Abstract
Many interoceptive tasks (i.e. measuring the sensitivity to bodily signals) are based upon heartbeats perception. However, the temporal perception of heartbeats—when heartbeats are felt—varies among individuals. Moreover, the spatial perception of heartbeats—where on the body heartbeats are felt—has not been characterized in relation to temporal. This study used a multi-interval heartbeat discrimination task in which participants judged the timing of their own heartbeats in relation to external tones. The perception of heartbeats in both time and spatial domains, and relationship between these domains was investigated. Heartbeat perception occurred on average ~ 250 ms after the ECG R-wave, most frequently sampled from the left part of the chest. Participants’ confidence in discriminating the timing of heartbeats from external tones was maximal at 0 ms (tone played at R-wave). Higher confidence was related to reduced dispersion of sampling locations, but Bayesian statistics indicated the absence of relationship between temporal and spatial heartbeats perception. Finally, the spatial precision of heartbeat perception was related to state-anxiety scores, yet largely independent of cardiovascular parameters. This investigation of heartbeat perception provides fresh insights concerning interoceptive signals that contribute to emotion, cognition and behaviour.
Highlights
Results of the mixed-effects regression model provided further insight We report 95% confidence interval, Savage-Dickey density ratio Bayes Factor (BF), the most credible value, and 95% Credible Interval (95% CrI): We observed that a delay of 200 ms from R-wave produced the highest probability of answering “Yes” for a judgment of simultaneity (β = 0.59, SE = 0.11, 95% CI [0.40, 0.76], p value < 0.001, BF = 252.44, 62.84%, 95% CrI [58.78, 66.99]), compared to the non-delay condition (β = − 0.007, SE = 0.141, 95% CI [− 0.20, 0.20], p value = 0.961, BF = 0.01, 49.66%, 95% CrI [45.62, 53.90])
The observed pattern of perceptual lateralization may have a basis in peripheral anatomy (Craig 2002) and central neural organisation where interoceptive inputs, integrated within right and the left anterior insula respectively, are putatively re-represented in the dominant right anterior insula[3]. This may mean that, in general, most participants base their judgments of cardiac timing and synchrony on spinothalamocortical information rather than vagus nerve afferents. Such right-side dominance merits further evaluation, not least because it was not reflected in confidence ratings for the simultaneity judgments; higher judgment confidence was signalled for heartbeat sensations felt in the left head/ear/neck compared to left chest
It has been shown that the somatosensory pathway that gathers information from the skin and from Pacinian and non-Pacinian somatosensory mechanoreceptors located on the chest wall contributes to the spatial precision of heartbeat p erception[21, 51]
Summary
The present study aimed to examine in detail the perception of heartbeat sensations, using a multi-interval heartbeat discrimination task[10], to address the following questions:. When do people perceive their own heartbeats ? We quantified the timing of heartbeat perception using a simultaneity judgement of heartbeat sensation relative to the presentation of an external auditory tone, triggered at different delays (SOAs) from the ECG R-wave. After listening to an individual sequence, the participant decided whether or not the tones were played simultaneously with perceived own heartbeats. We explored how subclinical affective measures such as Anxiety, Depression, and Alexithymia related to temporal and spatial perception of heartbeats. We predicted that individual differences in affective symptoms will influence both aspects of heartbeat s ensation[8, 23, 28, 35]
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