Respiratory entrainment of the locus coeruleus modulates arousal level to avoid physical risks from external vibration

Abstract

Slow rocking chairs can easily put people to sleep, while violent shaking, such as during earthquakes, may lead to rapid awakening. However, the influence of external body vibrations on arousal remains unclear. Herein, a computational model of a locus coeruleus (LC)-norepinephrine (NE) system and cardio-respiratory system were used to show that respiratory entrainment of the LC modulates arousal levels, which is an adaptation to avoid physical risks from external vibration. External vibrations of sinusoidal waves with different frequencies ranging from 0.1 to 20 [Hz] were applied to the LC based on the results of previous studies. We found that respiratory entrainment of the LC decreased the breathing rate (BR) and heart rate (HR) to maintain the HR within its normal range. Furthermore, 1:1 phase locking enhanced arousal level while phase-amplitude coupling decreased it for larger vibration stimuli. These findings suggest that respiratory entrainment of the LC might automatically modulate cardio-respiratory system homeostasis and arousal levels for performance readiness (fight/flight or freeze) to avoid physical risks from larger external vibrations.

Variations of autonomic arousal mediate the reportability of mind-blanking occurrences

“…Neurophysiologically, this model has translated to investigations of pupil dilation, an index of LC-NE firing, as a function of mental state and task-engagement with pupil size yielding both positive 26,84 and null results 11 in discriminating on-task vs off-task mental states, as well as contrasting MB and MW. Part of the ascending arousal network, the LC modulates cardiac, galvanic, respiratory and pupillary activity 28,85 . In addition, the LC innervates projections responsible for eyelid openness 86 .…”