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