Neural sensitivity to the heartbeat is modulated by spontaneous fluctuations in subjective arousal during wakeful rest
bioRxiv – March 26, 2025
Source: medRxiv/bioRxiv/arXiv
Summary
Our sensitivity to our own heartbeat can change based on our emotional state. In a study, participants reported their feelings while their brain activity was monitored. Results showed that lower subjective arousal heightened brain responses to heartbeats, especially in those with higher anxiety. This suggests a unique link between emotions and bodily awareness.
Abstract
Spontaneous thoughts, occupying much of one’s awake time in daily time, are often colored by emotional qualities. While spontaneous thoughts have been associated with various neural correlates, the relationship between subjective qualities of ongoing experiences and the brain’s sensitivity to bodily signals (i.e., interoception) remains largely unexplored. Given the well-established role of interoception in emotion, clarifying this relationship may elucidate how processes relevant to mental health, such as arousal and anxiety, are regulated. We used EEG and ECG to measure the heartbeat evoked potential (HEP), an index of interoceptive processing, while 51 adult participants (34 male, 20 female) visually fixated on a cross image and let their minds wander freely. At pseudo-random intervals, participants reported their momentary level of arousal. This measure of subjective arousal was highly variable within and between individuals but was statistically unrelated to several markers of physiological arousal, including heart rate, heart rate variability, time on task, and EEG alpha power at posterior electrodes. A cluster-based permutation analysis revealed that the HEP amplitude was increased during low relative to high subjective arousal in a set of frontal electrodes during the 0.328 s – 0.364 s window after heartbeat onset. This HEP effect was more pronounced in individuals who reported high, relative to low, levels of state anxiety. Together, our results offer novel evidence that at varying levels of state anxiety, the brain differentially modulates sensitivity to bodily signals in coordination with the momentary, spontaneous experience of subjective arousal—a mechanism that may operate independently of physiological arousal.