A neuroanatomical framework for the central modulation of respiratory sensory processing and cough by the periaqueductal grey.

Sensory information arising from the airways is processed in a distributed brain network that encodes for the discriminative and affective components of the resultant sensations. These higher brain networks in turn regulate descending motor control circuits that can both promote or suppress behavioural responses. Here we explore the existence of possible descending neural control pathways that regulate airway afferent processing in the brainstem, analogous to the endogenous descending analgesia system described for noxious somatosensation processing and placebo analgesia. A key component of this circuitry is the midbrain periaqueductal grey, a region of the brainstem recently highlighted for its altered activity in patients with chronic cough. Understanding the nature and plasticity of descending neural control may help identify novel central therapeutic targets to alleviate the neuronal hypersensitivity underpinning many symptoms of respiratory disease.