Hi Deborah
what about a second level model with the runs as repeated measures? this
way you can still conbine the estimates from each run like in 1st level
contrast + model changes over runs while controling (covarying) hunger
... that could work -
maybe somebody on the list knows about papers modeling runs as repeated
measures? never seen it but seems ok to do ..
Cyril
> Dear SPM Community,
>
> I have an fMRI dataset where I have hunger ratings from each
> participant before and after each run of functional data. I want to
> add hunger in as a covariate for each run (to control for changes in
> hunger throughout scanning), but am having trouble doing this.
>
> So far I've tried:
> 1) Modelling hunger as parametric regressor, and specifying hunger as
> a variable of no interest. This doesn't work because I don't have a
> hunger rating for each event specified, leading to a contrast not
> unique error.
> 2) Adding hunger as a covariate in the second-level analysis. This is
> not ideal because I can only enter one hunger rating for each subject
> (not across runs).
>
> Neither of these two methods are quite what I want to do. Is there any
> other way to control for the hunger rating in my first level analysis?
>
> Thank you!
> Deborah Tang, Doctoral Candidate
> McGill University
> Montreal Neurological Institute
> 3801 University St, Room WB 214D
> Montreal, QC H3A 2B4
> Canada
>
> Phone: (514) 398-6644 Ext. 089469
> Fax: (514) 398-8948
> [log in to unmask]
>
>
--
Dr Cyril Pernet,
Academic Fellow
SBIRC fMRI Manager
SFC Brain Imaging Research Center
Division of Clinical Neurosciences
University of Edinburgh
Western General Hospital
Crewe Road
Edinburgh
EH4 2XU
Scotland, UK
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tel: +44(0)1315373661
http://www.sbirc.ed.ac.uk/cyril
http://www.sinapse.ac.uk/
The University of Edinburgh is a charitable body, registered in
Scotland, with registration number SC005336.
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