Canadian Association of Neuroscience Review: Respiratory Control and Behavior in Humans: Lessons from Imaging and Experiments of Nature

Abstract

The concept behind this article is that respiration is not just an automatic function. Rather, it is a complex behavior that is controlled at many brain levels and structures, some autonomic and others voluntary. This article will offer a review of the organization of respiratory control and its special features as gleaned from work in animals, and from relatively recent studies in humans using updated imaging techniques. The importance of the brainstem in autonomic respiratory control, of sleep-wake states in modulating respiration, and of supramedullary regulation of breathing during volition, with emotion, and at the ABSTRACT: The purpose of this review is to demonstrate that respiration is a complex behavior comprising both brainstem autonomic control and supramedullary influences, including volition. Whereas some fundamental mechanisms had to be established using animal models, this review focuses on clinical cases and physiological studies in humans to illustrate normal and abnormal respiratory behavior. To summarize, central respiratory drive is generated in the rostroventrolateral medulla, and transmitted to both the upper airway and to the main and accessory respiratory muscles. Afferent feedback is provided from lung and muscle mechnoreceptors, peripheral carotid and aortic chemoreceptors, and multiple central chemoreceptors. Supramedullary regions, including cortex and subcortex, modulate or initiate breathing with volition, emotion and at the onset of exercise. Autonomic breathing control can be perturbed by brainstem pathology including space occupying lesions, compression, congenital central hypoventilation syndrome and sudden infant death syndrome. Sleep-wake states are important in regulating breathing. Thus, respiratory control abnormalities are most often evident during sleep, or during transition from sleep to wakefulness. Previously undiagnosed structural brainstem pathology may be revealed by abnormal breathing during sleep. Ondine's curse and 'the locked-in syndrome' serve to distinguish brainstem from supramedullary regulatory mechanisms in humans: The former comprises loss of autonomic respiratory control and requires volitional breathing for survival, and the latter entails loss of corticospinal or corticobulbar tracts required for volitional breathing, but preserves autonomic respiratory control. RÉSUMÉ: Contrôle et comportement respiratoire chez l'humain : leçons tirées de l'imagerie et des expériences naturelles.Le but de cette revue est de démontrer que la respiration est un acte complexe impliquant un contrôle neuro-végétatif provenant du tronc cérébral et des influences supramédullaires, entre autres la volonté. Alors que les mécanismes fondamentaux ont dû être établis grâce à des modèles animaux, cette revue est axée sur des cas cliniques et des études physiologiques chez l'humain afin d'illustrer le comportement respiratoire normal et anormal. En résumé, la stimulation respiratoire centrale origine de la moelle rostro-ventro-latérale et elle est transmise aux voies aériennes supé...

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