This R01 project will advance our understanding of the brainstem neural circuits that generate and control breathing behavior in humans and all mammals. Breathing is an integral part of cardiopulmonary physiology and understanding its neural origins has significant implications for human health. Rhythmic breathing movements begin during embryonic development and emanate from coordinated activity in brainstem respiratory neurons. One key population of rhythm-generating neurons is contained in a site called the preB""""""""tzinger complex (preB""""""""tC). The discovery of the preB""""""""tC made possible many powerful experiments that could be performed in vitro, and led to our contemporary understanding of the neurophysiology of respiration. Nevertheless, critical questions remain unanswered. Given the heterogeneity of respiratory-related and non-respiratory neurons in the preB""""""""tC, can we discover which neurons are the key rhythm generators? If rhythmogenic neurons can be identified (and we argue that indeed they can), then can we ascertain the cellular, synaptic, and molecular-level mechanisms that underlie rhythm generation? Finally, the importance of peptidergic modulation of respiratory rhythm has been widely recognized in the past decade, but its underlying biophysical mechanisms remain incompletely understood. This project seeks answers to these specific questions by studying the preB""""""""tC in thin brainstem slice preparations in vitro.
SPECIFIC AIM 1 will evaluate the cellular composition of the preB""""""""tC. Transgenic mouse models will be used to apply fluorescent tags to genetically distinct sub-populations, and then selectively and serially lesion them to test their respective roles in rhythmogenesis.
SPECIFIC AIM 2 will examine the synaptic-dendritic active membrane properties that generate inspiratory-related bursts.
SPECIFIC AIM 3 will investigate whether presynaptic depression of excitatory transmission contributes to burst termination.
SPECIFIC AIM 4 is designed to complement SPECIFIC AIM 3 by examining the postsynaptic membrane properties that also act to terminate inspiratory bursts. Finally, SPECIFIC AIM 5 will determine the ion channels that underlie respiratory modulation by key neuropeptides (and other neuromessengers). The new knowledge acquired during this project will aid in the treatment and prophylaxis of breathing disorders that result from failures in the brain and central nervous system. Moreover, studying a measurable behavior like breathing under controlled in vitro conditions helps reveal important principles that link neurons, synapses, and molecules to full-scale physiological behaviors, which will be of great interest in neuroscience as well as cardiopulmonary physiology.

Public Health Relevance

Breathing is a vital human behavior that is essential to maintain homeostasis and life itself. This project will advance our understanding of the brainstem neural circuits that generate and control breathing rhythms by analyzing their function at multiple levels including: neuron type (i.e., genotype), cellular properties, ion channels, synaptic receptors, and intracellular signaling. The new knowledge obtained will serve as a foundation for the treatment and prevention of respiratory disorders with a central neural etiology, and elucidate circuit-level properties that underlie rhythmic motor behaviors in general.

National Institute of Health (NIH)
National Heart, Lung, and Blood Institute (NHLBI)
Research Project (R01)
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Study Section
Respiratory Integrative Biology and Translational Research Study Section (RIBT)
Program Officer
Laposky, Aaron D
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College of William and Mary
Schools of Arts and Sciences
United States
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Phillips, Wiktor S; Del Negro, Christopher A; Rekling, Jens C (2018) Dendritic A-Current in Rhythmically Active PreBötzinger Complex Neurons in Organotypic Cultures from Newborn Mice. J Neurosci 38:3039-3049
Kottick, Andrew; Martin, Caroline A; Del Negro, Christopher A (2017) Fate mapping neurons and glia derived from Dbx1-expressing progenitors in mouse preBötzinger complex. Physiol Rep 5:
Akins, Victoria T; Weragalaarachchi, Krishanthi; Picardo, Maria Cristina D et al. (2017) Morphology of Dbx1 respiratory neurons in the preBötzinger complex and reticular formation of neonatal mice. Sci Data 4:170097
Hayes, John A; Kottick, Andrew; Picardo, Maria Cristina D et al. (2017) Transcriptome of neonatal preBötzinger complex neurones in Dbx1 reporter mice. Sci Rep 7:8669
Vann, Nikolas C; Pham, Francis D; Hayes, John A et al. (2016) Transient Suppression of Dbx1 PreBötzinger Interneurons Disrupts Breathing in Adult Mice. PLoS One 11:e0162418
Phillips, Wiktor S; Herly, Mikkel; Del Negro, Christopher A et al. (2016) Organotypic slice cultures containing the preBötzinger complex generate respiratory-like rhythms. J Neurophysiol 115:1063-70
Song, Hanbing; Hayes, John A; Vann, Nikolas C et al. (2016) Functional Interactions between Mammalian Respiratory Rhythmogenic and Premotor Circuitry. J Neurosci 36:7223-33
Kottick, Andrew; Del Negro, Christopher A (2015) Synaptic Depression Influences Inspiratory-Expiratory Phase Transition in Dbx1 Interneurons of the preBötzinger Complex in Neonatal Mice. J Neurosci 35:11606-11
Revill, Ann L; Vann, Nikolas C; Akins, Victoria T et al. (2015) Dbx1 precursor cells are a source of inspiratory XII premotoneurons. Elife 4:
Song, Hanbing; Hayes, John A; Vann, Nikolas C et al. (2015) Mechanisms Leading to Rhythm Cessation in the Respiratory PreBötzinger Complex Due to Piecewise Cumulative Neuronal Deletions eNeuro 2:

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