Ged:
Many thanks for your reply. I will re-try MELODIC with different FWHN value.
Best
Xuelin
****************************************
Xuelin Cui
Department of Electrical Engineering
University of Hawaii-Manoa
Honolulu HI 96822
Tel: 1-808-349-0983
Email: [log in to unmask]
****************************************
----- Original Message -----
From: Ged Ridgway <[log in to unmask]>
Date: Monday, June 25, 2007 6:02 am
Subject: Re: [FSL] question on MELODIC spatial map smoothing
To: [log in to unmask]
> Hi Xuelin,
>
> > I have a question on spatial map in MELODIC. My spatial map seems a
> > bit discrete for those orange and blue dots. I wonder how can I
> > make the spatial maps seem more blurred. ig. Maybe I can apply some
> > mask to post process those spatial maps. Is there such a method in
> > MELODIC?
>
> I think it would be unusual to smooth the ICs as a post-processing
> step. Instead, it would be more typical to smooth the input data as
> the final pre-processing step, much like with the usual GLM
> approach.
> (Smoothing would be pre-stats, but post- other pre-processing, such
> as
> motion correction, realignment, normalisation, etc.)
>
> > Also, there are 2 options in the 2nd tab in MELODIC GUI, and they
> > are Spatial smoothing FWHM and Temporal filtering respectively.
> > What can they do in MELODIC?
>
> These options are passed to the "ip" program, which Melodic calls
> to
> perform spatial smoothing (Gaussian blurring) and low-pass
> filtering
> of its input data.
>
> > Is it gonna blur the spatial map if I modify any of these 2
> parameters?
> By increasing the FWHM for the spatial smoothing, the input data
> will
> be smoother, and this will probably make the resulting ICs smoother
> as
> well. You should probably choose the FWHM to approximately match
> the
> smallest scale of the activations/effects that you are looking for,
> but a bit of experimentation might be needed.
>
> HTH,
> Ged
>
> P.S. I hope that saves CB a reply, but I'm sure he'll correct me if
> I'm wrong...
>
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