Heartbeat perception is causally linked to frontal delta oscillations.

The ability to accurately perceive one's own bodily signals, such as the heartbeat, plays a vital role in physical and mental health. However, the neurophysiological mechanisms underlying this ability, termed interoception, are not fully understood. Converging evidence suggests that cardiac rhythms are linked to frontal brain activity, particularly oscillations in the delta (0.5 - 4 Hz) band, but their causal relationship remained elusive. Here, we identified a frontal network of delta oscillations that was anticorrelated with both heartbeat perception and heartbeat-evoked brain responses. Using amplitude-modulated transcranial alternating current stimulation (AM-tACS), a method to enhance or suppress brain oscillations in a phase-specific manner, we investigated whether frontal delta oscillations are causally linked to heartbeat perception. We found that enhancement of delta phase synchrony suppressed heartbeat detection accuracy, while suppression of delta phase synchrony enhanced heartbeat detection accuracy. These findings suggest that frontal delta oscillations play a significant role in heartbeat perception, paving the way for causal investigations of interoception and potential clinical applications.