Dear Maria,
> I am running a box car analysis of our functional images.
>
> I have 108 volumes, TR = 5 seconds which consist of:
>
> first breathing(60sec.) narrative(30sec.) imagine(30sec.) post
> breathing(60sec.) this repeated three times.
>
> I have set up my analysis for three conditions: narrative, imagine,
> post breathing, with the 'first breathing' being my implicit baseline
> When using 0 1 0 as the contrast I have found the activation during
> imagine vs implicit baseline. Now I would like to generate a map of
> the activation during the 'first breathing' (implicit baseline) and an
> average of all three 'first breathing'. How do I go about this?
I assume you mean the difference between the first 'first breathing'
and an average of all three 'first breathing'. This would be a simple
main effect of time under the 'first breathing' level of the condition
factor. In fact you cannot really address this because the implicit
baseline is used to remove these time-effects that can be thought of as
signal drifts. As such the effect you are interested in is removed
during filtering. To look at time-dependent changes in activation
relative to the implicit baseline you would ahve to model these
explicitly when you specify the design matrix.
I hope this helps - Karl
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