Dear Peter,
In spm99 you can enter an image to specify the volume that you wish to correct
for (in your case you could make a copy of one of the MNI template and trace
either the DLPFC or OFC or both, using Analyze or MRIcro or similar software).
Matthew Brett has a tutorial on this on his web page (small vol correction) and
he also explains how to implement svc for spm96.
http://www.mrc-cbu.cam.ac.uk/Imaging/
Cheers.
Alex.
>
> Dear SPM list
>
> I've followed with interest the recent exchanges regarding the importance of a
> small volume correction for areas related to an a priori hypothesis. However,
> could someone tell me how to perform a small volume correction or point me
> towards a useful reference/resource.
>
> Specifically, we've been using a pharmacological manipulation and blood
> flow SPECT, and have hypothesised that the manipulation will give
> rise to reductions of rCBF in dorsolateral prefrontal cortex (DLPFC) and
> orbitofrontal cortex. Using SPM96 we do indeed find these reductions (and
> several others) using uncorrected statistics, but no blobs survive a full
> correction. So, to what extent must I raise the threshold to correct for the
> volumes of the DLPFC and OFC only? If this requires knowing what proportion of
> total gray matter is OFC & DLPFC then can anyone supply this info etc. Also,
> what other information is needed?
>
> Thanks in advance
>
> Peter
> ----------------------
> Dr Peter Talbot
> Department of Mental Health
> Queens University Belfast
> Whitla Medical Building
> Lisburn Road
> Belfast BT9 7BL,
> NORTHERN IRELAND, U.K.
>
> Phone: +44 (0)28 9027 2166
> Phone: +44 (0)28 9033 5791
>
> Fax: +44 (0)28 9032 4543
> Email: [log in to unmask]
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