fMRI Adaptation Design and MVPA

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Hey Folks,

I am PhD student running my first fMRI study, and I wanted some inputs on my design. I am using an oddball fMRI adaptation paradigm with the following parameters:

  1. Two condition-pairs: (a) A & B and (b) X & Y
  2. In alternate blocks 1 condition of each pair (A/B or X/Y) is presented as adaptation stimuli. 16 tokens, 1 second apart. This is followed by a single instance of the other member of the pair as test stimulus.

My intention is to compare first and last adapter of each block to determine adaptation, and compare the last adapter and test to determine condition contrasts. I am wondering if it would make more sense to use the penultimate token of the adapter series as the “last adapter” in order to avoid colinearity violations?

I would also like to attempt an MVPA on the data set at some point, and I am wondering if this design is amenable enough?

Thanks for any inputs folks!