Listen to the beat: Behavioral and neurophysiological correlates of slow and fast heartbeat sounds

Background: Listening to heartbeat sounds have been found to affect cardiac activity and behavior. However, less is known about the effects of these stimuli on brain activity and cognition. Alpha oscillations (8–13 Hz) are considered markers of cortical activation. Frontal alpha Asymmetry (FαA) reflects the valence attributed to the stimulus and the tendency to approach/avoid it. Aim: This study investigates the effects of sounds mimicking heart pulsations at different rhythms on reaction times and neurophysiological activity. Method: EEG data were collected during a resting-state condition and two Simple Reaction Time tasks (SRT), during which artificially generated heartbeat sounds at fast (120 bpm, FastBeat condition) or slow (60 bpm, SlowBeat condition) rhythms were administered. Alpha power was compared across the three conditions. Differences in the SRT and FαA values were examined between the FastBeat and SlowBeat conditions. Results: Compared to the resting-state condition, decreased alpha activity over bilateral frontocentral regions was observed in both tasks. The comparison between the FastBeat and the SlowBeat conditions revealed faster response times, a pattern of alpha suppression over right frontal regions, and lower FαA values in the former. Conclusions: The similarity of alpha reductions elicited in the comparison between the resting-state and the two task conditions suggests that these patterns were ascribable to processes common to both conditions (SRT task, auditory stimulation). In contrast, the differences between the two conditions suggest that fast heartbeat sounds are perceived as more adverse and stressful stimuli, inducing cortical activation over regions associated with negative states and avoidant tendencies.