Hello SPM-users,
we are intending to explore the influence of genetical polymorphims onto
regional brain volume, esp. a disease-gene-interaction in a large sample of
patients and controls.
Here we thought to initially use a GLM in a VBM approach with standard
covariates to remove large influences on brain volumes and to continue with
the residuals into the genetical analysis.
There are two questions I have,
(1) Is the an easy way to calculate a map of residuals for each subject from
the output of the estimation (e. g. ANCOVA model or multiple regression
model)?
(2) Rather independently of this, I would like to understand if Jacobian
modulation is sensitive for only the non-linear warps or also affine
transformation? Given a generally smaller brain due to brain size, which
should come near to an average size after normalization, would the
potentially massive increase of whole brain volume be reflected in the
modulated maps?
Thanks a lot in advance,
Ph. Saemann
Max-Planck-Institute of Psychiatry
Kraepelinstr. 2-10
80804 Munich
tel 0049-89-30622-0
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