Dear John and the SPM list,
In carrying out a VBM analysis using modulated images on a sample of 100
normal subjects to investigate correlations with age, I get results which
I'm not sure how to explain. VBM was conducted in SPM2 using John's scripts
for modulated VBM. I've attached the results to the message.
It appears that there's large clusters in the ventricles when looking at
negative correlation with age (i.e. gray matter loss with increasing age).
Could this be indicative of ventricular enlargement with increasing age?
Also, in carrying out the reverse analysis looking at the positive
correlation, I get clusters surrounding the ventricles, and some in the
medial temporal lobe? I'm not sure how this can be explained.
When similar analyses were conducted with unmodulated data, we saw a lot of
clusters in the frontal lobe in addition to the periventricular clusters,
and nothing in the medial temporal lobe in the case of the reverse analysis.
I know that with modulated data, we're looking at differences in volume vs.
differences in density, but I still don't see how this interprets these
results.
Your help is sincerely appreciated.
Thanks
Mike
--
Michael A. Yassa, B.A. Psychiatric Neuro-Imaging
Sr Research Technician JHU School of Medicine
Tel: 410-955-7861 600 N. Wolfe St.
Fax: 410-614-3676 Phipps 322
Email: [log in to unmask] Baltimore MD 21287
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