Utilizing heartbeat evoked potentials to identify cardiac regulation of vagal afferents during emotion and resonant breathing

The importance of the bi-directional communication between the heart and brain has been known for over 100 years (Lane, et al., 2009) and plays an important role in many of the prominent theories of psychophysiology today. While the efferent vagal neurons have been explored and examined, there is much to be discovered about the cardiac afferent pathway. Many researchers and theorists have speculated about the pathway from the heart to the brain but due to the lack of an experimental design to explore this arena, it has received little interest. Utilizing heart beat evoked potentials (HEPs) we sought to determine whether heart rate variability (HRV) was related to the strength of the connection between the heart and brain. We also hypothesized that differing emotion states would result in differing amplitudes of HEPs. Subjects were induced into emotional states with an autobiographical script consisting of their happiest and saddest memory. HEPs were also recorded during diaphragmatic breathing at six breaths per minute. The evoked potentials during the emotional conditions, especially negative emotion were most attenuated. We believe that the signal from the heart to the brain may be filtered by central limbic structures affecting the level of the signal at the cortex. It also appears that HRV mediates the strength of HEPs, especially during resonant breathing. Significant neurocardiac gender differences were also present across conditions. The results of this study support the theory and speculation of many authors who believe vagal afferents play a role in brain function.