When the Heart Meets the Mind: Exploring the Brain-Heart Interaction during Time Perception

Abstract

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 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 s 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 did not 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 8 s and the 4 s intervals. The larger the increase in HEP2, the greater the under-reproduction of the estimated duration. 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 toward time. We conclude that interoceptive awareness (SAQ) and cortical responses to heartbeats (HEP) predict duration reproductions, emphasizing the embodied nature of time.

Keywords: contingent negative variation (CNV); duration reproduction; heartbeat-counting task; heartbeat-evoked potential (HEP); time perception.

Figure 1.

Overview of the experimental design. The schematic illustration of (a) the study design, (b) duration-reproduction task, and (c) reaction-time task. For details, see the Materials and Methods section.

Figure 2.

Behavioral results. a, Histogram and density curves of the mean reproduced durations for different intervals. b, Boxplot illustrating the accuracy scores across different intervals. c, Boxplot illustrating the absolute accuracy scores across different intervals. Each box represents the interquartile range (IQR) with the line inside indicating the median. The outliers are represented as individual points which are >1.5 * IQR away from the top or bottom of the box.

Figure 3.

Distinct CNV for the encoding phase of the duration-reproduction task compared with the reaction-time task. The top plots (a–c) show the grand-average ERPs from the frontocentral scalp electrodes time locked to the first sound in the reaction-time task (blue) and the encoding phase of the duration-reproduction task (orange) for the 4 s (a), 8 s (b), and 12 s (c) intervals. The error shade represents the standard error, and the gray traces represent the interval portion beyond the target interval. Black traces in the time axes show the time interval in which the difference between two ERPs was significant according to the cluster-based permutation test. The bottom plots (a–c) present the corresponding topography for the ERPs within these intervals (corresponding to the phases of the reaction-time task and duration encoding, respectively). d, The average iCNV amplitude with corresponding standard errors for the reaction-time task and the encoding phase of the duration-reproduction task. e, The average lCNV amplitude with corresponding standard errors for both tasks. f, The average CNV slopes for both tasks and three intervals.

Figure 4.

Distinct CNV signals for the reproduction phase of the duration-reproduction task compared with the reaction-time task. The grand-average frontocentral ERPs time-locked to the button press in both the duration-reproduction phase (red trace) and the reaction-time phase (blue trace).

Figure 5.

Characteristics of the CNV signals during the reproduction phase. a, The grand-average frontocentral ERPs time locked to the duration-reproduction cue (second sound). b, Mean iCNV amplitude with corresponding standard errors for different durations of duration-reproduction phase. c, Mean lCNV amplitude with corresponding standard errors for different durations of the duration-reproduction phase. d, The average CNV slope for the three different durations of the duration-reproduction phase. e, The association between mean reproduced durations and the mean lCNV amplitudes during the duration-reproduction phase.

Figure 6.

The HEPs during the encoding phase. The left panel shows the grand-average HEPs correspond to the three target intervals in the encoding phase of the duration-reproduction task. Highlighted time windows show significantly different HEPs among the durations. The average topographies within the first time window (HEP1) and the second time windows (HEP2) are presented in the right panel.

Figure 7.

Development of the HEP components during the encoding phase compared with the reaction-time task. Second-by-second HEP1 (left column) and HEP2 (right column) amplitudes for (a) 4 s interval, (b) 8 s interval, and (c) 12 s interval during the reaction-time task and the duration-encoding phase. All significant differences are demonstrated with black and red lines. The red lines show that the corresponding difference was only significant in the encoding phase of the duration-reproduction task.

Figure 8.

The cumulative HEP2 trend. The cumulative HEP2 amplitudes for (a) 4 s interval, (b) 8 s interval, and (c) 12 s interval during the encoding phase of the duration-reproduction and the reaction-time task. The solid lines show significant effects for the 8 and 12 s intervals.

Figure 9.

Development of the HEP components during the reproduction phase. Second-by-second development of the HEP1 and HEP2 amplitudes for the duration-reproduction phase during the (a) 4 s, (b) 8 s, and (c) 12 s intervals. d, The average change in the HEP2 amplitude between the first and last seconds during the reproduction phase correlated negatively with the reproduced duration in the 8 and 12 s intervals.