Hello all,
To facilitate DCM, I have concatenated a series of five sessions into a
single series. There are obvious (though not terrible) effects of inter-
session motion apparent in the series.
It struck me today that perhaps if I set up five session constants (as in
the 'proper' session design, which would have ten regressors) for the
concatenated series (so a total of six regressors) this may alleviate the
problem somewhat. Then again, perhaps not…
My specific questions are two:
1. Have I correctly understood the role of the session constant? and might
this help reduce the variance seen over the two scans which lie on the
cusp of two sessions?
2. Is there a way to implement this directly or be altering the SPM.mat
data structure? (when I use 'regressors' the results are not quite right
and I would need to remove/change the default constant also).
Thanks is advance
Scott
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