Thanks! That's very helpful!
Esther
Chang, Maria wrote:
> Including motion parameters should not remove any power from your signal
> of interest if movement isn’t correlated with the task. I have always
> been advised to check for task-motion correlations before including
> motion parameters in the first level analysis. For example, sometimes
> kids bob their head a little when they press a response button. In this
> case, if you use motion parameters as a regressor you may model out your
> task effects. You can calculate task-motion correlations with Sue
> Whitfield-Gabrieli’s brain imaging toolbox.
>
>
>
> -maria
>
>
>
> ------------------------------------------------------------------------
>
> *From:* SPM (Statistical Parametric Mapping) [mailto:[log in to unmask]]
> *On Behalf Of *Michael T Rubens
> *Sent:* Thursday, April 30, 2009 5:39 PM
> *To:* [log in to unmask]
> *Subject:* Re: [SPM] include motion parameters only for some subjects?
>
>
>
> I don't really see any drawback to including motion parameters for
> everyone. You are not should not be removing any power from your signal
> of interest, you are only reducing noise by explaining signal variance
> to due to motion.
>
> -Michael
>
> On Thu, Apr 30, 2009 at 2:18 PM, Esther Fujiwara <[log in to unmask]
> <mailto:[log in to unmask]>> wrote:
>
> How about dummy motion regressors for those subjects whose motion
> parameters I don't want to include (trying to keep down the amount of
> data to throw out ...)?
>
> Michael T Rubens wrote:
>
> You need to keep the number of covariates constant across subjects.
>
> -Michael
>
> On Thu, Apr 30, 2009 at 1:59 PM, Esther Fujiwara <[log in to unmask]
> <mailto:[log in to unmask]> <mailto:[log in to unmask]
> <mailto:[log in to unmask]>>> wrote:
>
> Is it possible to include motion parameters in first level analyses
> for some
> subjects (i.e., those moving around more) but not others if all
> subjects are
> later combined in a second level analysis? I suppose not, but I am
> not sure why.
> Thanks for any comments!
> Esther
>
>
>
>
> --
> Research Associate
> Gazzaley Lab
> Department of Neurology
> University of California, San Francisco
>
>
>
>
>
>
> --
> Research Associate
> Gazzaley Lab
> Department of Neurology
> University of California, San Francisco
>
--
Esther Fujiwara, Ph.D.
Assistant Professor
Department of Psychiatry
University of Alberta
3087 Research Transition Facility
Edmonton, AB
Canada T6G 2V2
Phone: 780 492-6524
Fax: 780 492-6841
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