Increasing coordination and responsivity of emotion-related brain regions with a heart rate variability biofeedback randomized trial

Heart rate variability is a robust biomarker of emotional well-being, consistent with the shared brain networks regulating emotion regulation and heart rate. While high heart rate oscillatory activity clearly indicates healthy regulatory brain systems, can increasing this oscillatory activity also affect brain function? To test this possibility, we randomly assigned 106 young adult participants to one of two 5-week interventions involving daily biofeedback that either increased heart rate oscillations (Osc+ condition) or had little effect on heart rate oscillations (Osc- condition) and examined effects on brain activity during rest and during regulating emotion. While there were no significant changes in the right amygdala-medial prefrontal cortex (MPFC) functional connectivity (our primary outcome), the Osc+ intervention increased left amygdala-MPFC functional connectivity and functional connectivity in emotion-related resting-state networks during rest. It also increased down-regulation of activity in somatosensory brain regions during an emotion regulation task. The Osc- intervention did not have these effects. In this healthy cohort, the two conditions did not differentially affect anxiety, depression or mood. These findings indicate that heart rate oscillatory activity not only provides a measure of the current state of regulatory brain systems but also changes emotion network coordination in the brain. Significance Statement People whose breathing makes their heart rate oscillate more (leading to higher heart rate variability or HRV) generally have better regulated emotion. Thus, HRV may indicate functioning of brain networks regulating emotion and internal body states. But heart rate oscillations may not only reflect brain regulatory networks but also help shape these networks. We randomly assigned participants to practice either increasing heart rate oscillations using slow-paced breathing or decreasing them using personalized strategies. Daily practice increasing heart rate oscillations affected brain activity in emotion-related networks even during times when participants breathed no differently than the comparison group. Thus, HRV is more than just an outcome measure--it can help shape the subsequent functioning of emotion-related brain networks.