Neurotransmission from the heart to the brain results in a heartbeat-evoked potential (HEP). In this study, the influence of the ability to detect one's heartbeats based on the HEP was examined. According to their results in a heartbeat perception task, subjects were classified as good (n=18) or poor (n=26) heartbeat perceivers. EEG, EOG, and ECG were recorded while participants attended to their heartbeats. The R-wave of the ECG served as a trigger for EEG averaging. In the latency range of 250-350 ms after the ECG R-wave, the HEP amplitude at the right central location was significantly higher in good heartbeat perceivers. A significantly positive correlation was observed between the heartbeat perception score and the mean HEP amplitude. Our results confirm that the accuracy of heartbeat perception is reflected in the amplitude of the HEP. Thus, the HEP may be a suitable research tool for the study of brain processes related to visceral perception.

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Accuracy of heartbeat perception is reflected in the amplitude of the heartbeat-evoked brain potential.

Afferent signals from the body play an important role for emotional and motivational aspects of behavior. Nevertheless, little is known about the cortical and subcortical structures involved in interoceptive processes. Recently, a functional MRI study demonstrated that insula, somatomotor, and cingulated cortices are activated when subjects focus attention on their heartbeats. Aside from the use of imaging data, cardiac awareness has frequently been studied by using the heartbeat-evoked potential (HEP), a brain wave that appears contingent on the heartbeat. The present study aimed at localizing sources of the HEP. Multichannel EEG was recorded in 44 subjects while they performed a heartbeat perception task. This task was used to quantify interoceptive awareness and to subdivide the subjects into good and poor heartbeat perceivers. Analyses showed highest HEP amplitudes over frontal and frontocentral electrode locations in the time range of later than 200 ms after R-wave onset. By means of a BESA dipole-source-analysis, four sources of the HEP were identified which were located in the anterior cingulate, the right insula, the prefrontal cortex, and the left secondary somatosensory cortex. Good heartbeat perceivers showed both significantly higher HEP amplitudes and higher dipole strength than poor heartbeat perceivers in all four cortical sources. We conclude that the identified structures are involved in the processing of cardiac signals, whereby anterior cingulate and right insula seem to serve as interoceptive centers for cardioception.

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Brain structures involved in interoceptive awareness and cardioafferent signal processing: A dipole source localization study

Visceral Signals Shape Brain Dynamics and Cognition.

Heartbeat evoked potentials mirror altered body perception in depressed patients

Recent research has shown that heartbeat-evoked potentials (HEPs), brain activity in response to heartbeats, are a useful neural measure for investigating the functional role of brain-body interactions in cognitive processes including self-consciousness. In 2 experiments, using intracranial electroencephalography (EEG), we investigated (1) the neural sources of HEPs, (2) the underlying mechanisms for HEP generation, and (3) the functional role of HEPs in bodily self-consciousness. In Experiment-1, we found that shortly after the heartbeat onset, phase distributions across single trials were significantly concentrated in 10% of the recording sites, mainly in the insula and the operculum, but also in other regions including the amygdala and fronto-temporal cortex. Such phase concentration was not accompanied by increased spectral power, and did not correlate with spectral power changes, suggesting that a phase resetting, rather than an additive "evoked potential" mechanism, underlies HEP generation. In Experiment-2, we further aimed to anatomically refine previous scalp EEG data that linked HEPs with bodily self-consciousness. We found that HEP modulations in the insula reflected an experimentally induced altered sense of self-identification. Collectively, these results provide novel and solid electrophysiological evidence on the neural sources and underlying mechanisms of HEPs, and their functional role in self-consciousness.

M. Plaschke

Papers

Cardiac field effects on the EEG