Robustly measuring vascular reactivity differences with breath-hold: Normalising stimulus-evoked and resting state BOLD fMRI data

►BOLD breath-hold response is best modelled using HRF-convolved end-tidal CO2 traces. ►Correcting stimulus-evoked responses with breath-hold measures increases significance. ►Subject differences in CO2 increases during breath-hold should be taken into account. ►Breath-hold normalisation can increase the extent of resting state correlations.