Dear All,
We work with children, who tend to move a lot, Becasue we also work in a
difficult torecruoit clinical population, we keep data which may otherwise
have too much motion for other research projects to consider including. To
deal with this, the lab has tried to find ways of completely regressing out
time points with excessive motion (movement of more than 2 mm). First, a
motion EV is created, where any TR with excessive motion is assigned a 1 and
all others a 0. This EV is of course not convolved with anything. However,
this alone could potentially leave some effect of motion in the data. To
deal with that, the lab has been editing the stimulus EVs by placing 0s in
TRs where there is a corresponding 1 in the motion regressor. This we now
believe is problematic as these 0s are convolved with an HRF, having a long
lasting impact on the model, where motion should only have a discrete effect
on the data. Instead, would orthogonalizing the stimuli wrt EVmotion do what
we want?
Thanks
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