Conscious cardiac awareness and interoceptive attention differentially modulate heartbeat-evoked neural dynamics

Heartbeat-evoked response (HER) is considered a neural correlate of interoceptive information processing. While HERs are modulated during interoception tasks, distinguishing the unique contributions of conscious cardiac awareness (the subjective recognition of a heartbeat) from interoceptive attention (the state of focusing on one's heartbeat) remains challenging. To dissociate these processes, we developed a novel task where participants (N = 29) reported the timing of perceived heartbeats using a clock hand, followed by objective feedback. We analyzed electroencephalography data using HERs, phase-based connectivity, and microstate analysis. Our results revealed distinct neural mechanisms underlying conscious cardiac awareness and interoceptive attention. Specifically, conscious cardiac awareness was associated with earlier HER modulation localized to the dorsomedial prefrontal cortex, increased beta synchronization between key nodes of the interoceptive network, and a higher prevalence of microstates involving temporal/opercular regions. Conversely, interoceptive attention modulated HERs at later latencies, localized to the somatosensory cortex and insula, and preferentially engaged microstates associated with the visual and frontoparietal network. These findings confirm the multifaceted nature of HERs. We argue that HER modulations reflect not only the optimization of precision via attention but also the emergence of cardiac awareness through the integration of bottom-up afferent inputs and top-down predictions.