Hi,
On 9 Feb 2009, at 21:16, Michael wrote:
> Hello,
>
> I'm using MELODIC for the 1st time.
>
> Here are my questions:
>
> 1) Is the resulting time course for each component the average of
> all voxels
> significantly activated (based on the threshold) in the
> corresponding spatial
> activation map for that component?
Nearly, yes, in effect they are more like the average across voxels
_without_ the thresholding applied to the corresponding spatial map -
it's not _exactly_ that, but it's close.
> 2) are the resulting maps the result of a correlation analysis?
Not sure what you're asking.....the maps are the result of ICA (see
the MELODIC, McKeown, etc, journal papers), which is not accurately
simply summarised as a "correlation analysis", though that is part of
it.
> 3). what exactly do the negative (blue) cluster of voxels of
> activation indicate?
In any given component the voxels with negative values have negative
correlation with the component's timecourse.
Cheers.
>
>
> Your help would greatly be appreciated.
>
> Michael
>
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Stephen M. Smith, Professor of Biomedical Engineering
Associate Director, Oxford University FMRIB Centre
FMRIB, JR Hospital, Headington, Oxford OX3 9DU, UK
+44 (0) 1865 222726 (fax 222717)
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