When the heart meets the mind: Exploring the brain-heart interaction during time perception

Recent studies suggest that time estimation relies on bodily rhythms and interoceptive signals. We provide the first direct electrophysiological evidence suggesting an association between the brain's processing of heartbeat signals and duration judgment. We examined heartbeat-evoked potential (HEP) and contingent negative variation (CNV) during an auditory duration-reproduction task and a control reaction-time task spanning 4, 8, and 12-second intervals, in both male and female participants. Interoceptive awareness was assessed with the Self-Awareness Questionnaire (SAQ) and interoceptive accuracy through the heartbeat-counting task (HCT). Results revealed that SAQ scores, but not the HCT, correlated with mean reproduced durations with higher SAQ scores associating with longer and more accurate duration reproductions. Notably, the HEP amplitude changes during the encoding phase of the timing task, particularly within 130-270 ms (HEP1) and 470-520 ms (HEP2) after the R peak, demonstrated interval-specific modulations that didn’t emerge in the control task. A significant ramp-like increase in HEP2 amplitudes occurred during the duration-encoding phase of the timing but not during the control task. This increase within the reproduction phase of the timing task correlated significantly with the reproduced durations for the 8s and the 4s intervals. The larger the increase in HEP2, the greater the under-reproduction of the estimated duration. Additionally, CNV components during the encoding phase of the timing task were more negative than those in the reaction-time task, suggesting greater executive resources orientation towards time. We conclude that interoceptive awareness (SAQ) and cortical responses to heartbeats (HEP) predict duration reproductions, emphasizing the embodied nature of time. Significance statement Recent fMRI meta-analyses have confirmed that the insula, the primary interoceptive cortex, is one of two regions in the brain essential for processing time passage. It has also been shown that the heart rate influences subjective duration. The notion of embodiment in this context suggests that the interoceptive system creates the sense of time. Besides the neuroanatomical and heart-rate correlations with subjective time, not much is known about the heart-brain interactions while individuals judge duration. Here we show how specific components of the heartbeat-evoked potential in the EEG are related to performance in a duration-reproduction task. A ramp-like increase in HEP2 amplitudes across estimated durations predicts duration reproduction, a neural signature not found in a control reaction-time task.