Dear Sukhi Shergill,
>
> I was trying to obtain a connectivity map by entering the y(times series
> from a voxel of interest) as a regressor during an AB design.
Since you use SPM99 you have the opportunity to use spm_extract by simply
pressing the VOI button in the data extraction frame. It will ask you the
radius of the sphere to extract and will give you the first eigenvector (the
temporal one). The data will be save under VOI_???.mat, but is also available
from the matlab prompt with the name Y (since you were using 'y', I supposed
that you extracted a unique voxel from the spm plot, you may gain power by this
approach).
> The spm 99
> did not allow me to enter y as a regressor... I saw from your e-mail to the
> spm-group that you had been able to do this and wondered if you had a
> suggestion as to where I was going wrong?
>
I do have a small problem here since I have poor data from your design and from
the problem you faced (error message ? where did it stop ...), so I may not
fully respond to your question, but don't hesitate to precise it further.
First, if you only use self specified regressor, you may experience problem
using the 'specify a model' option (use specify and estimate), this may be a
bug of SPM99.
Did you check for the size of your regressor with the one of your data. Part of
the problem may be due to the fact that you have a multi-subject study. In this
case you will have to specify the 'good' part of 'y' for each subject.
This is all the generic problem I could see by now ...
May I ask you if it is PPI that you intend to perform ? I was asking this
question since I may not well understood what AB design mean. I hope that you
didn't mean a 2 conditions study ?
I hope this could be helpful
Best regards
Jack
PS : would you mind if I post this response to the spm mail list ?
PS 2: you will find an attachment of a preceding post on PPI available in the
archives.
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