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Wrench AA. The Compartmental Tongue. JOURNAL OF SPEECH, LANGUAGE, AND HEARING RESEARCH : JSLHR 2024:1-27. [PMID: 38959159 DOI: 10.1044/2024_jslhr-23-00125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/05/2024]
Abstract
PURPOSE Tongue anatomy and function is widely described as consisting of four extrinsic muscles to control position and four intrinsic muscles to control shape. This myoarchitecture cannot, however, explain independent tongue body and blade movement nor accurately model the subtlety of observed lingual shapes. This study presents the case for a finer neuromuscular structure and functional description. METHOD Using the theoretical framework of the partitioning hypothesis, evidence for neuromuscular compartments of each of the lingual muscles was discerned by reviewing studies of lingual anatomy, hypoglossal nerve staining, hypoglossal motoneuron axon tracing, muscle fiber type distribution, and electromyography. Muscle fibers of the visible human female were manually traced to produce a three-dimensional atlas of muscular compartments. A kinematic study was undertaken to determine the degree of independent movement between different parts of the tongue. A simple biomechanical model was used to demonstrate how synergistic groups of compartments can control sectors of the tongue. RESULTS Results indicated as many as 10 compartments of genioglossus, two each of superior and inferior longitudinal, eight of styloglossus, three of hyoglossus, and six each of transversus and verticalis, while palatoglossus may not have a significant role in tongue function. Kinematic analysis indicated independent control of five sectors of the tongue body, and biomechanical modeling demonstrated how this control may be achieved. CONCLUSION Evidence is presented for a lingual structure based on neuromuscular compartments, which work together to position and shape sectors of the tongue and independently control tongue body and blade.
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Affiliation(s)
- Alan A Wrench
- Queen Margaret University, Edinburgh, United Kingdom
- Articulate Instruments Ltd, Edinburgh, United Kingdom
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2
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Yeung J, Burke PGR, Knapman FL, Patti J, Brown EC, Gandevia SC, Eckert DJ, Butler JE, Bilston LE. Task-dependent neural control of regions within human genioglossus. J Appl Physiol (1985) 2022; 132:527-540. [PMID: 34989652 DOI: 10.1152/japplphysiol.00478.2021] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Anatomical and imaging evidence suggests neural control of oblique and horizontal compartments of the genioglossus differs. However, neurophysiological evidence for differential control remains elusive. This study aimed to determine whether there are differences in neural drive to the oblique and horizontal regions of the genioglossus during swallowing and tongue protrusion. Adult participants (N=63; 48M) were recruited from a sleep clinic; 41 had Obstructive Sleep Apnoea (OSA: 34M, 8F). Electromyographic (EMG) was recorded at rest (awake, supine) using 4 intramuscular fine-wire electrodes inserted percutaneously into the anterior oblique, posterior oblique, anterior horizontal and posterior horizontal genioglossus. Epiglottic pressure and nasal airflow were also measured. During swallowing, two distinct EMG patterns were observed- a monophasic response (single EMG peak) and a biphasic response (two bursts of EMG). Peak EMG and timing of the peak relative to epiglottic pressure were significantly different between patterns (linear mixed models, p<0.001). Monophasic activation was more likely in the horizontal than oblique region during swallowing (OR=6.83, CI=3.46-13.53, p<0.001). In contrast, during tongue protrusion, activation patterns and EMG magnitude were not different between regions. There were no systematic differences in EMG patterns during swallowing or tongue protrusion between OSA and non-OSA groups. These findings provide evidence for functional differences in the motoneuronal output to the oblique and horizontal compartments, enabling differential task-specific drive. Given this, it is important to identify the compartment from which EMG is acquired. We propose that the EMG patterns during swallowing may be used to identify the compartment where a recording electrode is located.
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Affiliation(s)
- Jade Yeung
- grid.250407.4Neuroscience Research Australia, Sydney, New South Wales, Australia
| | | | - Fiona L Knapman
- grid.250407.4Neuroscience Research Australia, Sydney, New South Wales, Australia
| | - Jessica Patti
- grid.250407.4Neuroscience Research Australia, Randwick, Australia
| | - Elizabeth C Brown
- Neuroscience Research Australia, University of New South Wales, Randwick, NSW, Australia
| | - Simon C Gandevia
- grid.250407.4Neuroscience Research Australia, Randwick, Sydney, New South Wales, Australia
| | - Danny J Eckert
- Adelaide Institute for Sleep Health (AISH)/ Flinders Health and Medical Research Institute Sleep Health, grid.1014.4Flinders University, Bedford Park, SA, Australia
| | - Jane E Butler
- grid.250407.4Neuroscience Research Australia, Randwick, New South Wales, Australia
| | - Lynne E Bilston
- Neuroscience Research Australia, grid.1005.4Neuroscience Research Australia, Randwick, Australia
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3
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Doyle BM, Singer ML, Fleury-Curado T, Rana S, Benevides ES, Byrne BJ, Polotsky VY, Fuller DD. Gene delivery to the hypoglossal motor system: preclinical studies and translational potential. Gene Ther 2021; 28:402-412. [PMID: 33574581 PMCID: PMC8355248 DOI: 10.1038/s41434-021-00225-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 12/16/2020] [Accepted: 01/15/2021] [Indexed: 12/15/2022]
Abstract
Dysfunction and/or reduced activity in the tongue muscles contributes to conditions such as dysphagia, dysarthria, and sleep disordered breathing. Current treatments are often inadequate, and the tongue is a readily accessible target for therapeutic gene delivery. In this regard, gene therapy specifically targeting the tongue motor system offers two general strategies for treating lingual disorders. First, correcting tongue myofiber and/or hypoglossal (XII) motoneuron pathology in genetic neuromuscular disorders may be readily achieved by intralingual delivery of viral vectors. The retrograde movement of viral vectors such as adeno-associated virus (AAV) enables targeted distribution to XII motoneurons via intralingual viral delivery. Second, conditions with impaired or reduced tongue muscle activation can potentially be treated using viral-driven chemo- or optogenetic approaches to activate or inhibit XII motoneurons and/or tongue myofibers. Further considerations that are highly relevant to lingual gene therapy include (1) the diversity of the motoneurons which control the tongue, (2) the patterns of XII nerve branching, and (3) the complexity of tongue muscle anatomy and biomechanics. Preclinical studies show considerable promise for lingual directed gene therapy in neuromuscular disease, but the potential of such approaches is largely untapped.
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Affiliation(s)
- Brendan M Doyle
- Department of Physical Therapy, University of Florida, Gainesville, FL, USA
- McKnight Brain Institute, University of Florida, Gainesville, FL, USA
- Rehabilitation Science PhD Program, University of Florida, Gainesville, FL, USA
- Breathing Research and Therapeutics Center, University of Florida, Gainesville, FL, USA
| | - Michele L Singer
- Department of Physical Therapy, University of Florida, Gainesville, FL, USA
- McKnight Brain Institute, University of Florida, Gainesville, FL, USA
- Rehabilitation Science PhD Program, University of Florida, Gainesville, FL, USA
- Breathing Research and Therapeutics Center, University of Florida, Gainesville, FL, USA
| | - Thomaz Fleury-Curado
- Department of Pediatrics and Powell Gene Therapy Center, University of Florida, Gainesville, FL, USA
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Sabhya Rana
- Department of Physical Therapy, University of Florida, Gainesville, FL, USA
- McKnight Brain Institute, University of Florida, Gainesville, FL, USA
- Breathing Research and Therapeutics Center, University of Florida, Gainesville, FL, USA
| | - Ethan S Benevides
- Department of Physical Therapy, University of Florida, Gainesville, FL, USA
- McKnight Brain Institute, University of Florida, Gainesville, FL, USA
- Rehabilitation Science PhD Program, University of Florida, Gainesville, FL, USA
- Breathing Research and Therapeutics Center, University of Florida, Gainesville, FL, USA
| | - Barry J Byrne
- Department of Pediatrics and Powell Gene Therapy Center, University of Florida, Gainesville, FL, USA
| | - Vsevolod Y Polotsky
- Department of Pediatrics and Powell Gene Therapy Center, University of Florida, Gainesville, FL, USA
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - David D Fuller
- Department of Physical Therapy, University of Florida, Gainesville, FL, USA.
- McKnight Brain Institute, University of Florida, Gainesville, FL, USA.
- Breathing Research and Therapeutics Center, University of Florida, Gainesville, FL, USA.
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4
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Fleury Curado T, Pho H, Freire C, Amorim MR, Bonaventura J, Kim LJ, Lee R, Cabassa ME, Streeter SR, Branco LG, Sennes LU, Fishbein K, Spencer RG, Schwartz AR, Brennick MJ, Michaelides M, Fuller DD, Polotsky VY. Designer Receptors Exclusively Activated by Designer Drugs Approach to Treatment of Sleep-disordered Breathing. Am J Respir Crit Care Med 2021; 203:102-110. [PMID: 32673075 DOI: 10.1164/rccm.202002-0321oc] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Rationale: Obstructive sleep apnea is recurrent upper airway obstruction caused by a loss of upper airway muscle tone during sleep. The main goal of our study was to determine if designer receptors exclusively activated by designer drugs (DREADD) could be used to activate the genioglossus muscle as a potential novel treatment strategy for sleep apnea. We have previously shown that the prototypical DREADD ligand clozapine-N-oxide increased pharyngeal diameter in mice expressing DREADD in the hypoglossal nucleus. However, the need for direct brainstem viral injections and clozapine-N-oxide toxicity diminished translational potential of this approach, and breathing during sleep was not examined.Objectives: Here, we took advantage of our model of sleep-disordered breathing in diet-induced obese mice, retrograde properties of the adeno-associated virus serotype 9 (AAV9) viral vector, and the novel DREADD ligand J60.Methods: We administered AAV9-hSyn-hM3(Gq)-mCherry or control AAV9 into the genioglossus muscle of diet-induced obese mice and examined the effect of J60 on genioglossus activity, pharyngeal patency, and breathing during sleep.Measurements and Main Results: Compared with control, J60 increased genioglossus tonic activity by greater than sixfold and tongue uptake of 2-deoxy-2-[18F]fluoro-d-glucose by 1.5-fold. J60 increased pharyngeal patency and relieved upper airway obstruction during non-REM sleep.Conclusions: We conclude that following intralingual administration of AAV9-DREADD, J60 can activate the genioglossus muscle and improve pharyngeal patency and breathing during sleep.
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Affiliation(s)
- Thomaz Fleury Curado
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland.,Department of Otolaryngology, University of São Paulo, São Paulo, Brazil
| | - Huy Pho
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Carla Freire
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland.,Department of Otolaryngology, University of São Paulo, São Paulo, Brazil
| | - Mateus R Amorim
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland.,Dental School of Ribeirao Preto, University of São Paulo, Ribeirao Preto, Brazil
| | - Jordi Bonaventura
- Biobehavioral Imaging and Molecular Neuropsychopharmacology Unit, National Institute on Drug Abuse, and
| | - Lenise J Kim
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland.,Laboratory of Clinical Investigation, National Institute on Aging, NIH, Baltimore, Maryland
| | - Rachel Lee
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Meaghan E Cabassa
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Stone R Streeter
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Luiz G Branco
- Dental School of Ribeirao Preto, University of São Paulo, Ribeirao Preto, Brazil
| | - Luiz U Sennes
- Department of Otolaryngology, University of São Paulo, São Paulo, Brazil
| | - Kenneth Fishbein
- Departament of Psychobiology, Federal University of São Paulo, São Paulo, Brazil
| | - Richard G Spencer
- Departament of Psychobiology, Federal University of São Paulo, São Paulo, Brazil
| | - Alan R Schwartz
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland.,Department of Otorhinolaryngology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; and
| | - Michael J Brennick
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Michael Michaelides
- Biobehavioral Imaging and Molecular Neuropsychopharmacology Unit, National Institute on Drug Abuse, and
| | - David D Fuller
- Center for Respiratory Research and Rehabilitation, University of Florida, Gainesville, Florida
| | - Vsevolod Y Polotsky
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
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5
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Cao R, Zhang MJ, Zhou YT, Liu YJ, Wang HH, Zhang QX, Shi YW, Li JC, Wong TS, Yin M. The dorsal and the ventral side of hypoglossal motor nucleus showed different response to chronic intermittent hypoxia in rats. Sleep Breath 2020; 25:325-330. [PMID: 32562172 DOI: 10.1007/s11325-020-02125-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2020] [Revised: 06/03/2020] [Accepted: 06/05/2020] [Indexed: 11/29/2022]
Abstract
PURPOSE To study neurochemical reactions to chronic intermittent hypoxia (CIH) in the hypoglossal nucleus (HN) of rats. METHODS Adult male Sprague-Dawley rats (n = 12) were randomly divided into two groups (the CIH and the control group). The CIH rats were housed in a hypoxic chamber with the fraction of oxygen volume alternating between 21% and 5% by providing air for 60 s and then providing nitrogen for 60 s from 8:30 am to 16:30 pm each day for 35 days. The control group was housed in a cabin with normal oxygen levels. We studied the expression of c-fos protein, 5-hydroxytryptamine (5-HT) positive terminals, and its 2A receptors in hypoglossal nuclei by immunohistochemistry. RESULTS The expression of c-fos, 5-HT positive terminals, and accordingly 5-HT 2A receptors in the CIH group were significantly higher than that in the controls (p < 0.05). The ventral side of the HN showed a clearly higher expression of 5-HT and its 2A receptors than the dorsal side (p < 0.05). CONCLUSION There were 2 responses of the HN to CIH. First, CIH induced a higher expression of 5-HT positive terminals and its 2A receptors, and second, this reaction was much more evident in ventral side than in the dorsal side. We postulate that these responses may serve to be a protective and compensatory mechanism for CIH.
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Affiliation(s)
- Rui Cao
- Department of Otorhinolaryngology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, China
| | - Min-Juan Zhang
- Department of Otorhinolaryngology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, China
| | - Yun-Tao Zhou
- Experimental Teaching Demonstration Centre, School of Rehabilitation Medicine, Nanjing Medical University, Nanjing, China
| | - Ya-Jie Liu
- Department of Otorhinolaryngology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, China
| | - Huan-Huan Wang
- Department of Otorhinolaryngology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, China
| | - Qin-Xin Zhang
- Department of Otorhinolaryngology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, China
| | - Ya-Wen Shi
- Department of Otorhinolaryngology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, China
| | - Jia-Chen Li
- Department of Otorhinolaryngology, The First Affiliated Hospital of Soochow University, Suzhou, 215006, China
| | - Thian-Sze Wong
- Division of Head and Neck, the department of surgery, the faculty of medicine, The University of Hong Kong, Hong Kong, China
| | - Min Yin
- Department of Otorhinolaryngology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, China.
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Sörös P, Schäfer S, Witt K. Model-Based and Model-Free Analyses of the Neural Correlates of Tongue Movements. Front Neurosci 2020; 14:226. [PMID: 32265635 PMCID: PMC7105808 DOI: 10.3389/fnins.2020.00226] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2019] [Accepted: 03/02/2020] [Indexed: 12/11/2022] Open
Abstract
The tongue performs movements in all directions to subserve its diverse functions in chewing, swallowing, and speech production. Using task-based functional MRI in a group of 17 healthy young participants, we studied (1) potential differences in the cerebral control of frontal (protrusion), horizontal (side to side), and vertical (elevation) tongue movements and (2) inter-individual differences in tongue motor control. To investigate differences between different tongue movements, we performed voxel-wise multiple linear regressions. To investigate inter-individual differences, we applied a novel approach, spatio-temporal filtering of independent components. For this approach, individual functional data were decomposed into spatially independent components and corresponding time courses using independent component analysis. A temporal filter (correlation with the expected brain response) was used to identify independent components time-locked to the tongue motor tasks. A spatial filter (cross-correlation with established neurofunctional systems) was used to identify brain activity not time-locked to the tasks. Our results confirm the importance of an extended bilateral cortical and subcortical network for the control of tongue movements. Frontal (protrusion) tongue movements, highly overlearned movements related to speech production, showed less activity in the frontal and parietal lobes compared to horizontal (side to side) and vertical (elevation) movements and greater activity in the left frontal and temporal lobes compared to vertical movements (cluster-forming threshold of Z > 3.1, cluster significance threshold of p < 0.01, corrected for multiple comparisons). The investigation of inter-individual differences revealed a component representing the tongue primary sensorimotor cortex time-locked to the task in all participants. Using the spatial filter, we found the default mode network in 16 of 17 participants, the left fronto-parietal network in 16, the right fronto-parietal network in 8, and the executive control network in four participants (Pearson's r > 0.4 between neurofunctional systems and individual components). These results demonstrate that spatio-temporal filtering of independent components allows to identify individual brain activity related to a specific task and also structured spatiotemporal processes representing known neurofunctional systems on an individual basis. This novel approach may be useful for the assessment of individual patients and results may be related to individual clinical, behavioral, and genetic information.
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Affiliation(s)
- Peter Sörös
- Neurology, School of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany.,Research Center Neurosensory Science, University of Oldenburg, Oldenburg, Germany
| | - Sarah Schäfer
- Neurology, School of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany
| | - Karsten Witt
- Neurology, School of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany.,Research Center Neurosensory Science, University of Oldenburg, Oldenburg, Germany
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7
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Wealing JC, Cholanian M, Flanigan EG, Levine RB, Fregosi RF. Diverse physiological properties of hypoglossal motoneurons innervating intrinsic and extrinsic tongue muscles. J Neurophysiol 2019; 122:2054-2060. [PMID: 31533009 PMCID: PMC6879950 DOI: 10.1152/jn.00478.2019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 09/05/2019] [Accepted: 09/13/2019] [Indexed: 12/16/2022] Open
Abstract
The mammalian tongue contains eight muscles that collaborate to ensure that suckling, swallowing, and other critical functions are robust and reliable. Seven of the eight tongue muscles are innervated by hypoglossal motoneurons (XIIMNs). A somatotopic organization of the XII motor nucleus, defined in part by the mechanical action of a neuron's target muscle, has been described, but whether or not XIIMNs within a compartment are functionally specialized is unsettled. We hypothesize that developing XIIMNs are assigned unique functional properties that reflect the challenges that their target muscle faces upon the transition from in utero to terrestrial life. To address this, we studied XIIMNs that innervate intrinsic and extrinsic tongue muscles, because intrinsic muscles play a more prominent role in suckling than the extrinsic muscles. We injected dextran-rhodamine into the intrinsic longitudinal muscles (IL) and the extrinsic genioglossus, and physiologically characterized the labeled XIIMNs. Consistent with earlier work, IL XIIMNs (n = 150) were located more dorsally within the nucleus, and GG XIIMNs (n = 55) more ventrally. Whole cell recordings showed that resting membrane potential was, on average, 9 mV more depolarized in IL than in GG XIIMNs (P = 0.0019), and the firing threshold in response to current injection was lower in IL (-31 ± 23 pA) than in GG XIIMNs (225 ± 39 pA; P < 0.0001). We also found that the appearance of net outward currents in GG XIIMNs occurred at more hyperpolarized membrane potentials than IL XIIMNs, consistent with lower excitability in GG XIIMNs. These observations document muscle-specific functional specializations among XIIMNs.NEW & NOTEWORTHY The hypoglossal motor nucleus contains motoneurons responsible for innervating one of seven different muscles with notably different biomechanics and patterns of use. Whether or not motoneurons innervating the different muscles also have unique functional properties (e.g., spiking behavior, synaptic physiology) is poorly understood. In this work we show that neonatal hypoglossal motoneurons innervating muscles that shape the tongue (intrinsic longitudinal muscles) have different electrical properties than those innervating the genioglossus, which controls tongue position.
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Affiliation(s)
- J. C. Wealing
- Department of Physiology, The University of Arizona, Tucson, Arizona
| | - M. Cholanian
- Department of Physiology, The University of Arizona, Tucson, Arizona
| | - E. G. Flanigan
- Department of Physiology, The University of Arizona, Tucson, Arizona
| | - R. B. Levine
- Department of Physiology, The University of Arizona, Tucson, Arizona
- Department of Neuroscience, The University of Arizona, Tucson, Arizona
| | - R. F. Fregosi
- Department of Physiology, The University of Arizona, Tucson, Arizona
- Department of Neuroscience, The University of Arizona, Tucson, Arizona
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8
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Chaimowicz C, Ruffault PL, Chéret C, Woehler A, Zampieri N, Fortin G, Garratt AN, Birchmeier C. Teashirt 1 (Tshz1) is essential for the development, survival and function of hypoglossal and phrenic motor neurons in mouse. Development 2019; 146:dev.174045. [PMID: 31427287 PMCID: PMC6765129 DOI: 10.1242/dev.174045] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Accepted: 08/09/2019] [Indexed: 11/20/2022]
Abstract
Feeding and breathing are essential motor functions and rely on the activity of hypoglossal and phrenic motor neurons that innervate the tongue and diaphragm, respectively. Little is known about the genetic programs that control the development of these neuronal subtypes. The transcription factor Tshz1 is strongly and persistently expressed in developing hypoglossal and phrenic motor neurons. We used conditional mutation of Tshz1 in the progenitor zone of motor neurons (Tshz1MN Δ) to show that Tshz1 is essential for survival and function of hypoglossal and phrenic motor neurons. Hypoglossal and phrenic motor neurons are born in correct numbers, but many die between embryonic day 13.5 and 14.5 in Tshz1MN Δ mutant mice. In addition, innervation and electrophysiological properties of phrenic and hypoglossal motor neurons are altered. Severe feeding and breathing problems accompany this developmental deficit. Although motor neuron survival can be rescued by elimination of the pro-apoptotic factor Bax, innervation, feeding and breathing defects persist in Bax-/-; Tshz1MN Δ mutants. We conclude that Tshz1 is an essential transcription factor for the development and physiological function of phrenic and hypoglossal motor neurons.
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Affiliation(s)
- Charlotte Chaimowicz
- Developmental Biology/Signal Transduction, Max Delbrück Center for Molecular Medicine (MDC) in the Helmholtz Society, 13125 Berlin, Germany
| | - Pierre-Louis Ruffault
- Developmental Biology/Signal Transduction, Max Delbrück Center for Molecular Medicine (MDC) in the Helmholtz Society, 13125 Berlin, Germany
| | - Cyril Chéret
- Developmental Biology/Signal Transduction, Max Delbrück Center for Molecular Medicine (MDC) in the Helmholtz Society, 13125 Berlin, Germany
| | - Andrew Woehler
- Systems Biology Imaging, Max Delbrück Center for Molecular Medicine (MDC) in the Helmholtz Society, 13125 Berlin, Germany
| | - Niccolò Zampieri
- Development and Function of Neural Circuits, Max Delbrück Center for Molecular Medicine (MDC) in the Helmholtz Society, 13125 Berlin, Germany
| | - Gilles Fortin
- UMR9197, CNRS/Université Paris-Sud, Paris-Saclay Institute of Neuroscience, 1 Avenue de la Terrasse, 91190 Gif-sur-Yvette, France
| | - Alistair N Garratt
- Institute of Cell Biology and Neurobiology, Charité-Universitätsmedizin Berlin, Virchowweg 6, 10117 Berlin, Germany
| | - Carmen Birchmeier
- Developmental Biology/Signal Transduction, Max Delbrück Center for Molecular Medicine (MDC) in the Helmholtz Society, 13125 Berlin, Germany
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9
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Fleury Curado TA, Pho H, Dergacheva O, Berger S, Lee R, Freire C, Asherov A, Sennes LU, Mendelowitz D, Schwartz AR, Polotsky VY. Silencing of Hypoglossal Motoneurons Leads to Sleep Disordered Breathing in Lean Mice. Front Neurol 2018; 9:962. [PMID: 30487776 PMCID: PMC6246694 DOI: 10.3389/fneur.2018.00962] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Accepted: 10/25/2018] [Indexed: 12/15/2022] Open
Abstract
Obstructive Sleep Apnea (OSA) is a prevalent condition and a major cause of morbidity and mortality in Western Society. The loss of motor input to the tongue and specifically to the genioglossus muscle during sleep is associated with pharyngeal collapsibility and the development of OSA. We applied a novel chemogenetic method to develop a mouse model of sleep disordered breathing Our goal was to reversibly silence neuromotor input to the genioglossal muscle using an adeno-associated viral vector carrying inhibitory designer receptors exclusively activated by designer drugs AAV5-hM4Di-mCherry (DREADD), which was delivered bilaterally to the hypoglossal nucleus in fifteen C57BL/6J mice. In the in vivo experiment, 4 weeks after the viral administration mice were injected with a DREADD ligand clozapine-N-oxide (CNO, i.p., 1mg/kg) or saline followed by a sleep study; a week later treatments were alternated and a second sleep study was performed. Inspiratory flow limitation was recognized by the presence of a plateau in mid-respiratory flow; oxyhemoglobin desaturations were defined as desaturations >4% from baseline. In the in vitro electrophysiology experiment, four males and three females of 5 days of age were used. Sixteen-nineteen days after DREADD injection brain slices of medulla were prepared and individual hypoglossal motoneurons were recorded before and after CNO application. Positive mCherry staining was detected in the hypoglossal nucleus in all mice confirming successful targeting. In sleep studies, CNO markedly increased the frequency of flow limitation n NREM sleep (from 1.9 ± 1.3% after vehicle injection to 14.2 ± 3.4% after CNO, p < 0.05) and REM sleep (from 22.3% ± 4.1% to 30.9 ± 4.6%, respectively, p < 0.05) compared to saline treatment, but there was no significant oxyhemoglobin desaturation or sleep fragmentation. Electrophysiology recording in brain slices showed that CNO inhibited firing frequency of DREADD-containing hypoglossal motoneurons. We conclude that chemogenetic approach allows to silence hypoglossal motoneurons in mice, which leads to sleep disordered breathing manifested by inspiratory flow limitation during NREM and REM sleep without oxyhemoglobin desaturation or sleep fragmentation. Other co-morbid factors, such as compromised upper airway anatomy, may be needed to achieve recurrent pharyngeal obstruction observed in OSA.
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Affiliation(s)
- Thomaz A Fleury Curado
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States.,Department of Otolaryngology, University of Sao Paulo, São Paulo, Brazil
| | - Huy Pho
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Olga Dergacheva
- Department of Pharmacology and Physiology, The George Washington University, Washington, DC, United States
| | - Slava Berger
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Rachel Lee
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Carla Freire
- Department of Otolaryngology, University of Sao Paulo, São Paulo, Brazil
| | - Aya Asherov
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Luis U Sennes
- Department of Otolaryngology, University of Sao Paulo, São Paulo, Brazil
| | - David Mendelowitz
- Department of Pharmacology and Physiology, The George Washington University, Washington, DC, United States
| | - Alan R Schwartz
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Vsevolod Y Polotsky
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States
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10
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Kanjhan R, Fogarty MJ, Noakes PG, Bellingham MC. Developmental changes in the morphology of mouse hypoglossal motor neurons. Brain Struct Funct 2016; 221:3755-86. [PMID: 26476929 PMCID: PMC5009180 DOI: 10.1007/s00429-015-1130-8] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Accepted: 10/03/2015] [Indexed: 12/19/2022]
Abstract
Hypoglossal motor neurons (XII MNs) innervate tongue muscles important in breathing, suckling and vocalization. Morphological properties of 103 XII MNs were studied using Neurobiotin™ filling in transverse brainstem slices from C57/Bl6 mice (n = 34) from embryonic day (E) 17 to postnatal day (P) 28. XII MNs from areas thought to innervate different tongue muscles showed similar morphology in most, but not all, features. Morphological properties of XII MNs were established prior to birth, not differing between E17-18 and P0. MN somatic volume gradually increased for the first 2 weeks post-birth. The complexity of dendritic branching and dendrite length of XII MNs increased throughout development (E17-P28). MNs in the ventromedial XII motor nucleus, likely to innervate the genioglossus, frequently (42 %) had dendrites crossing to the contralateral side at all ages, but their number declined with postnatal development. Unexpectedly, putative dendritic spines were found in all XII MNs at all ages, and were primarily localized to XII MN somata and primary dendrites at E18-P4, increased in distal dendrites by P5-P8, and were later predominantly found in distal dendrites. Dye-coupling between XII MNs was common from E18 to P7, but declined strongly with maturation after P7. Axon collaterals were found in 20 % (6 of 28) of XII MNs with filled axons; collaterals terminated widely outside and, in one case, within the XII motor nucleus. These results reveal new morphological features of mouse XII MNs, and suggest that dendritic projection patterns, spine density and distribution, and dye-coupling patterns show specific developmental changes in mice.
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Affiliation(s)
- Refik Kanjhan
- School of Biomedical Sciences, University of Queensland, Brisbane, QLD, 4072, Australia
| | - Matthew J Fogarty
- School of Biomedical Sciences, University of Queensland, Brisbane, QLD, 4072, Australia
| | - Peter G Noakes
- School of Biomedical Sciences, University of Queensland, Brisbane, QLD, 4072, Australia
- Queensland Brain Institute, University of Queensland, Brisbane, QLD, 4072, Australia
| | - Mark C Bellingham
- School of Biomedical Sciences, University of Queensland, Brisbane, QLD, 4072, Australia.
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11
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Abstract
AbstractMore than 35 years ago, Meltzoff and Moore (1977) published their famous article, “Imitation of facial and manual gestures by human neonates.” Their central conclusion, that neonates can imitate, was and continues to be controversial. Here, we focus on an often-neglected aspect of this debate, namely, neonatal spontaneous behaviors themselves. We present a case study of a paradigmatic orofacial “gesture,” namely tongue protrusion and retraction (TP/R). Against the background of new research on mammalian aerodigestive development, we ask: How does the human aerodigestive system develop, and what role does TP/R play in the neonate's emerging system of aerodigestion? We show that mammalian aerodigestion develops in two phases: (1) from the onset of isolated orofacial movementsin uteroto the postnatal mastery of suckling at 4 months after birth; and (2) thereafter, from preparation to the mastery of mastication and deglutition of solid foods. Like other orofacial stereotypies, TP/R emerges in the first phase and vanishes prior to the second. Based upon recent advances in activity-driven early neural development, we suggest a sequence of three developmental events in which TP/R might participate: the acquisition of tongue control, the integration of the central pattern generator (CPG) for TP/R with other aerodigestive CPGs, and the formation of connections within the cortical maps of S1 and M1. If correct, orofacial stereotypies are crucial to the maturation of aerodigestion in the neonatal period but also unlikely to co-occur with imitative behavior.
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12
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Kubin L, Jordan AS, Nicholas CL, Cori JM, Semmler JG, Trinder J. Crossed motor innervation of the base of human tongue. J Neurophysiol 2015; 113:3499-510. [PMID: 25855691 DOI: 10.1152/jn.00051.2015] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 04/06/2015] [Indexed: 12/15/2022] Open
Abstract
Muscle fibers of the genioglossus (GG) form the bulk of the muscle mass at the base of the tongue. The motor control of the tongue is critical for vocalization, feeding, and breathing. Our goal was to assess the patterns of motor innervation of GG single motor units (SMUs) in humans. Simultaneous monopolar recordings were obtained from four sites in the base of the tongue bilaterally at two antero-posterior levels from 16 resting, awake, healthy adult males, who wore a face mask with airway pressure and airflow sensors. We analyzed 69 data segments in which at least one lead contained large action potentials generated by an SMU. Such potentials served as triggers for spike-triggered averaging (STA) of signals recorded from the other three sites. Spontaneous activity of the SMUs was classified as inspiratory modulated, expiratory modulated, or tonic. Consistent with the antero-posterior orientation of GG fibers, 44 STAs (77%) recorded ipsilateral to the trigger yielded sharp action potentials with a median amplitude of 52 μV [interquartile range (IQR): 25-190] that were time shifted relative to the trigger by about 1 ms. Notably, 48% of recordings on the side opposite to the trigger also yielded sharp action potentials. Of those, 17 (29%) had a median amplitude of 63 μV (IQR: 39-96), and most were generated by tonic SMUs. Thus a considerable proportion of GG muscle fibers receive a crossed motor innervation. Crossed innervation may help ensure symmetry and stability of tongue position and movements under normal conditions and following injury or degenerative changes affecting the tongue.
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Affiliation(s)
- Leszek Kubin
- School of Psychological Sciences, University of Melbourne, Melbourne, Australia;
| | - Amy S Jordan
- School of Psychological Sciences, University of Melbourne, Melbourne, Australia
| | | | - Jennifer M Cori
- School of Psychological Sciences, University of Melbourne, Melbourne, Australia
| | - John G Semmler
- School of Medical Sciences, University of Adelaide, Adelaide, Australia
| | - John Trinder
- School of Psychological Sciences, University of Melbourne, Melbourne, Australia
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13
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Yoshikawa M, Hirabayashi M, Ito R, Ozaki S, Aizawa S, Masuda T, Senzaki K, Shiga T. Contribution of the Runx1 transcription factor to axonal pathfinding and muscle innervation by hypoglossal motoneurons. Dev Neurobiol 2015; 75:1295-314. [PMID: 25762373 DOI: 10.1002/dneu.22285] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2014] [Revised: 02/18/2015] [Accepted: 03/01/2015] [Indexed: 11/12/2022]
Abstract
The runt-related transcription factor Runx1 contributes to cell type specification and axonal targeting projections of the nociceptive dorsal root ganglion neurons. Runx1 is also expressed in the central nervous system, but little is known of its functions in brain development. At mouse embryonic day (E) 17.5, Runx1-positive neurons were detected in the ventrocaudal subdivision of the hypoglossal nucleus. Runx1-positive neurons lacked calcitonin gene-related peptide (CGRP) expression, whereas Runx1-negative neurons expressed CGRP. Expression of CGRP was not changed in Runx1-deficient mice at E17.5, suggesting that Runx1 alone does not suppress CGRP expression. Hypoglossal axon projections to the intrinsic vertical (V) and transverse (T) tongue muscles were sparser in Runx1-deficient mice at E17.5 compared to age-matched wild-type littermates. Concomitantly, vesicular acetylcholine transporter-positive axon terminals and acetylcholine receptor clusters were less dense in the V and T tongue muscles of Runx1-deficient mice. These abnormalities in axonal projection were not caused by a reduction in the total number hypoglossal neurons, failed synaptogenesis, or tongue muscles deficits. Our results implicate Runx1 in the targeting of ventrocaudal hypoglossal axons to specific tongue muscles. However, Runx1 deficiency did not alter neuronal survival or the expression of multiple motoneuron markers as in other neuronal populations. Thus, Runx1 appears to have distinct developmental functions in different brain regions.
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Affiliation(s)
- Masaaki Yoshikawa
- Division of Anatomical Science, Department of Functional Morphology, Nihon University School of Medicine, 30-1 Oyaguchi-Kamicho, Itabashi, Tokyo, 173-8610, Japan.,Doctoral Program in Kansei, Behavioral and Brain Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8577, Japan
| | - Mizuki Hirabayashi
- Doctoral Program in Kansei, Behavioral and Brain Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8577, Japan
| | - Ryota Ito
- Doctoral Program in Kansei, Behavioral and Brain Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8577, Japan
| | - Shigeru Ozaki
- Doctoral Program in Kansei, Behavioral and Brain Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8577, Japan
| | - Shin Aizawa
- Division of Anatomical Science, Department of Functional Morphology, Nihon University School of Medicine, 30-1 Oyaguchi-Kamicho, Itabashi, Tokyo, 173-8610, Japan
| | - Tomoyuki Masuda
- Doctoral Program in Kansei, Behavioral and Brain Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8577, Japan
| | - Kouji Senzaki
- Doctoral Program in Kansei, Behavioral and Brain Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8577, Japan
| | - Takashi Shiga
- Doctoral Program in Kansei, Behavioral and Brain Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8577, Japan
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14
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Mu L, Sanders I. Human tongue neuroanatomy: Nerve supply and motor endplates. Clin Anat 2015; 23:777-91. [PMID: 20607833 DOI: 10.1002/ca.21011] [Citation(s) in RCA: 118] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2009] [Revised: 04/25/2010] [Accepted: 05/04/2010] [Indexed: 02/02/2023]
Abstract
The human tongue has a critical role in speech, swallowing, and respiration, however, its motor control is poorly understood. Fundamental gaps include detailed information on the course of the hypoglossal (XII) nerve within the tongue, the branches of the XII nerve within each tongue muscle, and the type and arrangement of motor endplates (MEP) within each muscle. In this study, five adult human tongues were processed with Sihler's stain, a whole-mount nerve staining technique, to map out the entire intra-lingual course of the XII nerve and its branches. An additional five specimens were microdissected into individual muscles and stained with acetylcholinesterase and silver staining to study their MEP morphology and banding patterns. Using these techniques the course of the entire XII nerve was mapped from the main nerve to the smallest intramuscular branches. It was found that the human tongue innervation is extremely dense and complex. Although the basic mammalian pattern of XII is conserved in humans, there are notable differences. In addition, many muscle fibers contained multiple en grappe MEP, suggesting that they are some variant of the highly specialized slow tonic muscle fiber type. The transverse muscle group that comprises the core of the tongue appears to have the most complex innervation and has the highest percentage of en grappe MEP. In summary, the innervation of the human tongue has specializations not reported in other mammalian tongues, including nonhuman primates. These specializations appear to allow for fine motor control of tongue shape.
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Affiliation(s)
- Liancai Mu
- Upper Airway Research Laboratory, Department of Research, Hackensack University Medical Center, Hackensack, New Jersey.
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15
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Fregosi RF, Ludlow CL. Activation of upper airway muscles during breathing and swallowing. J Appl Physiol (1985) 2013; 116:291-301. [PMID: 24092695 DOI: 10.1152/japplphysiol.00670.2013] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The upper airway is a complex muscular tube that is used by the respiratory and digestive systems. The upper airway is invested with several small and anatomically peculiar muscles. The muscle fiber orientations and their nervous innervation are both extremely complex, and how the activity of the muscles is initiated and adjusted during complex behaviors is poorly understood. The bulk of the evidence suggests that the entire assembly of tongue and laryngeal muscles operate together but differently during breathing and swallowing, like a ballet rather than a solo performance. Here we review the functional anatomy of the tongue and laryngeal muscles, and their neural innervation. We also consider how muscular activity is altered as respiratory drive changes, and briefly address upper airway muscle control during swallowing.
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Affiliation(s)
- Ralph F Fregosi
- Department of Physiology, University of Arizona, Tucson, Arizona
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16
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Three-dimensional observation of mouse tongue muscles using micro-computed tomography. Odontology 2013; 103:1-8. [DOI: 10.1007/s10266-013-0131-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Accepted: 07/17/2013] [Indexed: 01/27/2023]
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17
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Lee KZ, Fuller DD, Hwang JC. Pulmonary C-fiber activation attenuates respiratory-related tongue movements. J Appl Physiol (1985) 2012; 113:1369-76. [PMID: 22936725 DOI: 10.1152/japplphysiol.00031.2012] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The functional impact of pulmonary C-fiber activation on upper airway biomechanics has not been evaluated. Here, we tested the hypothesis that pulmonary C-fiber activation alters the respiratory-related control of tongue movements. The force produced by tongue movements was quantified in spontaneously breathing, anesthetized adult rats before and after stimulation of pulmonary C fibers via intrajugular delivery of capsaicin (0.625 and 1.25 μg/kg). Brief occlusion of the trachea was used to increase the respiratory drive to the tongue muscles, and hypoglossal (XII) nerve branches were selectively sectioned to denervate the protrusive and retrusive tongue musculature. Tracheal occlusion triggered inspiratory-related tongue retrusion in rats with XII nerves intact or following section of the medial XII nerve branch, which innervates the genioglossus muscle. Inspiratory-related tongue protrusion was only observed after section of the lateral XII branch, which innervates the primary tongue retrusor muscles. The tension produced by inspiratory-related tongue movement was significantly attenuated by capsaicin, but tongue movements remained retrusive, unless the medial XII branch was sectioned. Capsaicin also significantly delayed the onset of tongue movements such that tongue forces could not be detected until after onset of the inspiratory diaphragm activity. We conclude that altered neural drive to the tongue muscles following pulmonary C-fiber activation has a functionally significant effect on tongue movements. The diminished tongue force and delay in the onset of tongue movements following pulmonary C-fiber activation are potentially unfavorable for upper airway patency.
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Affiliation(s)
- Kun-Ze Lee
- Department of Biological Sciences, College of Science, National Sun Yat-sen University, Kaohsiung, Taiwan.
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18
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Behan M, Moeser AE, Thomas CF, Russell JA, Wang H, Leverson GE, Connor NP. The effect of tongue exercise on serotonergic input to the hypoglossal nucleus in young and old rats. JOURNAL OF SPEECH, LANGUAGE, AND HEARING RESEARCH : JSLHR 2012; 55:919-29. [PMID: 22232395 PMCID: PMC3326185 DOI: 10.1044/1092-4388(2011/11-0091)] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
PURPOSE Breathing and swallowing problems affect elderly people and may be related to age-associated tongue dysfunction. Hypoglossal motoneurons that innervate the tongue receive a robust, excitatory serotonergic (5HT) input and may be affected by aging. We used a rat model of aging and progressive resistance tongue exercise to determine whether age-related alterations in 5HT inputs to the hypoglossal nucleus can be modified. We hypothesized that tongue forces would increase with exercise, 5HT input to the tongue would decrease with age, and tongue exercise would augment 5HT input to the hypoglossal nucleus. METHOD Young (9-10 months), middle-aged (24-25 months), and old (32-33 months) male F344/BN rats received tongue exercise for 8 weeks. Immunoreactivity for 5HT was measured in digital images of sections through the hypoglossal nucleus using ImageJ software. RESULTS Tongue exercise resulted in increased maximum tongue forces at all ages. There was a statistically significant increase in 5HT immunoreactivity in the hypoglossal nucleus in exercised, young rats but only in the caudal third of the nucleus and primarily in the ventral half. CONCLUSION Specificity found in serotonergic input following exercise may reflect the topographic organization of motoneurons in the hypoglossal nucleus and the tongue muscles engaged in the exercise paradigm.
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19
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Yokota S, Niu JG, Tsumori T, Oka T, Yasui Y. Glutamatergic Kölliker-Fuse nucleus neurons innervate hypoglossal motoneurons whose axons form the medial (protruder) branch of the hypoglossal nerve in the rat. Brain Res 2011; 1404:10-20. [PMID: 21724177 DOI: 10.1016/j.brainres.2011.06.025] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2011] [Revised: 05/31/2011] [Accepted: 06/09/2011] [Indexed: 10/18/2022]
Abstract
This study was performed to understand the anatomical substrates for Kölliker-Fuse nucleus (KFN) modulation of respiratory-related tongue movement. After application of cholera toxin B subunit (CTb) to the medial branch of the hypoglossal nerve (HGn) and injection of biotinylated dextran amine (BDA) into the KFN ipsilaterally, an overlapping distribution of BDA-labeled axon terminals and CTb-labeled neurons was found in the ventral compartment of the hypoglossal nucleus (HGN) ipsilateral to the application and injection sites. At the electron microscopic level, the BDA-labeled terminals made asymmetrical synaptic contacts predominantly with dendrites of the HGN neurons, some of which were labeled with CTb. Using retrograde tracing combined with in situ hybridization, we demonstrated that almost all the KFN neurons sending their axons to the HGN were positive for vesicular glutamate transporter (VGLUT) 2 mRNA but not glutamic acid decarboxylase 67 mRNA. Using a combination of anterograde and retrograde tracing techniques and immunohistochemistry for VGLUT2, we further demonstrated that the KFN axon terminals with VGLUT2 immunoreactivity established close contact with the HGN motoneurons whose axons constitute the medial branch of the HGn. The present results suggest that glutamatergic KFN fibers may exert excitatory influence upon the HGN motoneurons sending their axons to the medial branch of the HGn for the control of protruder tongue muscles contraction to maintain airway patency during respiration.
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Affiliation(s)
- Shigefumi Yokota
- Department of Anatomy and Morphological Neuroscience, Shimane University School of Medicine, Izumo 693-8501, Japan
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20
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Rice A, Fuglevand AJ, Laine CM, Fregosi RF. Synchronization of presynaptic input to motor units of tongue, inspiratory intercostal, and diaphragm muscles. J Neurophysiol 2011; 105:2330-6. [PMID: 21307319 DOI: 10.1152/jn.01078.2010] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The respiratory central pattern generator distributes rhythmic excitatory input to phrenic, intercostal, and hypoglossal premotor neurons. The degree to which this input shapes motor neuron activity can vary across respiratory muscles and motor neuron pools. We evaluated the extent to which respiratory drive synchronizes the activation of motor unit pairs in tongue (genioglossus, hyoglossus) and chest-wall (diaphragm, external intercostals) muscles using coherence analysis. This is a frequency domain technique, which characterizes the frequency and relative strength of neural inputs that are common to each of the recorded motor units. We also examined coherence across the two tongue muscles, as our previous work shows that, despite being antagonists, they are strongly coactivated during the inspiratory phase, suggesting that excitatory input from the premotor neurons is distributed broadly throughout the hypoglossal motoneuron pool. All motor unit pairs showed highly correlated activity in the low-frequency range (1-8 Hz), reflecting the fundamental respiratory frequency and its harmonics. Coherence of motor unit pairs recorded either within or across the tongue muscles was similar, consistent with broadly distributed premotor input to the hypoglossal motoneuron pool. Interestingly, motor units from diaphragm and external intercostal muscles showed significantly higher coherence across the 10-20-Hz bandwidth than tongue-muscle units. We propose that the lower coherence in tongue-muscle motor units over this range reflects a larger constellation of presynaptic inputs, which collectively lead to a reduction in the coherence between hypoglossal motoneurons in this frequency band. This, in turn, may reflect the relative simplicity of the respiratory drive to the diaphragm and intercostal muscles, compared with the greater diversity of functions fulfilled by muscles of the tongue.
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Affiliation(s)
- Amber Rice
- Department of Physiology, The University of Arizona, Tucson, AZ 85721-0093, USA
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21
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Cheetham J, Pigott JH, Hermanson JW, Campoy L, Soderholm LV, Thorson LM, Ducharme NG. Role of the hypoglossal nerve in equine nasopharyngeal stability. J Appl Physiol (1985) 2009; 107:471-7. [DOI: 10.1152/japplphysiol.91177.2008] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The equine upper airway is highly adapted to provide the extremely high oxygen demand associated with strenuous aerobic exercise in this species. The tongue musculature, innervated by the hypoglossal nerve, plays an important role in airway stability in humans who also have a highly adapted upper airway to allow speech. The role of the hypoglossal nerve in stabilizing the equine upper airway has not been established. Isolated tongues from eight mature horses were dissected to determine the distal anatomy and branching of the equine hypoglossal nerve. Using this information, a peripheral nerve location technique was used to perform bilateral block of the common trunk of the hypoglossal nerve in 10 horses. Each horse was subjected to two trials with bilateral hypoglossal nerve block and two control trials (unblocked). Upper airway stability at exercise was determined using videoendoscopy and measurement of tracheal and pharyngeal pressure. Three main nerve branches were identified, medial and lateral branches and a discrete branch that innervated the geniohyoid muscle alone. Bilateral hypoglossal block induced nasopharyngeal instability in 10/19 trials, and none of the control trials (0/18) resulted in instability ( P < 0.001). Mean treadmill speed (± SD) at the onset of instability was 10.8 ± 2.5 m/s. Following its onset, nasopharyngeal instability persisted until the end of the treadmill test. This instability, induced by hypoglossal nerve block, produced an expiratory obstruction similar to that seen in a naturally occurring equine disease (dorsal displacement of the soft palate, DDSP) with reduced inspiratory and expiratory pharyngeal pressure and increased expiratory tracheal pressure. These data suggest that stability of the equine upper airway at exercise may be mediated through the hypoglossal nerve. Naturally occurring DDSP in the horse shares a number of anatomic similarities with obstructive sleep apnea. Study of species with extreme respiratory adaptation, such as the horse, may provide insight into respiratory functioning in humans.
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22
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Barker JR, Thomas CF, Behan M. Serotonergic projections from the caudal raphe nuclei to the hypoglossal nucleus in male and female rats. Respir Physiol Neurobiol 2009; 165:175-84. [PMID: 19073285 PMCID: PMC2762192 DOI: 10.1016/j.resp.2008.11.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2008] [Revised: 11/18/2008] [Accepted: 11/19/2008] [Indexed: 10/21/2022]
Abstract
The respiratory control system is sexually dimorphic. In many brain regions, including respiratory motor nuclei, serotonin (5HT) levels are higher in females than in males. We hypothesized that there could be sex differences in 5HT input to the hypoglossal nucleus, a region of the brainstem involved in upper airway control. Adult Fischer 344 rats were anesthetized and a retrograde transsynaptic neuroanatomical tracer, Bartha pseudorabies virus (PRV), was injected into the tongue. Sections through the medulla were reacted immunocytochemically for the presence of (i) PRV, (ii) tryptophan hydroxylase (TPH; marker of 5HT neurons), (iii) PRV combined with TPH, and (iv) 5HT. Sex hormone levels were measured in female rats and correlated with TPH immunoreactivity, as hypoglossal 5HT levels vary with the estrous cycle. The number of PRV neurons was comparable in male and female rats. The number and distribution of TPH immunoreactive neurons in the caudal raphe nuclei were similar in male and female rats. The subset of 5HT neurons that innervate hypoglossal motoneurons was also similar in male and female rats. With the exception of the ventrolateral region of the hypoglossal nucleus, 5HT immunoreactivity was similar in male and female rats. These data suggest that sex differences in 5HT modulation of hypoglossal motoneurons in male and female rats are not the result of sex differences in TPH or 5HT, but may result from differences in neurotransmitter release and reuptake, location of 5HT synaptic terminals on hypoglossal motoneurons, pre- and postsynaptic 5HT receptor expression, or the distribution of sex hormone receptors on hypoglossal or caudal raphe neurons.
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Affiliation(s)
- Jessica R Barker
- Department of Comparative Biosciences, University of Wisconsin, 2015 Linden Drive, Madison, WI 53706-1102, United States
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23
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Mu L, Sanders I. Newly revealed cricothyropharyngeus muscle in the human laryngopharynx. Anat Rec (Hoboken) 2008; 291:927-38. [PMID: 18521893 DOI: 10.1002/ar.20727] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Humans have a uniquely curved pharynx and tongue that is believed to have evolved for speech. The most inferior part of the pharynx consists of the laryngopharynx, the critical crossroad where swallowing, breathing, and phonation overlap. We hypothesized that the human laryngopharynx has unique neuromuscular specializations that may be speech related. Laryngopharynx specimens from 15 humans and 20 nonhuman mammals (dog, pig, rabbit, and rat) were studied. Microdissection revealed that only human specimens had a muscle originating from the anterior arch of the cricoid cartilage, and coursing between the inferior pharyngeal constrictor and cricopharyngeus muscles to insert into the median raphe at the posterior midline of the pharynx. On the basis of these anatomic features, we termed it the "cricothyropharyngeus" (CTP). The structure, innervation, and muscle fiber types of the human CTP were further investigated by histological methods, Sihler's stain, and myosin heavy chain (MHC) immunocytochemistry. The innervation and muscle fiber types of the CTP were found to differ from those of neighboring muscles. The laryngeal portion of the CTP was innervated by the external superior laryngeal nerve, whereas the pharyngeal portion of the muscle was supplied by the pharyngeal plexus. Most notable was that the CTP contained specialized muscle fibers expressing some unusual MHC isoforms (i.e., slow-tonic, alpha-cardiac, neonatal, and embryonic). In conclusion, the CTP appears to be a newly described and uniquely human muscle with characteristics suggesting a specialized function that may be speech related.
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Affiliation(s)
- Liancai Mu
- Department of Otolaryngology, Upper Airway Research Laboratory, Mount Sinai School of Medicine, New York, New York 10029-6574, USA.
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Schwarz EC, Thompson JM, Connor NP, Behan M. The effects of aging on hypoglossal motoneurons in rats. Dysphagia 2008; 24:40-8. [PMID: 18716837 DOI: 10.1007/s00455-008-9169-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2007] [Accepted: 04/24/2008] [Indexed: 11/28/2022]
Abstract
Aging can result in a loss of neuronal cell bodies and a decrease in neuronal size in some regions of the brain and spinal cord. Motoneuron loss in the spinal cord is thought to contribute to the progressive decline in muscle mass and strength that occurs with age (sarcopenia). Swallowing disorders represent a large clinical problem in elderly persons; however, age-related alterations in cranial motoneurons that innervate muscles involved in swallowing have been understudied. We aimed to determine if age-related alterations occurred in the hypoglossal nucleus in the brainstem. If present, these changes might help explain alterations at the neuromuscular junction and changes in the contractile properties of tongue muscle that have been reported in older rats. We hypothesized that with increasing age there would be a loss of motoneurons and a reduction in neuronal size and the number of primary dendrites associated with each hypoglossal motoneuron. Neurons in the hypoglossal nucleus were visualized with the neuronal marker NeuN in young (9-10 months), middle-aged (24-25 months), and old (32-33 months) male F344/BN rats. Hypoglossal motoneurons were retrograde-labeled with injections of Cholera Toxin beta into the genioglossus muscle of the tongue and visualized using immunocytochemistry. Results indicated that the number of primary dendrites of hypoglossal motoneurons decreased significantly with age, while no age-associated changes were found in the number or size of hypoglossal motoneurons. Loss of primary dendrites could reduce the number of synaptic inputs and thereby impair function.
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Affiliation(s)
- Emilie C Schwarz
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI 53706, USA
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25
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Functional imaging, spatial reconstruction, and biophysical analysis of a respiratory motor circuit isolated in vitro. J Neurosci 2008; 28:2353-65. [PMID: 18322082 DOI: 10.1523/jneurosci.3553-07.2008] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
We combined real-time calcium-based neural activity imaging with whole-cell patch-clamp recording techniques to map the spatial organization and analyze electrophysiological properties of respiratory neurons forming the circuit transmitting rhythmic drive from the pre-Bötzinger complex (pre-BötC) through premotoneurons to hypoglossal (XII) motoneurons. Inspiratory pre-BötC neurons, XII premotoneurons (preMNs), and XII motoneurons (MNs) were retrogradely labeled with Ca(2+)-sensitive dye in neonatal rat in vitro brainstem slices. PreMN cell bodies were arrayed dorsomedially to pre-BötC neurons with little spatial overlap; axonal projections to MNs were ipsilateral. Inspiratory MNs were distributed in dorsal and ventral subnuclei of XII. Voltage-clamp recordings revealed that two currents, persistent sodium current (NaP) and K(+)-dominated leak current (Leak), primarily contribute to preMN/MN subthreshold current-voltage relationships. NaP or Leak conductance densities in preMNs and MNs were not significantly different. We quantified preMN and MN action potential time course and spike frequency-current (f-I) relationships and found no significant differences in repetitive spiking dynamics, steady-state f-I gains, and afterpolarizing potentials. Rhythmic synaptic drive current densities were similar in preMNs and MNs. Our results indicate that, despite topographic and morphological differences, preMNs and MNs have some common intrinsic membrane, synaptic integration, and spiking properties that we postulate ensure fidelity of inspiratory drive transmission and conversion of synaptic drive into (pre)motor output. There also appears to be a common architectonic organization for some respiratory drive transmission circuits whereby many preMNs are spatially segregated from pre-BötC rhythm-generating neurons, which we hypothesize may facilitate downstream integration of convergent inputs for premotor pattern formation.
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26
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Lorenzo LE, Barbe A, Portalier P, Fritschy JM, Bras H. Differential expression of GABAA and glycine receptors in ALS-resistant vs. ALS-vulnerable motoneurons: possible implications for selective vulnerability of motoneurons. Eur J Neurosci 2007; 23:3161-70. [PMID: 16820006 DOI: 10.1111/j.1460-9568.2006.04863.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Summary Amyotrophic lateral sclerosis (ALS) is a devastating motoneuronal degenerative disease, which is inevitably fatal in adults. ALS is characterized by an extensive loss of motoneurons in the cerebrospinal axis, except for those motoneurons that control eye movements and bladder contraction. The reason for this selectivity is not known. Systematic differences have been found in the organization of excitatory synaptic transmission in ALS-resistant vs. ALS-susceptible motor nuclei. However, although motoneurons express high levels of glycine receptors (GlyR) and GABA(A) receptors (GABA(A)R), no such studies have been carried out yet for inhibitory synaptic transmission. In this study, we compared the subunit composition, patterns of expression, density and synaptic localization of inhibitory synaptic receptors in ALS-resistant (oculomotor, trochlear and abducens) and ALS-vulnerable motoneurons (trigeminal, facial and hypoglossi). Triple immunofluorescent stainings of the major GABA(A)R subunits (alpha1, alpha2, alpha3, and alpha5), the GlyR alpha1 subunit and gephyrin, were visualized by confocal microscopy and analysed quantitatively. A strong correlation was observed between the vulnerability of motoneurons and the subunit composition of GABA(A)R, the GlyR/GABA(A)R density ratios and the incidence of synaptic vs. extrasynaptic GABA(A)R. These differences contrast strikingly with the uniform gephyrin cluster density and synaptic GlyR levels recorded in all motor nuclei examined. These results suggest that the specific patterns of inhibitory receptor organization observed might reflect functional differences that are relevant to the physiopathology of ALS.
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27
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Chamberlin NL, Eikermann M, Fassbender P, White DP, Malhotra A. Genioglossus premotoneurons and the negative pressure reflex in rats. J Physiol 2006; 579:515-26. [PMID: 17185342 PMCID: PMC2075396 DOI: 10.1113/jphysiol.2006.121889] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Reflex increases in genioglossus (GG) muscle activity in response to negative pharyngeal pressure are important for maintenance of upper airway patency in humans. However, little is known of the central circuitry that mediates this negative pressure reflex (NPR). We used two approaches to determine which GG premotoneurons relay negative pressure-related information to the hypoglossal motor nucleus. First, to identify GG premotoneurons, we injected pseudorabies virus (PRV152) into the GG muscle. We found that medullary GG premotoneurons were concentrated mainly in the reticular formation adjacent to the hypoglossal motor nucleus. Second, in order to determine whether these perihypoglossal neurons were involved in the NPR, we quantified GG EMG responses to negative pressure applied to the isolated upper airway in anaesthetized rats before and after microinjection of muscimol (9 nl; 0.25 mM), a GABA-A receptor agonist, into the perihypoglossal premotor field. Pressures as low as -4 cm H(2)O increased inspiratory phase-related GG activity. The NPR was abolished following bilateral injections of muscimol into the perihypoglossal premotor field at and up to 500 mum rostral to the obex. Muscimol in this location also increased the amplitude of basal, unstimulated phasic GG activity. By contrast, inhibition of neurons caudal to the obex decreased phasic GG activity but had no impact on the NPR. These results suggest that perihypoglossal GG premotoneurons near the obex mediate the NPR and those caudal to the obex are important mediators of respiratory-related GG activity but are not involved in the NPR.
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Affiliation(s)
- Nancy L Chamberlin
- Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA.
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28
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Gestreau C, Dutschmann M, Obled S, Bianchi AL. Activation of XII motoneurons and premotor neurons during various oropharyngeal behaviors. Respir Physiol Neurobiol 2005; 147:159-76. [PMID: 15919245 DOI: 10.1016/j.resp.2005.03.015] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2004] [Revised: 03/11/2005] [Accepted: 03/13/2005] [Indexed: 12/11/2022]
Abstract
Neural control of tongue muscles plays a crucial role in a broad range of oropharyngeal behaviors. Tongue movements must be rapidly and accurately adjusted in response to the demands of multiple complex motor tasks including licking/mastication, swallowing, vocalization, breathing and protective reflexes such as coughing. Yet, central mechanisms responsible for motor and premotor control of hypoglossal (XII) activity during these behaviors are still largely unknown. The aim of this article is to review the functional organization of the XII motor nucleus with particular emphasis on breathing, coughing and swallowing. Anatomical localization of XII premotor neurons is also considered. We discuss results concerned with multifunctional activity of medullary and pontine populations of XII premotor neurons, representing a single network that can be reconfigured to produce different oromotor response patterns. In this context, we introduce new data on swallowing-related activity of XII (and trigeminal) motoneurons, and finally suggest a prominent role for the pontine Kölliker-Fuse nucleus in the control of inspiratory-related activity of XII motoneurons supplying tongue protrusor and retrusor muscles.
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Affiliation(s)
- Christian Gestreau
- Laboratoire de Physiologie Neurovégétative, UMR CNRS 6153 INRA 1147, Université Paul Cézanne Aix-Marseille III, Av. Escadrille Normandie-Niemen, 13397 Marseille Cedex 20, France.
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29
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Fuller DD. Episodic hypoxia induces long-term facilitation of neural drive to tongue protrudor and retractor muscles. J Appl Physiol (1985) 2005; 98:1761-7. [PMID: 15640385 DOI: 10.1152/japplphysiol.01142.2004] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Hypoxic episodes can evoke a prolonged augmentation of inspiratory motor output called long-term facilitation (LTF). Hypoglossal (XII) LTF has been assumed to represent increased tongue protrudor muscle activation and pharyngeal airway dilation. However, recent studies indicate that tongue protrudor and retractor muscles are coactivated during inspiration, a behavior that promotes upper airway patency by reducing airway compliance. These experiments tested the hypothesis that XII LTF is manifest as increased inspiratory drive to both tongue protrudor and retractor muscles. Neurograms were recorded in the medial XII nerve branch (XIIMED; contains tongue protrudor motor axons), the lateral XII nerve branch (XIILAT; contains tongue retractor motor axons), and the phrenic nerve in anesthetized, vagotomized, paralyzed, ventilated male rats. Strict isocapnia was maintained for 60 min after five 3-min hypoxic episodes (arterial Po2 = 35 ± 2 Torr) or sham treatment. Peak inspiratory burst amplitude showed a persistent increase in XIIMED, XIILAT, and phrenic nerves during the hour after episodic hypoxia ( P < 0.05 vs. sham). This effect was present regardless of the quantification method (e.g., % baseline vs. percent maximum); however, comparisons of the relative magnitude of LTF between neurograms (e.g., XIIMED vs. XIILAT) varied with the normalization procedure. There was no persistent effect of episodic hypoxia on inspiratory burst frequency ( P > 0.05 vs. sham). These data demonstrate that episodic hypoxia induces LTF of inspiratory drive to both tongue protrudor and retractor muscles and underscore the potential contribution of tongue muscle coactivation to regulation of upper airway patency.
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Affiliation(s)
- D D Fuller
- Department of Physical Therapy, University of Florida, 100 S. Newell Dr., PO Box 100154, Gainesville, FL 32610, USA.
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Behan M, Thomas CF. Sex hormone receptors are expressed in identified respiratory motoneurons in male and female rats. Neuroscience 2005; 130:725-34. [PMID: 15590155 DOI: 10.1016/j.neuroscience.2004.09.058] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/17/2004] [Indexed: 11/30/2022]
Abstract
Sex hormones including estrogen, progesterone and testosterone can influence breathing. However, it is not clear whether such hormones exert their effects directly on respiratory motoneurons. We used immunocytochemistry to demonstrate that estrogen receptor alpha, estrogen receptor beta and androgen receptor are localized in respiratory motor neurons. Motoneurons in the hypoglossal (XII) and the phrenic nuclei were retrogradely labeled from the tongue and the diaphragm respectively. Double-label fluorescence immunocytochemistry was used to show that sex hormone receptors are present in respiratory motoneurons of both male and female rats. These data suggest that in male and female rats, sex hormones can modulate the output of respiratory motoneurons directly.
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Affiliation(s)
- M Behan
- Department of Comparative Biosciences, University of Wisconsin, 2015 Linden Drive, Madison, WI 53706-1102, USA.
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31
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Cotter LA, Arendt HE, Cass SP, Jian BJ, Mays DF, Olsheski CJ, Wilkinson KA, Yates BJ. Effects of postural changes and vestibular lesions on genioglossal muscle activity in conscious cats. J Appl Physiol (1985) 2003; 96:923-30. [PMID: 14594855 DOI: 10.1152/japplphysiol.01013.2003] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Previous studies in humans showed that genioglossal muscle activity is higher when individuals are supine than when they are upright, and prior experiments in anesthetized or decerebrate animals suggested that vestibular inputs might participate in triggering these alterations in muscle firing. The present study determined the effects of whole body tilts in the pitch (nose-up) plane on genioglossal activity in a conscious feline model and compared these responses with those generated by roll (ear-down) tilts. We also ascertained the effects of a bilateral vestibular neurectomy on the alterations in genioglossal activity elicited by changes in body position. Both pitch and roll body tilts produced modifications in muscle firing that were dependent on the amplitude of the rotation; however, the relative effects of ear-down and nose-up tilts on genioglossal activity were variable from animal to animal. The response variability observed might reflect the fact that genioglossus has a complex organization and participates in a variety of tongue movements; in each animal, electromyographic recordings presumably sampled the firing of different proportions of fibers in the various compartments and subcompartments of the muscle. Furthermore, removal of labyrinthine inputs resulted in alterations in genioglossal responses to postural changes that persisted until recordings were discontinued approximately 1 mo later, demonstrating that the vestibular system participates in regulating the muscle's activity. Peripheral vestibular lesions were subsequently demonstrated to be complete through the postmortem inspection of temporal bone sections or by observing that vestibular nucleus neurons did not respond to rotations in vertical planes.
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Affiliation(s)
- L A Cotter
- University of Pittsburgh, Department of Otolaryngology, PA 15213, USA
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