Hi - yes, this is straightforward. You probably want to do a separate
mixed or fixed-effects cross-section analysis for each subject to get a
single summary result for each subject and then feed those into a
third-level cross-subject analysis.
Cheers, Steve.
On Wed, 4 Jan 2006, Richard Albistegui-DuBois wrote:
> One additional question on this issue, if I might.
>
> The research question is whether a correlation exists between the
> voxel-wise
> task-related changes in BOLD signal and the degree of recovery across
> sessions in each subject (i.e. examining for voxels in which there is a
> linear correlation between the recovery score and the parameter
> estimates
> for the covariates representing the main effects of hand grip across
> sessions; the specific contrasts were weighted by the mean recovery
> scores).
> Within SPM, this can be addressed using multiple session fixed
> effects model
> per subject. Is there a similar approach within FSL which can be used
> to answer this question?
>
> On Nov 23, 2005, at 11:22 AM, Richard Albistegui-DuBois wrote:
>
> > Thanks much!
> >
> > On Nov 23, 2005, at 11:18 AM, Christian Beckmann wrote:
> >
> >> Richard,
> >>
> >> yes, please check
> >>
> >> http://www.jiscmail.ac.uk/cgi-bin/webadmin?
> >> A2=ind0511&L=fsl&T=0&F=&S=&X=277BF81CC45B74C17B&Y=beckmann%
> >> 40fmrib.ox.ac.uk&P=2357
> >>
> >> cheers
> >> christian
> >>
> >> On 23 Nov 2005, at 19:02, Richard Albistegui-DuBois wrote:
> >>
> >>> Hi...did someone post any suggestions on this and I missed them?
> >>> Just wanted to check.
> >>>
> >>> On Nov 3, 2005, at 3:25 PM, Richard Albistegui-DuBois wrote:
> >>>
> >>>> I have data from several subjects, and I want to make sure I'm
> >>>> planning my multilevel design properly.
> >>>>
> >>>> Each subject was scanned twice on a simple motor task, with a
> >>>> behavioral measure of interest acquired at each timepoint. What
> >>>> I'm interested in is knowing whether there are any group changes
> >>>> in activity in motor cortex which are associated with the
> >>>> difference in the two behavioral measures.
> >>>>
> >>>> My current plan is to do a first-level analysis of each
> >>>> timepoint separately, with a second-level analysis within each
> >>>> subject, comparing the two timepoints. For example, with
> >>>> timepoints A and B:
> >>>>
> >>>> Level 1: Timepoint A
> >>>> Level 1: Timepoint B
> >>>> Level 2: A.feat-B.feat
> >>>>
> >>>> Then, at the third level, take the .gfeat from each single
> >>>> subject A-B comparison, and combine them all with two EVs: EV1
> >>>> is one for all subjects, EV2 is the difference in behavioral
> >>>> score between A and B for that subject. I would have three
> >>>> contrasts: EV1=1, EV2=0; EV1=0, EV2=1; EV1=0, EV2=-1
> >>>>
> >>>> Does this sound correct to y'all? Have I explained it
> >>>> comprehensibly?
> >>>>
> >>>> Many thanks.
> >>>>
> >>>> Richard Albistegui-DuBois
> >>>> UCLA NeuroRehab, lab of Bruce Dobkin, MD.
> >>>> Office: 1-132 Reed
> >>>> Phone: 310-825-4016
> >>>> Mobile: 310-774-1305
> >>>> Fax: 310-794-9486
> >>>> AIM: dubistegui
> >>>> email: [log in to unmask]
> >>>>
> >>
> >> --
> >> Christian F. Beckmann
> >> Oxford University Centre for Functional
> >> Magnetic Resonance Imaging of the Brain,
> >> John Radcliffe Hospital, Headington, Oxford OX3 9DU, UK
> >> Email: [log in to unmask] - http://www.fmrib.ox.ac.uk/
> >> ~beckmann/
> >> Phone: +44(0)1865 222551 Fax: +44(0)1865 222717
>
--
Stephen M. Smith, Professor of Biomedical Engineering
Associate Director, Oxford University FMRIB Centre
FMRIB, John Radcliffe 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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