Autonomic and cortical responses to heartbeat-synchronous auditory omissions during an auditory attention task

Cardiovascular regulation depends on bidirectional communication between autonomic cardiac control and cardiac afferent signals ascending to the central nervous system, forming a heart-brain loop. Cardio-auditory omission paradigms provide a non-invasive way to probe this loop in humans by withholding scheduled tones within heartbeat-contingent auditory sequences and measuring the resulting autonomic cardiac and heartbeat-related cortical responses. Previous studies have shown omission-evoked cardiac deceleration and neural responses mainly in specific contexts such as passive listening or synchrony-judgement tasks. The present study examined whether these responses also occur under the more general condition of active responses to external stimuli. We tested 40 adults in an auditory detection task in which tones were presented either 200 ms after the ECG R-peak (synch) or at pseudo-random intervals matched to each participants resting heart rate (asynch). A five-minute no-stimulation resting recording was used to generate the asynch sequence and served as the resting comparison condition. In both auditory conditions, 10% of scheduled tones were omitted, yielding synch and asynch omissions. Heartbeat-synchronous omissions induced sustained RR-interval prolongation that exceeded responses to asynch omissions, sound-present conditions, and rest. HEP amplitude was selectively enhanced in the synch-omission condition relative to all other conditions. Reaction times to the first post-omission tone were slightly delayed, whereas overall performance remained comparable across conditions. These findings show that heartbeat-synchronous auditory omissions produce a distinct autonomic-cortical response profile under active response demands, indicating that heart-brain loop dynamics continue to shape physiological responses during ongoing behaviour.