"the time courses are demeaned and then subjected to variance normalisation" Does it mean that melodic subtracts the mean (mean voxel time course) from the time course and then divide the results by the variance? I did not tried to run melodic without variance normalisation because I have no idea about the correct command line for that.
Thank you very much
----- Mail original -----
De: "Christian F. Beckmann" <[log in to unmask]>
À: [log in to unmask]
Envoyé: Vendredi 18 Juin 2010 23:40:39
Objet: Re: [FSL] Melodic ICA question
> do that? How the time courses are normalized in melodic ICA process?
time courses are demeaned and then subjected to variance normalisation,
i.e. scaled by a robust estimate of the voxel-wise residual noise std
deviation to make sure that mere differences in the voxel-wise std
derivations do not bias the PCA step and ICA cost function.