Investigation of vagal afferent functioning using the Heartbeat Event Related Potential

Although there has been much support for HRV Biofeedback as an effective intervention for various disorders, there is a lack of comprehension of the underlying mechanisms. The predominant theories of increased vagal efferents and baroreflex gain are insufficient in explaining the frequent observations that HRV Biofeedback impacts changes in constructs beyond ANS mediation, such as emotion regulation, attentional control, and self-regulatory reserve. It has been suspected that vagal afferent functioning may be the underlying mechanism, but little research has explored this. Previously, researchers measured cortical evoked potentials contingent to the heart, or an indication of vagal afferent functioning (Schandry et al., 1986). Twenty-five participants were randomly stratified to HRV Biofeedback or EMG Biofeedback for four sessions. Repeated measures ANOVAs revealed that the HRV group exhibited statistically significantly increased baseline Heartbeat Event-Related Potentials (updated term for 'evoked potential') while the relaxation control group did not. The results of this study provide initial support to the premise that HRV Biofeedback stimulates changes in the vagal afferent pathway that are longer lasting than simply the short term effects of breathing.