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RESPIRATORY |
1 Division of Pulmonary, Critical Care and Sleep Medicine, Departments of Medicine and Neurosciences, University Hospitals Research Institute, Case Western Reserve University, Cleveland, OH 44106-4941, USA
2
Department of Molecular Pharmacology and Physiology, and Neuroscience Program, School of Biomedical Sciences, College of Medicine, University of South Florida, Tampa, FL 33612-4799, USA
The dorsolateral (DL) pons modulates the respiratory pattern. With the prevention of lung inflation during central inspiratory phase (no-inflation (no-I or delayed-I) tests), DL pontine neuronal activity increased the strength and consistency of its respiratory modulation, properties measured statistically by the 
2 value. This increase could result from enhanced respiratory-modulated drive arising from the medulla normally gated by vagal activity. We hypothesized that DL pontine activity during delayed-I tests would be comparable to that following vagotomy. Ensemble recordings of neuronal activity were obtained before and after vagotomy and during delayed-I tests in decerebrate, paralysed and ventilated cats. In general, changes in activity pattern during the delayed-I tests were similar to those after vagotomy, with the exception of firing-rate differences at the inspiratory–expiratory phase transition. Even activity that was respiratory-modulated with the vagi intact became more modulated while withholding lung inflation and following vagotomy. Furthermore, we recorded activity that was excited by lung inflation as well as changes that persisted past the stimulus cycle. Computer simulations of a recurrent inhibitory neural network model account not only for enhanced respiratory modulation with vagotomy but also the varied activities observed with the vagi intact. We conclude that (a) DL pontine neurones receive both vagal-dependent excitatory inputs and central respiratory drive; (b) even though changes in pontine activity are transient, they can persist after no-I tests whether or not changes in the respiratory pattern occur in the subsequent cycles; and (c) models of respiratory control should depict a recurrent inhibitory circuitry, which can act to maintain the stability and provide plasticity to the respiratory pattern.
(Received 4 February 2008;
accepted after revision 30 June 2008;
first published online 3 July 2008)
Corresponding author T. E. Dick: Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106-4941, USA. Email: thomas.dick{at}case.edu
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  Erratum J. Physiol., November 1, 2008; 586(21): 5279 - 5279. [Full Text] [PDF]
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 I. A. Rybak, R. O'Connor, A. Ross, N. A. Shevtsova, S. C. Nuding, L. S. Segers, R. Shannon, T. E. Dick, W. L. Dunin-Barkowski, J. M. Orem, et al. Reconfiguration of the Pontomedullary Respiratory Network: A Computational Modeling Study With Coordinated In Vivo Experiments J Neurophysiol, October 1, 2008; 100(4): 1770 - 1799. [Abstract] [Full Text] [PDF]
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