Moment-to-Moment Heart–Brain Interactions: How Cardiac Signals Influence Cortical Processing and Time Estimation

Our everyday behavior is affected by sensations originating from our internal organs. These interoceptive sensations are conveyed to the brain, providing moment-to-moment information of the body's physiological state. Interoceptive information is integrated in the brain and influences its function, whether it is consciously perceived or not (Craig, 2009). Cardiac activity is a key interoceptive source that continuously shapes brain dynamics (Skora et al., 2022). The phases of the cardiac cycle, driven by contraction (i.e., systole) and relaxation (i.e., diastole) of the heart, are encoded by baroreceptors that sense pressure changes in blood vessels. This information travels to the brainstem and from there to various cortical regions, where it is integrated with exteroceptive and other interoceptive information. This enables cardiac activity to influence various cognitive, perceptual, and motor processes and optimize behavior (Marshall et al., 2019; Skora et al., 2022; Fouragnan et al., 2024; Mussini et al., 2024; Paci et al., 2024). The cardiac activity and the ability to perceive it, often termed interoceptive awareness, are linked to time perception. Indeed, individuals with high interoceptive awareness more accurately estimate elapsed time than those with low interoceptive awareness. This increased accuracy stems from a reduced tendency to contract the duration of (i.e., under-reproduce) intervals lasting several seconds (Meissner and Wittmann, 2011; Richter and Ibáñez, 2021). In addition, the phase of the cardiac cycle influences time perception at the subsecond level, with stimuli presented during diastole being perceived as longer than those presented during systole (Arslanova et al., 2023). Finally, the interbeat interval (IBI), which is a proxy of the vagal tone, increases over time during the encoding of time intervals, and this increase is positively associated with time estimation accuracy (Meissner and Wittmann, 2011). Thus, several cardiac signals influence time estimation at both suprasecond and … Correspondence should be addressed to Paolo Di Luzio at paolo.diluzio{at}essex.ac.uk or Elena Mussini at elena.mussini{at}unimi.it.