scholarly journals Essential Role of the cVRG in the Generation of Both the Expiratory and Inspiratory Components of the Cough Reflex

2020 ◽  
pp. S19-S27
Author(s):  
E. Cinelli ◽  
L. Iovino ◽  
F. Bongianni ◽  
T. Pantaleo ◽  
D. Mutolo
Keyword(s):  
Essential Role ◽  
Motor Pattern ◽  
Fine Tuning ◽  
Cough Reflex ◽  
Defensive Responses ◽  
Inspiratory Muscles ◽  
Prominent Component ◽  
Expiratory Neurons ◽  
Inspiratory Activity ◽  
Experimental Findings

As stated by Korpáš and Tomori (1979), cough is the most important airway protective reflex which provides airway defensive responses to nociceptive stimuli. They recognized that active expiratory efforts, due to the activation of caudal ventral respiratory group (cVRG) expiratory premotoneurons, are the prominent component of coughs. Here, we discuss data suggesting that neurons located in the cVRG have an essential role in the generation of both the inspiratory and expiratory components of the cough reflex. Some lines of evidence indicate that cVRG expiratory neurons, when strongly activated, may subserve the alternation of inspiratory and expiratory cough bursts, possibly owing to the presence of axon collaterals. Of note, experimental findings such as blockade or impairment of glutamatergic transmission to the cVRG neurons lead to the view that neurons located in the cVRG are crucial for the production of the complete cough motor pattern. The involvement of bulbospinal expiratory neurons seems unlikely since their activation affects differentially expiratory and inspiratory muscles, while their blockade does not affect baseline inspiratory activity. Thus, other types of cVRG neurons with their medullary projections should have a role and possibly contribute to the fine tuning of the intensity of inspiratory and expiratory efforts.

scholarly journals Sequential Activity in Asymmetrically Coupled Winner-Take-All Circuits

2014 ◽  
Vol 26 (9) ◽  
pp. 1973-2004 ◽  
Author(s):  
Hesham Mostafa ◽  
Giacomo Indiveri
Keyword(s):  
Network Architecture ◽  
External Input ◽  
Spike Timing ◽  
Fine Tuning ◽  
Learning Mechanisms ◽  
State Dependent ◽  
Synaptic Dynamics ◽  
Experimental Findings ◽  
Winner Take All ◽  
Take All

Understanding the sequence generation and learning mechanisms used by recurrent neural networks in the nervous system is an important problem that has been studied extensively. However, most of the models proposed in the literature are either not compatible with neuroanatomy and neurophysiology experimental findings, or are not robust to noise and rely on fine tuning of the parameters. In this work, we propose a novel model of sequence learning and generation that is based on the interactions among multiple asymmetrically coupled winner-take-all (WTA) circuits. The network architecture is consistent with mammalian cortical connectivity data and uses realistic neuronal and synaptic dynamics that give rise to noise-robust patterns of sequential activity. The novel aspect of the network we propose lies in its ability to produce robust patterns of sequential activity that can be halted, resumed, and readily modulated by external input, and in its ability to make use of realistic plastic synapses to learn and reproduce the arbitrary input-imposed sequential patterns. Sequential activity takes the form of a single activity bump that stably propagates through multiple WTA circuits along one of a number of possible paths. Because the network can be configured to either generate spontaneous sequences or wait for external inputs to trigger a transition in the sequence, it provides the basis for creating state-dependent perception-action loops. We first analyze a rate-based approximation of the proposed spiking network to highlight the relevant features of the network dynamics and then show numerical simulation results with spiking neurons, realistic conductance-based synapses, and spike-timing dependent plasticity (STDP) rules to validate the rate-based model.

scholarly journals The Paraventricular Nucleus of the Thalamus as an Integrating and Relay Node in the Brain Anxiety Network

2021 ◽  
Vol 15 ◽  
Author(s):  
Gilbert J. Kirouac
Keyword(s):  
Paraventricular Nucleus ◽  
Relay Node ◽  
Central Nucleus ◽  
Social Avoidance ◽  
Bed Nucleus ◽  
Defensive Responses ◽  
Subcortical Regions ◽  
Cortical Regions ◽  
Experimental Findings ◽  
The Brain

The brain anxiety network is composed of a number of interconnected cortical regions that detect threats and execute appropriate defensive responses via projections to the shell of the nucleus accumbens (NAcSh), dorsolateral region of the bed nucleus of the stria terminalis (BSTDL) and lateral region of the central nucleus of the amygdala (CeL). The paraventricular nucleus of the thalamus (PVT) is anatomically positioned to integrate threat- and arousal-related signals from cortex and hypothalamus and then relay these signals to neural circuits in the NAcSh, BSTDL, and CeL that mediate defensive responses. This review describes the anatomical connections of the PVT that support the view that the PVT may be a critical node in the brain anxiety network. Experimental findings are reviewed showing that the arousal peptides orexins (hypocretins) act at the PVT to promote avoidance of potential threats especially following exposure of rats to a single episode of footshocks. Recent anatomical and experimental findings are discussed which show that neurons in the PVT provide divergent projections to subcortical regions that mediate defensive behaviors and that the projection to the NAcSh is critical for the enhanced social avoidance displayed in rats exposed to footshocks. A theoretical model is proposed for how the PVT integrates cortical and hypothalamic signals to modulate the behavioral responses associated with anxiety and other challenging situations.

From infinities in quantum electrodynamics to the general renormalization group

2019 ◽  
pp. 53-68
Author(s):  
Jean Zinn-Justin
Keyword(s):  
Effective Field Theory ◽  
Quantum Electrodynamics ◽  
Particle Physics ◽  
Essential Role ◽  
Effective Field ◽  
Fine Tuning ◽  
Field Theories ◽  
Higgs Particle ◽  
Renormalization Groups ◽  
Statistical Field

Chapter 4 describes a few important steps which have led from the discovery of infinities in quantum electrodynamics in the calculation of Feynman diagrams (ultraviolet divergences (UV divergences)) to the concept of renormalization and renormalization groups (RG). The constructions of quantum (or statistical) field theories (QFTs) and the deeply related RG have been some of the major theoretical achievements in physics of the last century. RG today plays an essential role in the understanding of the properties of QFT and of continuous macroscopic phase transitions. The existence of RG fixed points makes it possible to understand universality when there is no scale decoupling. In particle physics, it leads to the notion of effective field theory and the fine tuning problem in the Higgs particle sector.

Respiratory muscle control during vomiting

1990 ◽  
Vol 68 (2) ◽  
pp. 237-241 ◽  
Author(s):  
Alan D. Miller
Keyword(s):  
Response Pattern ◽  
Respiratory Muscles ◽  
Respiratory Neurons ◽  
Abdominal Muscles ◽  
Inspiratory Muscles ◽  
Medullary Respiratory Neurons ◽  
Gastric Contents ◽  
Expiratory Neurons ◽  
Expiratory Muscles ◽  
Thoracic And Abdominal

The changes in thoracic and abdominal pressures that generate vomiting are produced by coordinated action of the major respiratory muscles. During vomiting, the diaphragm and external intercostal (inspiratory) muscles co-contract with abdominal (expiratory) muscles in a series of bursts of activity that culminates in expulsion. Internal intercostal (expiratory) muscles contract out of phase with these muscles during retching and are inactive during expulsion. The periesophageal portion of the diaphragm relaxes during expulsion, presumably facilitating rostral movement of gastric contents. Recent studies have begun to examine to what extent medullary respiratory neurons are involved in the control of these muscles during vomiting. Bulbospinal expiratory neurons in the ventral respiratory group caudal to the obex discharge at the appropriate time during (fictive) vomiting to activate either abdominal or internal intercostal motoneurons. The pathways that drive phrenic and external intercostal motoneurons during vomiting have yet to be identified. Most bulbospinal inspiratory neurons in the dorsal and ventral respiratory groups do not have the appropriate response pattern to initiate activation of these motoneurons during (fictive) vomiting. Relaxation of the periesophageal diaphragm during vomiting could be brought about, at least in part, by reduced firing of bulbospinal inspiratory neurons.Key words: brain stem, bulbospinal respiratory neurons, vomiting center critique, diaphragm, abdominal muscles.

Interplay Between the Inspiratory and Postural Functions of the Human Parasternal Intercostal Muscles

2010 ◽  
Vol 103 (3) ◽  
pp. 1622-1629 ◽  
Author(s):  
Anna L. Hudson ◽  
Jane E. Butler ◽  
Simon C. Gandevia ◽  
Andre De Troyer
Keyword(s):  
Motor Units ◽  
Axial Rotation ◽  
Inspiratory Flow ◽  
Discharge Frequency ◽  
Dependent Manner ◽  
Intercostal Muscles ◽  
Inspiratory Muscles ◽  
Inspiratory Activity ◽  
The Right ◽  
Contralateral Rotation

The parasternal intercostal muscles are obligatory inspiratory muscles. To test the hypothesis that they are also involved in trunk rotation and to assess the effect of any postural role on inspiratory drive to the muscles, intramuscular electromyographic (EMG) recordings were made from the parasternal intercostals on the right side in six healthy subjects during resting breathing in a neutral posture (“neutral breaths”), during an isometric axial rotation effort of the trunk to the right (“ipsilateral rotation”) or left (“contralateral rotation”), and during resting breathing with the trunk rotated. The parasternal intercostals were commonly active during ipsilateral rotation but were consistently silent during contralateral rotation. In addition, with ipsilateral rotation, peak parasternal inspiratory activity was 201 ± 19% (mean ± SE) of the peak inspiratory activity in neutral breaths ( P < 0.001), and activity commenced earlier relative to the onset of inspiratory flow. These changes resulted from an increase in the discharge frequency of motor units (14.3 ± 0.3 vs. 11.0 ± 0.3 Hz; P < 0.001) and the recruitment of new motor units. The majority of units that discharged during ipsilateral rotation were also active in inspiration. However, with contralateral rotation, parasternal inspiratory activity was delayed relative to the onset of inspiratory flow, and peak activity was reduced to 72 ± 4% of that in neutral breaths ( P < 0.001). This decrease resulted from a decrease in the inspiratory discharge frequency of units (10.5 ± 0.2 vs. 12.0 ± 0.2 Hz; P < 0.001) and the derecruitment of units. These observations confirm that in addition to an inspiratory function, the parasternal intercostal muscles have a postural function. Furthermore the postural and inspiratory drives depolarize the same motoneurons, and the postural contraction of the muscles alters their output during inspiration in a direction-dependent manner.

scholarly journals Respiratory responses to thyrotropin-releasing hormone microinjected into the rabbit medulla oblongata

1999 ◽  
Vol 277 (5) ◽  
pp. R1331-R1338 ◽  
Author(s):  
Donatella Mutolo ◽  
Fulvia Bongianni ◽  
Marco Carfì ◽  
Tito Pantaleo
Keyword(s):  
Area Postrema ◽  
Thyrotropin Releasing Hormone ◽  
Releasing Hormone ◽  
Dorsal Respiratory Group ◽  
Bötzinger Complex ◽  
Expiratory Neurons ◽  
Inspiratory Activity ◽  
First Time ◽  
Respiratory Responses

We investigated the respiratory role of thyrotropin-releasing hormone (TRH) input to medullary structures involved in the control of breathing in anesthetized, vagotomized, paralyzed, and artificially ventilated rabbits. Microinjections (10–20 nl) of 1 or 10 mM TRH were performed in different regions of the ventral respiratory group (VRG), namely the rostral expiratory portion or Bötzinger complex (Böt. c.), the inspiratory portion, the transition zone between these two neuronal pools, and the caudal expiratory component. TRH microinjections were also performed in the dorsal respiratory group (DRG) and the area postrema (AP). Injection sites were localized by using stereotaxic coordinates and extracellular recordings of neuronal activity; their locations were confirmed by subsequent histological control. TRH microinjections in the Böt. c. and the directly caudally located region where a mix of inspiratory and expiratory neurons were encountered elicited depressant respiratory responses. TRH microinjections were completely ineffective at sites within the inspiratory and the caudal expiratory components of the VRG. TRH microinjections in either the DRG or the AP induced excitatory effects on inspiratory activity. The results show for the first time that TRH may exert inhibitory influences on respiration at medullary levels by acting on rostral expiratory neurons and that not only the DRG, as previously suggested, but also the AP may mediate TRH-induced excitatory effects on respiration.

Cricothyroid muscle responses to increased chemical drive in awake normal humans

1991 ◽  
Vol 70 (5) ◽  
pp. 2233-2241 ◽  
Author(s):  
J. R. Wheatley ◽  
A. Brancatisano ◽  
L. A. Engel
Keyword(s):  
Lead Time ◽  
Upper Airway ◽  
Inspiratory Flow ◽  
Inspiratory Time ◽  
Cricothyroid Muscle ◽  
Inspiratory Muscles ◽  
Inspiratory Activity ◽  
Normal Humans ◽  
Muscle Responses ◽  
Muscle Ct

To examine the response of the cricothyroid muscle (CT) to increased chemical drive, we measured its electromyogram simultaneously with that of the alae nasi (AN) in seven normal awake subjects. During both progressive hyperoxic hypercapnia and hypoxia, peak integrated inspiratory activity (moving time average, MTA) of the CT and AN increased as a power function of mean inspiratory flow (ratio of tidal volume to inspiratory time, VT/TI), given by MTA = a(VT/TI)b + c (where a, b, and c are constants). The exponent b varied from 0.009 to 3.4 among subjects but was correlated between CT and AN both during hypercapnia (r = 0.86) and hypoxia (r = 0.81). The onset of inspiratory activity of the CT and AN preceded that of inspiratory flow. Expressed as a percentage of expiratory time, the CT lead time rose from 7% at rest to 20% during hyperpnea. The corresponding values for the AN were from 22 to 52% (both P less than 0.03). Thus the pattern of response of the CT and AN is similar and related to that of the inspiratory muscles in a curvilinear manner. The findings suggest that during chemical stimulation the electrical activity of the CT is analogous to that of the AN, an upper airway dilator.

scholarly journals Non-equilibrium landscape and flux reveal how the central amygdala circuit gates passive and active defensive responses

2019 ◽  
Vol 16 (153) ◽  
pp. 20180756 ◽  
Author(s):  
Han Yan ◽  
Bo Li ◽  
Jin Wang
Keyword(s):  
Phase Transitions ◽  
Neural Circuit ◽  
Equilibrium Phase ◽  
Physical Mechanisms ◽  
Defensive Responses ◽  
Sufficient Energy ◽  
Experimental Findings ◽  
Physical Principles ◽  
Selection Of ◽  
Non Equilibrium

Uncovering the underlying physical principles of biology is important for understanding the biological function yet challenging. Take an example, the animals’ defensive systems are very effective to threats. However, the underlying physical mechanisms are still unclear. We developed a non-equilibrium physics framework in terms of landscape and flux to study a central lateral amygdala (CeL) neural circuit based on experimental findings. We show that the distinct active and passive defensive responses of the animals upon threats are a result of non-equilibrium phase transitions. Such non-equilibrium phase transitions result from thermodynamic symmetry breaking, which is induced dynamically by the non-equilibrium flux. This gives rise to the emergence and selection of passive and active fear defensive responses, which can be quantified by the changes on the topography of the underlying non-equilibrium landscape. We have found the strengthened synaptic transmissions to both the SOM + and SOM − CeL neurons are necessary for the acquisition and expression of active fear responses. This suggests a way to induce active responses and facilitates the design of new therapeutic strategies for cognitive dysfunction. We have also found that sufficient energy supply is crucial for the ability of selecting the appropriate defensive responses through stabilizing functional states against fluctuations.

scholarly journals Regulatory T Cells, a Potent Immunoregulatory Target for CAM Researchers: Modulating Allergic and Infectious Disease Pathology (II)

2006 ◽  
Vol 3 (2) ◽  
pp. 209-215 ◽  
Author(s):  
Aristo Vojdani ◽  
Jonathan Erde
Keyword(s):  
Infectious Disease ◽  
T Cells ◽  
Regulatory T Cells ◽  
Immune Responses ◽  
Tissue Damage ◽  
Essential Role ◽  
Treg Cells ◽  
Defensive Responses ◽  
Cell Suppression ◽  
Foreign Materials

Regulatory T (Treg) cells maintain dominant control of immune responses to foreign materials and microbes. Appropriate Treg cell suppression of immune responses is essential for the maintenance of efficacious defensive responses and the limitation of collateral tissue damage due to excess inflammation. Allergy and infection are well studied and frequent afflictions in which Treg cells play an essential role. As such, they provide excellent models to communicate the significance and relevance of Treg cells to complementary and alternative medicine (CAM).

Respiratory neuronal activity during apnea and poststimulatory effects of laryngeal origin in the cat

2000 ◽  
Vol 89 (3) ◽  
pp. 917-925 ◽  
Author(s):  
Fulvia Bongianni ◽  
Donatella Mutolo ◽  
Marco Carfì ◽  
Giovanni A. Fontana ◽  
Tito Pantaleo
Keyword(s):  
Respiratory Depression ◽  
Superior Laryngeal Nerve ◽  
Respiratory Neurons ◽  
Inhibitory Input ◽  
Phase Theory ◽  
Inspiratory Neurons ◽  
Three Phase ◽  
Expiratory Neurons ◽  
Inspiratory Activity ◽  
Respiratory Reflexes

We investigated the behavior of medullary respiratory neurons in cats under pentobarbitone anesthesia, vagotomized, paralysed, and artificially ventilated to elucidate neural mechanisms underlying apnea and poststimulatory respiratory depression induced by superior laryngeal nerve (SLN) stimulation. Inspiratory neurons were completely inhibited during SLN stimulation and poststimulatory apnea. During recovery of inspiratory activity, augmenting inspiratory neurons were depressed, decrementing inspiratory neurons were excited, and late inspiratory neurons displayed unchanged bursts closely locked to the end of the inspiratory phase. Augmenting expiratory neurons were either silenced or displayed different levels of tonic activity during SLN stimulation; some of them were clearly activated. These expiratory neurons displayed activity during poststimulatory apnea, before the onset of the first recovery phrenic burst. Postinspiratory or decrementing expiratory neurons were activated during SLN stimulation; their discharge continued with a decreasing trend during poststimulatory apnea. The results support the three-phase theory of rhythm generation and the view that SLN stimulation provokes a postinspiratory apnea that could represent the inhibitory component of respiratory reflexes of laryngeal origin, such as swallowing. In addition, because a subpopulation of augmenting expiratory neurons displays activation during SLN stimulation, the hypothesis can be advanced that not only postinspiratory, or decrementing expiratory neurons, but also augmenting expiratory neurons may be involved in the genesis of apnea and poststimulatory phenomena. Finally, the increase in the activity of decrementing inspiratory neurons after the end of SLN stimulation may contribute to the generation of poststimulatory respiratory depression by providing an inhibitory input to bulbospinal augmenting inspiratory neurons.

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