Coordination of Swallowing and Breathing: How Is the Respiratory Control System Connected to the Swallowing System?

Temporal variations in the pattern of breathing: techniques, sources, and applications to translational sciences

The breathing process possesses a complex variability caused in part by the respiratory central pattern generator in the brainstem; however, it also arises from chemical and mechanical feedback control loops, network reorganization and network sharing with nonrespiratory motor acts, as well as inputs from cortical and subcortical systems. The notion that respiratory fluctuations contain hidden information has prompted scientists to decipher respiratory signals to better understand the fundamental mechanisms of respiratory pattern generation, interactions with emotion, influences on the cortical neuronal networks associated with cognition, and changes in variability in healthy and disease-carrying individuals. Respiration can be used to express and control emotion. Furthermore, respiration appears to organize brain-wide network oscillations via cross-frequency coupling, optimizing cognitive performance. With the aid of information theory-based techniques and machine learning, the hidden information can be translated into a form usable in clinical practice for diagnosis, emotion recognition, and mental conditioning.

Swallowing Dynamics and Breathing-Swallowing Coordination Are Altered in Patients with Mild Cognitive Impairment

INTRODUCTION

Postinspiratory activity, which is essential for laryngeal closure during swallowing to prevent aspiration of food into the airways, is reduced in a mouse model of tauopathy. Therefore, we hypothesized that patients at the stage of mild cognitive impairment (MCI) exhibit alterations in swallowing dynamics and coordination between swallowing and breathing.

METHODS

We examined breathing-swallowing coordination in patients with MCI. Patients who scored ≥24 on the Mini-Mental State Examination and <26 on the Japanese version of the Montreal Cognitive Assessment were recruited at Sumoto Itsuki Hospital. Parameters associated with breathing-swallowing coordination were assessed using a combination of two sensors: a respiratory flow sensor and a piezoelectric sensor attached to the skin surface of the anterior neck.

RESULTS

Nineteen patients met the criteria for MCI; 16 of these patients (79.5 ± 9.1 years old) scored <3 on the 10-item Eating Assessment Tool and were enrolled in the study. Their data were compared with those of an age-matched elderly cohort (79.9 ± 2.9 years old). The frequencies of swallowing during inspiration and swallowing immediately followed by inspiration in patients with MCI were 6.9% and 9.6%, respectively; these frequencies were not significantly different from those of the age-matched elderly cohort. However, the timing of swallowing in the respiratory cycle was significantly delayed in the MCI patients, and both time from the onset to the peak of laryngeal elevation and the duration between the onset of rapid laryngeal elevation and the time when the larynx returned to the resting position were significantly lengthened in this group.

CONCLUSION

At the stage of MCI, breathing-swallowing coordination has already started to decline.