Dear SPMers, does no-one have a comment or an explanation for the observed phenomenon below? Thanks a lot! Jan > Dear SPMers, > > after checking a few subjects in my latest data set, I found that the global mean of an EPI time series (computed with spm_global) changes significantly > after spatial preprocessing (i.e. even plain realignment). Attached is an example: While slice timing changes the time series only very subtly, both > realignment and realign&unwarp change the pattern significantly (i.e. they alleviate some of the spiking ripples, while introducing others at different > time points.) Any comments or explanations for this are greatly appreciated. > > Best wishes, > Jan