Dear DCM experts,
I have a question regarding the interpretation of DCM results under mean centering. I understand that when mean centering, the A-matrix reflects the mean connectivity across experimental conditions (as opposed to connectivity during implicit baseline when not mean centering). But does mean centering also change the interpretation of the B-matrix, i.e. is a connectivity change under experimental condition 1 now relative to the other conditions? This seems crucial to be able to say whether a connection is excitatory or inhibitory under different conditions.
Specifically, using mean centering, I found that a connection is negatively modulated under experimental condition 1. When I apply formula 3 in Zeidman et al. (2019 - tutorial 1) to calculate the resulting Hz change, I find that the normally positive connection indeed becomes negative. Can we now conclude that this normally excitatory connection becomes inhibitory (region A inhibits region B) during experimental condition 1? Or can we only say that the connectivity is lower during condition 1 than during (the average of) the other conditions?
Thanks a lot in advance and all the best,
Philipp
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