The time-course of cortico-limbic neural responses to air hunger

•This is the first report of the time-course of dyspnea related neural activity.•Sub-regions of neural circuitry relate to early and late dyspnea components.•The length of dyspnea stimulus used is more pertinent to clinical dyspnea.•Our findings may explain discrepancies in previous dyspnea brain mapping studies.

Several studies have mapped brain regions associated with acute dyspnea perception. However, the time-course of brain activity during sustained dyspnea is unknown. Our objective was to determine the time-course of neural activity when dyspnea is sustained. Eight healthy subjects underwent brain blood oxygen level dependent functional magnetic imaging (BOLD-fMRI) during mechanical ventilation with constant mild hypercapnia (∼45 mmHg). Subjects rated dyspnea (air hunger) via visual analog scale (VAS). Tidal volume (VT) was alternated every 90 s between high VT (0.96 ± 0.23 L) that provided respiratory comfort (12 ± 6% full scale) and low VT (0.48 ± 0.08 L) which evoked air hunger (56 ± 11% full scale). BOLD signal was extracted from a priori brain regions and combined with VAS data to determine air hunger related neural time-c