Comparison of fMRI BOLD Effect and Arterial Pulsation Harmonic Distribution among Different Breathing Rate.

The phenomenon of respiratory sinus arrhythmia (RSA) had been studied since 1733. Most researches were focused on the heart rates or blood pressure variability. It was well known that heart rate variability (HRV) induced by respiration decreased progressively with age. In general, it is caused by the function of the autonomic nervous system (ANS). Seldom researches studied the relationship of this phenomenon with cerebral circulation. In our previous research, we found that different breathing rate could redistribute the proportion of systemic circulation, and also observed that the slower the breathing rate the more proportion of cerebral circulation appeared on head. In this paper, we further examined the BOLD (Blood Oxygenation Level Dependent) signal fluctuations in brain stem among different breathing rate by the technique of functional magnetic resonance imaging (fMRI). We found that the BOLD signal changes were hinged on the breathing rate, and the variability was consistent with the pulsatile pressure study.