Neural signal changes associated with cardiac and respiratory measures vs boxcar analysis in functional magnetic resonance imaging (fMRI)

Functional magnetic resonance imaging (fMRl) was used to measure signal changes in the brain during a respiratory challenge that elevated blood pressure. Subjects were scanned during a baseline period and during a Valsalva maneuver. Results were compared using fixed-effects analysis with the SPM99 package, and examined once using a boxcar model and once by models generated from changes in cardiac and respiratory signals during the breathing challenge. Models based on physiological measures resulted in greater localization of signal changes.