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Helou LB, Dum RP. Volitional inspiration is mediated by two independent output channels in the primary motor cortex. J Comp Neurol 2023; 531:1796-1811. [PMID: 37723869 PMCID: PMC10591979 DOI: 10.1002/cne.25540] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Revised: 09/04/2023] [Accepted: 09/07/2023] [Indexed: 09/20/2023]
Abstract
The diaphragm is a multifunctional muscle that mediates both autonomic and volitional inspiration. It is critically involved in vocalization, postural stability, and expulsive core-trunk functions, such as coughing, hiccups, and vomiting. In macaque monkeys, we used retrograde transneuronal transport of rabies virus injected into the left hemidiaphragm to identify cortical neurons that have multisynaptic connections with phrenic motoneurons. Our research demonstrates that representation of the diaphragm in the primary motor cortex (M1) is split into two spatially separate and independent sites. No cortico-cortical connections are known to exist between these two sites. One site is located dorsal to the arm representation within the central sulcus and the second site is lateral to the arm. The dual representation of the diaphragm warrants a revision to the somatotopic map of M1. The dorsal diaphragm representation overlaps with trunk and axial musculature. It is ideally situated to coordinate with these muscles during volitional inspiration and in producing intra-abdominal pressure gradients. The lateral site overlaps the origin of M1 projections to a laryngeal muscle, the cricothyroid. This observation suggests that the coordinated control of laryngeal muscles and the diaphragm during vocalization may be achieved, in part, by co-localization of their representations in M1. The neural organization of the two diaphragm sites underlies a new perspective for interpreting functional imaging studies of respiration and/or vocalization. Furthermore, our results provide novel evidence supporting the concept that overlapping output channels within M1 are a prerequisite for the formation of muscle synergies underlying fine motor control.
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Affiliation(s)
- Leah B. Helou
- University of Pittsburgh, Department of Communication Science and Disorders, Pittsburgh, PA 15260
| | - Richard P. Dum
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260
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Bordoni B, Escher AR, Toccafondi A, Mapelli L, Banfi P. Obstructive Sleep Apnea and Role of the Diaphragm. Cureus 2022; 14:e29004. [PMID: 36159353 PMCID: PMC9495286 DOI: 10.7759/cureus.29004] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/10/2022] [Indexed: 11/07/2022] Open
Abstract
Obstructive sleep apnea (OSA) causes multiple local and systemic pathophysiological consequences, which lead to an increase in morbidity and mortality in patients suffering from this disorder. OSA presents with various nocturnal events of apnoeas or hypopneas and with sub-clinical airflow limitations during wakefulness. OSA involves a large percentage of the population, particularly men, but the estimate of OSA patients could be much broader than data from the literature. Most of the research carried out in the muscle field is to understand the causes of the presence of chronic nocturnal desaturation and focus on the genioglossus muscle and other muscles related to dilating the upper airways. Sparse research has been published regarding the diaphragm muscle, which is the main muscle structure to insufflate air into the airways. The article reviews the functional anatomy of the muscles used to open the upper respiratory tract and the non-physiological adaptation that follows in the presence of OSA, as well as the functional anatomy and pathological adaptive aspects of the diaphragm muscle. The intent of the text is to highlight the disparity of clinical interest between the dilator muscles and the diaphragm, trying to stimulate a broader approach to patient evaluation.
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Pitts LL, Rogers L, Wang X, Bahia MM, Cherney LR. Functionally navigated transcranial magnetic stimulation to evoke lingual pressure in stroke survivors with dysphagia and healthy adults: a proof of concept trial. Top Stroke Rehabil 2019; 27:241-250. [PMID: 31838961 DOI: 10.1080/10749357.2019.1701175] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Background: Post-stroke dysphagia is characterized by reduced corticolingual excitability and lingual pressure; however, it remains unknown if transcranial magnetic stimulation (TMS) directly facilitates lingual pressure generation.Objectives: To explore optimal procedures for single pulse TMS using neuronavigation to evoke lingual pressure in intact and disrupted neural networks.Methods: Using co-registered functional magnetic resonance imaging, stimulation sites were determined for five healthy adults (Mage = 67) and four stroke survivors with dysphagia and reduced tongue strength (Mage = 66). Evoked lingual pressures were sampled across 45-65% of maximum stimulator output. Healthy participants repeated TMS with a bite block to isolate lingual pressure from off-target stimulation of mandibular elevators.Results: Only one functionally-guided stimulation site fell within previously reported optimal lateral (8-11cm) and anterior (2-4.25cm) coordinates. Lingual pressure was stable prior to pulse and increased linearly with intensity for both groups (p = .005). Post-stroke active motor thresholds were elevated compared to healthy adults (p = .025). Lingual pressure latency remained stable across intensities (p > .05). Jaw stabilization via bite block reduced the mean magnitude of evoked lingual pressure by approximately 16%.Conclusions: Single pulse TMS directly evokes higher lingual pressure and can define motor thresholds in intact and disordered corticolingual pathways. Stimulation sites using neuronavigation in healthy adults and stroke survivors largely differed from external coordinates in the literature that were predominantly established in young adults. Procedures to investigate motor thresholds for lingual pressure generation are proposed. The therapeutic role of TMS to address post-stroke deficits in lingual pressure and corticolingual excitability warrants continued investigation.
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Affiliation(s)
- Laura L Pitts
- Communication Sciences and Disorders, University of Northern Iowa, Cedar Falls, IA, USA.,Physical Medicine and Rehabilitation, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA.,Think and Speak Lab, Shirley Ryan AbilityLab, Chicago, IL, USA
| | - Lynn Rogers
- Physical Medicine and Rehabilitation, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA.,Think and Speak Lab, Shirley Ryan AbilityLab, Chicago, IL, USA
| | - Xue Wang
- Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Mariana M Bahia
- Communication Sciences and Disorders, University of Northern Iowa, Cedar Falls, IA, USA
| | - Leora R Cherney
- Physical Medicine and Rehabilitation, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA.,Think and Speak Lab, Shirley Ryan AbilityLab, Chicago, IL, USA
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Borel JC, Melo-Silva CA, Gakwaya S, Rousseau E, Series F. Diaphragm and genioglossus corticomotor excitability in patients with obstructive sleep apnea and control subjects. J Sleep Res 2015; 25:23-30. [DOI: 10.1111/jsr.12337] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Accepted: 08/02/2015] [Indexed: 11/27/2022]
Affiliation(s)
- Jean-Christian Borel
- Unité de recherche en pneumologie; Centre de recherche; Institut universitaire de cardiologie et de pneumologie de Québec; Université Laval; Quebec QC Canada
| | - Cesar A. Melo-Silva
- Unité de recherche en pneumologie; Centre de recherche; Institut universitaire de cardiologie et de pneumologie de Québec; Université Laval; Quebec QC Canada
| | - Simon Gakwaya
- Unité de recherche en pneumologie; Centre de recherche; Institut universitaire de cardiologie et de pneumologie de Québec; Université Laval; Quebec QC Canada
| | - Eric Rousseau
- Unité de recherche en pneumologie; Centre de recherche; Institut universitaire de cardiologie et de pneumologie de Québec; Université Laval; Quebec QC Canada
| | - Frederic Series
- Unité de recherche en pneumologie; Centre de recherche; Institut universitaire de cardiologie et de pneumologie de Québec; Université Laval; Quebec QC Canada
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Bordoni B, Zanier E. The continuity of the body: hypothesis of treatment of the five diaphragms. J Altern Complement Med 2015; 21:237-42. [PMID: 25775273 DOI: 10.1089/acm.2013.0211] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
The diaphragm muscle should not be seen as a segment but as part of a body system. This muscle is an important crossroads of information for the entire body, from the trigeminal system to the pelvic floor, passing from thoracic diaphragm to the floor of the mouth: the network of breath. Viola Frymann first spoke of the treatment of three diaphragms, and more recently four diaphragms have been discussed. Current scientific knowledge has led to discussion of the manual treatment of five diaphragms. This article highlights the anatomic connections and fascial and neurologic aspects of the diaphragm muscle, with four other structures considered as diaphragms: that is, the five diaphragms. The logic of the manual treatment proposed here is based on a concept and diagnostic work that should be the basis for any area of the body: The patient never just has a localized symptom but rather a system that adapts to a question.
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Affiliation(s)
- Bruno Bordoni
- 1 Don Carlo Gnocchi IRCCS , Department of Cardiology, IRCCS S. Maria Nascente, Don Carlo Gnocchi Foundation, Milano, Italy
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Raphe serotonergic neurons modulate genioglossus corticomotor activity in intermittent hypoxic rats. Respir Res 2014; 15:76. [PMID: 25001907 PMCID: PMC4100526 DOI: 10.1186/1465-9921-15-76] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Accepted: 07/01/2014] [Indexed: 11/26/2022] Open
Abstract
Background Genioglossus activity is greater during wakefulness but decreases to a weaker state during sleep in obstructive sleep apnea syndrome (OSAS) patients, compared to healthy subjects. Previous studies suggested that the corticomotor control of the genioglossus was modified in OSAS patients. Intermittent hypoxia (IH), the typical pathophysiological change in OSAS, can induce genioglossus facilitation. The serotonergic neurons of the raphe dorsal (DRN) and magnus nuclei (RMg) are responsive to hypoxia and play important roles in the control of the genioglossus. However, it remains unknown whether DRN and RMg serotonergic neurons are responsible for the facilitated corticomotor activity of the genioglossus during IH. This study explored the influence of IH on the corticomotor activity of the genioglossus by transcranial magnetic stimulation (TMS), and the role of DRN and RMg serotonergic neurons in this effect. Methods Rats were exposed to IH and divided into two groups. In one group, anti-SERT-SAP was microinjected into the DRN and RMg respectively to kill serotonergic neurons. In the other group, artificial cerebrospinal fluid (ACSF) was injected. Comparisons were conducted between the two groups during four weeks of IH and four weeks after IH. Results Compared to the corresponding ACSF-injected group, the DRN lesion group and RMg lesion group showed longer TMS latencies and lower amplitudes during IH from the 1st to the 28th day. After 28 days of IH, longer latencies and lower amplitudes were seen only in the DRN lesion group. Conclusion These results indicate that DRN and RMg serotonergic neurons play different roles in the facilitation of genioglossus corticomotor activity induced by IH.
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Bordoni B, Zanier E. Anatomic connections of the diaphragm: influence of respiration on the body system. J Multidiscip Healthc 2013; 6:281-91. [PMID: 23940419 PMCID: PMC3731110 DOI: 10.2147/jmdh.s45443] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The article explains the scientific reasons for the diaphragm muscle being an important crossroads for information involving the entire body. The diaphragm muscle extends from the trigeminal system to the pelvic floor, passing from the thoracic diaphragm to the floor of the mouth. Like many structures in the human body, the diaphragm muscle has more than one function, and has links throughout the body, and provides the network necessary for breathing. To assess and treat this muscle effectively, it is necessary to be aware of its anatomic, fascial, and neurologic complexity in the control of breathing. The patient is never a symptom localized, but a system that adapts to a corporeal dysfunction.
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Affiliation(s)
- Bruno Bordoni
- Rehabilitation Cardiology Institute of Hospitalization and Care with Scientific Address, S Maria Nascente Don Carlo Gnocchi Foundation
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Borel JC, Melo-Silva CA, Gakwaya S, Sériès F. Influence of CO2 on upper airway muscles and chest wall/diaphragm corticomotor responses assessed by transcranial magnetic stimulation in awake healthy subjects. J Appl Physiol (1985) 2012; 112:798-805. [DOI: 10.1152/japplphysiol.00713.2011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Rationale: functional interaction between upper airway (UA) dilator muscles and the diaphragm is crucial in the maintenance of UA patency. This interaction could be altered by increasing respiratory drive. The aim of our study was to compare the effects of hypercapnic stimulation on diaphragm and genioglossus corticomotor responses to transcranial magnetic stimulation (TMS). Methods: 10 self-reported healthy men (32 ± 9 yr; body mass index = 24 ± 3 kg/m−2) breathed, in random order, room air or 5% and then 7% FiCO2, both balanced with pure O2. Assessments included ventilatory variables, isoflow UA resistance (at 300 ml/s), measurement of lower chest wall/diaphragm (LCW/diaphragm), and genioglossus motor threshold (MT) and motor-evoked potential (MEP) characteristics. TMS twitches were applied during early inspiration and end expiration at stimulation intensity 30% above LCW/diaphragm and genioglossus MT. Results: compared with room air, CO2 inhalation significantly augmented minute ventilation, maximal inspiratory flow, tidal volume, and tidal volume/respiratory time ratio. UA resistance was unchanged with CO2 inhalation. During 7% CO2 breathing, LCW/diaphragm MT decreased by 9.6 ± 10.1% whereas genioglossus MT increased by 7.2 ± 9%. CO2-induced ventilatory stimulation led to elevation of LCW/diaphragm MEP amplitudes during inspiration but not during expiration. LCW/diaphragm MEP latencies remained unaltered both during inspiration and expiration. Genioglossus MEP latencies and amplitudes were unchanged with CO2. Conclusion: in awake, healthy subjects, CO2-induced hyperventilation is associated with heightened LCW/diaphragm corticomotor activation without modulating genioglossus MEP responses. This imbalance may promote UA instability during increased respiratory drive.
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Affiliation(s)
- Jean-Christian Borel
- Unité de Recherche en Pneumologie, Centre de Recherche, Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, Canada
| | - Cesar Augusto Melo-Silva
- Unité de Recherche en Pneumologie, Centre de Recherche, Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, Canada
| | - Simon Gakwaya
- Unité de Recherche en Pneumologie, Centre de Recherche, Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, Canada
| | - Frédéric Sériès
- Unité de Recherche en Pneumologie, Centre de Recherche, Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, Canada
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WANG W, KANG J, KONG D. The central motor conductivity of genioglossus in obstructive sleep apnoea. Respirology 2010; 15:1209-14. [DOI: 10.1111/j.1440-1843.2010.01858.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Sériès F, Wang W, Similowski T. Corticomotor control of the genioglossus in awake OSAS patients: a transcranial magnetic stimulation study. Respir Res 2009; 10:74. [PMID: 19678922 PMCID: PMC2738672 DOI: 10.1186/1465-9921-10-74] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2009] [Accepted: 08/13/2009] [Indexed: 11/16/2022] Open
Abstract
Background Upper airway collapse does not occur during wake in obstructive sleep apnea patients. This points to wake-related compensatory mechanisms, and possibly to a modified corticomotor control of upper airway dilator muscles. The objectives of the study were to characterize the responsiveness of the genioglossus to transcranial magnetic stimulation during respiratory and non-respiratory facilitatory maneuvers in obstructive sleep apnea patients, and to compare it to the responsiveness of the diaphragm, with reference to normal controls. Methods Motor evoked potentials of the genioglossus and of the diaphragm, with the corresponding motor thresholds, were recorded in response to transcranial magnetic stimulation applied during expiration, inspiration and during maximal tongue protraction in 13 sleep apnea patients and 8 normal controls. Main Results In the sleep apnea patients: 1) combined genioglossus and diaphragm responses occurred more frequently than in controls (P < 0.0001); 2) the amplitude of the genioglossus response increased during inspiratory maneuvers (not observed in controls); 3) the latency of the genioglossus response decreased during tongue protraction (not observed in controls). A significant negative correlation was found between the latency of the genioglossus response and the apnea-hypopnea index; 4) the difference in diaphragm and genioglossus cortico-motor responses during tongue protraction and inspiratory loading differed between sleep apnea and controls. Conclusion Sleep apnea patients and control subjects differ in the response pattern of the genioglossus and of the diaphragm to facilitatory maneuvers, some of the differences being related to the frequency of sleep-related events.
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Affiliation(s)
- Frédéric Sériès
- Centre de recherche, Hôpital Laval, Institut universitaire de cardiologie et de pneumologie de l'Université Laval, Quebec City, Quebec, Canada.
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Influence of topical anaesthesia on the corticomotor response to tongue training. Arch Oral Biol 2009; 54:696-704. [DOI: 10.1016/j.archoralbio.2009.04.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2008] [Revised: 04/04/2009] [Accepted: 04/13/2009] [Indexed: 11/21/2022]
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Sériès F, Wang W, Mélot C, Similowski T. Concomitant responses of upper airway stabilizing muscles to transcranial magnetic stimulation in normal men. Exp Physiol 2008; 93:496-502. [DOI: 10.1113/expphysiol.2007.039610] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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