Neurogenesis of patterns of automatic ventilatory activity

John, Walter M. St.

doi:10.1016/s0301-0082(98)00031-8

Cited by 163 publications

(119 citation statements)

References 111 publications

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“…These observations suggest that the increase in central respiratory rate was due to the release of inhibition of the rhythm generator responsible for eupnea rather than conversion to gasping. In gasping, instead of increasing in a ramplike fashion, peak inspiratory activity is reached almost instantaneously (51). Central respiratory rate also increased in all four spontaneously breathing cats after chemical inactivation of the LTF.…”

Section: Ltf and Control Of Central Respiratory Ratementioning

confidence: 79%

Medullary lateral tegmental field: control of respiratory rate and vagal lung inflation afferent influences on sympathetic nerve discharge

Phillips¹,

Gebber²,

Barman³

2005

American Journal of Physiology-Regulatory, Integrative and Comp

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Phillips, Shaun W., Gerard L. Gebber, and Susan M. Barman. Medullary lateral tegmental field: control of respiratory rate and vagal lung inflation afferent influences on sympathetic nerve discharge. Am J Physiol Regul Integr Comp Physiol 288: R1396 -R1410, 2005. First published December 16, 2004; doi:10.1152/ajpregu.00632.2004.-We used spectral analysis and event-triggered averaging to determine the effects of chemical inactivation of the medullary lateral tegmental field (LTF) on 1) the relationship of intratracheal pressure (ITP, an index of vagal lung inflation afferent activity) to sympathetic nerve discharge (SND) and phrenic nerve activity (PNA) and 2) central respiratory rate in paralyzed, artificially ventilated dial-urethane-anesthetized cats. ITP-SND coherence value at the frequency of artificial ventilation was significantly (P Ͻ 0.05; n ϭ 18) reduced from 0.73 Ϯ 0.04 (mean Ϯ SE) to 0.24 Ϯ 0.04 after bilateral microinjection of muscimol into the LTF. Central respiratory rate was unexpectedly increased in 12 of these experiments (0.28 Ϯ 0.03 vs. 0.95 Ϯ 0.25 Hz). The ITP-PNA coherence value was variably affected by chemical inactivation of the LTF. It was unchanged when central respiratory rate was also not altered, decreased when respiratory rate was increased above the rate of artificial ventilation, and increased when respiratory rate was raised from a value below the rate of artificial ventilation to the same frequency as the ventilator. Chemical inactivation of the LTF increased central respiratory rate in four of six vagotomized cats but did not significantly affect the PNA-SND coherence value. These data demonstrate that the LTF 1) plays a critical role in mediating the effects of vagal lung inflation afferents on SND but not PNA, 2) helps maintain central respiratory rate in the physiological range, but 3) is not involved in the coupling of central respiratory and sympathetic circuits. cardiorespiratory synchronization; dorsal respiratory group; HeringBreuer reflex; phrenic nerve activity; respiratory-related rhythm; ventral respiratory group IT HAS LONG BEEN RECOGNIZED that neural mechanisms controlling the respiratory and cardiovascular systems are tightly linked (25,34,38,49,55). This interaction facilitates the complementary functions of the two systems: respiration maintains appropriate levels of arterial blood gases, while the cardiovascular system transports these gases to and from tissues. One indication of this cardiorespiratory coordination was noted by Adrian et al. (1) in 1932 when they made the first recordings of sympathetic nerve discharge (SND). They found that the amplitude of the cardiac-related bursts of SND waxed and waned on the time scale of the respiratory cycle. There are at least two sources of respiratory modulation of SND: input from vagal lung inflation afferents and an influence of the respiratory rhythm generator on central sympathetic neurons (4 -6, 21, 25, 33-35, 59). Although some investigators (38, 49) have proposed that there is a common network controlling bo...

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Section: Ltf and Control Of Central Respiratory Ratementioning

confidence: 79%

Medullary lateral tegmental field: control of respiratory rate and vagal lung inflation afferent influences on sympathetic nerve discharge

Phillips¹,

Gebber²,

Barman³

2005

American Journal of Physiology-Regulatory, Integrative and Comp

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“…Severe hypoxia in vivo produces brief, low-frequency, and highamplitude phrenic bursts with a decremental pattern (St-John, 1998;Paton et al, 2006). For unknown reasons, the phrenic discharge of the Suzue preparation has somewhat similar characteristics (Brockhaus et al, 1993;Dutschmann et al, 2000;Taccola et al, 2007).…”

Section: Pre-i Pattern and Respiratory Network Reconfigurationmentioning

confidence: 99%

Bötzinger Expiratory-Augmenting Neurons and the Parafacial Respiratory Group

Fortuna¹,

West²,

Stornetta³

et al. 2008

J. Neurosci.

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In neonatal rat brains in vitro, the rostral ventral respiratory column (rVRC) contains neurons that burst just before the phrenic nerve discharge (PND) and rebound after inspiration (pre-I neurons). These neurons, called parafacial respiratory group (pfRG), have been interpreted as a master inspiratory oscillator, an expiratory rhythm generator or simply as neonatal precursors of retrotrapezoid (RTN) chemoreceptor neurons. pfRG neurons have not been identified in adults, and their phenotype is unknown. Here, we confirm that the rVRC normally lacks pre-I neurons in adult anesthetized rats. However, we show that, during hypercapnic hypoxia, a population of rVRC expiratory-augmenting (E-AUG) neurons consistently develops a pre-I discharge. These cells reside in the Bötzinger region of the rVRC, they express glycine-transporter-2, and their axons arborize throughout the VRC. Hypoxia triggers an identical pre-I pattern in retroambigual expiratory bulbospinal neurons, but this pattern is not elicited in Bötzinger expiratory-decrementing neurons, Bötzinger inspiratory neurons, RTN neurons, and blood pressure-regulating neurons. In conclusion, under hypoxia in vivo, abdominal expiratory premotor neurons of adult rats develop a pre-I pattern reminiscent of that observed in neonate brainstems in vitro. In the rVRC of adult rats, pre-I cells include selected rhythmogenic neurons (glycinergic Bötzinger neurons) but not RTN chemoreceptors. We suggest that the pfRG may not be an independent rhythm generator but a heterogeneous collection of E-AUG neurons (glycinergic Bötzinger neurons, possibly facial motor and premotor neurons), the discharge of which becomes preinspiratory under specific experimental conditions resulting from, in part, a prolonged and intensified activity of postinspiratory neurons.

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“…The specific role of pontine structures in the generation and control of the respiratory pattern has hitherto not been well defined. However, the pontine structures appear to have specific interactions with multiple medullary compartments, and the pons as a whole provides strong modulation of the medullary respiratory network via tonic and/or respiratory modulated drives (St.-John, 1998;Alheid et al, 2004). In addition, several medullary structures, specifically the retrotrapezoid nucleus (RTN, located rostrally to BötC below the facial nucleus) and the medullary raphe nucleus, both involved in the central chemoreception, also modulate the medullary respiratory network performance via various drives defining the metabolic state of the system (the level of oxygen and carbon dioxide, pH, etc.)…”

Section: Introductionmentioning

confidence: 99%

Spatial organization and state-dependent mechanisms for respiratory rhythm and pattern generation

Rybak

Abdala

Markin

et al. 2007

Progress in Brain Research

134

199

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The brainstem respiratory network can operate in multiple functional states engaging different statedependent neural mechanisms. These mechanisms were studied in the in situ perfused rat brainstemspinal cord preparation using sequential brainstem transections and administration of riluzole, a pharmacological blocker of persistent sodium current (I NaP ). Dramatic transformations in the rhythmogenic mechanisms and respiratory motor pattern were observed after removal of the pons and subsequent medullary transactions down to the rostral end of pre-Bötzinger complex (pre-BötC). A computational model of the brainstem respiratory network was developed to reproduce and explain these experimental findings. The model incorporates several interacting neuronal compartments, including the ventral respiratory group (VRG), pre-BötC, Bötzinger complex (BötC), and pons. Simulations mimicking the removal of circuit components following transections closely reproduce the respiratory motor output patterns recorded from the intact and sequentially reduced brainstem preparations. The model suggests that both the operating rhythmogenic mechanism (i.e., networkbased or pacemaker-driven) and the respiratory pattern generated (e.g., three-phase, two-phase, or one-phase) depend on the state of the pre-BötC (expression of I NaP -dependent intrinsic rhythmogenic mechanisms) and the BötC (providing expiratory inhibition in the network). At the same time, tonic drives from pons and multiple medullary chemoreceptive sites appear to control the state of these compartments and hence the operating rhythmogenic mechanism and motor pattern. Our results suggest that the brainstem respiratory network has a spatial (rostral-to-caudal) organization extending from the rostral pons to the VRG, in which each functional compartment is controlled by more rostral compartments. The model predicts a continuum of respiratory network states relying on different contributions of intrinsic cellular properties versus synaptic interactions for the generation and control of the respiratory rhythm and pattern.

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Neurogenesis of patterns of automatic ventilatory activity

Cited by 163 publications

References 111 publications

Medullary lateral tegmental field: control of respiratory rate and vagal lung inflation afferent influences on sympathetic nerve discharge

Medullary lateral tegmental field: control of respiratory rate and vagal lung inflation afferent influences on sympathetic nerve discharge

Bötzinger Expiratory-Augmenting Neurons and the Parafacial Respiratory Group

Spatial organization and state-dependent mechanisms for respiratory rhythm and pattern generation

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