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Abstract
The clinical term dyspnea (a.k.a. breathlessness or shortness of breath) encompasses at least three qualitatively distinct sensations that warn of threats to breathing: air hunger, effort to breathe, and chest tightness. Air hunger is a primal homeostatic warning signal of insufficient alveolar ventilation that can produce fear and anxiety and severely impacts the lives of patients with cardiopulmonary, neuromuscular, psychological, and end-stage disease. The sense of effort to breathe informs of increased respiratory muscle activity and warns of potential impediments to breathing. Most frequently associated with bronchoconstriction, chest tightness may warn of airway inflammation and constriction through activation of airway sensory nerves. This chapter reviews human and functional brain imaging studies with comparison to pertinent neurorespiratory studies in animals to propose the interoceptive networks underlying each sensation. The neural origins of their distinct sensory and affective dimensions are discussed, and areas for future research are proposed. Despite dyspnea's clinical prevalence and impact, management of dyspnea languishes decades behind the treatment of pain. The neurophysiological bases of current therapeutic approaches are reviewed; however, a better understanding of the neural mechanisms of dyspnea may lead to development of novel therapies and improved patient care.
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Affiliation(s)
- Andrew P Binks
- Department of Basic Science Education, Virginia Tech Carilion School of Medicine, Roanoke, VA, United States; Faculty of Health Sciences, Virginia Tech, Blacksburg, VA, United States.
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Abbass Y, Saleh M, Dosen S, Valle M. Embedded Electrotactile Feedback System for Hand Prostheses Using Matrix Electrode and Electronic Skin. IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS 2021; 15:912-925. [PMID: 34432633 DOI: 10.1109/tbcas.2021.3107723] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
As the technology moves towards more human-like bionic limbs, it is necessary to develop a feedback system that provides active touch feedback to a user of a prosthetic hand. Most of the contemporary sensory substitution methods comprise simple position and force sensors combined with few discrete stimulation units, and hence they are characterized with a limited amount of information that can be transmitted by the feedback. The present study describes a novel system for tactile feedback integrating advanced multipoint sensing (electronic skin) and stimulation (matrix electrodes). The system comprises a flexible sensing array (16 sensors) integrated on the index finger of a Michelangelo prosthetic hand mockup, embedded interface electronics and multichannel stimulator connected to a flexible matrix electrode (24 pads). The developed system conveys contact information (binary detections) to the user. To demonstrate the feasibility, the system was tested in six able-bodied subjects who were asked to recognize static patterns (contact position) with two different spatial resolutions and dynamic movement patterns (i.e., sliding along and/or across the finger) presented on the electronic skin. The experiments demonstrated that the system successfully translated the mechanical interaction into electrotactile profiles, which the subjects could recognize with good performance. The success rates (mean ± standard deviation) for the static patterns were 91 ± 4% and 58 ± 10% for low and high spatial resolution, respectively, while the success rate for sliding touch was 94 ± 4%. These results demonstrate that the developed system is an important step towards a new generation of tactile feedback interfaces that can provide high-bandwidth connection between the user and his/her bionic limb. Such systems would allow mimicking spatially distributed natural feedback, thereby facilitating the control and embodiment of the artificial device into the user body scheme.
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Tsutsumi Y, Mizuno Y, Haque T, Sato F, Furuta T, Oka A, Moritani M, Bae YC, Yamashiro T, Tachibana Y, Yoshida A. Widespread corticopetal projections from the oval paracentral nucleus of the intralaminar thalamic nuclei conveying orofacial proprioception in rats. Brain Struct Funct 2021; 226:1115-1133. [PMID: 33543335 DOI: 10.1007/s00429-021-02228-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 01/21/2021] [Indexed: 12/18/2022]
Abstract
The oval paracentral nucleus (OPC) was initially isolated from the paracentral nucleus (PC) within the intralaminar thalamic nuclei in rats. We have recently shown that the rat OPC receives proprioceptive inputs from jaw-closing muscle spindles (JCMSs). However, it remains unknown which cortical areas receive thalamic inputs from the OPC, and whether the cortical areas receiving the OPC inputs are distinct from those receiving inputs from the other intralaminar nuclei and sensory thalamic nuclei. To address this issue, we injected an anterograde tracer, biotinylated dextranamine (BDA), into the OPC, which was electrophysiologically identified by recording of proprioceptive inputs from the JCMSs. Many BDA-labeled axonal fibers and terminals from the OPC were ipsilaterally observed in the rostral and rostroventral regions of the primary somatosensory cortex (S1), the rostral region of the secondary somatosensory cortex (S2), and the most rostrocaudal levels of the granular insular cortex (GI). In contrast, a BDA injection into the caudal PC, which was located slightly rostral to the OPC, resulted in ipsilateral labeling of axonal fibers and terminals in the rostrolateral region of the medial agranular cortex and the rostromedial region of the lateral agranular cortex. Furthermore, injections of a retrograde tracer, Fluorogold, into these S1, S2, and GI regions, resulted in preferential labeling of neurons in the ipsilateral OPC among the intralaminar and sensory thalamic nuclei. These findings reveal that the rat OPC has widespread, but strong corticopetal projections, indicating that there exist divergent corticopetal pathways from the intralaminar thalamic nucleus, which process JCMS proprioceptive sensation.
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Affiliation(s)
- Yumi Tsutsumi
- Department of Oral Anatomy and Neurobiology, Osaka University Graduate School of Dentistry, Suita, Osaka, 565-0871, Japan
| | - Yuka Mizuno
- Department of Oral Anatomy and Neurobiology, Osaka University Graduate School of Dentistry, Suita, Osaka, 565-0871, Japan.,Department of Orthodontics and Dentofacial Orthopedics, Osaka University Graduate School of Dentistry, Suita, Osaka, 565-0871, Japan
| | - Tahsinul Haque
- Department of Oral Anatomy and Neurobiology, Osaka University Graduate School of Dentistry, Suita, Osaka, 565-0871, Japan.,Department of Oral Medicine and Diagnostic Sciences, College of Dentistry, King Saud University, Riyadh, 11545, Saudi Arabia
| | - Fumihiko Sato
- Department of Oral Anatomy and Neurobiology, Osaka University Graduate School of Dentistry, Suita, Osaka, 565-0871, Japan
| | - Takahiro Furuta
- Department of Oral Anatomy and Neurobiology, Osaka University Graduate School of Dentistry, Suita, Osaka, 565-0871, Japan
| | - Ayaka Oka
- Department of Orthodontics and Dentofacial Orthopedics, Osaka University Graduate School of Dentistry, Suita, Osaka, 565-0871, Japan
| | - Masayuki Moritani
- Department of Physical Therapy, Faculty of Health Science, Morinomiya University of Medical Sciences, Osaka, 559-8611, Japan
| | - Yong Chul Bae
- Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu, 700-412, Korea
| | - Takashi Yamashiro
- Department of Orthodontics and Dentofacial Orthopedics, Osaka University Graduate School of Dentistry, Suita, Osaka, 565-0871, Japan
| | - Yoshihisa Tachibana
- Division of System Neuroscience, Kobe University Graduate School of Medicine, Kobe, Hyogo, 650-0017, Japan.
| | - Atsushi Yoshida
- Department of Oral Anatomy and Neurobiology, Osaka University Graduate School of Dentistry, Suita, Osaka, 565-0871, Japan.
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Fukushi I, Pokorski M, Okada Y. Mechanisms underlying the sensation of dyspnea. Respir Investig 2020; 59:66-80. [PMID: 33277231 DOI: 10.1016/j.resinv.2020.10.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 10/13/2020] [Accepted: 10/17/2020] [Indexed: 01/17/2023]
Abstract
Dyspnea is defined as a subjective experience of breathing discomfort that consists of qualitatively distinct sensations that vary in intensity. It is a common symptom among patients with respiratory diseases that reduces daily activities, induces deconditioning, and is self-perpetuating. Although clinical interventions are needed to reduce dyspnea, its underlying mechanism is poorly understood depending on the intertwined peripheral and central neural mechanisms as well as emotional factors. Nonetheless, experimental and clinical observations suggest that dyspnea results from dissociation or a mismatch between the intended respiratory motor output set caused by the respiratory neuronal network in the lower brainstem and the ventilatory output accomplished. The brain regions responsible for detecting the mismatch between the two are not established. The mechanism underlying the transmission of neural signals for dyspnea to higher sensory brain centers is not known. Further, information from central and peripheral chemoreceptors that control the milieu of body fluids is summated at higher brain centers, which modify dyspneic sensations. The mental status also affects the sensitivity to and the threshold of dyspnea perception. The currently used methods for relieving dyspnea are not necessarily fully effective. The search for more effective therapy requires further insights into the pathophysiology of dyspnea.
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Affiliation(s)
- Isato Fukushi
- Faculty of Health Sciences, Uekusa Gakuen University, 1639-3 Ogura-cho, Wakaba-ku, Chiba, 264-0007, Japan; Clinical Research Center, Murayama Medical Center, 2-37-1 Gakuen, Musashimurayama, Tokyo, 208-0011, Japan.
| | - Mieczyslaw Pokorski
- Clinical Research Center, Murayama Medical Center, 2-37-1 Gakuen, Musashimurayama, Tokyo, 208-0011, Japan; Faculty of Health Sciences, The Jan Dlugosz University in Czestochowa, 4/8 Jerzego Waszyngtona Street, 42-200, Czestochowa, Poland
| | - Yasumasa Okada
- Clinical Research Center, Murayama Medical Center, 2-37-1 Gakuen, Musashimurayama, Tokyo, 208-0011, Japan
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Uemura Y, Haque T, Sato F, Tsutsumi Y, Ohara H, Oka A, Furuta T, Bae YC, Yamashiro T, Tachibana Y, Yoshida A. Proprioceptive thalamus receiving forelimb and neck muscle spindle inputs via the external cuneate nucleus in the rat. Brain Struct Funct 2020; 225:2177-2192. [PMID: 32748090 DOI: 10.1007/s00429-020-02118-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2020] [Accepted: 07/18/2020] [Indexed: 11/30/2022]
Abstract
Proprioceptive signals from body muscles have historically been considered to project to the rostrodorsal shell of the ventrobasal thalamic complex [the ventral posterolateral nucleus (VPL) and ventral posteromedial nucleus (VPM)]. However, we have recently found that proprioception from rat jaw-closing muscle spindles (JCMSs) is conveyed via the supratrigeminal nucleus to the caudo-ventromedial edge of the VPM, but not to the rostrodorsal shell of the VPM. Therefore, proprioception from other body muscles may also project to thalamic regions other than the rostrodorsal shell of the VPL. We thus examined the thalamic projection from the rat external cuneate nucleus (ECu), which receives proprioceptive inputs from forelimb and neck muscles. After injection of anterograde tracer into the ECu, axon terminals were contralaterally labeled in the ventromedial part (VPLvm) of the VPL, but not in the rostrodorsal shell of the VPL. After anterograde tracer injection into the cuneate nucleus (Cu), axon terminals were widely labeled in the contralateral VPL including the VPLvm. In the VPLvm, we electrophysiologically confirmed the proprioceptive inputs responsive to electrical stimulation of the ECu or median nerve and to the pressure of forelimb/neck muscles or wrist flexion. After retrograde tracer injection into the VPLvm, neurons were contralaterally labeled in the ECu and Cu. After retrograde tracer injection into the VPL where no such proprioceptive inputs were recorded, no ECu neurons were labeled. These findings indicate that proprioception from forelimb/neck muscle spindles and JCMSs is somatotopically transmitted to the ventromedial floor of the ventrobasal thalamic complex, but not to its rostrodorsal shell.
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Affiliation(s)
- Yume Uemura
- Department of Oral Anatomy and Neurobiology, Osaka University Graduate School of Dentistry, 1-8 Yamadaoka, Suita, Osaka, 565-0871, Japan.,Department of Orthodontics and Dentofacial Orthopedics, Graduate School of Dentistry, Osaka University, Suita, Osaka, 565-0871, Japan
| | - Tahsinul Haque
- Department of Oral Anatomy and Neurobiology, Osaka University Graduate School of Dentistry, 1-8 Yamadaoka, Suita, Osaka, 565-0871, Japan.,Department of Oral Medicine and Diagnostic Sciences, College of Dentistry, King Saud University, Riyadh, 11545, Saudi Arabia
| | - Fumihiko Sato
- Department of Oral Anatomy and Neurobiology, Osaka University Graduate School of Dentistry, 1-8 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Yumi Tsutsumi
- Department of Oral Anatomy and Neurobiology, Osaka University Graduate School of Dentistry, 1-8 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Haruka Ohara
- Department of Orthodontics and Dentofacial Orthopedics, Graduate School of Dentistry, Osaka University, Suita, Osaka, 565-0871, Japan
| | - Ayaka Oka
- Department of Orthodontics and Dentofacial Orthopedics, Graduate School of Dentistry, Osaka University, Suita, Osaka, 565-0871, Japan
| | - Takahiro Furuta
- Department of Oral Anatomy and Neurobiology, Osaka University Graduate School of Dentistry, 1-8 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Yong Chul Bae
- Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu, 700-412, Korea
| | - Takashi Yamashiro
- Department of Orthodontics and Dentofacial Orthopedics, Graduate School of Dentistry, Osaka University, Suita, Osaka, 565-0871, Japan
| | - Yoshihisa Tachibana
- Department of Oral Anatomy and Neurobiology, Osaka University Graduate School of Dentistry, 1-8 Yamadaoka, Suita, Osaka, 565-0871, Japan. .,Division of System Neuroscience, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki, Chuo, Kobe, Hyogo, 650-0017, Japan.
| | - Atsushi Yoshida
- Department of Oral Anatomy and Neurobiology, Osaka University Graduate School of Dentistry, 1-8 Yamadaoka, Suita, Osaka, 565-0871, Japan.
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A Multidimensional Profile of Dyspnea in Hospitalized Patients. Chest 2019; 156:507-517. [PMID: 31128117 DOI: 10.1016/j.chest.2019.04.128] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Revised: 03/26/2019] [Accepted: 04/02/2019] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND Dyspnea is prevalent among hospitalized patients but little is known about the experience of dyspnea among inpatients. We sought to characterize the multiple sensations and associated emotions of dyspnea in patients admitted with dyspnea to a tertiary care hospital. METHODS We selected patients who reported breathing discomfort of at least 4/10 on admission (10 = unbearable). Research staff recruited 156 patients within 24 hours of admission and evaluated daily patients' current and worst dyspnea with the Multidimensional Dyspnea Profile; patients participated in the study 2.6 days on average. The Multidimensional Dyspnea Profile assesses overall breathing discomfort (A1), intensity of five sensory qualities of dyspnea, and 5 negative emotional responses to dyspnea. Patients were also asked to rate whether current levels of dyspnea were "acceptable." RESULTS At the time of the first research interview, patients reported slight to moderate dyspnea (A1 median 4); however, most patients reported experiencing severe dyspnea in the 24 hours before the interview (A1 mean 7.8). A total of 54% of patients with dyspnea ≥4 on day 1 found the symptom unacceptable. The worst dyspnea each day in the prior 24 hours usually occurred at rest. Dyspnea declined but persisted through hospitalization for most patients. "Air hunger" was the dominant sensation, especially when dyspnea was strong (>4). Anxiety and frustration were the dominant emotions associated with dyspnea. CONCLUSIONS This first multidimensional portrait of dyspnea in a general inpatient population characterizes the sensations and emotions dyspneic patients endure. The finding that air hunger is the dominant sensation of severe dyspnea has implications for design of laboratory models of these sensations and may have implications for targets of palliation of symptoms.
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Sato F, Uemura Y, Kanno C, Tsutsumi Y, Tomita A, Oka A, Kato T, Uchino K, Murakami J, Haque T, Tachibana Y, Yoshida A. Thalamo-insular pathway conveying orofacial muscle proprioception in the rat. Neuroscience 2017; 365:158-178. [PMID: 28993238 DOI: 10.1016/j.neuroscience.2017.09.050] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Revised: 09/23/2017] [Accepted: 09/26/2017] [Indexed: 10/18/2022]
Abstract
Little is known about how proprioceptive signals arising from muscles reach to higher brain regions such as the cerebral cortex. We have recently shown that a particular thalamic region, the caudo-ventromedial edge (VPMcvm) of ventral posteromedial thalamic nucleus (VPM), receives the proprioceptive signals from jaw-closing muscle spindles (JCMSs) in rats. In this study, we further addressed how the orofacial thalamic inputs from the JCMSs were transmitted from the thalamus (VPMcvm) to the cerebral cortex in rats. Injections of a retrograde and anterograde neuronal tracer, wheat-germ agglutinin-conjugated horseradish peroxidase (WGA-HRP), into the VPMcvm demonstrated that the thalamic pathway terminated mainly in a rostrocaudally narrow area in the dorsal part of granular insular cortex rostroventrally adjacent to the rostralmost part of the secondary somatosensory cortex (dGIrvs2). We also electrophysiologically confirmed that the dGIrvs2 received the proprioceptive inputs from JCMSs. To support the anatomical evidence of the VPMcvm-dGIrvs2 pathway, injections of a retrograde neuronal tracer Fluorogold into the dGIrvs2 demonstrated that the thalamic neurons projecting to the dGIrvs2 were confined in the VPMcvm and the parvicellular part of ventral posterior nucleus. In contrast, WGA-HRP injections into the lingual nerve area of core VPM demonstrated that axon terminals were mainly labeled in the core regions of the primary and secondary somatosensory cortices, which were far from the dGIrvs2. These results suggest that the dGIrvs2 is a specialized cortical region receiving the orofacial proprioceptive inputs. Functional contribution of the revealed JCMSs-VPMcvm-dGIrvs2 pathway to Tourette syndrome is also discussed.
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Affiliation(s)
- Fumihiko Sato
- Department of Oral Anatomy and Neurobiology, Graduate School of Dentistry, Osaka University, Suita, Osaka 565-0871, Japan
| | - Yume Uemura
- Department of Oral Anatomy and Neurobiology, Graduate School of Dentistry, Osaka University, Suita, Osaka 565-0871, Japan; Department of Orthodontics and Dentofacial Orthopedics, Graduate School of Dentistry, Osaka University, Suita, Osaka 565-0871, Japan
| | - Chiharu Kanno
- Department of Oral Anatomy and Neurobiology, Graduate School of Dentistry, Osaka University, Suita, Osaka 565-0871, Japan
| | - Yumi Tsutsumi
- Department of Oral Anatomy and Neurobiology, Graduate School of Dentistry, Osaka University, Suita, Osaka 565-0871, Japan
| | - Akiko Tomita
- Department of Oral Anatomy and Neurobiology, Graduate School of Dentistry, Osaka University, Suita, Osaka 565-0871, Japan
| | - Ayaka Oka
- Department of Orthodontics and Dentofacial Orthopedics, Graduate School of Dentistry, Osaka University, Suita, Osaka 565-0871, Japan
| | - Takafumi Kato
- Department of Neuroscience and Oral Physiology, Graduate School of Dentistry, Osaka University, Suita, Osaka 565-0871, Japan
| | - Katsuro Uchino
- Department of Oral Anatomy and Neurobiology, Graduate School of Dentistry, Osaka University, Suita, Osaka 565-0871, Japan
| | - Jumpei Murakami
- Division of Special Care Dentistry, Dental Hospital, Osaka University, Suita, Osaka 565-0871, Japan
| | - Tahsinul Haque
- Department of Oral Anatomy and Neurobiology, Graduate School of Dentistry, Osaka University, Suita, Osaka 565-0871, Japan
| | - Yoshihisa Tachibana
- Division of Systrem Neuroscience, Kobe University Graduate School of Medicine, Kobe, Hyogo 650-0017, Japan
| | - Atsushi Yoshida
- Department of Oral Anatomy and Neurobiology, Graduate School of Dentistry, Osaka University, Suita, Osaka 565-0871, Japan.
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Fujita S, Kaneko M, Nakamura H, Kobayashi M. Spatiotemporal Profiles of Proprioception Processed by the Masseter Muscle Spindles in Rat Cerebral Cortex: An Optical Imaging Study. Front Neural Circuits 2017; 11:4. [PMID: 28194098 PMCID: PMC5276849 DOI: 10.3389/fncir.2017.00004] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Accepted: 01/10/2017] [Indexed: 11/23/2022] Open
Abstract
Muscle spindles in the jaw-closing muscles, which are innervated by trigeminal mesencephalic neurons (MesV neurons), control the strength of occlusion and the position of the mandible. The mechanisms underlying cortical processing of proprioceptive information are critical to understanding how sensory information from the masticatory muscles regulates orofacial motor function. However, these mechanisms are mostly unknown. The present study aimed to identify the regions that process proprioception of the jaw-closing muscles using in vivo optical imaging with a voltage-sensitive dye in rats under urethane anesthesia. First, jaw opening that was produced by mechanically pulling down the mandible evoked an optical response, which reflects neural excitation, in two cortical regions: the most rostroventral part of the primary somatosensory cortex (S1) and the border between the ventral part of the secondary somatosensory cortex (S2) and the insular oral region (IOR). The kinetics of the optical signal, including the latency, amplitude, rise time, decay time and half duration, in the S1 region for the response with the largest amplitude were comparable to those in the region with the largest response in S2/IOR. Second, we visualized the regions responding to electrical stimulation of the masseter nerve, which activates both motor efferent fibers and somatosensory afferent fibers, including those that transmit nociceptive and proprioceptive information. Masseter nerve stimulation initially excited the rostral part of the S2/IOR region, and an adjacent region responded to jaw opening. The caudal part of the region showing the maximum response overlapped with the region responding to jaw opening, whereas the rostral part overlapped with the region responding to electrical stimulation of the maxillary and mandibular molar pulps. These findings suggest that proprioception of the masseter is processed in S1 and S2/IOR. Other sensory information, such as nociception, is processed in a region that is adjacent to these pulpal regions and is located in the rostral part of S2/IOR, which receives nociceptive inputs from the molar pulps. The spatial proximity of these regions may be associated with the mechanisms by which masseter muscle pain is incorrectly perceived as dental pain.
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Affiliation(s)
- Satoshi Fujita
- Department of Pharmacology, School of Dentistry, Nihon UniversityTokyo, Japan; Division of Oral and Craniomaxillofacial Research, Dental Research Center, School of Dentistry, Nihon UniversityTokyo, Japan
| | - Mari Kaneko
- Department of Pharmacology, School of Dentistry, Nihon UniversityTokyo, Japan; Department of Orthodontics, School of Dentistry, Nihon UniversityTokyo, Japan
| | - Hiroko Nakamura
- Department of Pharmacology, School of Dentistry, Nihon UniversityTokyo, Japan; Department of Pediatric Dentistry, School of Dentistry, Nihon UniversityTokyo, Japan
| | - Masayuki Kobayashi
- Department of Pharmacology, School of Dentistry, Nihon UniversityTokyo, Japan; Division of Oral and Craniomaxillofacial Research, Dental Research Center, School of Dentistry, Nihon UniversityTokyo, Japan; Molecular Dynamics Imaging Unit, RIKEN Center for Life Science TechnologiesKobe, Japan
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O'Donnell DE, Webb KA, Harle I, Neder JA. Pharmacological management of breathlessness in COPD: recent advances and hopes for the future. Expert Rev Respir Med 2016; 10:823-34. [PMID: 27115291 DOI: 10.1080/17476348.2016.1182867] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
INTRODUCTION Activity-related breathlessness is often the dominant symptom in patients with chronic obstructive pulmonary disease (COPD) and usually persists despite optimal medical therapy. Currently, our inability to meaningfully alter the pathophysiology of the underlying disease means that we must focus our attention on relieving this distressing symptom so as to improve exercise tolerance and quality of life. AREAS COVERED The current review examines the neurobiology of breathlessness and constructs a solid physiological rationale for amelioration of this distressing symptom. We will examine the efficacy of interventions which: 1) reduce the increased central drive to breathe (opioids); 2) improve the respiratory system's ability to appropriately respond to this increased demand (bronchodilators); and 3) address the important affective dimension of breathlessness (anxiolytics). Expert commentary: Advances in our understanding of the mechanisms of activity-related breathlessness in COPD, and its measurement in the clinical domain, now set the stage for the development of effective management strategies on an individual patient basis.
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Affiliation(s)
- Denis E O'Donnell
- a Department of Medicine , Queen's University & Kingston General Hospital , Kingston , ON , Canada
| | - Katherine A Webb
- a Department of Medicine , Queen's University & Kingston General Hospital , Kingston , ON , Canada
| | - Ingrid Harle
- a Department of Medicine , Queen's University & Kingston General Hospital , Kingston , ON , Canada
| | - J Alberto Neder
- a Department of Medicine , Queen's University & Kingston General Hospital , Kingston , ON , Canada
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Ozaki I, Kurata K. The effects of voluntary control of respiration on the excitability of the primary motor hand area, evaluated by end-tidal CO2 monitoring. Clin Neurophysiol 2015; 126:2162-9. [PMID: 25698305 DOI: 10.1016/j.clinph.2014.12.032] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Revised: 12/29/2014] [Accepted: 12/31/2014] [Indexed: 10/24/2022]
Abstract
OBJECTIVE To investigate the effects of voluntary deep breathing on the excitability of the hand area in the primary motor cortex (M1). METHODS We applied near-threshold transcranial magnetic stimulation (TMS) over M1 during the early phase of inspiration or expiration in both normal automatic and voluntary deep, but not "forced", breathing in eight healthy participants at rest. We monitored exhaled CO2 levels continuously, and recorded motor-evoked potentials (MEPs) simultaneously from the abductor pollicis brevis, first dorsal interosseous, abductor digiti minimi, flexor digitorum superficialis, and extensor incidis muscles. RESULTS We observed that, during voluntary deep breathing, MEP amplitude increased by up to 50% for all recorded muscles and the latency of MEPs decreased by approximately 1ms, compared with normal automatic breathing. We found no difference in the amplitude or latency of MEPs between inspiratory and expiratory phases in either normal automatic or voluntary deep breathing. CONCLUSIONS Voluntary deep breathing at rest facilitates MEPs following TMS over the hand area of M1, and MEP enhancement occurs throughout the full respiratory cycle. SIGNIFICANCE The M1 hand region is continuously driven by top-down neural signals over the entire respiratory cycle of voluntary deep breathing.
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Affiliation(s)
- Isamu Ozaki
- Department of Physical Therapy, Faculty of Health Sciences, Aomori University of Health and Welfare, 58-1 Mase, Hamadate, Aomori 030-8505, Japan.
| | - Kiyoshi Kurata
- Department of Physiology, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki 036-8562, Japan
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Mathiassen SE, Hallman DM, Lyskov E, Hygge S. Can cognitive activities during breaks in repetitive manual work accelerate recovery from fatigue? A controlled experiment. PLoS One 2014; 9:e112090. [PMID: 25375644 PMCID: PMC4222971 DOI: 10.1371/journal.pone.0112090] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Accepted: 10/13/2014] [Indexed: 11/18/2022] Open
Abstract
Neurophysiologic theory and some empirical evidence suggest that fatigue caused by physical work may be more effectively recovered during “diverting” periods of cognitive activity than during passive rest; a phenomenon of great interest in working life. We investigated the extent to which development and recovery of fatigue during repeated bouts of an occupationally relevant reaching task was influenced by the difficulty of a cognitive activity between these bouts. Eighteen male volunteers performed three experimental sessions, consisting of six 7-min bouts of reaching alternating with 3 minutes of a memory test differing in difficulty between sessions. Throughout each session, recordings were made of upper trapezius muscle activity using electromyography (EMG), heart rate and heart rate variability (HRV) using electrocardiography, arterial blood pressure, and perceived fatigue (Borg CR10 scale and SOFI). A test battery before, immediately after and 1 hour after the work period included measurements of maximal shoulder elevation strength (MVC), pressure pain threshold (PPT) over the trapezius muscles, and a submaximal isometric contraction. As expected, perceived fatigue and EMG amplitude increased during the physical work bouts. Recovery did occur between the bouts, but fatigue accumulated throughout the work period. Neither EMG changes nor recovery of perceived fatigue during breaks were influenced by cognitive task difficulty, while heart rate and HRV recovered the most during breaks with the most difficult task. Recovery of perceived fatigue after the 1 hour work period was also most pronounced for the most difficult cognitive condition, while MVC and PPT showed ambiguous patterns, and EMG recovered similarly after all three cognitive protocols. Thus, we could confirm that cognitive tasks between bouts of fatiguing physical work can, indeed, accelerate recovery of some factors associated with fatigue, even if benefits may be moderate and some responses may be equivocal. Our results encourage further research into combinations of physical and mental tasks in an occupational context.
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Affiliation(s)
- Svend Erik Mathiassen
- Centre for Musculoskeletal Research, Department of Occupational and Public Health Sciences, University of Gävle, Gävle, Sweden
- * E-mail:
| | - David M. Hallman
- Centre for Musculoskeletal Research, Department of Occupational and Public Health Sciences, University of Gävle, Gävle, Sweden
| | - Eugene Lyskov
- Centre for Musculoskeletal Research, Department of Occupational and Public Health Sciences, University of Gävle, Gävle, Sweden
| | - Staffan Hygge
- Department of Building, Energy and Environmental Engineering, University of Gävle, Gävle, Sweden
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Consider opioid therapy for chronic refractory breathlessness. DRUGS & THERAPY PERSPECTIVES 2014. [DOI: 10.1007/s40267-014-0132-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Inspiratory high frequency airway oscillation attenuates resistive loaded dyspnea and modulates respiratory function in young healthy individuals. PLoS One 2014; 9:e91291. [PMID: 24651392 PMCID: PMC3961233 DOI: 10.1371/journal.pone.0091291] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Accepted: 02/10/2014] [Indexed: 11/27/2022] Open
Abstract
Direct chest-wall percussion can reduce breathlessness in Chronic Obstructive Pulmonary Disease and respiratory function may be improved, in health and disease, by respiratory muscle training (RMT). We tested whether high-frequency airway oscillation (HFAO), a novel form of airflow oscillation generation can modulate induced dyspnoea and respiratory strength and/or patterns following 5 weeks of HFAO training (n = 20) compared to a SHAM-RMT (conventional flow-resistive RMT) device (n = 15) in healthy volunteers (13 males; aged 20–36 yrs). HFAO causes oscillations with peak-to-peak amplitude of 1 cm H2O, whereas the SHAM-RMT device was identical but created no pressure oscillation. Respiratory function, dyspnoea and ventilation during 3 minutes of spontaneous resting ventilation, 1 minute of maximal voluntary hyperventilation and 1 minute breathing against a moderate inspiratory resistance, were compared PRE and POST 5-weeks of training (2×30 breaths at 70% peak flow, 5 days a week). Training significantly reduced NRS dyspnoea scores during resistive loaded ventilation, both in the HFAO (p = 0.003) and SHAM-RMT (p = 0.005) groups. Maximum inspiratory static pressure (cm H2O) was significantly increased by HFAO training (vs. PRE; p<0.001). Maximum inspiratory dynamic pressure was increased by training in both the HFAO (vs. PRE; p<0.001) and SHAM-RMT (vs. PRE; p = 0.021) groups. Peak inspiratory flow rate (L.s−1) achieved during the maximum inspiratory dynamic pressure manoeuvre increased significantly POST (vs. PRE; p = 0.001) in the HFAO group only. HFAO reduced inspiratory resistive loading–induced dyspnoea and augments static and dynamic maximal respiratory manoeuvre performance in excess of flow-resistive IMT (SHAM-RMT) in healthy individuals without the respiratory discomfort associated with RMT.
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Abstract
During dynamic exercise, the healthy pulmonary system faces several major challenges, including decreases in mixed venous oxygen content and increases in mixed venous carbon dioxide. As such, the ventilatory demand is increased, while the rising cardiac output means that blood will have considerably less time in the pulmonary capillaries to accomplish gas exchange. Blood gas homeostasis must be accomplished by precise regulation of alveolar ventilation via medullary neural networks and sensory reflex mechanisms. It is equally important that cardiovascular and pulmonary system responses to exercise be precisely matched to the increase in metabolic requirements, and that the substantial gas transport needs of both respiratory and locomotor muscles be considered. Our article addresses each of these topics with emphasis on the healthy, young adult exercising in normoxia. We review recent evidence concerning how exercise hyperpnea influences sympathetic vasoconstrictor outflow and the effect this might have on the ability to perform muscular work. We also review sex-based differences in lung mechanics.
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Affiliation(s)
- Andrew William Sheel
- The School of Kinesiology, The University of British Columbia, Vancouver, Canada.
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The representation of egocentric space in the posterior parietal cortex. Behav Brain Sci 2013; 15 Spec No 4:691-700. [PMID: 23842408 DOI: 10.1017/s0140525x00072605] [Citation(s) in RCA: 244] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The posterior parietal cortex (PPC) is the most likely site where egocentric spatial relationships are represented in the brain. PPC cells receive visual, auditory, somaesthetic, and vestibular sensory inputs; oculomotor, head, limb, and body motor signals; and strong motivational projections from the limbic system. Their discharge increases not only when an animal moves towards a sensory target, but also when it directs its attention to it. PPC lesions have the opposite effect: sensory inattention and neglect. The PPC does not seem to contain a "map" of the location of objects in space but a distributed neural network for transforming one set of sensory vectors into other sensory reference frames or into various motor coordinate systems. Which set of transformation rules is used probably depends on attention, which selectively enhances the synapses needed for making a particular sensory comparison or aiming a particular movement.
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Jeran J, Koritnik B, Zidar I, Belič A, Zidar J. Sniffing-related motor cortical potential: topography and possible generators. Respir Physiol Neurobiol 2012; 185:249-56. [PMID: 23078972 DOI: 10.1016/j.resp.2012.10.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Revised: 10/04/2012] [Accepted: 10/05/2012] [Indexed: 11/19/2022]
Abstract
This study estimated the whole-scalp topography and possible generators of the cortical potential associated with volitional self-paced inspirations (sniffs). In 17 healthy subjects we recorded a 32-channel electroencephalogram (EEG) during sniffing, for comparison during finger flexions. We averaged the EEG with respect to movement onset, and performed current source density and principal component analysis on the grand averaged data. We identified an early negative sniffing-related cortical potential starting ∼1.5s before movement at the vertex, which, in its time-course and dipole orientation, closely resembled Bereitshaftspotential preceding finger flexions. Around the movement onset, its topography became unique with three negative current sources: one at the vertex, and two bilaterally over the fronto-temporal derivations. We conclude that sequential cortical activation in preparation for sniffing is similar to other volitional movements. The current sources at sniff onset at the vertex likely reflect somatotopic motor representation of the diaphragm, neck and intercostal muscles, whereas current sources over fronto-temporal derivations likely reflect the somatotopic representation of the orofacial muscles.
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Affiliation(s)
- Judita Jeran
- Institute of Clinical Neurophysiology, University Medical Centre Ljubljana, Zaloška cesta 7, SI-1000 Ljubljana, Slovenia.
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Parshall MB, Schwartzstein RM, Adams L, Banzett RB, Manning HL, Bourbeau J, Calverley PM, Gift AG, Harver A, Lareau SC, Mahler DA, Meek PM, O'Donnell DE. An official American Thoracic Society statement: update on the mechanisms, assessment, and management of dyspnea. Am J Respir Crit Care Med 2012; 185:435-52. [PMID: 22336677 PMCID: PMC5448624 DOI: 10.1164/rccm.201111-2042st] [Citation(s) in RCA: 1109] [Impact Index Per Article: 92.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Dyspnea is a common, distressing symptom of cardiopulmonary and neuromuscular diseases. Since the ATS published a consensus statement on dyspnea in 1999, there has been enormous growth in knowledge about the neurophysiology of dyspnea and increasing interest in dyspnea as a patient-reported outcome. PURPOSE The purpose of this document is to update the 1999 ATS Consensus Statement on dyspnea. METHODS An interdisciplinary committee of experts representing ATS assemblies on Nursing, Clinical Problems, Sleep and Respiratory Neurobiology, Pulmonary Rehabilitation, and Behavioral Science determined the overall scope of this update through group consensus. Focused literature reviews in key topic areas were conducted by committee members with relevant expertise. The final content of this statement was agreed upon by all members. RESULTS Progress has been made in clarifying mechanisms underlying several qualitatively and mechanistically distinct breathing sensations. Brain imaging studies have consistently shown dyspnea stimuli to be correlated with activation of cortico-limbic areas involved with interoception and nociception. Endogenous and exogenous opioids may modulate perception of dyspnea. Instruments for measuring dyspnea are often poorly characterized; a framework is proposed for more consistent identification of measurement domains. CONCLUSIONS Progress in treatment of dyspnea has not matched progress in elucidating underlying mechanisms. There is a critical need for interdisciplinary translational research to connect dyspnea mechanisms with clinical treatment and to validate dyspnea measures as patient-reported outcomes for clinical trials.
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Parshall MB, Schwartzstein RM, Adams L, Banzett RB, Manning HL, Bourbeau J, Calverley PM, Gift AG, Harver A, Lareau SC, Mahler DA, Meek PM, O'Donnell DE. An official American Thoracic Society statement: update on the mechanisms, assessment, and management of dyspnea. Am J Respir Crit Care Med 2012. [PMID: 22336677 DOI: 10.1164/rccm.201111–2042st] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Dyspnea is a common, distressing symptom of cardiopulmonary and neuromuscular diseases. Since the ATS published a consensus statement on dyspnea in 1999, there has been enormous growth in knowledge about the neurophysiology of dyspnea and increasing interest in dyspnea as a patient-reported outcome. PURPOSE The purpose of this document is to update the 1999 ATS Consensus Statement on dyspnea. METHODS An interdisciplinary committee of experts representing ATS assemblies on Nursing, Clinical Problems, Sleep and Respiratory Neurobiology, Pulmonary Rehabilitation, and Behavioral Science determined the overall scope of this update through group consensus. Focused literature reviews in key topic areas were conducted by committee members with relevant expertise. The final content of this statement was agreed upon by all members. RESULTS Progress has been made in clarifying mechanisms underlying several qualitatively and mechanistically distinct breathing sensations. Brain imaging studies have consistently shown dyspnea stimuli to be correlated with activation of cortico-limbic areas involved with interoception and nociception. Endogenous and exogenous opioids may modulate perception of dyspnea. Instruments for measuring dyspnea are often poorly characterized; a framework is proposed for more consistent identification of measurement domains. CONCLUSIONS Progress in treatment of dyspnea has not matched progress in elucidating underlying mechanisms. There is a critical need for interdisciplinary translational research to connect dyspnea mechanisms with clinical treatment and to validate dyspnea measures as patient-reported outcomes for clinical trials.
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Abstract
Abstract
This target article draws together two groups of experimental studies on the control of human movement through peripheral feedback and centrally generated signals of motor commands. First, during natural movement, feedback from muscle, joint, and cutaneous afferents changes; in human subjects these changes have reflex and kinesthetic consequences. Recent psychophysical and microneurographic evidence suggests that joint and even cutaneous afferents may have a proprioceptive role. Second, the role of centrally generated motor commands in the control of normal movements and movements following acute and chronic deafferentation is reviewed. There is increasing evidence that subjects can perceive their motor commands under various conditions, but that this is inadequate for normal movement; deficits in motor performance arise when the reliance on proprioceptive feedback is abolished either experimentally or because of pathology. During natural movement, the CNS appears to have access to functionally useful input from a range of peripheral receptors as well as from internally generated command signals. The unanswered questions that remain suggest a number of avenues for further research.
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Equilibrium-point hypothesis, minimum effort control strategy and the triphasic muscle activation pattern. Behav Brain Sci 2011. [DOI: 10.1017/s0140525x00073209] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Successive approximation in targeted movement: An alternative hypothesis. Behav Brain Sci 2011. [DOI: 10.1017/s0140525x00072848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Abstract
AbstractEngineers use neural networks to control systems too complex for conventional engineering solutions. To examine the behavior of individual hidden units would defeat the purpose of this approach because it would be largely uninterpretable. Yet neurophysiologists spend their careers doing just that! Hidden units contain bits and scraps of signals that yield only arcane hints about network function and no information about how its individual units process signals. Most literature on single-unit recordings attests to this grim fact. On the other hand, knowing a system's function and describing it with elegant mathematics tell one very little about what to expect of interneuronal behavior. Examples of simple networks based on neurophysiology are taken from the oculomotor literature to suggest how single-unit interpretability might decrease with increasing task complexity. It is argued that trying to explain how any real neural network works on a cell-by-cell, reductionist basis is futile and we may have to be content with trying to understand the brain at higher levels of organization.
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27
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Does the nervous system use equilibrium-point control to guide single and multiple joint movements? Behav Brain Sci 2011; 15:603-13. [PMID: 23302290 DOI: 10.1017/s0140525x00072538] [Citation(s) in RCA: 303] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Li S, Rymer WZ. Voluntary breathing influences corticospinal excitability of nonrespiratory finger muscles. J Neurophysiol 2010; 105:512-21. [PMID: 21160006 DOI: 10.1152/jn.00946.2010] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The present study aimed to investigate neurophysiologic mechanisms mediating the newly discovered phenomenon of respiratory-motor interactions and to explore its potential clinical application for motor recovery. First, young and healthy subjects were instructed to breathe normally (NORM); to exhale (OUT) or inhale (IN) as fast as possible in a self-paced manner; or to voluntarily hold breath (HOLD). In experiment 1 (n = 14), transcranial magnetic stimulation (TMS) was applied during 10% maximal voluntary contraction (MVC) finger flexion force production or at rest. The motor-evoked potentials (MEPs) were recorded from flexor digitorum superficialis (FDS), extensor digitorum communis (EDC), and abductor digiti minimi (ADM) muscles. Similarly, in experiment 2 (n = 11), electrical stimulation (ES) was applied to FDS or EDC during the described four breathing conditions while subjects maintained 10%MVC of finger flexion or extension and at rest. In the exploratory clinical experiments (experiment 3), four patients with chronic neurological disorders (three strokes, one traumatic brain injury) received a 30-min session of breathing-controlled ES to the impaired EDC. In experiment 1, the EDC MEP magnitudes increased significantly during IN and OUT at both 10%MVC and rest; the FDS MEPs were enhanced only at 10%MVC, whereas the ADM MEP increased only during OUT, compared with NORM for both at rest and 10%MVC. No difference was found between NORM and HOLD for all three muscles. In experiment 2, when FDS was stimulated, force response was enhanced during both IN and OUT, but only at 10%MVC. When EDC was stimulated, force response increased at both 10%MVC and rest, only during IN, but not OUT. The averaged response latency was 83 ms for the finger extensors and 79 ms for the finger flexors. After a 30-min intervention of ES to EDC triggered by forced inspiration in experiment 3, we observed a significant reduction in finger flexor spasticity. The spasticity reduction lasted for ≥ 4 wk in all four patients. TMS and ES data, collectively, support the phenomenon that there is an overall respiration-related enhancement on the motor system, with a strong inspiration-finger extension coupling during voluntary breathing. As such, breathing-controlled electrical stimulation (i.e., stimulation to finger extensors delivered during the voluntary inspiratory phase) could be applied for enhancing finger extension strength and finger flexor spasticity reduction in poststroke patients.
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Affiliation(s)
- Sheng Li
- University of Texas Health Science Center at Houston, Department of Physical Medicine and Rehabilitation, Houston, TX 77030, USA.
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Gigliotti F. Mechanisms of dyspnea in healthy subjects. Multidiscip Respir Med 2010; 5:195-201. [PMID: 22958405 PMCID: PMC3463042 DOI: 10.1186/2049-6958-5-3-195] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2010] [Accepted: 04/06/2010] [Indexed: 11/18/2022] Open
Abstract
Dyspnea is a general term used to characterize a range of different descriptors; it varies in intensity, and is influenced by a wide variety of factors such as cultural expectations and the patient's experiences. Healthy subjects can experience dyspnea in different situations, e.g. at high altitude, after breath-holding, during stressful situations that cause anxiety or panic, and more commonly during strenuous exercise. Discussing the mechanisms of dyspnea we need to briefly take into account the physiological mechanisms underlying the sensation of dyspnea: the functional status of the respiratory muscles, the role of chemoreceptors and mechanoreceptors, and how the sense of respiratory motor output reaches a level of conscious awareness. We also need to take into account theories on the pathophysiological mechanisms of the sensation of dyspnea and the possibility that each pathophysiological mechanism produces a distinct quality of breathing discomfort. The terms used by subjects to identify different characteristics of breathing discomfort - dyspnea descriptors - may contribute to understanding the mechanisms of dyspnea and providing the rationale for a specific diagnosis.
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Affiliation(s)
- Francesco Gigliotti
- Department of Pulmonary Rehabilitation, Fondazione Don C, Gnocchi, Florence, Italy.
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Laveneziana P. Qualitative aspects of exertional dyspnea in patients with restrictive lung disease. Multidiscip Respir Med 2010; 5:211-5. [PMID: 22958444 PMCID: PMC3463046 DOI: 10.1186/2049-6958-5-3-211] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2009] [Accepted: 01/10/2010] [Indexed: 11/30/2022] Open
Abstract
Restrictive lung disease is a broad term encompassing a number of conditions in which lung volumes are reduced. Dyspnea is a common clinical manifestation of restrictive lung disease and frequently becomes a prominent and disabling symptom that undermines patients' ability to function and engage in activities of daily living (especially in those with more advanced restriction). Effective management of this disabling symptom awaits a better understanding of its underlying physiology. In recent decades, our understanding of the mechanisms of dyspnea in restrictive lung disease has been improved by a small, but significant, body of research. One approach to the study of dyspnea is to identify the major qualitative dimensions of the symptom in an attempt to uncover different underlying neurophysiologic mechanisms. This article will review the existing literature on the intensity and qualitative dimensions of dyspnea during exercise in patients with restrictive lung disease. The main focus will be on interstitial lung disease (ILD), since it is the prototypical restrictive disease.
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Hudson AL, Butler JE, Gandevia SC, De Troyer A. Interplay Between the Inspiratory and Postural Functions of the Human Parasternal Intercostal Muscles. J Neurophysiol 2010; 103:1622-9. [DOI: 10.1152/jn.00887.2009] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The parasternal intercostal muscles are obligatory inspiratory muscles. To test the hypothesis that they are also involved in trunk rotation and to assess the effect of any postural role on inspiratory drive to the muscles, intramuscular electromyographic (EMG) recordings were made from the parasternal intercostals on the right side in six healthy subjects during resting breathing in a neutral posture (“neutral breaths”), during an isometric axial rotation effort of the trunk to the right (“ipsilateral rotation”) or left (“contralateral rotation”), and during resting breathing with the trunk rotated. The parasternal intercostals were commonly active during ipsilateral rotation but were consistently silent during contralateral rotation. In addition, with ipsilateral rotation, peak parasternal inspiratory activity was 201 ± 19% (mean ± SE) of the peak inspiratory activity in neutral breaths ( P < 0.001), and activity commenced earlier relative to the onset of inspiratory flow. These changes resulted from an increase in the discharge frequency of motor units (14.3 ± 0.3 vs. 11.0 ± 0.3 Hz; P < 0.001) and the recruitment of new motor units. The majority of units that discharged during ipsilateral rotation were also active in inspiration. However, with contralateral rotation, parasternal inspiratory activity was delayed relative to the onset of inspiratory flow, and peak activity was reduced to 72 ± 4% of that in neutral breaths ( P < 0.001). This decrease resulted from a decrease in the inspiratory discharge frequency of units (10.5 ± 0.2 vs. 12.0 ± 0.2 Hz; P < 0.001) and the derecruitment of units. These observations confirm that in addition to an inspiratory function, the parasternal intercostal muscles have a postural function. Furthermore the postural and inspiratory drives depolarize the same motoneurons, and the postural contraction of the muscles alters their output during inspiration in a direction-dependent manner.
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Affiliation(s)
- Anna L. Hudson
- Prince of Wales Medical Research Institute and University of New South Wales, Sydney, New South Wales, Australia; and
| | - Jane E. Butler
- Prince of Wales Medical Research Institute and University of New South Wales, Sydney, New South Wales, Australia; and
| | - Simon C. Gandevia
- Prince of Wales Medical Research Institute and University of New South Wales, Sydney, New South Wales, Australia; and
| | - Andre De Troyer
- Laboratory of Cardiorespiratory Physiology, Brussels School of Medicine and Chest Service, Erasme University Hospital, Brussels, Belgium
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McKay LC, Critchley HD, Murphy K, Frackowiak RS, Corfield DR. Sub-cortical and brainstem sites associated with chemo-stimulated increases in ventilation in humans. Neuroimage 2010; 49:2526-35. [DOI: 10.1016/j.neuroimage.2009.11.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2009] [Revised: 11/03/2009] [Accepted: 11/04/2009] [Indexed: 01/29/2023] Open
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Davenport PW, Reep RL, Thompson FJ. Phrenic nerve afferent activation of neurons in the cat SI cerebral cortex. J Physiol 2010; 588:873-86. [PMID: 20064855 DOI: 10.1113/jphysiol.2009.181735] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Stimulation of respiratory afferents elicits neural activity in the somatosensory region of the cerebral cortex in humans and animals. Respiratory afferents have been stimulated with mechanical loads applied to breathing and electrical stimulation of respiratory nerves and muscles. It was hypothesized that stimulation of the phrenic nerve myelinated afferents will activate neurons in the 3a and 3b region of the somatosensory cortex. This was investigated in cats with electrical stimulation of the intrathoracic phrenic nerve and C(5) root of the phrenic nerve. The somatosensory cortical response to phrenic afferent stimulation was recorded from the cortical surface, contralateral to the phrenic nerve, ispilateral to the phrenic nerve and with microelectrodes inserted into the cortical site of the surface dipole. Short-latency, primary cortical evoked potentials (1 degrees CEP) were recorded with stimulation of myelinated afferents of the intrathoracic phrenic nerve in the contralateral post-cruciate gyrus of all animals (n = 42). The mean onset and peak latencies were 8.5 +/- 5.7 ms and 21.8 +/- 9.8 ms, respectively. The rostro-caudal surface location of the 1 degrees CEP was found between the rostral edge of the post-cruciate dimple (PCD) and the rostral edge of the ansate sulcus, medio-lateral location was between 2 mm lateral to the sagittal sulcus and the lateral end of the cruciate sulcus. Histological examination revealed that the 1 degrees CEP sites were recorded over areas 3a and 3b of the SI somatosensory cortex. Intracortical activation of 16 neurons with two patterns of neural activity was recorded: (1) short-latency, short-duration activation of neurons and (2) long-latency, long-duration activation of neurons. Short-latency neurons had a mean onset latency of 10.4 +/- 3.1 ms and mean burst duration of 10.1 +/- 3.2 ms. The short-latency units were recorded at an average depth of 1.7 +/- 0.5 mm below the cortical surface. The long-latency neurons had a mean onset latency of 36.0 +/- 4.2 ms and mean burst duration of 32.2 +/- 8.4 ms. The long-latency units were recorded at an average depth of 2.4 +/- 0.2 mm below the cortical surface. The results of the study demonstrated that phrenic nerve afferents have a short-latency central projection to the SI somatosensory cortex. The phrenic afferents activated neurons in lamina III and IV of areas 3a and 3b. The cortical representation of phrenic nerve afferents is medial to the forelimb, lateral to the hindlimb, similar to thoracic loci, hence the phrenic afferent SI site in the cat homunculus is consistent with body position (thoracic region) rather than spinal segment (C(5)-C(7)). The phrenic afferent activation of the somatosensory cortex is bilateral, with the ipsilateral cortical activation occurring subsequent to the contralateral. These results support the hypothesis that phrenic afferents provide somatosensory information to the cerebral cortex which can be used for diaphragmatic proprioception and somatosensation.
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Affiliation(s)
- Paul W Davenport
- Department of Physiological Sciences, Box 100144, HSC, University of Florida, Gainesville, FL 32610, USA.
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Abstract
Dyspnea and activity limitation are the primary symptoms of chronic obstructive pulmonary disease and progress relentlessly as the disease advances. In COPD, dyspnea is multifactorial but abnormal dynamic ventilatory mechanics are believed to be important. Dynamic lung hyperinflation occurs during exercise in the majority of flow-limited patients with chronic obstructive pulmonary disease and may have serious sensory and mechanical consequences. This proposition is supported by several studies, which have shown a close correlation between indices of dynamic lung hyperinflation and measures of both exertional dyspnea and exercise performance. The strength of this association has been further confirmed by studies that have therapeutically manipulated this dependent variable. Relief of exertional dyspnea and improved exercise endurance following bronchodilator therapy correlate well with reduced lung hyperinflation. The mechanisms by which dynamic lung hyperinflation give rise to exertional dyspnea and exercise intolerance are complex. However, recent mechanistic studies suggest that dynamic lung hyperinflation-induced volume restriction and consequent neuromechanical uncoupling of the respiratory system are key mechanisms. This review examines, in some detail, the derangements of ventilatory mechanics that are peculiar to chronic obstructive pulmonary disease and attempts to provide a mechanistic rationale for the attendant respiratory discomfort and activity limitation.
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Affiliation(s)
- Denis E O'Donnell
- Division of Respiratory and Critical Care Medicine, Department of Medicine, Queen's University, Kingston, Ontario, Canada.
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Mechanisms of activity-related dyspnea in pulmonary diseases. Respir Physiol Neurobiol 2009; 167:116-32. [DOI: 10.1016/j.resp.2009.01.010] [Citation(s) in RCA: 161] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2009] [Accepted: 01/30/2009] [Indexed: 01/22/2023]
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Ofir D, Laveneziana P, Webb KA, Lam YM, O'Donnell DE. Sex differences in the perceived intensity of breathlessness during exercise with advancing age. J Appl Physiol (1985) 2008; 104:1583-93. [DOI: 10.1152/japplphysiol.00079.2008] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The prevalence of activity-related breathlessness increases with age, particularly in women, but the specific underlying mechanisms have not been studied. This novel cross-sectional study was undertaken to examine the effects of age and sex, and their interaction, on the perceptual and ventilatory responses to incremental treadmill exercise in 73 healthy participants (age range 40–80 yr old) with normal pulmonary function. Age-related changes at a standardized oxygen uptake (V̇o2) during exercise included significant increases in breathlessness ratings (Borg scale), ventilation (V̇e), ventilatory equivalent for carbon dioxide, and the ratio of tidal volume (Vt) to dynamic inspiratory capacity (IC) (all P < 0.05). These changes were quantitatively similar in women ( n = 39) and in men ( n = 34). For the group as a whole, exertional breathlessness ratings increased as resting static inspiratory muscle strength diminished ( P = 0.05), as exercise ventilation increased relative to capacity ( P = 0.013) and as the Vt/IC ratio increased ( P = 0.003) during exercise. Older women (60–80 yr old, n = 23) reported greater ( P < 0.05) intensity of exertional breathlessness at a standardized V̇o2 and V̇e than age-matched men ( n = 16), despite similar age-related changes in ventilatory demand and dynamic ventilatory mechanics. These increases in breathlessness ratings in older women disappeared when sex differences in baseline maximal ventilatory capacity were accounted for. In conclusion, although increased exertional breathlessness with advancing age is multifactorial, contributory factors included higher ventilatory requirements during exercise, progressive inspiratory muscle weakness, and restrictive mechanical constraints on Vt expansion related to reduced IC. The sensory consequences of this age-related respiratory impairment were more pronounced in women, who, by nature, have relatively reduced maximal ventilatory reserve.
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Laveneziana P, Parker CM, O'Donnell DE. Ventilatory constraints and dyspnea during exercise in chronic obstructive pulmonary disease. Appl Physiol Nutr Metab 2008; 32:1225-38. [PMID: 18059601 DOI: 10.1139/h07-119] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Dyspnea (respiratory difficulty) and activity limitation are the primary symptoms of chronic obstructive pulmonary disease (COPD) and progress relentlessly as the disease advances, contributing to reduced quality of life. In COPD, the mechanisms of dyspnea are multifactorial, but abnormal dynamic ventilatory mechanics are believed to play a central role. In flow-limited patients with COPD, dynamic lung hyperinflation (DH) occurs during exercise and has serious sensory and mechanical consequences. In several studies, indices of DH strongly correlate with ratings of dyspnea intensity during exercise, and strategies that reduce resting hyperinflation (either pharmacological or surgical) consistently result in reduced exertional dyspnea. The mechanisms by which DH gives rise to exertional dyspnea and exercise intolerance are complex, but recent mechanistic studies suggest that DH-induced inspiratory muscle loading, restriction of tidal volume expansion during exercise, and consequent neuromechanical uncoupling of the respiratory system are key components. This review examines the specific derangements of ventilatory mechanics that occur in COPD during exercise and attempts to provide a mechanistic rationale for the attendant respiratory discomfort and activity limitation.
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Affiliation(s)
- Pierantonio Laveneziana
- Division of Respiratory and Critical Care Medicine, Department of Medicine, Queen's University, 102 Stuart St., Kingston, ON K7L 2V6
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Ofir D, Laveneziana P, Webb KA, Lam YM, O'Donnell DE. Mechanisms of dyspnea during cycle exercise in symptomatic patients with GOLD stage I chronic obstructive pulmonary disease. Am J Respir Crit Care Med 2007; 177:622-9. [PMID: 18006885 DOI: 10.1164/rccm.200707-1064oc] [Citation(s) in RCA: 244] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
RATIONALE Smokers with a relatively preserved FEV(1) may experience dyspnea and activity limitation but little is known about underlying mechanisms. OBJECTIVES To examine ventilatory constraints during exercise in symptomatic smokers with GOLD (Global Initiative for Chronic Obstructive Lung Disease) stage I chronic obstructive lung disease (COPD) so as to uncover potential mechanisms of dyspnea and exercise curtailment. METHODS We compared resting pulmonary function and ventilatory responses (breathing pattern, operating lung volumes, pulmonary gas exchange) with incremental cycle exercise as well as Borg scale ratings of dyspnea intensity in 21 patients (post-bronchodilator FEV(1), 91 +/- 7% predicted, and FEV(1)/FVC, 60 +/- 6%; mean +/- SD) with significant breathlessness and 21 healthy age- and sex-matched control subjects with normal spirometry. MEASUREMENTS AND MAIN RESULTS In patients with COPD compared with control subjects, peak oxygen consumption and power output were significantly reduced by more than 20% and dyspnea ratings were higher for a given work rate and ventilation (P < 0.05). Compared with the control group, the COPD group had evidence of extensive small airway dysfunction with increased ventilatory requirements during exercise, likely on the basis of greater ventilation/perfusion abnormalities. Changes in end-expiratory lung volume during exercise were greater in COPD than in health (0.54 +/- 0.34 vs. 0.06 +/- 0.32 L, respectively; P < 0.05) and breathing pattern was correspondingly more shallow and rapid. Across groups, dyspnea intensity increased as ventilation expressed as a percentage of capacity increased (P < 0.0005) and as inspiratory reserve volume decreased (P < 0.0005). CONCLUSIONS Exertional dyspnea in symptomatic patients with mild COPD is associated with the combined deleterious effects of higher ventilatory demand and abnormal dynamic ventilatory mechanics, both of which are potentially amenable to treatment.
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Affiliation(s)
- Dror Ofir
- F.R.C.P.C., 102 Stuart Street, Kingston, ON, K7L 2V6 Canada.
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Ofir D, Laveneziana P, Webb KA, O'Donnell DE. Ventilatory and perceptual responses to cycle exercise in obese women. J Appl Physiol (1985) 2007; 102:2217-26. [PMID: 17234804 DOI: 10.1152/japplphysiol.00898.2006] [Citation(s) in RCA: 129] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The main purpose of this study was to examine the relative contribution of respiratory mechanical factors and the increased metabolic cost of locomotion to exertional breathlessness in obese women. We examined the relationship of intensity of breathlessness to ventilation (V̇e) when exertional oxygen uptake (V̇o2) of obesity was minimized by cycle exercise. Eighteen middle-aged (54 ± 8 yr, mean ± SD) obese [body mass index (BMI) 40.2 ± 7.8 kg/m2] and 13 age-matched normal-weight (BMI 23.3 ± 1.7 kg/m2) women were studied. Breathlessness at higher submaximal cycle work rates was significantly increased (by ≥1 Borg unit) in obese compared with normal-weight women, in association with a 35–45% increase in V̇e and a higher metabolic cost of exercise. Obese women demonstrated greater resting expiratory flow limitation, reduced resting end-expiratory lung volume (EELV)(by 20%), and progressive increases in dynamic EELV during exercise: peak inspiratory capacity (IC) decreased by 16% (0.39 liter) of the resting value. V̇e/V̇o2 slopes were unchanged in obesity. Breathlessness ratings at any given V̇e or V̇o2 were not increased in obesity, suggesting that respiratory mechanical factors were not contributory. Our results indicate that in obese women, recruitment of resting IC and dynamic increases in EELV with exercise served to optimize operating lung volumes and to attenuate expiratory flow limitation so as to accommodate the increased ventilatory demand without increased breathlessness.
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Affiliation(s)
- Dror Ofir
- Respiratory Investigation Unit, Department of Medicine, Queen's University, 102 Stuart St., Kingston, Ontario, Canada K7L 2V6
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Davenport PW, Chan PYS, Zhang W, Chou YL. Detection threshold for inspiratory resistive loads and respiratory-related evoked potentials. J Appl Physiol (1985) 2007; 102:276-85. [PMID: 17008431 DOI: 10.1152/japplphysiol.01436.2005] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The relationship between detection threshold of inspiratory resistive loads and the peaks of the respiratory-related evoked potential (RREP) is unknown. It was hypothesized that the short-latency and long-latency peaks of the RREP would only be elicited by inspiratory loads that exceeded the detection threshold. The detection threshold for inspiratory resistive loads was measured in healthy subjects with inspiratory-interruption or onset load presentations. In a separate protocol, the RREPs were recorded with resistive loads that spanned the detection threshold. The loads were presented in stimulus attend and ignore sessions. Onset and interruption load presentations had the same resistive load detection threshold. The P1, Nf, and N1 peaks of the RREP were observed with loads that exceeded the detection threshold in both attend and ignore conditions. The P300 was present with loads that exceeded the detection threshold only in the attend condition. No RREP components were elicited with subthreshold loads. The P1, Nf, and P300 amplitudes varied with resistive load magnitude. The results support the hypothesis that there is a resistive load threshold for eliciting the RREPs. The amplitude of the RREP peaks vary as a function of load magnitude. The cognitive P300 RREP peak is present only for detectable loads and when the subject attends to the stimulus. The absence of the RREP with loads below the detection threshold and the presence of the RREP elicited by suprathreshold loads are consistent with the gating of these neural measures of respiratory mechanosensory information processing.
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Affiliation(s)
- Paul W Davenport
- Department of Physiological Sciences, Box 100144, HSC, University of Florida, Gainesville, FL 32610, USA.
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Lanctin C, Magot A, Chambellan A, Tich SNT, Pereon Y. Respiratory evoked potentials and occlusion elicited sympathetic skin response. Neurophysiol Clin 2005; 35:119-25. [PMID: 16311207 DOI: 10.1016/j.neucli.2005.07.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2004] [Accepted: 07/07/2005] [Indexed: 11/24/2022] Open
Abstract
INTRODUCTION Neurophysiological study of respiratory structures usually relies upon diaphragm electromyography and phrenic nerve conduction study, which do not assess the afferent sensory pathways. OBJECTIVE To assess the feasibility of respiratory evoked potentials (REPs) and sympathetic skin responses (SSRs) elicited by inspiratory occlusion. METHODS REPs and SSRs were studied in 12 healthy adults. REPs were elicited by inspiratory occlusions triggered by the physician within 1 s after the onset of a respiratory effort. They were recorded from C3, C4 and Cz needle electrodes (referenced to Fz). Each individual trial consisted of two superimposed 30-sweep averaged responses to inspiratory occlusions. SSRs were recorded from surface electrodes placed on the subject's hand and elicited by similar inspiratory occlusions. RESULTS Reproducible REPs and SSRs were obtained in all subjects. Mean latencies of initial P1 and N1 cortical responses were 41 and 72 ms, respectively. SSRs were similar to those usually elicited by peripheral nerve electrical stimulation. CONCLUSION Brief occlusion of inspiration induces cortical and sympathetic activation, both are easily recordable. Since REPs are considered to be the neurophysiological substrate of certain types of respiratory sensations and are altered in different chronic respiratory diseases, they, in addition to SSR, represent attractive new techniques that may provide better understanding of respiratory dysfunction.
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Affiliation(s)
- Caroline Lanctin
- Laboratoire d'Explorations Fonctionnelles, Hôtel Dieu, Nantes, France
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Abstract
Dyspnea is a common, unpleasant, and impairing symptom in various respiratory diseases and other diseases. Despite growing understanding of the multiple peripheral mechanisms giving rise to dyspnea, little is known about the cortical mechanisms underlying its perception. The results of neuroimaging studies have shown that distinct brain areas process the dyspneic sensation, among which the anterior insular seems to be the most important. Based on the findings of the first relevant neuroimaging studies, this review describes the cortical structures associated with the perception of dyspnea. Moreover, similarities to the perception of pain are discussed, and implications for future research are provided.
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Affiliation(s)
- Andreas von Leupoldt
- Psychological Institute III, University of Hamburg, Von-Melle-Park 5, 20146 Hamburg, Germany.
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Straus C, Locher C, Zelter M, Derenne JP, Similowski T. Facilitation of the diaphragm response to transcranial magnetic stimulation by increases in human respiratory drive. J Appl Physiol (1985) 2004; 97:902-12. [PMID: 15133007 DOI: 10.1152/japplphysiol.00989.2003] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The human respiratory neural drive has an automatic component (bulbospinal pathway) and a volitional component (corticospinal pathway). The aim of this study was to assess the effects of a hypercapnia-induced increase in the automatic respiratory drive on the function of the diaphragmatic corticospinal pathway as independently as possible of any other influence. Thirteen healthy volunteers breathed room air and then 5 and 7% hyperoxic CO2. Cervical (cms) and transcranial (tms) magnetic stimulations were performed during early inspiration and expiration. Transdiaphragmatic pressure (Pdi) and surface electromyogram of the diaphragm (DiEMG) and of the abductor pollicis brevis (apbEMG) were recorded in response to cms and tms. During inspiration, Pdi,cms was unaffected by CO2, but Pdi,tms increased significantly with 7% CO2. During expiration, Pdi,cms was significantly reduced by CO2, whereas Pdi,tms was preserved. DiEMG,tms latencies decreased significantly during early inspiration and expiration (air vs. 5% CO2 and air vs. 7% CO2). DiEMG,tms amplitude increased significantly in response to early expiration-tms (air vs. 5% CO2 and air vs. 7% CO2) but not in response to early inspiration-tms. DiEMG,cms latencies and amplitudes were not affected by CO2 whereas 7% CO2 significantly increased the apbEMG,cms latency. The apbEMG,tms vs. apbEMG,cms latency difference was unaffected by CO2. In conclusion, increasing the automatic drive to breathe facilitates the response of the diaphragm to tms, during both inspiration and expiration. This could allow the corticospinal drive to breathe to keep the capacity to modulate respiration in conditions under which the automatic respiratory control is stimulated.
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Affiliation(s)
- C Straus
- UPRES EA 2397, Faculté de Médecine Pitié-Salpêtrière, Université Paris VI Pierre et Marie Curie, Paris, France
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Webster KE, Colrain IM, Davenport PW. P300 from inspiratory occlusion reflects orienting but not startle. Biol Psychol 2004; 66:21-33. [PMID: 15019168 DOI: 10.1016/j.biopsycho.2003.08.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2002] [Accepted: 08/11/2003] [Indexed: 11/22/2022]
Abstract
Sudden onset inspiratory occlusion stimuli elicit large amplitude P300 components and also startle blinks. The primary purpose of this study was to assess the influence of the startle reflex on the respiratory related P300. A secondary purpose was to assess changes in P300 scalp topography as a function of stimulus familiarity. Young adults (n=12) were exposed to 200 inspiratory occlusion stimuli, and EEG was recorded from 29 A1/A2 referenced sites. Data from the occlusions were divided into four consecutive blocks of 50 trials to assess blink and P300 habituation effects. Results showed that 40% of the occlusion stimuli elicited a blink response, and that blink amplitude showed significant habituation across the experimental session. Change in P300 amplitude across the experimental session varied according to scalp site. At central and parietal locations, P300 amplitude showed an initial decrease but then remained stable. Frontally, P300 amplitude decreased over each of the four trial blocks. P300 scalp topography showed a classic centro-parietal maximum, however, a more frontally orientated scalp focus was seen for the first trial block. P300 was not significantly different when derived from averages of responses containing and not containing blinks. These data indicate that the previously studied centro-parietal P300 is not related to a startle reflex. However, when occlusions are first presented, a scalp topography similar to that previously noted for novel stimuli is observed.
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Affiliation(s)
- Kate E Webster
- Musculoskeletal Research Centre, La Trobe University, La Trobe, Victoria, Australia
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. ASH. Obstructive Sleep Apnea in Elevated Cardiac Output Patients: Hypercapnea-induced Hypoapnea. JOURNAL OF MEDICAL SCIENCES 2004. [DOI: 10.3923/jms.2004.170.175] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Lim CL, Seto-Poon M, Clouston PD, Morris JGL. Sudomotor nerve conduction velocity and central processing time of the skin conductance response. Clin Neurophysiol 2004; 114:2172-80. [PMID: 14580616 DOI: 10.1016/s1388-2457(03)00204-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
OBJECTIVE To estimate the sudomotor nerve conduction velocity (CV), the central processing time (CPT) and habituation of the skin conductance response (SCR). METHODS SCRs in response to a single deep inspiratory breath, an electrical stimulus and a sound click were obtained from the fingers and toes of 30 healthy adults. Sudomotor nerve conduction velocities were determined after measuring extremity length and latency differences. CPT was estimated by subtracting the efferent time and the known afferent times and neuroeffector times from the onset latency. RESULTS The inspiratory SCR habituated slower than the auditory or electrical SCRs. CVs of the 3 modalities did not differ statistically and their mean was 1.07 m s(-1) (95% CI: 1.01-1.13). The inspiratory SCR arrived at the fingers 1.26+/-0.09 s after the onset of chest wall movement. Electrical and auditory SCR onset latencies at the fingers were 1.60+/-0.03 and 1.75+/-0.04 s, respectively. Their CPTs were 140 and 160 ms, estimated from the electrical and auditory SCR onset latencies to the fingers. The CPT for inspiratory SCR was estimated to occur during the inspiratory CPT after the inspiratory decision and before chest movement. CONCLUSIONS In contrast to the SCR following an electrical or auditory stimulus, initiation of deep inspiratory SCR occurs before the inspiratory act, precluding any possible input from respiratory afferent receptors and implicating a central generator. SIGNIFICANCE This study provides new insights into the origin of the SCR following inspiration.
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Affiliation(s)
- C L Lim
- Department of Neurology (A4a), Westmead Hospital, Cnr Hawkesbury & Darcy Roads, Westmead, NSW 2145, Australia.
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McKay LC, Evans KC, Frackowiak RSJ, Corfield DR. Neural correlates of voluntary breathing in humans. J Appl Physiol (1985) 2003; 95:1170-8. [PMID: 12754178 DOI: 10.1152/japplphysiol.00641.2002] [Citation(s) in RCA: 183] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
To investigate the functional neuroanatomy of voluntary respiratory control, blood O2 level-dependent functional magnetic resonance imaging was performed in six healthy right-handed individuals during voluntary hyperpnea. Functional images of the whole brain were acquired during 30-s periods of spontaneous breathing alternated with 30-s periods of isocapnic hyperpnea [spontaneous vs. voluntary: tidal volume = 0.5 +/- 0.01 vs. 1.3 +/- 0.1 (SE) liters and breath duration = 4.0 +/- 0.4 vs. 3.2 +/- 0.4 (SE) s]. For the group, voluntary hyperpnea was associated with significant (P < 0.05, corrected for multiple comparisons) neural activity bilaterally in the primary sensory and motor cortices, supplementary motor area, cerebellum, thalamus, caudate nucleus, and globus pallidum. Significant increases in activity were also identified in the medulla (corrected for multiple comparisons on the basis of a small volume correction for a priori region of interest) in a superior dorsal position (P = 0.012). Activity within the medulla suggests that the brain stem respiratory centers may have a role in mediating the voluntary control of breathing in humans.
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Affiliation(s)
- L C McKay
- National Heart and Lung Instiute, Imperial College London, London W6 8RP, United Kingdom
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