Dear community,

I'm looking into ways how to do an a-priori power analysis for an fMRI experiment where the main analysis will be a representational similarity analysis (RSA).

The experiment will present the same stimuli in two successive fMRI-sessions (with a behavioral training in between). For each fMRI session, I plan to do a model-based RSA on brain responses elicited by the stimuli. Voxel restriction will be done with a searchlight procedure. The most interesting outcome will be the difference in these results between the two training sessions, as estimated with a GLM contrast.

I think this is not uncommon as i found other experiments adopting a similar analysis procedure. I found no clue however on how to estimate the necessary sample size to achieve a certain statistical power (say 80%).

Since this is a bit of a frankenstein made from other common statistical approaches, I'm not sure if the general logic of fMRI-power analysis applies here.

Has anybody experience in this area or can point me to literature that contemplates this issue?

Thanks,

Oliver