Human Brain Activation Associated with Cough and Cough Suppression

Supramedullary brain regions may contribute to control of cough by facilitating or inhibiting brainstem reflex pathways. Using functional brain imaging, we put this putative model to the test. Blood oxygen level‐dependent (BOLD) contrast images were acquired from 15 healthy subjects after inhaling saline, inhaling capsaicin without cough, inhaling capsaicin with cough, and voluntary cough after inhaling saline. BOLD signals were analysed to identify changes associated with cough, capsaicin stimulation and their interactions. Contrary to the hypothesised effect, the positive interaction of cough and capsaicin stimulation did not implicate brain activation uniquely associated with evoked cough. However, the negative interaction revealed brain activations that may be requisite for the initiation of voluntary cough and suppression of evoked cough (inferior frontal gyrus, SMA, cingulate cortex) as well as ongoing sensations associated with capsaicin in the airways (insula, orbitofrontal cortex)(P<0.05). These data show that voluntary cough and suppression of evoked cough are associated with brain activation in excess of that associated with evoked cough. This outcome suggests that evoked cough is a default motor pattern that does not require active facilitation by higher order centres, but is under higher order inhibitory influences.Funding: NHMRC Australia #454776, #566734