hi
i am using retroicor to correct for physiological artifact with both ECG and respiratory data. when i use either ECG or resp traces individually, the fMRI timeseries does not change much and the standard deviation maps also do not change much. when i use both together, the fMRI data appear to be linearly detrended - thus the new timeseries is quite different and teh STD maps are also much lower.
my TR for this data is 3sec. i have interleaved (alt+z) slices.
thanks for clarifying. in reading the original manuscript, they do NOT discuss detrending, so why is it being done here? and why only for the combined cardiac AND resp?
thanks!
jieun
