Hi,
On 26 Feb 2009, at 17:17, Greg Burgess wrote:
> Hi FSL group,
>
> I've been curious about this for a while, and I'm hoping that
> someone can clear this up for
> me. Typically, I define ROIs spatially in standard space coordinates
> - either as a result of
> statistical effects in group-level analyses or atlas coordinates
> reported in MNI space.
> However, when extracting percent signal change from individual lower-
> level feat output,
> featquery will downsample my standard space ROI into the BOLD native
> space for that
> subject. When this occurs, it seems like I lose some of the spatial
> specificity of my ROI,
> which is undesirable.
But fundamentally unavoidable given that the FMRI data has no more
information spatially than contained in the native space resolution.
Just by upsampling FMRI data into higher-resolution standard space,
you don't get more information spatially!
Cheers.
> Is there a reason why we can't use the standard space images that
> are created for each
> participant (in reg_standard/ and reg_standard/stats) when the
> higher-level is run? Why
> does featquery go down to native BOLD space to extract percent
> signal change, rather than
> staying in MNI space?
>
>
> Thanks,
> Greg
>
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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)
[log in to unmask] http://www.fmrib.ox.ac.uk/~steve
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