The heart generates bioelectromagnetic fields that induce heart-brain coupling (HBC), which is associated with various perceptual, cognitive, and emotional functions. The amplitude of the heart's cyclical electrocardiography (ECG) potential varies within each heartbeat for different phases of the heart's contraction, affecting the HBC. This study aimed to explore the phasic variations in the HBC by examining the spatiotemporal Heartbeat-Evoked Potentials (HEPs) in the brain, corresponding to the ECG, in response to emotional stimuli of Heart Lock-In (HLI),  positive self-talk (PT) and negative self-talk (NT). Paced breathing at six breaths per minute was used to achieve a relaxed state for improved HBC. The study found a significant attenuation of the HEPs during both NT and PT conditions. However, the HBC was significantly enhanced during the heart's ventricular repolarization for HLI, PT and NT conditions. These findings suggest that increases in cardiovascular afferent signals, which have been previously shown to modulate brain functions and increase heart-brain synchronizations, may be the cause of increased HEP amplitudes. The study confirms the presence of HBC and affirms that the heart plays a significant role in modulating the brain's functioning and activity.

Keywords: afferent signals, Bioelectromagnetic, Electrocardiogram; Heart-Brain Coupling (HBC); Heartbeat Evoked Potential (HEP); Heart Lock-In (HLI); Phasic Induction