highlighted topics Plasticity in Respiratory Motor Control Invited Review: Neural network plasticity in respiratory control K. F. MORRIS, 1 D. M. BAEKEY, 1 S. C. NUDING, 1 T. E. DICK, 2 R. SHANNON, 1 AND B. G. LINDSEY 1 1 Department of Physiology and Biophysics, University of South Florida Health Sciences Center, Tampa, Florida 33612; and 2 Departments of Medicine, Pharmacology, and Neurosciences, Case Western Reserve University and University Hospitals Research Institute, Cleveland, Ohio 44106 Morris, K. F., D. M. Baekey, S. C. Nuding, T. E. Dick, R. Shannon, and B. G. Lindsey. Invited Review: Neural network plasticity in respiratory control. J Appl Physiol 94: 1242–1252, 2003; 10.1152/jappl- physiol.00715.2002.—Respiratory network plasticity is a modification in respiratory control that persists longer than the stimuli that evoke it or that changes the behavior produced by the network. Different durations and patterns of hypoxia can induce different types of respiratory mem- ories. Lateral pontine neurons are required for decreases in respiratory frequency that follow brief hypoxia. Changes in synchrony and firing rates of ventrolateral and midline medullary neurons may contribute to the long-term facilitation of breathing after brief intermittent hypoxia. Long-term changes in central respiratory motor control may occur after spinal cord injury, and the brain stem network implicated in the produc- tion of the respiratory rhythm could be reconfigured to produce the cough motor pattern. Preliminary analysis suggests that elements of brain stem respiratory neural networks respond differently to hypoxia and hypercapnia and interact with areas involved in cardiovascular control. Plasticity or alterations in these networks may contribute to the chronic upregulation of sympathetic nerve activity and hypertension in sleep apnea syndrome and may also be involved in sudden infant death syndrome. raphe; ventral respiratory group; hypoxia; memory; cough NEURAL PLASTICITY ALLOWS THE brain to adapt. The brain stem neural network that produces the respiratory rhythm and motor pattern must possess a multidimen- sional adaptability. Breathing is coordinated with mul- tiple behaviors that use the same muscles and struc- tures (swallowing, locomotion, posture, micturition, defecation, vocalization, vomiting, and coughing). Ven- tilation and blood flow are also coordinated to meet variable metabolic demands. For the purposes of this review, modulation refers to modifications of the respiratory motor output during acute or extended changes in metabolic demand. Mod- ifications that persist longer than the experimental manipulations or injury that evoked them (i.e., a mem- ory) is termed plasticity. Modifications that cause the network to produce a different behavior, such as cough- ing, also represent a type of plasticity. Recently, it has been shown that the network implicated in the produc- tion of eupnea in the ventrolateral medulla, the Bo ¨tz- inger-ventral respiratory group (Bo ¨t-VRG), reconfigures to produce the airway protective behavior cough (5, 86, 87). Coughing differs from breathing in kind and purpose. Numerous reports suggest that brain stem respira- tory networks contribute to the maintenance of modi- fications of output of greater duration than the stimu- lus that evoked them, i.e., express short- and long-term memories (e.g., Refs. 11, 52, 53, 54, 77; also see Ref. 20, Address for reprint requests and other correspondence: K. F. Morris, Dept. of Physiology and Biophysics, Univ. of South Florida Health Sciences Center, 12901 Bruce B. Downs Blvd., Tampa, Flor- ida 33612-4799 (E-mail: kmorris@hsc.usf.edu). J Appl Physiol 94: 1242–1252, 2003; 10.1152/japplphysiol.00715.2002. 8750-7587/03 $5.00 Copyright © 2003 the American Physiological Society http://www.jap.org 1242 by 10.220.32.247 on April 5, 2017 http://jap.physiology.org/ Downloaded from