Cortico-limbic circuitry and the airways: insights from functional neuroimaging of respiratory afferents and efferents

Abstract

After nearly two decades of active research, functional neuroimaging has demonstrated utility in the identification of cortical, limbic, and paralimbic (cortico-limbic) brain regions involved in respiratory control and respiratory perception. Before the recent boon of human neuroimaging studies, the location of the principal components of respiratory-related cortico-limbic circuitry had been unknown and their function had been poorly understood. Emerging neuroimaging evidence in both healthy and patient populations suggests that cognitive and emotional/affective processing within cortico-limbic circuitry modulates respiratory control and respiratory perception. This paper will review functional neuroimaging studies of respiration with a focus on whole brain investigations of sensorimotor pathways that have identified respiratory-related neural circuitry known to overlap emotional/affective cortico-limbic circuitry. To aid the interpretation of present and future findings, the complexities and challenges underlying neuroimaging methodologies will also be reviewed as applied to the study of respiration physiology.

Figure 1

Proposed cortico-limbic model for respiratory sensorimotor integration. Regional color-coding follows the same scheme presented in Table 1: blue, predominant motor functionality; red, predominant sensory functionality; purple, mixed sensorimotor functionality. Abbreviations: ACC, anterior cingulate cortex; DLPFC, dorsolateral prefrontal cortex; KF/PB, Kölliker–Fuse/parabrachial nuclei; LC, locus ceruleus; NTS, nucleus tract of solitarius; PAG, periaqueductal grey; SMA supplementary motor area.