Don't include motion parameters as regressors.

I'm sure you already do this, but I've seen that it's good to have a
practice session outside of the scanner to see how much they move when
doing the task. Then you can coach them into trying to move their body
less. Also, putting some pillows under their knees, so their feet are
elevated, helps quite a bit. And of course vacuum bags, tape across the
forehead, etc.

Gandolla Marta wrote:
> Hi Chris and list,
>
>    so, what do you suggest?
>
> 2010/8/26 Chris Watson <[log in to unmask]
> <mailto:[log in to unmask]>>
>
>     I think that for something as simple as ankle dorsiflexion, if the
>     results are in a plausible location, you can believe them. The
>     motion really isn't that bad. It's hard to keep a patient still
>     when doing foot movements, so there will probably always be
>     stimulus-correlated motion, and if you include the motion
>     parameters as regressors (as you have seen already), it'll get rid
>     of any true activation.
>
>     Gandolla Marta wrote:
>
>         Hi Chris and everyone else!!
>           indeed, we are looking at right ankle dorsiflexion and yes,
>         I definitively agree that the activation seems to be quite
>         posterior.
>         the graph I posted has on x axis the number of scan (TR=3secs,
>         5 minutes of acquisition). on the y axis there are mm for
>         blue, green and d line, and degrees for yellow, cyan and
>         magenta line. I superimposed all the realignemnt parameters
>         along with the block design to search for the eventual
>         correlation. I attached in any case te SPM output of realignment.
>
>         all my best
>         marta
>         2010/8/26 Chris Watson
>         <[log in to unmask]
>         <mailto:[log in to unmask]>
>         <mailto:[log in to unmask]
>         <mailto:[log in to unmask]>>>
>
>
>            Is it right ankle dorsiflexion that you're looking at?
>            It looks pretty posterior to the motor strip; what does it look
>            like overlaid on a structural?
>            What's the scale (units) of the graph you posted? Can you
>         post the
>            output of SPM's realignment?
>
>
>            Gandolla Marta wrote:
>
>                Hi everyone,
>                   I attached a pdf file instead of a docx of the previous
>                e-mail. sorry for the inconvenience!!
>                   I'd need some help about realignment parameters
>         effect that
>                seems to be huge in the acquisition I will now describe.
>                We have a 30 secs block design, starting from rest. The
>                patient is performing active ankle dorsiflexion during
>         on blocks.
>                We did the following preprocessing steps:
>                - realignment
>                - coreg
>                - normalize
>                - smooth (6mm)
>                 then we implemented the GLM with a 8 columns design matrix
>                (1-condition with the 30 secs block design, 2-7- realign
>                param, 8- baseline) and we found zero activation
>         (p<0.01 FWE
>                corrected).
>                we then chacked with the 2 columns design matrix
>         (1-condition
>                with the 30 secs block design, 2- baseline) and we found a
>                quite important activation (fig.1). should we trust this
>                activation? the realignemnt param plot along with the block
>                design protocol is shown in fig.2. is it possible that all
>                this effect depends on the correlation between the
>         realignment
>                parameters and the condition column in the design matrix?
>                should trust only the design with the realignement
>         parameters
>                as covariats of no interest? we are thinking in this
>         case why
>                we don't see any activation... do we miss something?
>                 thanks for your help
>                best regards
>                marta
>
>
>