Bidirectional Electrical Coupling Between Inspiratory Motoneurons in the Newborn Mouse Nucleus Ambiguus

1997 ◽  
Vol 78 (6) ◽  
pp. 3508-3510 ◽  
Author(s):  
Jens C. Rekling ◽  
Jack L. Feldman
Keyword(s):  
Brain Stem ◽  
Impulse Activity ◽  
Electrical Coupling ◽  
Postnatal Period ◽  
The Other ◽  
Nucleus Ambiguus ◽  
Newborn Mouse ◽  
Coupling Ratio ◽  
Newborn Mice ◽  
The Brain

Rekling, Jens C. and Jack L. Feldman. Bidirectional electrical coupling between inspiratory motoneurons in the newborn mouse nucleus ambiguus. J. Neurophysiol. 78: 3508–3510, 1997. Some spinal and brain stem motoneurons are electrically coupled in the early postnatal period. To test whether respiratory motoneurons in the brain stem are electrically coupled, we performed single and dual whole cell patch recordings from presumptive motoneurons in the nucleus ambiguus in a rhythmically active brain stem slice from newborn mice. Two of eight (25%) biocytin-injected neurons showed dye-coupling and 4 of 11 (36%) of intracellularly recorded pairs of neurons showed evidence of bidirectional electrical coupling. Impulse activity in one cell elicited small spikelets in the other and hyperpolarization of one cell led to hyperpolarization of the other with a coupling ratio (Δ V 2:Δ V 1) of 0.03–0.14. We conclude that inspiratory ambiguus motoneurons in the newborn mouse brain stem are bidirectionally electrically coupled, which may serve to transmit or coordinate signals, chemical or electrical.

Decreased energy metabolism in brain stem during central respiratory depression in response to hypoxia

1996 ◽  
Vol 81 (4) ◽  
pp. 1772-1777 ◽  
Author(s):  
J. C. Lamanna ◽  
M. A. Haxhiu ◽  
K. L. Kutina-Nelson ◽  
S. Pundik ◽  
B. Erokwu ◽  
...  
Keyword(s):  
Energy Metabolism ◽  
Brain Stem ◽  
Respiratory Depression ◽  
Intracellular Ph ◽  
Metabolic Changes ◽  
Nucleus Ambiguus ◽  
Electromyographic Activity ◽  
Respiratory Drive ◽  
Energy Deficiency ◽  
The Brain

LaManna, J. C., M. A. Haxhiu, K. L. Kutina-Nelson, S. Pundik, B. Erokwu, E. R. Yeh, W. D. Lust, and N. S. Cherniack.Decreased energy metabolism in brain stem during central respiratory depression in response to hypoxia. J. Appl. Physiol. 81(4): 1772–1777, 1996.—Metabolic changes in the brain stem were measured at the time when oxygen deprivation-induced respiratory depression occurred. Eucapnic ventilation with 8% oxygen in vagotomized urethan-anesthetized rats resulted in cessation of respiratory drive, monitored by recording diaphragm electromyographic activity, on average within 11 min (range 5–27 min), presumably via central depressant mechanisms. At that time, the brain stems were frozen in situ for metabolic analyses. By using 20-μm lyophilized sections from frozen-fixed brain stem, microregional analyses of ATP, phosphocreatine, lactate, and intracellular pH were made from 1) the ventral portion of the nucleus gigantocellularis and the parapyramidal nucleus; 2) the compact and ventral portions of the nucleus ambiguus; 3) midline neurons; 4) nucleus tractus solitarii; and 5) the spinal trigeminal nucleus. At the time of respiratory depression, lactate was elevated threefold in all regions. Both ATP and phosphocreatine were decreased to 50 and 25% of control, respectively. Intracellular pH was more acidic by 0.2–0.4 unit in these regions but was relatively preserved in the chemosensitive regions near the ventral and dorsal medullary surfaces. These results show that hypoxia-induced respiratory depression was accompanied by metabolic changes within brain stem regions involved in respiratory and cardiovascular control. Thus it appears that there was significant energy deficiency in the brain stem after hypoxia-induced respiratory depression had occurred.

Calcium-Dependent Plateau Potentials in Rostral Ambiguus Neurons in the Newborn Mouse Brain Stem In Vitro

1997 ◽  
Vol 78 (5) ◽  
pp. 2483-2492 ◽  
Author(s):  
Jens C. Rekling ◽  
Jack L. Feldman
Keyword(s):  
Brain Stem ◽  
Mouse Brain ◽  
Spike Activity ◽  
Nucleus Ambiguus ◽  
Newborn Mouse ◽  
Plateau Potentials ◽  
Calcium Dependent ◽  
Current Pulses ◽  
Voltage Dependent

Rekling, Jens C. and Jack L. Feldman. Calcium-dependent plateau potentials in rostral ambiguus neurons in the newborn mouse brain stem in vitro. J. Neurophysiol. 78: 2483–2492, 1997. The nucleus ambiguus contains vagal and glossopharyngeal motoneurons and preganglionic neurons involved in respiration, swallowing, vocalization, and control of heart beat. Here we show that the rostral compact formation's ambiguus neurons, which control the esophageal phase of swallowing, display calcium-dependent plateau potentials in response to tetanic orthodromic stimulation or current injection. Whole cell recordings were made from visualized neurons in the rostral nucleus ambiguus using a slice preparation from the newborn mouse. Biocytin-labeling revealed dendritic trees with pronounced rostrocaudal orientations confined to the nucleus ambiguus, a morphological profile matching that of vagal motoneurons projecting to the esophagus. Single-stimulus orthodromic activation, using an electrode placed in the dorsomedial slice near the nucleus tractus solitarius, evoked single excitatory postsynaptic potentials (EPSPs) or short trains of EPSPs (500 ms to 1 s). However, tetanic stimulation (5 pulses, 10 Hz) induced voltage-dependent afterdepolarizations or long-lasting plateau potentials (>1 min) with a constant firing pattern. Depolarizing or hyperpolarizing current pulses elicited voltage-dependent afterdepolarizations or plateau potentials lasting a few seconds to several minutes. Constant spike activity accompanied the long-lasting plateau potentials, which ended spontaneously or could be terminated by weak hyperpolarizing current pulses. Current-induced afterdepolarizations and plateau potentials were dependent on extracellularand intracellular Ca2+, as they were blocked completely by extracellular Co2+, Cd2+, or intracellular bis-( o-aminophenoxy)- N,N,N′,N′-tetraacetic acid (BAPTA). Orthodromically induced afterdepolarizations and plateau potentials were blocked by intracellular BAPTA. Afterdepolarizations and plateau potentials were completely blocked by substitution of extracellular Na+ with choline. Afterdepolarizations persisted in tetrodotoxin. We conclude that rostral ambiguus neurons have a Ca2+-activated inward current carried by Na+. Synaptic activation of this conductance may generate prolonged spike activity in these neurons during the esophageal phase of swallowing.

Postnatal changes in cytochrome oxidase expressions in brain stem nuclei of rats: implications for sensitive periods

2003 ◽  
Vol 95 (6) ◽  
pp. 2285-2291 ◽  
Author(s):  
Qiuli Liu ◽  
Margaret T. T. Wong-Riley
Keyword(s):  
Brain Stem ◽  
Cytochrome Oxidase ◽  
Vestibular Nucleus ◽  
Glycine Receptor ◽  
Nucleus Ambiguus ◽  
Medial Vestibular Nucleus ◽  
Hypoglossal Nucleus ◽  
Motor Nucleus ◽  
Sensitive Periods ◽  
The Brain

Previously, we reported that cytochrome oxidase (CO) activity in the rat pre-Bötzinger complex (PBC) exhibited a plateau on postnatal days (P) 3–4 and a prominent decrease on P12 (Liu and Wong-Riley, J Appl Physiol 92: 923–934, 2002). These changes were correlated with a concomitant reduction in the expression of glutamate and N-methyl-d-aspartate receptor subunit 1 and an increase in GABA, GABAB, glycine receptor, and glutamate receptor 2. To determine whether changes were limited to the PBC, the present study aimed at examining the expression of CO in a number of brain stem nuclei, with or without known respiratory functions from P0 to P21 in rats: the ventrolateral subnucleus of the solitary tract nucleus, nucleus ambiguus, hypoglossal nucleus, nucleus raphe obscurus, dorsal motor nucleus of the vagus nerve, medial accessory olivary nucleus, spinal nucleus of the trigeminal nerve, and medial vestibular nucleus (MVe). Results indicated that, in all of the brain stem nuclei examined, CO activity exhibited a general increase with age from P0 to P21, with MVe having the slowest rise. Notably, in all of the nuclei examined except for MVe, there was a plateau or decrease at P3–P4 and a prominent rise-fall-rise pattern at P11–P13, similar to that observed in the PBC. In addition, there was a fall-rise-fall pattern at P15–P17 in these nuclei, instead of a plateau pattern in the PBC. Our data suggest that the two postnatal periods with reduced CO activity, P3–P4 and especially P12, may represent common sensitive periods for most of the brain stem nuclei with known or suspected respiratory control functions.

scholarly journals Crossed activation of thoracic trunk motoneurons by medullary reticulospinal neurons

2019 ◽  
Vol 122 (6) ◽  
pp. 2601-2613
Author(s):  
Brandon K. LaPallo ◽  
Andrea Giorgi ◽  
Marie-Claude Perreault
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Brain Stem ◽  
Neural Circuits ◽  
Single Cells ◽  
The Other ◽  
Medullary Reticular Formation ◽  
Functional Connections ◽  
Cord Injury ◽  
The Brain

Activation of contralateral muscles by supraspinal neurons, or crossed activation, is critical for bilateral coordination. Studies in mammals have focused on the neural circuits that mediate cross activation of limb muscles, but the neural circuits involved in crossed activation of trunk muscles are still poorly understood. In this study, we characterized functional connections between reticulospinal (RS) neurons in the medial and lateral regions of the medullary reticular formation (medMRF and latMRF) and contralateral trunk motoneurons (MNs) in the thoracic cord (T7 and T10 segments). To do this, we combined electrical microstimulation of the medMRF and latMRF and calcium imaging from single cells in an ex vivo brain stem-spinal cord preparation of neonatal mice. Our findings substantiate two spatially distinct RS pathways to contralateral trunk MNs. Both pathways originate in the latMRF and are midline crossing, one at the level of the spinal cord via excitatory descending commissural interneurons (reticulo-commissural pathway) and the other at the level of the brain stem (crossed RS pathway). Activation of these RS pathways may enable different patterns of bilateral trunk coordination. Possible implications for recovery of trunk function after stroke or spinal cord injury are discussed. NEW & NOTEWORTHY We identify two spatially distinct reticulospinal pathways for crossed activation of trunk motoneurons. Both pathways cross the midline, one at the level of the brain stem and the other at the level of the spinal cord via excitatory commissural interneurons. Jointly, these pathways provide new opportunities for repair interventions aimed at recovering trunk functions after stroke or spinal cord injury.

Focal warming in the nucleus of the solitary tract prolongs the laryngeal chemoreflex in decerebrate piglets

2007 ◽  
Vol 102 (1) ◽  
pp. 54-62 ◽  
Author(s):  
L. Xia ◽  
T. A. Damon ◽  
J. C. Leiter ◽  
D. Bartlett
Keyword(s):  
Brain Stem ◽  
Brain Tissue ◽  
Rectal Temperature ◽  
Respiratory Activity ◽  
Nucleus Ambiguus ◽  
Tissue Temperature ◽  
Whole Body ◽  
Solitary Tract ◽  
Neonatal Piglets ◽  
The Brain

The laryngeal chemoreflex (LCR), elicited by a drop of water in the larynx, is exaggerated by mild hyperthermia (body temperature = 40–41°C) in neonatal piglets. We tested the hypothesis that thermal prolongation of the LCR results from heating the nucleus of the solitary tract (NTS), where laryngeal afferents first form synapses in the brain stem. Three- to 13-day-old piglets were decerebrated and vagotomized and studied without anesthesia while paralyzed and ventilated. Phrenic nerve activity and rectal temperature were recorded. A thermode was placed in the medulla, and the brain tissue temperature was recorded with a thermistor ∼1 mm from the tip of the thermode. When the thermode was inserted into the brain stem, respiratory activity was arrested or greatly distorted in eight animals. However, the thermode was inserted in nine animals without disrupting respiratory activity, and in these animals, warming the medullary thermode (thermistor temperature = 40–41°C) while holding rectal temperature constant reversibly exaggerated the LCR. The caudal raphé was warmed focally by ∼2°C in four additional animals; this did not alter the duration of the LCR in these animals. Thermodes placed in the NTS did not disrupt respiratory activity, but they did prolong the LCR when warmed. Thermodes that were placed deep to the NTS in the region of the nucleus ambiguus disrupted respiratory activity, which precluded any analysis of the LCR. We conclude that prolongation of the laryngeal chemoreflex by whole body hyperthermia originates from the elevation of brain tissue temperature within in the NTS.

Differential control over postganglionic neurons in rat cardiac ganglia by NA and DmnX neurons: anatomical evidence

2004 ◽  
Vol 286 (4) ◽  
pp. R625-R633 ◽  
Author(s):  
Zixi (Jack) Cheng ◽  
Hong Zhang ◽  
Shang Z. Guo ◽  
Robert Wurster ◽  
David Gozal
Keyword(s):  
Brain Stem ◽  
Motor Neurons ◽  
Nucleus Ambiguus ◽  
Motor Nucleus ◽  
Sprague Dawley ◽  
Tracer Injection ◽  
Cardiac Ganglia ◽  
Dorsal Motor Nucleus ◽  
Differential Control ◽  
The Brain

In previous single-labeling experiments, we showed that neurons in the nucleus ambiguus (NA) and the dorsal motor nucleus of the vagus (DmnX) project to intrinsic cardiac ganglia. Neurons in these two motor nuclei differ significantly in the size of their projection fields, axon caliber, and endings in cardiac ganglia. These differences in NA and DmnX axon cardiac projections raise the question as to whether they target the same, distinct, or overlapping populations of cardiac principal neurons. To address this issue, we examined vagal terminals in cardiac ganglia and tracer injection sites in the brain stem using two different anterograde tracers {1,1′-dioleyl-3,3,3′,3′-tetramethylindocarbocyanine methanesulfonate and 4-[4-(dihexadecylamino)-styryl]- N-methylpyridinium iodide} and confocal microscopy in male Sprague-Dawley rats. We found that 1) NA and DmnX neurons innervate the same cardiac ganglia, but these axons target separate subpopulations of principal neurons and 2) axons arising from neurons in the NA and DmnX in the contralateral sides of the brain stem enter the cardiac ganglionic plexus through separate bundles and preferentially innervate principal neurons near their entry regions, providing topographic mapping of vagal motor neurons in left and right brain stem vagal nuclei. Because the NA and DmnX project to distinct populations of cardiac principal neurons, we propose that they may play different roles in controlling cardiac function.

Reperfusion Therapy for Acute Vertebrobasilar Occlusion

1997 ◽  
Vol 3 (2_suppl) ◽  
pp. 69-74
Author(s):  
H. Ohta ◽  
S. Nakano ◽  
T. Yano ◽  
T. Ohnishi ◽  
D. Miyahara ◽  
...  
Keyword(s):  
Brain Stem ◽  
Clinical Improvement ◽  
Photon Emission ◽  
Reperfusion Therapy ◽  
Artery Occlusion ◽  
The Other ◽  
Basilar Artery Occlusion ◽  
Deep Coma ◽  
Decerebrate Rigidity ◽  
The Brain

We reviewed retrospectively our experience in treating 10 patients with acute vertebrobasilar occlusion. Nine patients were treated with interventional reperfusion therapy and the remaining one patient with top of the basilar embolism was treated conservatively because of deep coma and decerebrate rigidity with severely reduced cerebral blood flow (CBF) in the brain stem. Among 9 patients with reperfusion therapy, 8 patients underwent intra-arterial thrombolytic therapy and the other one patient had direct percutaneous transluminal angioplasty (PTA). Eight patients had basilar artery occlusion, 1 patient treated with direct PTA had bilateral intracranial vertebral artery occlusion and the other patient had left posterior cerebral artery occlusion presumably preceding top of the basilar embolism. In 4 of 10 patients, residual CBF was evaluated by single photon emission computed tomograpy (SPECT). Successful recanalization with clinical improvement was achieved in 6 of 9 patients (66.7%) treated with reperfusion therapy. In patients with progression or fluctuation of incomplete brain stem syndrome, SPECT revealed preserved residual CBF and successful recanalization with clinical improvement was achieved by interventional reperfusion therapy. On the other hand, in patients with persistent deep coma and decerebrate rigidity, SPECT revealed marked reduction of residual CBF in the brain stem and recanalization could not improve clinical outcome. Preoperative SPECT may be useful to make a decision whether reperfusion therapy should be performed or not in case of vertebrobasilar occlusion.

scholarly journals Inconsistency between the circulatory and the brain criteria of death in the Uniform Determination of Death Act

2021 ◽  
Author(s):  
Alberto Molina Pérez ◽  
James L. Bernat ◽  
Anne Dalle Ave
Keyword(s):  
Brain Stem ◽  
The Other ◽  
Determination Of Death ◽  
Entire Brain ◽  
The Law ◽  
The Brain ◽  
Irreversible Cessation ◽  
What Matters

The Uniform Determination of Death Act (UDDA) provides that “an individual who has sustained either (1) irreversible cessation of circulatory and respiratory functions or (2) irreversible cessation of all functions of the entire brain, including the brain stem, is dead.” We show that the UDDA contains two conflicting interpretations of the phrase “cessation of functions”. By one interpretation, what matters for the determination of death is the cessation of spontaneous functions only, regardless of their generation by artificial means. By the other, what matters is the cessation of both spontaneous and artificially supported functions. Because each UDDA criterion uses a different interpretation, the law is conceptually inconsistent. A single consistent interpretation would lead to the conclusion that conscious individuals whose respiratory and circulatory functions are artificially supported are actually dead, or that individuals whose brain is entirely and irreversibly destroyed may be alive. We explore solutions to mitigate the inconsistency.

scholarly journals Rhythm generation, coordination, and initiation in the vocal pathways of male African clawed frogs

2017 ◽  
Vol 117 (1) ◽  
pp. 178-194 ◽  
Author(s):  
Ayako Yamaguchi ◽  
Jessica Cavin Barnes ◽  
Todd Appleby
Keyword(s):  
Brain Stem ◽  
Anterior Commissure ◽  
Temporal Structure ◽  
Central Pattern Generators ◽  
Nucleus Ambiguus ◽  
Motor Nucleus ◽  
Vertebrate Species ◽  
Extended Amygdala ◽  
Pattern Generators ◽  
The Brain

Central pattern generators (CPGs) in the brain stem are considered to underlie vocalizations in many vertebrate species, but the detailed mechanisms underlying how motor rhythms are generated, coordinated, and initiated remain unclear. We addressed these issues using isolated brain preparations of Xenopus laevis from which fictive vocalizations can be elicited. Advertisement calls of male X. laevis that consist of fast and slow trills are generated by vocal CPGs contained in the brain stem. Brain stem central vocal pathways consist of a premotor nucleus [dorsal tegmental area of medulla (DTAM)] and a laryngeal motor nucleus [a homologue of nucleus ambiguus (n.IX-X)] with extensive reciprocal connections between the nuclei. In addition, DTAM receives descending inputs from the extended amygdala. We found that unilateral transection of the projections between DTAM and n.IX-X eliminated premotor fictive fast trill patterns but did not affect fictive slow trills, suggesting that the fast and slow trill CPGs are distinct; the slow trill CPG is contained in n.IX-X, and the fast trill CPG spans DTAM and n.IX-X. Midline transections that eliminated the anterior, posterior, or both commissures caused no change in the temporal structure of fictive calls, but bilateral synchrony was lost, indicating that the vocal CPGs are contained in the lateral halves of the brain stem and that the commissures synchronize the two oscillators. Furthermore, the elimination of the inputs from extended amygdala to DTAM, in addition to the anterior commissure, resulted in autonomous initiation of fictive fast but not slow trills by each hemibrain stem, indicating that the extended amygdala provides a bilateral signal to initiate fast trills. NEW & NOTEWORTHY Central pattern generators (CPGs) are considered to underlie vocalizations in many vertebrate species, but the detailed mechanisms underlying their functions remain unclear. We addressed this question using an isolated brain preparation of African clawed frogs. We discovered that two vocal phases are mediated by anatomically distinct CPGs, that there are a pair of CPGs contained in the left and right half of the brain stem, and that mechanisms underlying initiation of the two vocal phases are distinct.

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