[Mne_analysis] Applying the fMRI weighted w file on the inverse operator

[Alexandre Gramfort]

hi Thinh,

real quick and hand waving:

dSPM / sLORETA use scaling to downweight locations
where the noise is strong / highly amplified. This amplification
factor is proportional to the fMRI weight. So if you normalize
by division you pretty much cancel the main effect of the fMRI weight.

HTH
Alex



On Wed, Jun 25, 2014 at 10:42 PM, Thinh Nguyen
<thinhnguyen0405 at gmail.com> wrote:
> Hi MNE users,
>
> I'm currently trying to applying a a prior source constraints via the fMRI
> weighting file. But according to MNE documentation:
>  "It turns out that the fMRI weighting has a strong influence on the MNE but
> the noise-normalized estimates are much less affected by it."
> (http://martinos.org/mne/stable/manual/mne.html#cbbdijhi)
> Can anyone please explain to me why this is such a case, maybe in both
> mathematical and intuitive sense. Thank you very much in advance.
>
> Regards,
> Thinh Nguyen
> Research Assistant
> University of Houston - Biomedical Engineering department
>
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