title: Learning to breathe: habituation of Hering-Breuer inflation reflex emerges with postnatal brainstem maturation.
abstract: The Hering-Breuer (HBR) reflex is considered a major regulatory feedback for the generation and patterning of respiratory activity. While HBR is important in neonates, its significance in adults is controversial. Previous experiments that investigated the plasticity of entrainment of the respiratory rhythm by vagal input demonstrated postnatal changes in HBR plasticity. Here we analyzed postnatal changes in the plasticity of HBR by mimicking the classic lung inflation tests with repetitive tonic vagal stimulation across different postnatal stages in an in situ perfused brainstem preparation of rat. The study shows that neonates stereotypically exhibit HBR stimulus-dependent prolongation of expiration while juvenile preparations (>postnatal day 16) showed significant habituation of HBR following repetitive stimulation. Subsequent experiments employing physiological lung inflation tests in situ confirmed HBR habituation in juveniles. We conclude that postnatal emergence of HBR habituation explains the weak contribution and high activation threshold of HBR in the regulation of eupnea.
authors.affiliation: Florey Institute of Neuroscience and Mental Health, Melbourne, Australia; Bernstein Center for Computational Neurosciences, Göttingen, Germany. Electronic address: mathias.dutschmann@florey.edu.au.
authors.forename: Mathias
authors.initials: M
authors.lastname: Dutschmann
authors.affiliation: Florey Institute of Neuroscience and Mental Health, Melbourne, Australia.
authors.forename: Tara G
authors.initials: TG
authors.lastname: Bautista
authors.affiliation: Bernstein Center for Computational Neurosciences, Göttingen, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Mörschel
authors.affiliation: Department of Medicine, Case Western Reserve University, Cleveland, USA.
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Dick
mesh_terms: D000818:Animals; D001933:Brain Stem / Q000254:growth & development* / Q000502:physiology*; D004558:Electric Stimulation; D045853:Exhalation; D066298:In Vitro Techniques; D008168:Lung / Q000502:physiology; D009473:Neuronal Plasticity; D010791:Phrenic Nerve / Q000254:growth & development / Q000502:physiology; D051381:Rats; D012018:Reflex / Q000502:physiology*; D012119:Respiration; D014630:Vagus Nerve / Q000254:growth & development / Q000502:physiology
keywords: Brainstem; Hebbian plasticity; Postnatal development; Sensory processing