM.FR
Wed Mar 7 18:08:11 CET 2007

hi robert,

thanks for your quick help.

> Given that you do not report explicit errors, I suspect problems
> with different coordinates

indeed i overlooked to explicitely state the source and mri-units in

the nai-image looks better now, although perhaps a little deep (also
sme yellow in the middle; perhaps as a result of correlated bilateral
activity?). but it's not the mri of the individual and i still have
find out more about the usage and the options of sourceanalysis.

> I don't know whether the small number of electrodes would be a
> problem for beaming  the data.

don't know too ... but van Veen et al. used even less in their 1997

> Are the dipoles (grid.pos) in mm? It should be in mm, just as your
> head model. Note that beamforming is much more sensitive to head
> model misspecification than plain dipolefitting, so you may want to
> use a (standard) BEM model instead of a spherical model.

i found a standard bem in the dipfit plugin folder of eeglab

 >> vol

vol =

      bnd: [1x3 struct]
     cond: [0.3300 0.0041 0.3300]
      mat: [3000x3000 double]
     type: 'dipoli'

i guess that i can simply exchange my standard spherical model (same
as in eeglab) and use this bem volume for calculating the leadfield.
one aspect are the electrode locations: the positions are given on a
sphere ... so probably there'll has to be some transformation of the

> please use sourceplot with cfg.method='slice' instead (sliceinterp
> is deprecated).

still used sliceinterp this time ... found it a little more easy to use.

all the best,

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