How long are your blocks? It might turn out that they are too far apart
in time.
e.g. if your blocks are each 20s long, then blocks of task A will have a
separation of 120s (taskA + rest + B + rest + C + rest).
This is possibly too far apart, and your task-related activation might
get swamped by low-frequency noise.
Is there any way you can set up a factorial design to look at
interactions between conditions, and possibly avoid how far apart in
time your conditions are?
zpzhang wrote:
> Dear SPMers
>
> I have following fMRI block design in my experiment:
>
> There are three task sesions (task A, task B, task C 'combining the task A and
> task B' ) alternating rest session in my experiment.
>
> eg: rest--task A--rest--task B--rest--task C......
>
> The contrast table: 0,-1,0,-1,0,2
>
> Can I say the result show the interactions between the task A and task B?
>
> Or can anybody provide better experiment design for my study?
>
>
> ZP
>
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