When the inner clock fades: Interoceptive decline and consolidation of phase resetting in cortical rhythms by cardiac events underlie healthy lifespan ageing

The brain continuously tracks signals from the body, including the heartbeat, which influence internal states such as the perception of time, well-known to accelerate with age and disrupted in disorders such as Parkinsons disease and dementia. The present study examined whether the representation of cardiac events onto spontaneous neural oscillations maps to regions responsible for processing time-perception, show age-related differences, and uncovered the mechanisms that may underlie any such reorganization. From a large cohort (N = 620), cortical heartbeat-evoked responses (HERs) were characterized and their sources were pinned to frontotemporal regions. Phase-based analyses demonstrated that cardiac signals affect phase of ongoing neural oscillations in the theta frequency band, rather than altering overall power, with this effect consolidating in older adults. Advanced statistical analysis further indicated that these changes are primarily driven by enhanced bottom-up heart-to-brain influences, revealing that altered interoceptive signaling can shape the age-related changes in time perception.