Abstract
The human brain can infer temporal regularities in auditory sequences with fixed sound-to-sound intervals and in pseudo-regular sequences where sound onsets are locked to cardiac inputs. Here, we investigated auditory and cardio-audio regularity encoding during sleep, when reduced vigilance may result in altered bodily and environmental stimulus processing. Using electroencephalography and electrocardiography in healthy volunteers (N=26) during wakefulness and sleep, we measured the response to unexpected sound omissions within three regularity conditions: isochronous, with fixed sound-to-sound intervals, synchronous, where sound and heartbeat are temporally coupled, and a control condition without specific regularity. The isochronous and synchronous sequences induced a modulation of the omission-evoked neural response in wakefulness and N2 sleep, the latter accompanied by a background oscillatory activity reorganization. Cardio-audio regularity encoding was accompanied by a heartbeat deceleration upon omissions in all vigilance states. The violation of auditory and cardio-audio regularity elicits neural and cardiac surprise responses across vigilance stages.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
1. A reorganization of the manuscript structure for improving the logical sequence of hypotheses and experimental questions. 2. A complete data re-analysis based on non-parametric statistical methods which largely confirmed our previous results. In addition, inclusion of effect sizes for the main results strengthens the significance of any findings. 3. A new sets of data analysis to confirm the interpretability of the neural omission response in terms of neural correlates of sound omissions. 4. An improved results visualization based on raincloud plots and figures reorganization.
