Dear Jordan,
> I am performing a structural analysis of Pediatric Brains using Voxel-Based
> Morphometry (VBM). The results show significant activity, but I am uncertain
> if that means that there is more grey matter volume or larger voxels? Is
> there a meaningful difference between the two of these?
The interpretation of your results will really depend on what
preprocessing and statistical analysis you have done. A typical VBM
pipeline would involve something like:
1) Segmenting everyone's brain into different tissue classes (gray
matter, white matter, etc.)
2) Normalizing everyone's gray matter images into a common space
(usually MNI space)
3) Performing some statistical tests on these images. For example,
comparing gray matter volume between two groups, or its correlation
with a behavioral score, etc.
Step #2 involves putting everyone into the same space and the same
voxel sizes and orientations—there's really no meaningful analysis
that would look at voxel size, so you can ignore that.
If you have compared two groups of participants and find some
significant differences, then the interpretation depends on what the
inputs were. If you've used modulated gray matter images (which is
typical), then you would interpret this as there being more gray
matter in one group than the other.
Hope this helps!
Best regards,
Jonathan
--
Dr. Jonathan Peelle
Department of Neurology
University of Pennsylvania
3 West Gates
3400 Spruce Street
Philadelphia, PA 19104
USA
http://jonathanpeelle.net/
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