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Li J, Zhou T, Wang P, Yin R, Zhang S, Cao Y, Zong L, Xiao M, Zhang Y, Liu W, Deng L, Huang F, Sun J, Wang H. Magnetic Stimulation of Gigantocellular Reticular Nucleus with Iron Oxide Nanoparticles Combined Treadmill Training Enhanced Locomotor Recovery by Reorganizing Cortico-Reticulo-Spinal Circuit. Int J Nanomedicine 2024; 19:7473-7492. [PMID: 39071504 PMCID: PMC11283264 DOI: 10.2147/ijn.s464498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2024] [Accepted: 07/06/2024] [Indexed: 07/30/2024] Open
Abstract
Background Gigantocellular reticular nucleus (GRNs) executes a vital role in locomotor recovery after spinal cord injury. However, due to its unique anatomical location deep within the brainstem, intervening in GRNs for spinal cord injury research is challenging. To address this problem, this study adopted an extracorporeal magnetic stimulation system to observe the effects of selective magnetic stimulation of GRNs with iron oxide nanoparticles combined treadmill training on locomotor recovery after spinal cord injury, and explored the possible mechanisms. Methods Superparamagnetic iron oxide (SPIO) nanoparticles were stereotactically injected into bilateral GRNs of mice with moderate T10 spinal cord contusion. Eight-week selective magnetic stimulation produced by extracorporeal magnetic stimulation system (MSS) combined with treadmill training was adopted for the animals from one week after surgery. Locomotor function of mice was evaluated by the Basso Mouse Scale, Grid-walking test and Treadscan analysis. Brain MRI, anterograde virus tracer and immunofluorescence staining were applied to observe the tissue compatibility of SPIO in GRNs, trace GRNs' projections and evaluate neurotransmitters' expression in spinal cord respectively. Motor-evoked potentials and H reflex were collected for assessing the integrity of cortical spinal tract and the excitation of motor neurons in anterior horn. Results (1) SPIO persisted in GRNs for a minimum of 24 weeks without inducing apoptosis of GRN cells, and degraded slowly over time. (2) MSS-enabled treadmill training dramatically improved locomotor performances of injured mice, and promoted cortico-reticulo-spinal circuit reorganization. (3) MSS-enabled treadmill training took superimposed roles through both activating GRNs to drive more projections of GRNs across lesion site and rebalancing neurotransmitters' expression in anterior horn of lumbar spinal cord. Conclusion These results indicate that selective MSS intervention of GRNs potentially serves as an innovative strategy to promote more spared fibers of GRNs across lesion site and rebalance neurotransmitters' expression after spinal cord injury, paving the way for the structural remodeling of neural systems collaborating with exercise training, thus ultimately contributing to the reconstruction of cortico-reticulo-spinal circuit.
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Affiliation(s)
- Juan Li
- Department of Rehabilitation Medicine, Zhongda Hospital Southeast University, Nanjing, 210024, People’s Republic of China
| | - Ting Zhou
- Department of Rehabilitation Medicine, Zhongda Hospital Southeast University, Nanjing, 210024, People’s Republic of China
| | - Pei Wang
- Department of Rehabilitation Medicine, Zhongda Hospital Southeast University, Nanjing, 210024, People’s Republic of China
| | - Ruian Yin
- Department of Rehabilitation Medicine, Zhongda Hospital Southeast University, Nanjing, 210024, People’s Republic of China
| | - Shengqi Zhang
- Department of Rehabilitation Medicine, Zhongda Hospital Southeast University, Nanjing, 210024, People’s Republic of China
| | - Yile Cao
- Department of Rehabilitation Medicine, Zhongda Hospital Southeast University, Nanjing, 210024, People’s Republic of China
| | - Lijuan Zong
- Department of Rehabilitation Medicine, Zhongda Hospital Southeast University, Nanjing, 210024, People’s Republic of China
| | - Ming Xiao
- Jiangsu Key Laboratory of Neurodegeneration, Nanjing Medical University, Nanjing, 211166, People’s Republic of China
| | - Yongjie Zhang
- Department of Human Anatomy, Nanjing Medical University, Nanjing, 211166, People’s Republic of China
| | - Wentao Liu
- Department of Pharmacology, Jiangsu Key Laboratory of Neurodegeneration, Nanjing Medical University, Nanjing, 211166, People’s Republic of China
| | - Lingxiao Deng
- Department of Neurological Surgery, Spinal Cord and Brain Injury Research Group, Stark Neurosciences Research Institute, Indianapolis, IN, 46202-2266, USA
| | - Fei Huang
- Institute of Neurobiology, Binzhou Medical University, Yantai, 264003, People’s Republic of China
| | - Jianfei Sun
- State Key Laboratory of Bioelectronics, Jiangsu Key Laboratory of Biomaterials and Devices, School of Biological Science and Medical Engineering, Southeast University, Nanjing, 210009, People’s Republic of China
| | - Hongxing Wang
- Department of Rehabilitation Medicine, Zhongda Hospital Southeast University, Nanjing, 210024, People’s Republic of China
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Ryczko D. The Mesencephalic Locomotor Region: Multiple Cell Types, Multiple Behavioral Roles, and Multiple Implications for Disease. Neuroscientist 2024; 30:347-366. [PMID: 36575956 PMCID: PMC11107129 DOI: 10.1177/10738584221139136] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The mesencephalic locomotor region (MLR) controls locomotion in vertebrates. In humans with Parkinson disease, locomotor deficits are increasingly associated with decreased activity in the MLR. This brainstem region, commonly considered to include the cuneiform and pedunculopontine nuclei, has been explored as a target for deep brain stimulation to improve locomotor function, but the results are variable, from modest to promising. However, the MLR is a heterogeneous structure, and identification of the best cell type to target is only beginning. Here, I review the studies that uncovered the role of genetically defined MLR cell types, and I highlight the cells whose activation improves locomotor function in animal models of Parkinson disease. The promising cell types to activate comprise some glutamatergic neurons in the cuneiform and caudal pedunculopontine nuclei, as well as some cholinergic neurons of the pedunculopontine nucleus. Activation of MLR GABAergic neurons should be avoided, since they stop locomotion or evoke bouts flanked with numerous stops. MLR is also considered a potential target in spinal cord injury, supranuclear palsy, primary progressive freezing of gait, or stroke. Better targeting of the MLR cell types should be achieved through optimized deep brain stimulation protocols, pharmacotherapy, or the development of optogenetics for human use.
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Affiliation(s)
- Dimitri Ryczko
- Département de Pharmacologie-Physiologie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, Canada
- Centre de recherche du Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, Canada
- Neurosciences Sherbrooke, Sherbrooke, Canada
- Institut de Pharmacologie de Sherbrooke, Sherbrooke, Canada
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3
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Missaghi K, Le Gal JP, Mercier J, Grover M, Beauséjour PA, Chartré S, Messihad O, Auclair F, Dubuc R. Revisiting the two rhythm generators for respiration in lampreys. Front Neuroanat 2024; 17:1270535. [PMID: 38250023 PMCID: PMC10796688 DOI: 10.3389/fnana.2023.1270535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Accepted: 11/17/2023] [Indexed: 01/23/2024] Open
Abstract
In lampreys, respiration consists of a fast and a slow rhythm. This study was aimed at characterizing both anatomically and physiologically the brainstem regions involved in generating the two rhythms. The fast rhythm generator has been located by us and others in the rostral hindbrain, rostro-lateral to the trigeminal motor nucleus. More recently, this was challenged by researchers reporting that the fast rhythm generator was located more rostrally and dorsomedially, in a region corresponding to the mesencephalic locomotor region. These contradictory observations made us re-examine the location of the fast rhythm generator using anatomical lesions and physiological recordings. We now confirm that the fast respiratory rhythm generator is in the rostro-lateral hindbrain as originally described. The slow rhythm generator has received less attention. Previous studies suggested that it was composed of bilateral, interconnected rhythm generating regions located in the caudal hindbrain, with ascending projections to the fast rhythm generator. We used anatomical and physiological approaches to locate neurons that could be part of this slow rhythm generator. Combinations of unilateral injections of anatomical tracers, one in the fast rhythm generator area and another in the lateral tegmentum of the caudal hindbrain, were performed to label candidate neurons on the non-injected side of the lateral tegmentum. We found a population of neurons extending from the facial to the caudal vagal motor nuclei, with no clear clustering in the cell distribution. We examined the effects of stimulating different portions of the labeled population on the respiratory activity. The rostro-caudal extent of the population was arbitrarily divided in three portions that were each stimulated electrically or chemically. Stimulation of either of the three sites triggered bursts of discharge characteristic of the slow rhythm, whereas inactivating any of them stopped the slow rhythm. Substance P injected locally in the lateral tegmentum accelerated the slow respiratory rhythm in a caudal hindbrain preparation. Our results show that the fast respiratory rhythm generator consists mostly of a population of neurons rostro-lateral to the trigeminal motor nucleus, whereas the slow rhythm generator is distributed in the lateral tegmentum of the caudal hindbrain.
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Affiliation(s)
- Kianoush Missaghi
- Département de Neurosciences, Université de Montréal, Montréal, QC, Canada
| | | | - Julien Mercier
- Département de Neurosciences, Université de Montréal, Montréal, QC, Canada
- Groupe de Recherche en Activité Physique Adaptée (GRAPA), Département des Sciences de l’Activité Physique, Université du Québec à Montréal, Montréal, QC, Canada
| | - Martin Grover
- Groupe de Recherche en Activité Physique Adaptée (GRAPA), Département des Sciences de l’Activité Physique, Université du Québec à Montréal, Montréal, QC, Canada
| | | | - Shannon Chartré
- Groupe de Recherche en Activité Physique Adaptée (GRAPA), Département des Sciences de l’Activité Physique, Université du Québec à Montréal, Montréal, QC, Canada
| | - Omima Messihad
- Département de Neurosciences, Université de Montréal, Montréal, QC, Canada
| | - François Auclair
- Département de Neurosciences, Université de Montréal, Montréal, QC, Canada
| | - Réjean Dubuc
- Département de Neurosciences, Université de Montréal, Montréal, QC, Canada
- Groupe de Recherche en Activité Physique Adaptée (GRAPA), Département des Sciences de l’Activité Physique, Université du Québec à Montréal, Montréal, QC, Canada
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Ryczko D, Dubuc R. Dopamine control of downstream motor centers. Curr Opin Neurobiol 2023; 83:102785. [PMID: 37774481 DOI: 10.1016/j.conb.2023.102785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Revised: 08/18/2023] [Accepted: 08/26/2023] [Indexed: 10/01/2023]
Abstract
The role of dopamine in the control of movement is traditionally associated with ascending projections to the basal ganglia. However, more recently descending dopaminergic pathways projecting to downstream brainstem motor circuits were discovered. In lampreys, salamanders, and rodents, these include projections to the downstream Mesencephalic Locomotor Region (MLR), a brainstem region controlling locomotion. Such descending dopaminergic projections could prime brainstem networks controlling movement. Other descending dopaminergic projections have been shown to reach reticulospinal cells involved in the control of locomotion. In addition, dopamine directly modulates the activity of interneurons and motoneurons. Beyond locomotion, dopaminergic inputs modulate visuomotor transformations within the optic tectum (mammalian superior colliculus). Loss of descending dopaminergic inputs will likely contribute to pathological conditions such as in Parkinson's disease.
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Affiliation(s)
- Dimitri Ryczko
- Département de Pharmacologie-Physiologie, Université de Sherbrooke, Sherbrooke, Québec, Canada; Centre de recherche du Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, Canada; Neurosciences Sherbrooke, Sherbrooke, Canada; Institut de Pharmacologie de Sherbrooke, Sherbrooke, Canada.
| | - Réjean Dubuc
- Groupe de Recherche en Activité Physique Adaptée, Département des Sciences de l'Activité Physique, Université du Québec à Montréal, Montréal, Québec, Canada; Groupe de recherche sur la Signalisation Neurale et la Circuiterie, Département de Neurosciences, Université de Montréal, Montréal, Québec, Canada.
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5
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Gordleeva SY, Kastalskiy IA, Tsybina YA, Ermolaeva AV, Hramov AE, Kazantsev VB. Control of movement of underwater swimmers: Animals, simulated animates and swimming robots. Phys Life Rev 2023; 47:211-244. [PMID: 38072505 DOI: 10.1016/j.plrev.2023.10.037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Accepted: 10/29/2023] [Indexed: 12/18/2023]
Abstract
The control of movement in living organisms represents a fundamental task that the brain has evolved to solve. One crucial aspect is how the nervous system organizes the transformation of sensory information into motor commands. These commands lead to muscle activation and subsequent animal movement, which can exhibit complex patterns. One example of such movement is locomotion, which involves the translation of the entire body through space. Central Pattern Generators (CPGs) are neuronal circuits that provide control signals for these movements. Compared to the intricate circuits found in the brain, CPGs can be simplified into networks of neurons that generate rhythmic activation, coordinating muscle movements. Since the 1990s, researchers have developed numerous models of locomotive circuits to simulate different types of animal movement, including walking, flying, and swimming. Initially, the primary goal of these studies was to construct biomimetic robots. However, it became apparent that simplified CPGs alone were not sufficient to replicate the diverse range of adaptive locomotive movements observed in living organisms. Factors such as sensory modulation, higher-level control, and cognitive components related to learning and memory needed to be considered. This necessitated the use of more complex, high-dimensional circuits, as well as novel materials and hardware, in both modeling and robotics. With advancements in high-power computing, artificial intelligence, big data processing, smart materials, and electronics, the possibility of designing a new generation of true bio-mimetic robots has emerged. These robots have the capability to imitate not only simple locomotion but also exhibit adaptive motor behavior and decision-making. This motivation serves as the foundation for the current review, which aims to analyze existing concepts and models of movement control systems. As an illustrative example, we focus on underwater movement and explore the fundamental biological concepts, as well as the mathematical and physical models that underlie locomotion and its various modulations.
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Affiliation(s)
- S Yu Gordleeva
- National Research Lobachevsky State University of Nizhny Novgorod, 23 Gagarin Ave., Nizhny Novgorod, 603022, Russia; Immanuel Kant Baltic Federal University, 14 A. Nevskogo St., Kaliningrad, 236016, Russia; Moscow Institute of Physics and Technology, 9 Institutskiy Ln., Dolgoprudny, 141701, Moscow Region, Russia
| | - I A Kastalskiy
- National Research Lobachevsky State University of Nizhny Novgorod, 23 Gagarin Ave., Nizhny Novgorod, 603022, Russia; Moscow Institute of Physics and Technology, 9 Institutskiy Ln., Dolgoprudny, 141701, Moscow Region, Russia.
| | - Yu A Tsybina
- National Research Lobachevsky State University of Nizhny Novgorod, 23 Gagarin Ave., Nizhny Novgorod, 603022, Russia; I.M. Sechenov First Moscow State Medical University (Sechenov University), 2 Bol'shaya Pirogovskaya St., Moscow, 119435, Russia
| | - A V Ermolaeva
- National Research Lobachevsky State University of Nizhny Novgorod, 23 Gagarin Ave., Nizhny Novgorod, 603022, Russia; I.M. Sechenov First Moscow State Medical University (Sechenov University), 2 Bol'shaya Pirogovskaya St., Moscow, 119435, Russia
| | - A E Hramov
- Immanuel Kant Baltic Federal University, 14 A. Nevskogo St., Kaliningrad, 236016, Russia; Saint Petersburg State University, 7-9 Universitetskaya Emb., Saint Petersburg, 199034, Russia
| | - V B Kazantsev
- National Research Lobachevsky State University of Nizhny Novgorod, 23 Gagarin Ave., Nizhny Novgorod, 603022, Russia; Immanuel Kant Baltic Federal University, 14 A. Nevskogo St., Kaliningrad, 236016, Russia; Moscow Institute of Physics and Technology, 9 Institutskiy Ln., Dolgoprudny, 141701, Moscow Region, Russia
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6
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Carbo-Tano M, Lapoix M, Jia X, Thouvenin O, Pascucci M, Auclair F, Quan FB, Albadri S, Aguda V, Farouj Y, Hillman EMC, Portugues R, Del Bene F, Thiele TR, Dubuc R, Wyart C. The mesencephalic locomotor region recruits V2a reticulospinal neurons to drive forward locomotion in larval zebrafish. Nat Neurosci 2023; 26:1775-1790. [PMID: 37667039 PMCID: PMC10545542 DOI: 10.1038/s41593-023-01418-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 07/24/2023] [Indexed: 09/06/2023]
Abstract
The mesencephalic locomotor region (MLR) is a brain stem area whose stimulation triggers graded forward locomotion. How MLR neurons recruit downstream vsx2+ (V2a) reticulospinal neurons (RSNs) is poorly understood. Here, to overcome this challenge, we uncovered the locus of MLR in transparent larval zebrafish and show that the MLR locus is distinct from the nucleus of the medial longitudinal fasciculus. MLR stimulations reliably elicit forward locomotion of controlled duration and frequency. MLR neurons recruit V2a RSNs via projections onto somata in pontine and retropontine areas, and onto dendrites in the medulla. High-speed volumetric imaging of neuronal activity reveals that strongly MLR-coupled RSNs are active for steering or forward swimming, whereas weakly MLR-coupled medullary RSNs encode the duration and frequency of the forward component. Our study demonstrates how MLR neurons recruit specific V2a RSNs to control the kinematics of forward locomotion and suggests conservation of the motor functions of V2a RSNs across vertebrates.
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Affiliation(s)
- Martin Carbo-Tano
- Sorbonne Université, Paris Brain Institute (Institut du Cerveau, ICM), Institut National de la Santé et de la Recherche Médicale U1127, Centre National de la Recherche Scientifique Unité Mixte de Recherche 7225, Assistance Publique-Hôpitaux de Paris, Campus Hospitalier Pitié-Salpêtrière, Paris, France
| | - Mathilde Lapoix
- Sorbonne Université, Paris Brain Institute (Institut du Cerveau, ICM), Institut National de la Santé et de la Recherche Médicale U1127, Centre National de la Recherche Scientifique Unité Mixte de Recherche 7225, Assistance Publique-Hôpitaux de Paris, Campus Hospitalier Pitié-Salpêtrière, Paris, France
| | - Xinyu Jia
- Sorbonne Université, Paris Brain Institute (Institut du Cerveau, ICM), Institut National de la Santé et de la Recherche Médicale U1127, Centre National de la Recherche Scientifique Unité Mixte de Recherche 7225, Assistance Publique-Hôpitaux de Paris, Campus Hospitalier Pitié-Salpêtrière, Paris, France
| | - Olivier Thouvenin
- Institut Langevin, École Supérieure de Physique et de Chimie Industrielles de la Ville de Paris, Paris Sciences et Lettres, Centre National de la Recherche Scientifique, Paris, France
| | - Marco Pascucci
- Sorbonne Université, Paris Brain Institute (Institut du Cerveau, ICM), Institut National de la Santé et de la Recherche Médicale U1127, Centre National de la Recherche Scientifique Unité Mixte de Recherche 7225, Assistance Publique-Hôpitaux de Paris, Campus Hospitalier Pitié-Salpêtrière, Paris, France
- Université Paris-Saclay, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, Centre National de la Recherche Scientifique, NeuroSpin, Baobab, Centre d'études de Saclay, Gif-sur-Yvette, France
- The American University of Paris, Paris, France
| | - François Auclair
- Département de Neurosciences, Faculté de Médecine, Université de Montréal, Montréal, Quebec, Canada
| | - Feng B Quan
- Sorbonne Université, Paris Brain Institute (Institut du Cerveau, ICM), Institut National de la Santé et de la Recherche Médicale U1127, Centre National de la Recherche Scientifique Unité Mixte de Recherche 7225, Assistance Publique-Hôpitaux de Paris, Campus Hospitalier Pitié-Salpêtrière, Paris, France
| | - Shahad Albadri
- Sorbonne Université, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Institut de la Vision, Paris, France
| | - Vernie Aguda
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, Ontario, Canada
| | - Younes Farouj
- Institute of Neuroscience, Technical University of Munich, Munich, Germany
| | - Elizabeth M C Hillman
- Laboratory for Functional Optical Imaging, Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA
- Department of Biomedical Engineering, Columbia University, New York, NY, USA
- Kavli Institute for Brain Science, Columbia University, New York, NY, USA
| | - Ruben Portugues
- Institute of Neuroscience, Technical University of Munich, Munich, Germany
- Munich Cluster of Systems Neurology (SyNergy), Munich, Germany
| | - Filippo Del Bene
- Sorbonne Université, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Institut de la Vision, Paris, France
| | - Tod R Thiele
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, Ontario, Canada
| | - Réjean Dubuc
- Département de Neurosciences, Faculté de Médecine, Université de Montréal, Montréal, Quebec, Canada.
- Groupe de Recherche en Activité Physique Adaptée, Department of Exercise Science, Université du Québec à Montréal, Montréal, Quebec, Canada.
| | - Claire Wyart
- Sorbonne Université, Paris Brain Institute (Institut du Cerveau, ICM), Institut National de la Santé et de la Recherche Médicale U1127, Centre National de la Recherche Scientifique Unité Mixte de Recherche 7225, Assistance Publique-Hôpitaux de Paris, Campus Hospitalier Pitié-Salpêtrière, Paris, France.
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7
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Dubuc R, Cabelguen JM, Ryczko D. Locomotor pattern generation and descending control: a historical perspective. J Neurophysiol 2023; 130:401-416. [PMID: 37465884 DOI: 10.1152/jn.00204.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Revised: 07/11/2023] [Accepted: 07/12/2023] [Indexed: 07/20/2023] Open
Abstract
The ability to generate and control locomotor movements depends on complex interactions between many areas of the nervous system, the musculoskeletal system, and the environment. How the nervous system manages to accomplish this task has been the subject of investigation for more than a century. In vertebrates, locomotion is generated by neural networks located in the spinal cord referred to as central pattern generators. Descending inputs from the brain stem initiate, maintain, and stop locomotion as well as control speed and direction. Sensory inputs adapt locomotor programs to the environmental conditions. This review presents a comparative and historical overview of some of the neural mechanisms underlying the control of locomotion in vertebrates. We have put an emphasis on spinal mechanisms and descending control.
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Affiliation(s)
- Réjean Dubuc
- Groupe de Recherche en Activité Physique Adaptée, Département des Sciences de l'Activité Physique, Université du Québec à Montréal, Montreal, Quebec, Canada
- Groupe de Recherche sur le Système Nerveux Central, Département de Neurosciences, Université de Montréal, Montreal, Quebec, Canada
| | - Jean-Marie Cabelguen
- Institut National de la Santé et de la Recherche Médicale (INSERM) U 1215-Neurocentre Magendie, Université de Bordeaux, Bordeaux Cedex, France
| | - Dimitri Ryczko
- Département de Pharmacologie-Physiologie, Université de Sherbrooke, Sherbrooke, Quebec, Canada
- Centre de recherche du Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, Quebec, Canada
- Neurosciences Sherbrooke, Sherbrooke, Quebec, Canada
- Institut de Pharmacologie de Sherbrooke, Sherbrooke, Quebec, Canada
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8
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Lacroix-Ouellette P, Dubuc R. Brainstem neural mechanisms controlling locomotion with special reference to basal vertebrates. Front Neural Circuits 2023; 17:910207. [PMID: 37063386 PMCID: PMC10098025 DOI: 10.3389/fncir.2023.910207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 03/13/2023] [Indexed: 04/03/2023] Open
Abstract
Over the last 60 years, the basic neural circuitry responsible for the supraspinal control of locomotion has progressively been uncovered. Initially, significant progress was made in identifying the different supraspinal structures controlling locomotion in mammals as well as some of the underlying mechanisms. It became clear, however, that the complexity of the mammalian central nervous system (CNS) prevented researchers from characterizing the detailed cellular mechanisms involved and that animal models with a simpler nervous system were needed. Basal vertebrate species such as lampreys, xenopus embryos, and zebrafish became models of choice. More recently, optogenetic approaches have considerably revived interest in mammalian models. The mesencephalic locomotor region (MLR) is an important brainstem region known to control locomotion in all vertebrate species examined to date. It controls locomotion through intermediary cells in the hindbrain, the reticulospinal neurons (RSNs). The MLR comprises populations of cholinergic and glutamatergic neurons and their specific contribution to the control of locomotion is not fully resolved yet. Moreover, the downward projections from the MLR to RSNs is still not fully understood. Reporting on discoveries made in different animal models, this review article focuses on the MLR, its projections to RSNs, and the contribution of these neural elements to the control of locomotion. Excellent and detailed reviews on the brainstem control of locomotion have been recently published with emphasis on mammalian species. The present review article focuses on findings made in basal vertebrates such as the lamprey, to help direct new research in mammals, including humans.
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Affiliation(s)
| | - Réjean Dubuc
- Department of Neurosciences, Université de Montréal, Montréal, QC, Canada
- Department of Physical Activity Sciences, Université du Québec à Montréal, Montréal, QC, Canada
- Research Group for Adapted Physical Activity, Université du Québec à Montréal, Montréal, QC, Canada
- *Correspondence: Réjean Dubuc,
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Sobrido‐Cameán D, González‐Llera L, Anadón R, Barreiro‐Iglesias A. Organization of the corticotropin-releasing hormone and corticotropin-releasing hormone-binding protein systems in the central nervous system of the sea lamprey Petromyzon marinus. J Comp Neurol 2023; 531:58-88. [PMID: 36150899 PMCID: PMC9826344 DOI: 10.1002/cne.25412] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 08/27/2022] [Accepted: 08/30/2022] [Indexed: 01/11/2023]
Abstract
The expression of the corticotropin-releasing hormone (PmCRH) and the CRH-binding protein (PmCRHBP) mRNAs was studied by in situ hybridization in the brain of prolarvae, larvae, and adults of the sea lamprey Petromyzon marinus. We also generated an antibody against the PmCRH mature peptide to study the distribution of PmCRH-immunoreactive cells and fibers. PmCRH immunohistochemistry was combined with antityrosine hydroxylase immunohistochemistry, PmCRHBP in situ hybridization, or neurobiotin transport from the spinal cord. The most numerous PmCRH-expressing cells were observed in the magnocellular preoptic nucleus-paraventricular nucleus and in the superior and medial rhombencephalic reticular formation. PmCRH expression was more extended in adults than in larvae, and some cell populations were mainly (olfactory bulb) or only (striatum, ventral hypothalamus, prethalamus) observed in adults. The preopto-paraventricular fibers form conspicuous tracts coursing toward the neurohypophysis, but many immunoreactive fibers were also observed coursing in many other brain regions. Brain descending fibers in the spinal cord mainly come from cells located in the isthmus and in the medial rhombencephalic reticular nucleus. The distribution of PmCRHBP-expressing neurons was different from that of PmCRH cells, with cells mainly present in the septum, striatum, preoptic region, tuberal hypothalamus, pretectum, pineal complex, isthmus, reticular formation, and spinal cord. Again, expression in adults was more extended than in larvae. PmCRH- and PmCRHBP-expressing cells are different, excluding colocalization of these substances in the same neuron. Present findings reveal a complex CRH/CRHBP system in the brain of the oldest extant vertebrate group, the agnathans, which shows similarities but important divergences with that of mammals.
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Affiliation(s)
- Daniel Sobrido‐Cameán
- Department of Functional Biology, CIBUS, Faculty of BiologyUniversidade de Santiago de CompostelaSantiago de CompostelaSpain,Department of ZoologyUniversity of CambridgeCambridgeUK
| | - Laura González‐Llera
- Department of Functional Biology, CIBUS, Faculty of BiologyUniversidade de Santiago de CompostelaSantiago de CompostelaSpain
| | - Ramón Anadón
- Department of Functional Biology, CIBUS, Faculty of BiologyUniversidade de Santiago de CompostelaSantiago de CompostelaSpain
| | - Antón Barreiro‐Iglesias
- Department of Functional Biology, CIBUS, Faculty of BiologyUniversidade de Santiago de CompostelaSantiago de CompostelaSpain
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10
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Le Ray D, Bertrand SS, Dubuc R. Cholinergic Modulation of Locomotor Circuits in Vertebrates. Int J Mol Sci 2022; 23:ijms231810738. [PMID: 36142651 PMCID: PMC9501616 DOI: 10.3390/ijms231810738] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Revised: 09/08/2022] [Accepted: 09/09/2022] [Indexed: 11/24/2022] Open
Abstract
Locomotion is a basic motor act essential for survival. Amongst other things, it allows animals to move in their environment to seek food, escape predators, or seek mates for reproduction. The neural mechanisms involved in the control of locomotion have been examined in many vertebrate species and a clearer picture is progressively emerging. The basic muscle synergies responsible for propulsion are generated by neural networks located in the spinal cord. In turn, descending supraspinal inputs are responsible for starting, maintaining, and stopping locomotion as well as for steering and controlling speed. Several neurotransmitter systems play a crucial role in modulating the neural activity during locomotion. For instance, cholinergic inputs act both at the spinal and supraspinal levels and the underlying mechanisms are the focus of the present review. Much information gained on supraspinal cholinergic modulation of locomotion was obtained from the lamprey model. Nicotinic cholinergic inputs increase the level of excitation of brainstem descending command neurons, the reticulospinal neurons (RSNs), whereas muscarinic inputs activate a select group of hindbrain neurons that project to the RSNs to boost their level of excitation. Muscarinic inputs also reduce the transmission of sensory inputs in the brainstem, a phenomenon that could help in sustaining goal directed locomotion. In the spinal cord, intrinsic cholinergic inputs strongly modulate the activity of interneurons and motoneurons to control the locomotor output. Altogether, the present review underlines the importance of the cholinergic inputs in the modulation of locomotor activity in vertebrates.
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Affiliation(s)
- Didier Le Ray
- Institut des Neurosciences Cognitives et Intégratives d’Aquitaine (INCIA), UMR 5287, Université de Bordeaux-CNRS, F-33076 Bordeaux, France
- Correspondence: (D.L.R.); (R.D.)
| | - Sandrine S. Bertrand
- Institut des Neurosciences Cognitives et Intégratives d’Aquitaine (INCIA), UMR 5287, Université de Bordeaux-CNRS, F-33076 Bordeaux, France
| | - Réjean Dubuc
- Department of Neurosciences, Université de Montréal, Montréal, QC H3C 3J7, Canada
- Department of Physical Activity Sciences and Research Group in Adapted Physical Activity, Université du Québec à Montréal, Montréal, QC H3C 3P8, Canada
- Correspondence: (D.L.R.); (R.D.)
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11
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Abstract
The olfactory system allows animals to navigate in their environment to feed, mate, and escape predators. It is well established that odorant exposure or electrical stimulation of the olfactory system induces stereotyped motor responses in fishes. However, the neural circuitry responsible for the olfactomotor transformations is only beginning to be unraveled. A neural substrate eliciting motor responses to olfactory inputs was identified in the lamprey, a basal vertebrate used extensively to examine the neural mechanisms underlying sensorimotor transformations. Two pathways were discovered from the olfactory organ in the periphery to the brainstem motor nuclei responsible for controlling swimming. The first pathway originates from sensory neurons located in the accessory olfactory organ and reaches a single population of projection neurons in the medial olfactory bulb, which, in turn, transmit the olfactory signals to the posterior tuberculum and then to downstream brainstem locomotor centers. A second pathway originates from the main olfactory epithelium and reaches the main olfactory bulb, the neurons of which project to the pallium/cortex. The olfactory signals are then conveyed to the posterior tuberculum and then to brainstem locomotor centers. Olfactomotor behavior can adapt, and studies were aimed at defining the underlying neural mechanisms. Modulation of bulbar neural activity by GABAergic, dopaminergic, and serotoninergic inputs is likely to provide strong control over the hardwired circuits to produce appropriate motor behavior in response to olfactory cues. This review summarizes current knowledge relative to the neural circuitry producing olfactomotor behavior in lampreys and their modulatory mechanisms.
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12
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Ferreira-Pinto MJ, Kanodia H, Falasconi A, Sigrist M, Esposito MS, Arber S. Functional diversity for body actions in the mesencephalic locomotor region. Cell 2021; 184:4564-4578.e18. [PMID: 34302739 PMCID: PMC8382160 DOI: 10.1016/j.cell.2021.07.002] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 05/06/2021] [Accepted: 06/30/2021] [Indexed: 12/13/2022]
Abstract
The mesencephalic locomotor region (MLR) is a key midbrain center with roles in locomotion. Despite extensive studies and clinical trials aimed at therapy-resistant Parkinson's disease (PD), debate on its function remains. Here, we reveal the existence of functionally diverse neuronal populations with distinct roles in control of body movements. We identify two spatially intermingled glutamatergic populations separable by axonal projections, mouse genetics, neuronal activity profiles, and motor functions. Most spinally projecting MLR neurons encoded the full-body behavior rearing. Loss- and gain-of-function optogenetic perturbation experiments establish a function for these neurons in controlling body extension. In contrast, Rbp4-transgene-positive MLR neurons project in an ascending direction to basal ganglia, preferentially encode the forelimb behaviors handling and grooming, and exhibit a role in modulating movement. Thus, the MLR contains glutamatergic neuronal subpopulations stratified by projection target exhibiting roles in action control not restricted to locomotion.
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Affiliation(s)
- Manuel J Ferreira-Pinto
- Biozentrum, Department of Cell Biology, University of Basel, 4056 Basel, Switzerland; Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland
| | - Harsh Kanodia
- Biozentrum, Department of Cell Biology, University of Basel, 4056 Basel, Switzerland; Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland
| | - Antonio Falasconi
- Biozentrum, Department of Cell Biology, University of Basel, 4056 Basel, Switzerland; Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland
| | - Markus Sigrist
- Biozentrum, Department of Cell Biology, University of Basel, 4056 Basel, Switzerland; Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland
| | - Maria S Esposito
- Biozentrum, Department of Cell Biology, University of Basel, 4056 Basel, Switzerland; Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland
| | - Silvia Arber
- Biozentrum, Department of Cell Biology, University of Basel, 4056 Basel, Switzerland; Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland.
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13
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Wu MY, Carbo-Tano M, Mirat O, Lejeune FX, Roussel J, Quan FB, Fidelin K, Wyart C. Spinal sensory neurons project onto the hindbrain to stabilize posture and enhance locomotor speed. Curr Biol 2021; 31:3315-3329.e5. [PMID: 34146485 DOI: 10.1016/j.cub.2021.05.042] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 03/12/2021] [Accepted: 05/19/2021] [Indexed: 12/11/2022]
Abstract
In the spinal cord, cerebrospinal fluid-contacting neurons (CSF-cNs) are GABAergic interoceptive sensory neurons that detect spinal curvature via a functional coupling with the Reissner fiber. This mechanosensory system has recently been found to be involved in spine morphogenesis and postural control but the underlying mechanisms are not fully understood. In zebrafish, CSF-cNs project an ascending and ipsilateral axon reaching two to six segments away. Rostralmost CSF-cNs send their axons ipsilaterally into the hindbrain, a brain region containing motor nuclei and reticulospinal neurons (RSNs), which send descending motor commands to spinal circuits. Until now, the synaptic connectivity of CSF-cNs has only been investigated in the spinal cord, where they synapse onto motor neurons and premotor excitatory interneurons. The identity of CSF-cN targets in the hindbrain and the behavioral relevance of these sensory projections from the spinal cord to the hindbrain are unknown. Here, we provide anatomical and molecular evidence that rostralmost CSF-cNs synapse onto the axons of large RSNs including Mauthner cells and V2a neurons. Functional anatomy and optogenetically assisted mapping reveal that rostral CSF-cNs also synapse onto the soma and dendrites of cranial motor neurons innervating hypobranchial muscles. During acousto-vestibular evoked escape responses, ablation of rostralmost CSF-cNs results in a weaker escape response with a decreased C-bend amplitude, lower speed, and deficient postural control. Our study demonstrates that spinal sensory feedback enhances speed and stabilizes posture, and reveals a novel spinal gating mechanism acting on the output of descending commands sent from the hindbrain to the spinal cord.
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Affiliation(s)
- Ming-Yue Wu
- Sorbonne Université, Institut du Cerveau (ICM), Inserm U 1127, CNRS UMR 7225, 75013 Paris, France
| | - Martin Carbo-Tano
- Sorbonne Université, Institut du Cerveau (ICM), Inserm U 1127, CNRS UMR 7225, 75013 Paris, France.
| | - Olivier Mirat
- Sorbonne Université, Institut du Cerveau (ICM), Inserm U 1127, CNRS UMR 7225, 75013 Paris, France
| | - Francois-Xavier Lejeune
- Sorbonne Université, Institut du Cerveau (ICM), Inserm U 1127, CNRS UMR 7225, 75013 Paris, France
| | - Julian Roussel
- Sorbonne Université, Institut du Cerveau (ICM), Inserm U 1127, CNRS UMR 7225, 75013 Paris, France
| | - Feng B Quan
- Sorbonne Université, Institut du Cerveau (ICM), Inserm U 1127, CNRS UMR 7225, 75013 Paris, France
| | - Kevin Fidelin
- Sorbonne Université, Institut du Cerveau (ICM), Inserm U 1127, CNRS UMR 7225, 75013 Paris, France
| | - Claire Wyart
- Sorbonne Université, Institut du Cerveau (ICM), Inserm U 1127, CNRS UMR 7225, 75013 Paris, France.
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14
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van der Zouwen CI, Boutin J, Fougère M, Flaive A, Vivancos M, Santuz A, Akay T, Sarret P, Ryczko D. Freely Behaving Mice Can Brake and Turn During Optogenetic Stimulation of the Mesencephalic Locomotor Region. Front Neural Circuits 2021; 15:639900. [PMID: 33897379 PMCID: PMC8062873 DOI: 10.3389/fncir.2021.639900] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Accepted: 03/08/2021] [Indexed: 12/22/2022] Open
Abstract
A key function of the mesencephalic locomotor region (MLR) is to control the speed of forward symmetrical locomotor movements. However, the ability of freely moving mammals to integrate environmental cues to brake and turn during MLR stimulation is poorly documented. Here, we investigated whether freely behaving mice could brake or turn, based on environmental cues during MLR stimulation. We photostimulated the cuneiform nucleus (part of the MLR) in mice expressing channelrhodopsin in Vglut2-positive neurons in a Cre-dependent manner (Vglut2-ChR2-EYFP) using optogenetics. We detected locomotor movements using deep learning. We used patch-clamp recordings to validate the functional expression of channelrhodopsin and neuroanatomy to visualize the stimulation sites. In the linear corridor, gait diagram and limb kinematics were similar during spontaneous and optogenetic-evoked locomotion. In the open-field arena, optogenetic stimulation of the MLR evoked locomotion, and increasing laser power increased locomotor speed. Mice could brake and make sharp turns (~90°) when approaching a corner during MLR stimulation in the open-field arena. The speed during the turn was scaled with the speed before the turn, and with the turn angle. Patch-clamp recordings in Vglut2-ChR2-EYFP mice show that blue light evoked short-latency spiking in MLR neurons. Our results strengthen the idea that different brainstem neurons convey braking/turning and MLR speed commands in mammals. Our study also shows that Vglut2-positive neurons of the cuneiform nucleus are a relevant target to increase locomotor activity without impeding the ability to brake and turn when approaching obstacles, thus ensuring smooth and adaptable navigation. Our observations may have clinical relevance since cuneiform nucleus stimulation is increasingly considered to improve locomotion function in pathological states such as Parkinson's disease, spinal cord injury, or stroke.
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Affiliation(s)
- Cornelis Immanuel van der Zouwen
- Département de pharmacologie-physiologie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Joël Boutin
- Département de pharmacologie-physiologie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Maxime Fougère
- Département de pharmacologie-physiologie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Aurélie Flaive
- Département de pharmacologie-physiologie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Mélanie Vivancos
- Département de pharmacologie-physiologie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Alessandro Santuz
- Department of Medical Neuroscience, Atlantic Mobility Action Project, Brain Repair Center, Dalhousie University, Halifax, NS, Canada.,Department of Training and Movement Sciences, Humboldt-Universität zu Berlin, Berlin, Germany.,Berlin School of Movement Science, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Turgay Akay
- Department of Medical Neuroscience, Atlantic Mobility Action Project, Brain Repair Center, Dalhousie University, Halifax, NS, Canada
| | - Philippe Sarret
- Département de pharmacologie-physiologie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, QC, Canada.,Centre de recherche du Centre hospitalier universitaire de Sherbrooke, Sherbrooke, QC, Canada.,Centre d'excellence en neurosciences de l'Université de Sherbrooke, Sherbrooke, QC, Canada.,Institut de pharmacologie de Sherbrooke, Sherbrooke, QC, Canada
| | - Dimitri Ryczko
- Département de pharmacologie-physiologie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, QC, Canada.,Centre de recherche du Centre hospitalier universitaire de Sherbrooke, Sherbrooke, QC, Canada.,Centre d'excellence en neurosciences de l'Université de Sherbrooke, Sherbrooke, QC, Canada.,Institut de pharmacologie de Sherbrooke, Sherbrooke, QC, Canada
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15
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Flaive A, Fougère M, van der Zouwen CI, Ryczko D. Serotonergic Modulation of Locomotor Activity From Basal Vertebrates to Mammals. Front Neural Circuits 2020; 14:590299. [PMID: 33224027 PMCID: PMC7674590 DOI: 10.3389/fncir.2020.590299] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 09/28/2020] [Indexed: 12/14/2022] Open
Abstract
During the last 50 years, the serotonergic (5-HT) system was reported to exert a complex modulation of locomotor activity. Here, we focus on two key factors that likely contribute to such complexity. First, locomotion is modulated directly and indirectly by 5-HT neurons. The locomotor circuitry is directly innervated by 5-HT neurons in the caudal brainstem and spinal cord. Also, indirect control of locomotor activity results from ascending projections of 5-HT cells in the rostral brainstem that innervate multiple brain centers involved in motor action planning. Second, each approach used to manipulate the 5-HT system likely engages different 5-HT-dependent mechanisms. This includes the recruitment of different 5-HT receptors, which can have excitatory or inhibitory effects on cell activity. These receptors can be located far or close to the 5-HT release sites, making their activation dependent on the level of 5-HT released. Here we review the activity of different 5-HT nuclei during locomotor activity, and the locomotor effects of 5-HT precursors, exogenous 5-HT, selective 5-HT reuptake inhibitors (SSRI), electrical or chemical stimulation of 5-HT neurons, genetic deletions, optogenetic and chemogenetic manipulations. We highlight both the coherent and controversial aspects of 5-HT modulation of locomotor activity from basal vertebrates to mammals. This mini review may hopefully inspire future studies aiming at dissecting the complex effects of 5-HT on locomotor function.
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Affiliation(s)
- Aurélie Flaive
- Département de Pharmacologie-Physiologie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Maxime Fougère
- Département de Pharmacologie-Physiologie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Cornelis Immanuel van der Zouwen
- Département de Pharmacologie-Physiologie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Dimitri Ryczko
- Département de Pharmacologie-Physiologie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC, Canada.,Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, QC, Canada.,Institut de Pharmacologie de Sherbrooke, Sherbrooke, QC, Canada.,Centre des Neurosciences de Sherbrooke, Sherbrooke, QC, Canada
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16
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Ryczko D, Grätsch S, Alpert MH, Cone JJ, Kasemir J, Ruthe A, Beauséjour PA, Auclair F, Roitman MF, Alford S, Dubuc R. Descending Dopaminergic Inputs to Reticulospinal Neurons Promote Locomotor Movements. J Neurosci 2020; 40:8478-8490. [PMID: 32998974 PMCID: PMC7605428 DOI: 10.1523/jneurosci.2426-19.2020] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Revised: 09/01/2020] [Accepted: 09/24/2020] [Indexed: 01/25/2023] Open
Abstract
Meso-diencephalic dopaminergic neurons are known to modulate locomotor behaviors through their ascending projections to the basal ganglia, which in turn project to the mesencephalic locomotor region, known to control locomotion in vertebrates. In addition to their ascending projections, dopaminergic neurons were found to increase locomotor movements through direct descending projections to the mesencephalic locomotor region and spinal cord. Intriguingly, fibers expressing tyrosine hydroxylase (TH), the rate-limiting enzyme of dopamine synthesis, were also observed around reticulospinal neurons of lampreys. We now examined the origin and the role of this innervation. Using immunofluorescence and tracing experiments, we found that fibers positive for dopamine innervate reticulospinal neurons in the four reticular nuclei of lampreys. We identified the dopaminergic source using tracer injections in reticular nuclei, which retrogradely labeled dopaminergic neurons in a caudal diencephalic nucleus (posterior tuberculum [PT]). Using voltammetry in brain preparations isolated in vitro, we found that PT stimulation evoked dopamine release in all four reticular nuclei, but not in the spinal cord. In semi-intact preparations where the brain is accessible and the body moves, PT stimulation evoked swimming, and injection of a D1 receptor antagonist within the middle rhombencephalic reticular nucleus was sufficient to decrease reticulospinal activity and PT-evoked swimming. Our study reveals that dopaminergic neurons have access to command neurons that integrate sensory and descending inputs to activate spinal locomotor neurons. As such, our findings strengthen the idea that dopamine can modulate locomotor behavior both via ascending projections to the basal ganglia and through descending projections to brainstem motor circuits.SIGNIFICANCE STATEMENT Meso-diencephalic dopaminergic neurons play a key role in modulating locomotion by releasing dopamine in the basal ganglia, spinal networks, and the mesencephalic locomotor region, a brainstem region that controls locomotion in a graded fashion. Here, we report in lampreys that dopaminergic neurons release dopamine in the four reticular nuclei where reticulospinal neurons are located. Reticulospinal neurons integrate sensory and descending suprareticular inputs to control spinal interneurons and motoneurons. By directly modulating the activity of reticulospinal neurons, meso-diencephalic dopaminergic neurons control the very last instructions sent by the brain to spinal locomotor circuits. Our study reports on a new direct descending dopaminergic projection to reticulospinal neurons that modulates locomotor behavior.
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Affiliation(s)
- Dimitri Ryczko
- Department of Neuroscience, Université de Montréal, Montréal, Québec H3C 3J7, Canada
- Department of Pharmacology-Physiology, Université de Sherbrooke, Sherbrooke J1H 5N4, Québec Canada
- Centre de recherche du CHUS, Sherbrooke, J1H 5N4, Québec, Canada
| | - Swantje Grätsch
- Department of Neuroscience, Université de Montréal, Montréal, Québec H3C 3J7, Canada
| | - Michael H Alpert
- Department of Biological Sciences, University of Illinois at Chicago, Chicago IL 60607, Illinois
| | - Jackson J Cone
- Department of Psychology, University of Illinois at Chicago, Chicago IL 60607, Illinois
| | - Jacquelin Kasemir
- Department of Neuroscience, Université de Montréal, Montréal, Québec H3C 3J7, Canada
| | - Angelina Ruthe
- Department of Neuroscience, Université de Montréal, Montréal, Québec H3C 3J7, Canada
| | | | - François Auclair
- Department of Neuroscience, Université de Montréal, Montréal, Québec H3C 3J7, Canada
| | - Mitchell F Roitman
- Department of Psychology, University of Illinois at Chicago, Chicago IL 60607, Illinois
| | - Simon Alford
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago IL 60612-7308, Illinois
| | - Réjean Dubuc
- Department of Neuroscience, Université de Montréal, Montréal, Québec H3C 3J7, Canada
- Groupe de Recherche en Activité Physique Adaptée, Department of Exercise Science, Université du Québec à Montréal, Montréal, Québec H3C 3P8, Canada
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17
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Grillner S, El Manira A. Current Principles of Motor Control, with Special Reference to Vertebrate Locomotion. Physiol Rev 2019; 100:271-320. [PMID: 31512990 DOI: 10.1152/physrev.00015.2019] [Citation(s) in RCA: 227] [Impact Index Per Article: 45.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The vertebrate control of locomotion involves all levels of the nervous system from cortex to the spinal cord. Here, we aim to cover all main aspects of this complex behavior, from the operation of the microcircuits in the spinal cord to the systems and behavioral levels and extend from mammalian locomotion to the basic undulatory movements of lamprey and fish. The cellular basis of propulsion represents the core of the control system, and it involves the spinal central pattern generator networks (CPGs) controlling the timing of different muscles, the sensory compensation for perturbations, and the brain stem command systems controlling the level of activity of the CPGs and the speed of locomotion. The forebrain and in particular the basal ganglia are involved in determining which motor programs should be recruited at a given point of time and can both initiate and stop locomotor activity. The propulsive control system needs to be integrated with the postural control system to maintain body orientation. Moreover, the locomotor movements need to be steered so that the subject approaches the goal of the locomotor episode, or avoids colliding with elements in the environment or simply escapes at high speed. These different aspects will all be covered in the review.
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Affiliation(s)
- Sten Grillner
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
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19
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20
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21
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Lu Y, Zhang Z, Liang X, Chen Y, Zhang J, Yi H, Liu T, Yang L, Shi H, Zhang L. Study of gastrointestinal tract viability and motility via modulation of serotonin in a zebrafish model by probiotics. Food Funct 2019; 10:7416-7425. [DOI: 10.1039/c9fo02129a] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Investigated gastrointestinal tract viability and effect of potential probiotics on intestinal motility and the synthesis of serotonin in a zebrafish model.
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Affiliation(s)
- Youyou Lu
- College of Food Science and Engineering
- Ocean University of China
- Qingdao
- China
| | - Zhe Zhang
- College of Food Science and Engineering
- Ocean University of China
- Qingdao
- China
| | - Xi Liang
- College of Food Science and Engineering
- Ocean University of China
- Qingdao
- China
| | - Yujie Chen
- College of Food Science and Engineering
- Ocean University of China
- Qingdao
- China
| | - Junxue Zhang
- College of Food Science and Engineering
- Ocean University of China
- Qingdao
- China
| | - Huaxi Yi
- College of Food Science and Engineering
- Ocean University of China
- Qingdao
- China
| | - Tongjie Liu
- College of Food Science and Engineering
- Ocean University of China
- Qingdao
- China
| | - Liuqing Yang
- Department of Gastrointestinal Surgery/Department of Clinical Nutrition
- Beijing Shijitan Hospital
- Capital Medical University
- Department of Oncology
- Capital Medical University; Beijing International Science and Technology Cooperation Base for Cancer Metabolism and Nutrition
| | - Hanping Shi
- Department of Gastrointestinal Surgery/Department of Clinical Nutrition
- Beijing Shijitan Hospital
- Capital Medical University
- Department of Oncology
- Capital Medical University; Beijing International Science and Technology Cooperation Base for Cancer Metabolism and Nutrition
| | - Lanwei Zhang
- College of Food Science and Engineering
- Ocean University of China
- Qingdao
- China
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22
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A Brainstem Neural Substrate for Stopping Locomotion. J Neurosci 2018; 39:1044-1057. [PMID: 30541913 DOI: 10.1523/jneurosci.1992-18.2018] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 11/20/2018] [Accepted: 12/03/2018] [Indexed: 01/04/2023] Open
Abstract
Locomotion occurs sporadically and needs to be started, maintained, and stopped. The neural substrate underlying the activation of locomotion is partly known, but little is known about mechanisms involved in termination of locomotion. Recently, reticulospinal neurons (stop cells) were found to play a crucial role in stopping locomotion in the lamprey: their activation halts ongoing locomotion and their inactivation slows down the termination process. Intracellular recordings of these cells revealed a distinct activity pattern, with a burst of action potentials at the beginning of a locomotor bout and one at the end (termination burst). The termination burst was shown to be time linked to the end of locomotion, but the mechanisms by which it is triggered have remained unknown. We studied this in larval sea lampreys (Petromyzon marinus; the sex of the animals was not taken into account). We found that the mesencephalic locomotor region (MLR), which is known to initiate and control locomotion, stops ongoing locomotion by providing synaptic inputs that trigger the termination burst in stop cells. When locomotion is elicited by MLR stimulation, a second MLR stimulation stops the locomotor bout if it is of lower intensity than the initial stimulation. This occurs for MLR-induced, sensory-evoked, and spontaneous locomotion. Furthermore, we show that glutamatergic and, most likely, monosynaptic projections from the MLR activate stop cells during locomotion. Therefore, activation of the MLR not only initiates locomotion, but can also control the end of a locomotor bout. These results provide new insights onto the neural mechanisms responsible for stopping locomotion.SIGNIFICANCE STATEMENT The mesencephalic locomotor region (MLR) is a brainstem region well known to initiate and control locomotion. Since its discovery in cats in the 1960s, the MLR has been identified in all vertebrate species tested from lampreys to humans. We now demonstrate that stimulation of the MLR not only activates locomotion, but can also stop it. This is achieved through a descending glutamatergic signal, most likely monosynaptic, from the MLR to the reticular formation that activates reticulospinal stop cells. Together, our findings have uncovered a neural mechanism for stopping locomotion and bring new insights into the function of the MLR.
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23
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Yaeger DB, Coddington EJ. Calcium-induced calcium release activates spontaneous miniature outward currents in newt medullary reticular formation neurons. J Neurophysiol 2018; 120:3140-3154. [PMID: 29897864 DOI: 10.1152/jn.00616.2017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Neurons in the medullary reticular formation are involved in the control of postural and locomotor behaviors in all vertebrates. Reticulospinal neurons in this brain region provide one of the major descending projections to the spinal cord. Although neurons in the newt medullary reticular formation have been extensively studied using in vivo extracellular recordings, little is known of their intrinsic biophysical properties or of the underlying circuitry of this region. Using whole cell patch-clamp recordings in brain slices containing the rostromedial reticular formation from adult male newts, we observed spontaneous miniature outward currents (SMOCs) in ~2/3 of neurons. Although SMOCs superficially resembled inhibitory postsynaptic currents (IPSCs), they had slower risetimes and decay times than spontaneous IPSCs. SMOCs required intracellular Ca2+ release from ryanodine receptors and were also dependent on the influx of extracellular Ca2+. SMOCs were unaffected by apamin but were partially blocked by iberiotoxin and charybdotoxin, indicating that SMOCs were mediated by big-conductance Ca2+-activated K+ channels. Application of the sarco/endoplasmic Ca2+ ATPase inhibitor cyclopiazonic acid blocked the generation of SMOCs and also increased neural excitability. Neurons with SMOCs had significantly broader action potentials, slower membrane time constants, and higher input resistance than neurons without SMOCs. Thus, SMOCs may serve as a mechanism to regulate action potential threshold in a majority of neurons within the newt medullary reticular formation. NEW & NOTEWORTHY The medullary reticular formation exerts a powerful influence on sensorimotor integration and subsequent motor behavior, yet little is known about the neurons involved. In this study, we identify a transient potassium current that regulates action potential threshold in a majority of medullary reticular neurons.
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Daghfous G, Auclair F, Clotten F, Létourneau JL, Atallah E, Millette JP, Derjean D, Robitaille R, Zielinski BS, Dubuc R. GABAergic modulation of olfactomotor transmission in lampreys. PLoS Biol 2018; 16:e2005512. [PMID: 30286079 PMCID: PMC6191151 DOI: 10.1371/journal.pbio.2005512] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Revised: 10/16/2018] [Accepted: 09/18/2018] [Indexed: 12/21/2022] Open
Abstract
Odor-guided behaviors, including homing, predator avoidance, or food and mate searching, are ubiquitous in animals. It is only recently that the neural substrate underlying olfactomotor behaviors in vertebrates was uncovered in lampreys. It consists of a neural pathway extending from the medial part of the olfactory bulb (medOB) to locomotor control centers in the brainstem via a single relay in the caudal diencephalon. This hardwired olfactomotor pathway is present throughout life and may be responsible for the olfactory-induced motor behaviors seen at all life stages. We investigated modulatory mechanisms acting on this pathway by conducting anatomical (tract tracing and immunohistochemistry) and physiological (intracellular recordings and calcium imaging) experiments on lamprey brain preparations. We show that the GABAergic circuitry of the olfactory bulb (OB) acts as a gatekeeper of this hardwired sensorimotor pathway. We also demonstrate the presence of a novel olfactomotor pathway that originates in the non-medOB and consists of a projection to the lateral pallium (LPal) that, in turn, projects to the caudal diencephalon and to the mesencephalic locomotor region (MLR). Our results indicate that olfactory inputs can induce behavioral responses by activating brain locomotor centers via two distinct pathways that are strongly modulated by GABA in the OB. The existence of segregated olfactory subsystems in lampreys suggests that the organization of the olfactory system in functional clusters may be a common ancestral trait of vertebrates.
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Affiliation(s)
- Gheylen Daghfous
- Groupe de Recherche sur le Système Nerveux Central, Département de neurosciences, Université de Montréal, Montréal, Québec, Canada
- Groupe de Recherche en Activité Physique Adaptée, Département des sciences de l'activité physique, Université du Québec à Montréal, Montréal, Québec, Canada
| | - François Auclair
- Groupe de Recherche sur le Système Nerveux Central, Département de neurosciences, Université de Montréal, Montréal, Québec, Canada
| | - Felix Clotten
- Groupe de Recherche sur le Système Nerveux Central, Département de neurosciences, Université de Montréal, Montréal, Québec, Canada
| | - Jean-Luc Létourneau
- Groupe de Recherche en Activité Physique Adaptée, Département des sciences de l'activité physique, Université du Québec à Montréal, Montréal, Québec, Canada
| | - Elias Atallah
- Groupe de Recherche sur le Système Nerveux Central, Département de neurosciences, Université de Montréal, Montréal, Québec, Canada
| | - Jean-Patrick Millette
- Groupe de Recherche sur le Système Nerveux Central, Département de neurosciences, Université de Montréal, Montréal, Québec, Canada
| | - Dominique Derjean
- Groupe de Recherche sur le Système Nerveux Central, Département de neurosciences, Université de Montréal, Montréal, Québec, Canada
- Groupe de Recherche en Activité Physique Adaptée, Département des sciences de l'activité physique, Université du Québec à Montréal, Montréal, Québec, Canada
| | - Richard Robitaille
- Groupe de Recherche sur le Système Nerveux Central, Département de neurosciences, Université de Montréal, Montréal, Québec, Canada
| | - Barbara S. Zielinski
- Department of Biological Sciences, University of Windsor, Windsor, Ontario, Canada
- Great Lakes Institute for Environmental Research, University of Windsor, Windsor, Ontario, Canada
| | - Réjean Dubuc
- Groupe de Recherche sur le Système Nerveux Central, Département de neurosciences, Université de Montréal, Montréal, Québec, Canada
- Groupe de Recherche en Activité Physique Adaptée, Département des sciences de l'activité physique, Université du Québec à Montréal, Montréal, Québec, Canada
- * E-mail:
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Hamlet CL, Hoffman KA, Tytell ED, Fauci LJ. The role of curvature feedback in the energetics and dynamics of lamprey swimming: A closed-loop model. PLoS Comput Biol 2018; 14:e1006324. [PMID: 30118476 PMCID: PMC6114910 DOI: 10.1371/journal.pcbi.1006324] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Revised: 08/29/2018] [Accepted: 06/24/2018] [Indexed: 12/02/2022] Open
Abstract
Like other animals, lampreys have a central pattern generator (CPG) circuit that activates muscles for locomotion and also adjusts the activity to respond to sensory inputs from the environment. Such a feedback system is crucial for responding appropriately to unexpected perturbations, but it is also active during normal unperturbed steady swimming and influences the baseline swimming pattern. In this study, we investigate different functional forms of body curvature-based sensory feedback and evaluate their effects on steady swimming energetics and kinematics, since little is known experimentally about the functional form of curvature feedback. The distributed CPG is modeled as chains of coupled oscillators. Pairs of phase oscillators represent the left and right sides of segments along the lamprey body. These activate muscles that flex the body and move the lamprey through a fluid environment, which is simulated using a full Navier-Stokes model. The emergent curvature of the body then serves as an input to the CPG oscillators, closing the loop. We consider two forms of feedback, each consistent with experimental results on lamprey proprioceptive sensory receptors. The first, referred to as directional feedback, excites or inhibits the oscillators on the same side, depending on the sign of a chosen gain parameter, and has the opposite effect on oscillators on the opposite side. We find that directional feedback does not affect beat frequency, but does change the duration of muscle activity. The second feedback model, referred to as magnitude feedback, provides a symmetric excitatory or inhibitory effect to oscillators on both sides. This model tends to increase beat frequency and reduces the energetic cost to the lamprey when the gain is high and positive. With both types of feedback, the body curvature has a similar magnitude. Thus, these results indicate that the same magnitude of curvature-based feedback on the CPG with different functional forms can cause distinct differences in swimming performance. When animals move, they receive sensory inputs, which in turn are used to modulate the movement. Relatively little is known about how these inputs affect performance during steady locomotion. Using a computational model of a swimming lamprey, we investigated two different types of feedback, both consistent with experimental data. Both have strong, but different, effects on swimming speed and energy consumption, suggesting that sensory feedback is crucial not just for responding to perturbations, but also for high performance steady locomotion.
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Affiliation(s)
- Christina L. Hamlet
- Department of Mathematics, Bucknell University, Lewisburg, Pennsylvania, United States of America
- * E-mail:
| | - Kathleen A. Hoffman
- Department of Mathematics and Statistics, University of Maryland Baltimore County, Baltimore, Maryland, United States of America
| | - Eric D. Tytell
- Department of Biology, Tufts University, Medford, Massachusetts, United States of America
| | - Lisa J. Fauci
- Department of Mathematics, Tulane University, New Orleans, Louisiana, United States of America
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Namiki S, Dickinson MH, Wong AM, Korff W, Card GM. The functional organization of descending sensory-motor pathways in Drosophila. eLife 2018; 7:e34272. [PMID: 29943730 PMCID: PMC6019073 DOI: 10.7554/elife.34272] [Citation(s) in RCA: 171] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Accepted: 05/09/2018] [Indexed: 12/12/2022] Open
Abstract
In most animals, the brain controls the body via a set of descending neurons (DNs) that traverse the neck. DN activity activates, maintains or modulates locomotion and other behaviors. Individual DNs have been well-studied in species from insects to primates, but little is known about overall connectivity patterns across the DN population. We systematically investigated DN anatomy in Drosophila melanogaster and created over 100 transgenic lines targeting individual cell types. We identified roughly half of all Drosophila DNs and comprehensively map connectivity between sensory and motor neuropils in the brain and nerve cord, respectively. We find the nerve cord is a layered system of neuropils reflecting the fly's capability for two largely independent means of locomotion -- walking and flight -- using distinct sets of appendages. Our results reveal the basic functional map of descending pathways in flies and provide tools for systematic interrogation of neural circuits.
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Affiliation(s)
- Shigehiro Namiki
- Janelia Research Campus, Howard Hughes Medical InstituteAshburnUnited States
| | - Michael H Dickinson
- Division of Biology and BioengineeringCalifornia Institute of TechnologyPasadenaUnited States
| | - Allan M Wong
- Janelia Research Campus, Howard Hughes Medical InstituteAshburnUnited States
| | - Wyatt Korff
- Janelia Research Campus, Howard Hughes Medical InstituteAshburnUnited States
| | - Gwyneth M Card
- Janelia Research Campus, Howard Hughes Medical InstituteAshburnUnited States
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Josset N, Roussel M, Lemieux M, Lafrance-Zoubga D, Rastqar A, Bretzner F. Distinct Contributions of Mesencephalic Locomotor Region Nuclei to Locomotor Control in the Freely Behaving Mouse. Curr Biol 2018. [PMID: 29526593 DOI: 10.1016/j.cub.2018.02.007] [Citation(s) in RCA: 113] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The mesencephalic locomotor region (MLR) has been initially identified as a supraspinal center capable of initiating and modulating locomotion. Whereas its functional contribution to locomotion has been widely documented throughout the phylogeny from the lamprey to humans, there is still debate about its exact organization. Combining kinematic and electrophysiological recordings in mouse genetics, our study reveals that glutamatergic neurons of the cuneiform nucleus initiate locomotion and induce running gaits, whereas glutamatergic and cholinergic neurons of the pedunculopontine nucleus modulate locomotor pattern and rhythm, contributing to slow-walking gaits. By initiating, modulating, and accelerating locomotion, our study identifies and characterizes distinct neuronal populations of this functional region important to locomotor command.
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Affiliation(s)
- Nicolas Josset
- Centre de Recherche du CHU de Québec, CHUL-Neurosciences, 2705 boul. Laurier, Québec, QC G1V 4G2, Canada
| | - Marie Roussel
- Centre de Recherche du CHU de Québec, CHUL-Neurosciences, 2705 boul. Laurier, Québec, QC G1V 4G2, Canada
| | - Maxime Lemieux
- Centre de Recherche du CHU de Québec, CHUL-Neurosciences, 2705 boul. Laurier, Québec, QC G1V 4G2, Canada
| | - David Lafrance-Zoubga
- Centre de Recherche du CHU de Québec, CHUL-Neurosciences, 2705 boul. Laurier, Québec, QC G1V 4G2, Canada
| | - Ali Rastqar
- Centre de Recherche du CHU de Québec, CHUL-Neurosciences, 2705 boul. Laurier, Québec, QC G1V 4G2, Canada
| | - Frederic Bretzner
- Centre de Recherche du CHU de Québec, CHUL-Neurosciences, 2705 boul. Laurier, Québec, QC G1V 4G2, Canada; Faculty of Medicine, Department of Psychiatry and Neurosciences, Université Laval, Québec, QC G1V 4G2, Canada.
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Nigral Glutamatergic Neurons Control the Speed of Locomotion. J Neurosci 2017; 37:9759-9770. [PMID: 28924005 DOI: 10.1523/jneurosci.1810-17.2017] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Revised: 08/08/2017] [Accepted: 08/26/2017] [Indexed: 01/16/2023] Open
Abstract
The mesencephalic locomotor region (MLR) plays a crucial role in locomotor control. In vertebrates, stimulation of the MLR at increasing intensities elicits locomotion of growing speed. This effect has been presumed to result from higher brain inputs activating the MLR like a dimmer switch. Here, we show in lampreys (Petromyzon marinus) of either sex that incremental stimulation of a region homologous to the mammalian substantia nigra pars compacta (SNc) evokes increasing activation of MLR cells with a graded increase in the frequency of locomotor movements. Neurons co-storing glutamate and dopamine were found to project from the primal SNc to the MLR. Blockade of glutamatergic transmission largely diminished MLR cell responses and locomotion. Local blockade of D1 receptors in the MLR decreased locomotor frequency, but did not disrupt the SNc-evoked graded control of locomotion. Our findings revealed the presence of a glutamatergic input to the MLR originating from the primal SNc that evokes graded locomotor movements.SIGNIFICANCE STATEMENT The mesencephalic locomotor region (MLR) plays a crucial role in the control of locomotion. It projects downward to reticulospinal neurons that in turn activate the spinal locomotor networks. Increasing the intensity of MLR stimulation produces a growing activation of reticulospinal cells and a progressive increase in the speed of locomotor movements. Since the discovery of the MLR some 50 years ago, it has been presumed that higher brain regions activate the MLR in a graded fashion, but this has not been confirmed yet. Here, using a combination of techniques from cell to behavior, we provide evidence of a new glutamatergic pathway activating the MLR in a graded fashion, and consequently evoking a progressive increase in locomotor output.
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Ryczko D, Dubuc R. Dopamine and the Brainstem Locomotor Networks: From Lamprey to Human. Front Neurosci 2017; 11:295. [PMID: 28603482 PMCID: PMC5445171 DOI: 10.3389/fnins.2017.00295] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 05/11/2017] [Indexed: 11/13/2022] Open
Abstract
In vertebrates, dopamine neurons are classically known to modulate locomotion via their ascending projections to the basal ganglia that project to brainstem locomotor networks. An increased dopaminergic tone is associated with increase in locomotor activity. In pathological conditions where dopamine cells are lost, such as in Parkinson's disease, locomotor deficits are traditionally associated with the reduced ascending dopaminergic input to the basal ganglia. However, a descending dopaminergic pathway originating from the substantia nigra pars compacta was recently discovered. It innervates the mesencephalic locomotor region (MLR) from basal vertebrates to mammals. This pathway was shown to increase locomotor output in lampreys, and could very well play an important role in mammals. Here, we provide a detailed account on the newly found dopaminergic pathway in lamprey, salamander, rat, monkey, and human. In lampreys and salamanders, dopamine release in the MLR is associated with the activation of reticulospinal neurons that carry the locomotor command to the spinal cord. Dopamine release in the MLR potentiates locomotor movements through a D1-receptor mechanism in lampreys. In rats, stimulation of the substantia nigra pars compacta elicited dopamine release in the pedunculopontine nucleus, a known part of the MLR. In a monkey model of Parkinson's disease, a reduced dopaminergic innervation of the brainstem locomotor networks was reported. Dopaminergic fibers are also present in human pedunculopontine nucleus. We discuss the conserved locomotor role of this pathway from lamprey to mammals, and the hypothesis that this pathway could play a role in the locomotor deficits reported in Parkinson's disease.
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Affiliation(s)
- Dimitri Ryczko
- Groupe de Recherche sur le Système Nerveux Central, Département de Neurosciences, Université de MontréalMontréal, QC, Canada
| | - Réjean Dubuc
- Groupe de Recherche sur le Système Nerveux Central, Département de Neurosciences, Université de MontréalMontréal, QC, Canada.,Groupe de Recherche en Activité Physique Adaptée, Département des Sciences de l'Activité Physique, Université du Québec à MontréalMontréal, QC, Canada
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Harmon TC, Magaram U, McLean DL, Raman IM. Distinct responses of Purkinje neurons and roles of simple spikes during associative motor learning in larval zebrafish. eLife 2017; 6:e22537. [PMID: 28541889 PMCID: PMC5444900 DOI: 10.7554/elife.22537] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Accepted: 05/09/2017] [Indexed: 12/22/2022] Open
Abstract
To study cerebellar activity during learning, we made whole-cell recordings from larval zebrafish Purkinje cells while monitoring fictive swimming during associative conditioning. Fish learned to swim in response to visual stimulation preceding tactile stimulation of the tail. Learning was abolished by cerebellar ablation. All Purkinje cells showed task-related activity. Based on how many complex spikes emerged during learned swimming, they were classified as multiple, single, or zero complex spike (MCS, SCS, ZCS) cells. With learning, MCS and ZCS cells developed increased climbing fiber (MCS) or parallel fiber (ZCS) input during visual stimulation; SCS cells fired complex spikes associated with learned swimming episodes. The categories correlated with location. Optogenetically suppressing simple spikes only during visual stimulation demonstrated that simple spikes are required for acquisition and early stages of expression of learned responses, but not their maintenance, consistent with a transient, instructive role for simple spikes during cerebellar learning in larval zebrafish.
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Affiliation(s)
- Thomas C Harmon
- Department of Neurobiology, Northwestern University, Evanston, United States
- Interdepartmental Neuroscience Program, Northwestern University, Evanston, United States
| | - Uri Magaram
- Department of Neurobiology, Northwestern University, Evanston, United States
| | - David L McLean
- Department of Neurobiology, Northwestern University, Evanston, United States
- Interdepartmental Neuroscience Program, Northwestern University, Evanston, United States
| | - Indira M Raman
- Department of Neurobiology, Northwestern University, Evanston, United States
- Interdepartmental Neuroscience Program, Northwestern University, Evanston, United States
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Hsu LJ, Zelenin PV, Orlovsky GN, Deliagina TG. Supraspinal control of spinal reflex responses to body bending during different behaviours in lampreys. J Physiol 2016; 595:883-900. [PMID: 27589479 DOI: 10.1113/jp272714] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Accepted: 08/22/2016] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Spinal reflexes are substantial components of the motor control system in all vertebrates and centrally driven reflex modifications are essential to many behaviours, but little is known about the neuronal mechanisms underlying these modifications. To study this issue, we took advantage of an in vitro brainstem-spinal cord preparation of the lamprey (a lower vertebrate), in which spinal reflex responses to spinal cord bending (caused by signals from spinal stretch receptor neurons) can be evoked during different types of fictive behaviour. Our results demonstrate that reflexes observed during fast forward swimming are reversed during escape behaviours, with the reflex reversal presumably caused by supraspinal commands transmitted by a population of reticulospinal neurons. NMDA receptors are involved in the formation of these commands, which are addressed primarily to the ipsilateral spinal networks. In the present study the neuronal mechanisms underlying reflex reversal have been characterized for the first time. ABSTRACT Spinal reflexes can be modified during different motor behaviours. However, our knowledge about the neuronal mechanisms underlying these modifications in vertebrates is scarce. In the lamprey, a lower vertebrate, body bending causes activation of intraspinal stretch receptor neurons (SRNs) resulting in spinal reflexes: activation of motoneurons (MNs) with bending towards either the contralateral or ipsilateral side (a convex or concave response, respectively). The present study had two main aims: (i) to investigate how these spinal reflexes are modified during different motor behaviours, and (ii) to reveal reticulospinal neurons (RSNs) transmitting commands for the reflex modification. For this purpose in in vitro brainstem-spinal cord preparation, RSNs and reflex responses to bending were recorded during different fictive behaviours evoked by supraspinal commands. We found that during fast forward swimming MNs exhibited convex responses. By contrast, during escape behaviours, MNs exhibited concave responses. We found RSNs that were activated during both stimulation causing reflex reversal without initiation of any specific behaviour, and stimulation causing reflex reversal during escape behaviour. We suggest that these RSNs transmit commands for the reflex modification. Application of the NMDA antagonist (AP-5) to the brainstem significantly decreased the reversed reflex, suggesting involvement of NMDA receptors in the formation of these commands. Longitudinal split of the spinal cord did not abolish the reflex reversal caused by supraspinal commands, suggesting an important role for ipsilateral networks in determining this type of motor response. This is the first study to reveal the neuronal mechanisms underlying supraspinal control of reflex reversal.
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Affiliation(s)
- Li-Ju Hsu
- Department of Neuroscience, Karolinska Institute, SE-17177, Stockholm, Sweden
| | - Pavel V Zelenin
- Department of Neuroscience, Karolinska Institute, SE-17177, Stockholm, Sweden
| | - Grigori N Orlovsky
- Department of Neuroscience, Karolinska Institute, SE-17177, Stockholm, Sweden
| | - Tatiana G Deliagina
- Department of Neuroscience, Karolinska Institute, SE-17177, Stockholm, Sweden
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32
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The neural control of respiration in lampreys. Respir Physiol Neurobiol 2016; 234:14-25. [PMID: 27562521 DOI: 10.1016/j.resp.2016.08.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Revised: 08/08/2016] [Accepted: 08/21/2016] [Indexed: 11/24/2022]
Abstract
This review focuses on past and recent findings that have contributed to characterize the neural networks controlling respiration in the lamprey, a basal vertebrate. As in other vertebrates, respiration in lampreys is generated centrally in the brainstem. It is characterized by the presence of a fast and a slow respiratory rhythm. The anatomical and the basic physiological properties of the neural networks underlying the generation of the fast rhythm have been more thoroughly investigated; less is known about the generation of the slow respiratory rhythm. Comparative aspects with respiratory generators in other vertebrates as well as the mechanisms of modulation of respiration in association with locomotion are discussed.
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Juvin L, Grätsch S, Trillaud-Doppia E, Gariépy JF, Büschges A, Dubuc R. A Specific Population of Reticulospinal Neurons Controls the Termination of Locomotion. Cell Rep 2016; 15:2377-86. [DOI: 10.1016/j.celrep.2016.05.029] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Revised: 03/23/2016] [Accepted: 05/05/2016] [Indexed: 02/01/2023] Open
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Ryczko D, Cone JJ, Alpert MH, Goetz L, Auclair F, Dubé C, Parent M, Roitman MF, Alford S, Dubuc R. A descending dopamine pathway conserved from basal vertebrates to mammals. Proc Natl Acad Sci U S A 2016; 113:E2440-9. [PMID: 27071118 PMCID: PMC4855556 DOI: 10.1073/pnas.1600684113] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Dopamine neurons are classically known to modulate locomotion indirectly through ascending projections to the basal ganglia that project down to brainstem locomotor networks. Their loss in Parkinson's disease is devastating. In lampreys, we recently showed that brainstem networks also receive direct descending dopaminergic inputs that potentiate locomotor output. Here, we provide evidence that this descending dopaminergic pathway is conserved to higher vertebrates, including mammals. In salamanders, dopamine neurons projecting to the striatum or brainstem locomotor networks were partly intermingled. Stimulation of the dopaminergic region evoked dopamine release in brainstem locomotor networks and concurrent reticulospinal activity. In rats, some dopamine neurons projecting to the striatum also innervated the pedunculopontine nucleus, a known locomotor center, and stimulation of the dopaminergic region evoked pedunculopontine dopamine release in vivo. Finally, we found dopaminergic fibers in the human pedunculopontine nucleus. The conservation of a descending dopaminergic pathway across vertebrates warrants re-evaluating dopamine's role in locomotion.
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Affiliation(s)
- Dimitri Ryczko
- Groupe de Recherche sur le Système Nerveux Central, Département de Neurosciences, Université de Montréal, Montreal, QC, Canada H3C 3J7
| | - Jackson J Cone
- Department of Psychology, University of Illinois, Chicago, IL 60607
| | - Michael H Alpert
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL 60607
| | - Laurent Goetz
- Department of Psychiatry and Neuroscience, Faculty of Medicine, Centre de Recherche de l'Institut Universitaire en Santé Mentale de Québec, Université Laval, Quebec, QC, Canada G1J 2G3
| | - François Auclair
- Groupe de Recherche sur le Système Nerveux Central, Département de Neurosciences, Université de Montréal, Montreal, QC, Canada H3C 3J7
| | - Catherine Dubé
- Groupe de Recherche sur le Système Nerveux Central, Département de Neurosciences, Université de Montréal, Montreal, QC, Canada H3C 3J7
| | - Martin Parent
- Department of Psychiatry and Neuroscience, Faculty of Medicine, Centre de Recherche de l'Institut Universitaire en Santé Mentale de Québec, Université Laval, Quebec, QC, Canada G1J 2G3
| | | | - Simon Alford
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL 60607
| | - Réjean Dubuc
- Groupe de Recherche sur le Système Nerveux Central, Département de Neurosciences, Université de Montréal, Montreal, QC, Canada H3C 3J7; Département des Sciences de l'Activité Physique, Université du Québec à Montréal, Montreal, QC, Canada H3C 3P8
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35
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Daghfous G, Green WW, Alford ST, Zielinski BS, Dubuc R. Sensory Activation of Command Cells for Locomotion and Modulatory Mechanisms: Lessons from Lampreys. Front Neural Circuits 2016; 10:18. [PMID: 27047342 PMCID: PMC4801879 DOI: 10.3389/fncir.2016.00018] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Accepted: 03/07/2016] [Indexed: 11/13/2022] Open
Abstract
Sensorimotor transformation is one of the most fundamental and ubiquitous functions of the central nervous system (CNS). Although the general organization of the locomotor neural circuitry is relatively well understood, less is known about its activation by sensory inputs and its modulation. Utilizing the lamprey model, a detailed understanding of sensorimotor integration in vertebrates is emerging. In this article, we explore how the vertebrate CNS integrates sensory signals to generate motor behavior by examining the pathways and neural mechanisms involved in the transformation of cutaneous and olfactory inputs into motor output in the lamprey. We then review how 5-hydroxytryptamine (5-HT) acts on these systems by modulating both sensory inputs and motor output. A comprehensive review of this fundamental topic should provide a useful framework in the fields of motor control, sensorimotor integration and neuromodulation.
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Affiliation(s)
- Gheylen Daghfous
- Groupe de Recherche en Activité Physique Adaptée, Département des Sciences de l'Activité Physique, Université du Québec à MontréalMontréal, QC, Canada; Groupe de Recherche sur le Système Nerveux Central, Département de Neurosciences, Université de MontréalMontréal, QC, Canada
| | - Warren W Green
- Department of Biological Sciences and Great Lakes Institute for Environmental Research, University of Windsor Windsor, ON, Canada
| | - Simon T Alford
- Laboratory of Integrative Neuroscience, Department of Biological Sciences, University of Illinois at Chicago Chicago, IL, USA
| | - Barbara S Zielinski
- Department of Biological Sciences and Great Lakes Institute for Environmental Research, University of Windsor Windsor, ON, Canada
| | - Réjean Dubuc
- Groupe de Recherche en Activité Physique Adaptée, Département des Sciences de l'Activité Physique, Université du Québec à MontréalMontréal, QC, Canada; Groupe de Recherche sur le Système Nerveux Central, Département de Neurosciences, Université de MontréalMontréal, QC, Canada
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Ryczko D, Auclair F, Cabelguen JM, Dubuc R. The mesencephalic locomotor region sends a bilateral glutamatergic drive to hindbrain reticulospinal neurons in a tetrapod. J Comp Neurol 2015; 524:1361-83. [PMID: 26470600 PMCID: PMC5019149 DOI: 10.1002/cne.23911] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Revised: 10/01/2015] [Accepted: 10/07/2015] [Indexed: 01/09/2023]
Abstract
In vertebrates, stimulation of the mesencephalic locomotor region (MLR) on one side evokes symmetrical locomotor movements on both sides. How this occurs was previously examined in detail in a swimmer using body undulations (lamprey), but in tetrapods the downstream projections from the MLR to brainstem neurons are not fully understood. Here we examined the brainstem circuits from the MLR to identified reticulospinal neurons in the salamander Notophthalmus viridescens. Using neural tracing, we show that the MLR sends bilateral projections to the middle reticular nucleus (mRN, rostral hindbrain) and the inferior reticular nucleus (iRN, caudal hindbrain). Ca2+ imaging coupled to electrophysiology in in vitro isolated brains revealed very similar responses in reticulospinal neurons on both sides to a unilateral MLR stimulation. As the strength of MLR stimulation was increased, the responses increased in size in reticulospinal neurons of the mRN and iRN, but the responses in the iRN were smaller. Bath‐application or local microinjections of glutamatergic antagonists markedly reduced reticulospinal neuron responses, indicating that the MLR sends glutamatergic inputs to reticulospinal neurons. In addition, reticulospinal cells responded to glutamate microinjections and the size of the responses paralleled the amount of glutamate microinjected. Immunofluorescence coupled with anatomical tracing confirmed the presence of glutamatergic projections from the MLR to reticulospinal neurons. Overall, we show that the brainstem circuits activated by the MLR in the salamander are organized similarly to those previously described in lampreys, indicating that the anatomo‐physiological features of the locomotor drive are well conserved in vertebrates. J. Comp. Neurol. 524:1361–1383, 2016. © 2015 The Authors The Journal of Comparative Neurology Published by Wiley Periodicals, Inc.
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Affiliation(s)
- Dimitri Ryczko
- Groupe de Recherche sur le Système Nerveux Central, Département de neurosciences, Université de Montréal, Montréal, Québec, Canada
| | - Francois Auclair
- Groupe de Recherche sur le Système Nerveux Central, Département de neurosciences, Université de Montréal, Montréal, Québec, Canada
| | - Jean-Marie Cabelguen
- INSERM U862 - Neurocentre Magendie, Motor System Diseases Team, Bordeaux Cedex, France
| | - Réjean Dubuc
- Groupe de Recherche sur le Système Nerveux Central, Département de neurosciences, Université de Montréal, Montréal, Québec, Canada.,Groupe de Recherche en Activité Physique Adaptée, Département des sciences de l'activité physique, Université du Québec à Montréal, Québec, Canada
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37
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Wang WC, McLean DL. Selective responses to tonic descending commands by temporal summation in a spinal motor pool. Neuron 2014; 83:708-21. [PMID: 25066087 DOI: 10.1016/j.neuron.2014.06.021] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/19/2014] [Indexed: 12/12/2022]
Abstract
Motor responses of varying intensities rely on descending commands to heterogeneous pools of motoneurons. In vertebrates, numerous sources of descending excitatory input provide systematically more drive to progressively less excitable spinal motoneurons. While this presumably facilitates simultaneous activation of motor pools, it is unclear how selective patterns of recruitment could emerge from inputs weighted this way. Here, using in vivo electrophysiological and imaging approaches in larval zebrafish, we find that, despite weighted excitation, more excitable motoneurons are preferentially activated by a midbrain reticulospinal nucleus by virtue of longer membrane time constants that facilitate temporal summation of tonic drive. We confirm the utility of this phenomenon by assessing the activity of the midbrain and motoneuron populations during a light-driven behavior. Our findings demonstrate that weighted descending commands can generate selective motor responses by exploiting systematic differences in the biophysical properties of target motoneurons and their relative sensitivity to tonic input.
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Affiliation(s)
- Wei-Chun Wang
- Interdepartmental Neuroscience Program, Northwestern University, Evanston, IL 60208, USA
| | - David L McLean
- Interdepartmental Neuroscience Program, Northwestern University, Evanston, IL 60208, USA; Department of Neurobiology, Northwestern University, Evanston, IL 60208, USA.
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38
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Villar-Cerviño V, Fernández-López B, Celina Rodicio M, Anadón R. Aspartate-containing neurons of the brainstem and rostral spinal cord of the sea lampreyPetromyzon marinus: Distribution and comparison with γ-aminobutyric acid. J Comp Neurol 2014; 522:1209-31. [DOI: 10.1002/cne.23493] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Revised: 10/29/2013] [Accepted: 10/29/2013] [Indexed: 12/26/2022]
Affiliation(s)
- Verona Villar-Cerviño
- Departamento de Biología Celular y Ecología; Facultad de Biología, Universidad de Santiago de Compostela; Santiago de Compostela 15782 Spain
| | - Blanca Fernández-López
- Departamento de Biología Celular y Ecología; Facultad de Biología, Universidad de Santiago de Compostela; Santiago de Compostela 15782 Spain
| | - María Celina Rodicio
- Departamento de Biología Celular y Ecología; Facultad de Biología, Universidad de Santiago de Compostela; Santiago de Compostela 15782 Spain
| | - Ramón Anadón
- Departamento de Biología Celular y Ecología; Facultad de Biología, Universidad de Santiago de Compostela; Santiago de Compostela 15782 Spain
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Abstract
Motor behaviors result from the interplay between the brain and the spinal cord. Reticulospinal neurons, situated between the supraspinal structures that initiate motor movements and the spinal cord that executes them, play key integrative roles in these behaviors. However, the molecular identities of mammalian reticular formation neurons that mediate motor behaviors have not yet been determined, thus limiting their study in health and disease. In the medullary reticular formation of the mouse, we identified neurons that express the transcription factors Lhx3 and/or Chx10, and demonstrate that these neurons form a significant component of glutamatergic reticulospinal pathways. Lhx3-positive medullary reticular formation neurons express Fos following a locomotor task in the adult, indicating that they are active during walking. Furthermore, they receive functional inputs from the mesencephalic locomotor region and have electrophysiological properties to support tonic repetitive firing, both of which are necessary for neurons that mediate the descending command for locomotion. Together, these results suggest that Lhx3/Chx10 medullary reticular formation neurons are involved in locomotion.
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Bicanski A, Ryczko D, Cabelguen JM, Ijspeert AJ. From lamprey to salamander: an exploratory modeling study on the architecture of the spinal locomotor networks in the salamander. BIOLOGICAL CYBERNETICS 2013; 107:565-587. [PMID: 23463500 DOI: 10.1007/s00422-012-0538-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2012] [Accepted: 11/20/2012] [Indexed: 06/01/2023]
Abstract
The evolutionary transition from water to land required new locomotor modes and corresponding adjustments of the spinal "central pattern generators" for locomotion. Salamanders resemble the first terrestrial tetrapods and represent a key animal for the study of these changes. Based on recent physiological data from salamanders, and previous work on the swimming, limbless lamprey, we present a model of the basic oscillatory network in the salamander spinal cord, the spinal segment. Model neurons are of the Hodgkin-Huxley type. Spinal hemisegments contain sparsely connected excitatory and inhibitory neuron populations, and are coupled to a contralateral hemisegment. The model yields a large range of experimental findings, especially the NMDA-induced oscillations observed in isolated axial hemisegments and segments of the salamander Pleurodeles waltlii. The model reproduces most of the effects of the blockade of AMPA synapses, glycinergic synapses, calcium-activated potassium current, persistent sodium current, and [Formula: see text]-current. Driving segments with a population of brainstem neurons yields fast oscillations in the in vivo swimming frequency range. A minimal modification to the conductances involved in burst-termination yields the slower stepping frequency range. Slow oscillators can impose their frequency on fast oscillators, as is likely the case during gait transitions from swimming to stepping. Our study shows that a lamprey-like network can potentially serve as a building block of axial and limb oscillators for swimming and stepping in salamanders.
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Affiliation(s)
- Andrej Bicanski
- Biorobotics Laboratory, School of Engineering, École Polytechnique Fédérale de Lausanne, Station 14, 1015 , Lausanne, VD, Switzerland,
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Forebrain dopamine neurons project down to a brainstem region controlling locomotion. Proc Natl Acad Sci U S A 2013; 110:E3235-42. [PMID: 23918379 DOI: 10.1073/pnas.1301125110] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The contribution of dopamine (DA) to locomotor control is traditionally attributed to ascending dopaminergic projections from the substantia nigra pars compacta and the ventral tegmental area to the basal ganglia, which in turn project down to the mesencephalic locomotor region (MLR), a brainstem region controlling locomotion in vertebrates. However, a dopaminergic innervation of the pedunculopontine nucleus, considered part of the MLR, was recently identified in the monkey. The origin and role of this dopaminergic input are unknown. We addressed these questions in a basal vertebrate, the lamprey. Here we report a functional descending dopaminergic pathway from the posterior tuberculum (PT; homologous to the substantia nigra pars compacta and/or ventral tegmental area of mammals) to the MLR. By using triple labeling, we found that dopaminergic cells from the PT not only project an ascending pathway to the striatum, but send a descending projection to the MLR. In an isolated brain preparation, PT stimulation elicited excitatory synaptic inputs into patch-clamped MLR cells, accompanied by activity in reticulospinal cells. By using voltammetry coupled with electrophysiological recordings, we demonstrate that PT stimulation evoked DA release in the MLR, together with the activation of reticulospinal cells. In a semi-intact preparation, stimulation of the PT elicited reticulospinal activity together with locomotor movements. Microinjections of a D1 antagonist in the MLR decreased the locomotor output elicited by PT stimulation, whereas injection of DA had an opposite effect. It appears that this descending dopaminergic pathway has a modulatory role on MLR cells that are known to receive glutamatergic projections and promotes locomotor output.
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Villar-Cerviño V, Barreiro-Iglesias A, Fernández-López B, Mazan S, Rodicio MC, Anadón R. Glutamatergic neuronal populations in the brainstem of the sea lamprey, Petromyzon marinus: an in situ hybridization and immunocytochemical study. J Comp Neurol 2013; 521:522-57. [PMID: 22791297 DOI: 10.1002/cne.23189] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2012] [Accepted: 07/06/2012] [Indexed: 12/27/2022]
Abstract
Glutamate is the major excitatory neurotransmitter in vertebrates, and glutamatergic cells probably represent a majority of neurons in the brain. Physiological studies have demonstrated a wide presence of excitatory (glutamatergic) neurons in lampreys. The present in situ hybridization study with probes for the lamprey vesicular glutamate transporter (VGLUT) provides an anatomical basis for the general distribution and precise localization of glutamatergic neurons in the sea lamprey brainstem. Most glutamatergic neurons were found within the periventricular gray layer throughout the brainstem, with the following regions being of particular interest: the optic tectum, torus semicircularis, isthmus, dorsal and medial nuclei of the octavolateral area, dorsal column nucleus, solitary tract nucleus, motoneurons, and reticular formation. The reticular population revealed a high degree of cellular heterogeneity including small, medium-sized, large, and giant glutamatergic neurons. We also combined glutamate immunohistochemistry with neuronal tract-tracing methods or γ-aminobutyric acid (GABA) immunohistochemistry to better characterize the glutamatergic populations. Injection of Neurobiotin into the spinal cord revealed that retrogradely labeled small and medium-sized cells of some reticulospinal-projecting groups were often glutamate-immunoreactive, mostly in the hindbrain. In contrast, the large and giant glutamatergic reticulospinal perikarya mostly lacked glutamate immunoreactivity. These results indicate that glutamate immunoreactivity did not reveal the entire set of glutamatergic populations. Some spinal-projecting octaval populations lacked both VGLUT and glutamate. As regards GABA and glutamate, their distribution was largely complementary, but colocalization of glutamate and GABA was observed in some small neurons, suggesting that glutamate immunohistochemistry might also detect non-glutamatergic cells or neurons that co-release both GABA and glutamate.
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Affiliation(s)
- Verona Villar-Cerviño
- Departamento de Biología Celular y Ecología, Facultad de Biología, Universidad de Santiago de Compostela, Santiago de Compostela 15782, Spain
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Abstract
When animals move, respiration increases to adapt for increased energy demands; the underlying mechanisms are still not understood. We investigated the neural substrates underlying the respiratory changes in relation to movement in lampreys. We showed that respiration increases following stimulation of the mesencephalic locomotor region (MLR) in an in vitro isolated preparation, an effect that persists in the absence of the spinal cord and caudal brainstem. By using electrophysiological and anatomical techniques, including whole-cell patch recordings, we identified a subset of neurons located in the dorsal MLR that send direct inputs to neurons in the respiratory generator. In semi-intact preparations, blockade of this region with 6-cyano-7-nitroquinoxaline-2,3-dione and (2R)-amino-5-phosphonovaleric acid greatly reduced the respiratory increases without affecting the locomotor movements. These results show that neurons in the respiratory generator receive direct glutamatergic connections from the MLR and that a subpopulation of MLR neurons plays a key role in the respiratory changes linked to movement.
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Valle-Maroto S, Fernández-López B, Villar-Cerviño V, Barreiro-Iglesias A, Anadón R, Rodicio MC. Inhibitory descending rhombencephalic projections in larval sea lamprey. Neuroscience 2011; 194:1-10. [DOI: 10.1016/j.neuroscience.2011.08.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2011] [Revised: 07/29/2011] [Accepted: 08/06/2011] [Indexed: 10/17/2022]
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Zelenin PV. Reticulospinal neurons controlling forward and backward swimming in the lamprey. J Neurophysiol 2011; 105:1361-71. [DOI: 10.1152/jn.00887.2010] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Most vertebrates are capable of two forms of locomotion, forward and backward, strongly differing in the patterns of motor coordination. Basic mechanisms generating these patterns are located in the spinal cord; they are activated and regulated by supraspinal commands. In the lamprey, these commands are transmitted by reticulospinal (RS) neurons. The aim of this study was to reveal groups of RS neurons controlling different aspects of forward (FS) and backward (BS) swimming in the lamprey. Activity of individual larger RS neurons in intact lampreys was recorded during FS and BS by chronically implanted electrodes. It was found that among the neurons activated during locomotion, 27% were active only during FS, 3% only during BS, and 70% during both FS and BS. In a portion of RS neurons, their mean firing frequency was correlated with frequency of body undulations during FS (8%), during BS (34%), or during both FS and BS (22%), suggesting their involvement in control of locomotion intensity. RS activity was phasically modulated by the locomotor rhythm during FS (20% of neurons), during BS (29%), or during both FS and BS (16%). The majority of RS neurons responding to vestibular stimulation (and presumably involved in control of body orientation) were active mainly during FS. This explains the absence of stabilization of the body orientation observed during BS. We discuss possible functions of different groups of RS neurons, i.e., activation of the spinal locomotor CPG, inversion of the direction of propagation of locomotor waves, and postural control.
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Affiliation(s)
- P. V. Zelenin
- Department of Neuroscience, Karolinska Institute, Stockholm, Sweden
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46
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Mullins OJ, Hackett JT, Buchanan JT, Friesen WO. Neuronal control of swimming behavior: comparison of vertebrate and invertebrate model systems. Prog Neurobiol 2011; 93:244-69. [PMID: 21093529 PMCID: PMC3034781 DOI: 10.1016/j.pneurobio.2010.11.001] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2010] [Revised: 11/01/2010] [Accepted: 11/08/2010] [Indexed: 01/26/2023]
Abstract
Swimming movements in the leech and lamprey are highly analogous, and lack homology. Thus, similarities in mechanisms must arise from convergent evolution rather than from common ancestry. Despite over 40 years of parallel investigations into this annelid and primitive vertebrate, a close comparison of the approaches and results of this research is lacking. The present review evaluates the neural mechanisms underlying swimming in these two animals and describes the many similarities that provide intriguing examples of convergent evolution. Specifically, we discuss swim initiation, maintenance and termination, isolated nervous system preparations, neural-circuitry, central oscillators, intersegmental coupling, phase lags, cycle periods and sensory feedback. Comparative studies between species highlight mechanisms that optimize behavior and allow us a broader understanding of nervous system function.
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Affiliation(s)
- Olivia J. Mullins
- Dept. of Biology University of Virginia Charlottesville, VA 22904-4328
- Neuroscience Graduate Program University of Virginia Charlottesville, VA 22904-4328
| | - John T. Hackett
- Neuroscience Graduate Program University of Virginia Charlottesville, VA 22904-4328
- Dept. of Molecular Physiology and Biological Physics University of Virginia Charlottesville, VA 22904-4328
| | - James T. Buchanan
- Dept. of Biological Sciences Marquette University Milwaukee, WI 53233
| | - W. Otto Friesen
- Dept. of Biology University of Virginia Charlottesville, VA 22904-4328
- Neuroscience Graduate Program University of Virginia Charlottesville, VA 22904-4328
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Le Ray D, Juvin L, Ryczko D, Dubuc R. Supraspinal control of locomotion. PROGRESS IN BRAIN RESEARCH 2011; 188:51-70. [DOI: 10.1016/b978-0-444-53825-3.00009-7] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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48
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Derjean D, Moussaddy A, Atallah E, St-Pierre M, Auclair F, Chang S, Ren X, Zielinski B, Dubuc R. A novel neural substrate for the transformation of olfactory inputs into motor output. PLoS Biol 2010; 8:e1000567. [PMID: 21203583 PMCID: PMC3006349 DOI: 10.1371/journal.pbio.1000567] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2010] [Accepted: 11/04/2010] [Indexed: 12/03/2022] Open
Abstract
It is widely recognized that animals respond to odors by generating or modulating specific motor behaviors. These reactions are important for daily activities, reproduction, and survival. In the sea lamprey, mating occurs after ovulated females are attracted to spawning sites by male sex pheromones. The ubiquity and reliability of olfactory-motor behavioral responses in vertebrates suggest tight coupling between the olfactory system and brain areas controlling movements. However, the circuitry and the underlying cellular neural mechanisms remain largely unknown. Using lamprey brain preparations, and electrophysiology, calcium imaging, and tract tracing experiments, we describe the neural substrate responsible for transforming an olfactory input into a locomotor output. We found that olfactory stimulation with naturally occurring odors and pheromones induced large excitatory responses in reticulospinal cells, the command neurons for locomotion. We have also identified the anatomy and physiology of this circuit. The olfactory input was relayed in the medial part of the olfactory bulb, in the posterior tuberculum, in the mesencephalic locomotor region, to finally reach reticulospinal cells in the hindbrain. Activation of this olfactory-motor pathway generated rhythmic ventral root discharges and swimming movements. Our study bridges the gap between behavior and cellular neural mechanisms in vertebrates, identifying a specific subsystem within the CNS, dedicated to producing motor responses to olfactory inputs.
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Affiliation(s)
- Dominique Derjean
- Department of Kinesiology, Université du Québec à Montréal, Montréal, Québec, Canada
- Groupe de Recherche sur le Système Nerveux Central, Department of Physiology, Université de Montréal, Montréal, Québec, Canada
| | - Aimen Moussaddy
- Groupe de Recherche sur le Système Nerveux Central, Department of Physiology, Université de Montréal, Montréal, Québec, Canada
| | - Elias Atallah
- Groupe de Recherche sur le Système Nerveux Central, Department of Physiology, Université de Montréal, Montréal, Québec, Canada
| | - Melissa St-Pierre
- Groupe de Recherche sur le Système Nerveux Central, Department of Physiology, Université de Montréal, Montréal, Québec, Canada
| | - François Auclair
- Groupe de Recherche sur le Système Nerveux Central, Department of Physiology, Université de Montréal, Montréal, Québec, Canada
| | - Steven Chang
- Department of Biological Sciences, University of Windsor, Windsor, Ontario, Canada
| | - Xiang Ren
- Department of Biological Sciences, University of Windsor, Windsor, Ontario, Canada
| | - Barbara Zielinski
- Department of Biological Sciences, University of Windsor, Windsor, Ontario, Canada
| | - Réjean Dubuc
- Department of Kinesiology, Université du Québec à Montréal, Montréal, Québec, Canada
- Groupe de Recherche sur le Système Nerveux Central, Department of Physiology, Université de Montréal, Montréal, Québec, Canada
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Le Ray D, Juvin L, Boutin T, Auclair F, Dubuc R. A neuronal substrate for a state-dependent modulation of sensory inputs in the brainstem. Eur J Neurosci 2010; 32:53-9. [PMID: 20576031 DOI: 10.1111/j.1460-9568.2010.07276.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Central networks modulate sensory transmission during motor behavior. Sensory inputs may thus have distinct impacts according to the state of activity of the central networks. Using an in-vitro isolated lamprey brainstem preparation, we investigated whether a brainstem locomotor center, the mesencephalic locomotor region (MLR), modulates sensory transmission. The synaptic responses of brainstem reticulospinal (RS) cells to electrical stimulation of the sensory trigeminal nerve were recorded before and after electrical stimulation of the MLR. The RS cell synaptic responses were significantly reduced by MLR stimulation and the reduction of the response increased with the stimulation intensity of the MLR. Bath perfusion of atropine prevented the depression of sensory transmission, indicating that muscarinic receptor activation is involved. Previous studies have shown that, upon stimulation of the MLR, behavioral activity switches from a resting state to an active-locomotor state. Therefore, our results suggest that a state-dependent modulation of sensory transmission to RS cells occurs in the behavioral context of locomotion and that muscarinic inputs from the MLR are involved.
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Affiliation(s)
- Didier Le Ray
- Université de Bordeaux, CNRS, Laboratoire Mouvement Adaptation Cognition, Bordeaux, France
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50
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A parallel cholinergic brainstem pathway for enhancing locomotor drive. Nat Neurosci 2010; 13:731-8. [PMID: 20473293 PMCID: PMC2881475 DOI: 10.1038/nn.2548] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2010] [Accepted: 04/12/2010] [Indexed: 11/09/2022]
Abstract
The brainstem locomotor system is believed to be organized serially from the mesencephalic locomotor region (MLR) to reticulospinal neurons, which in turn project to locomotor neurons in the spinal cord. We identified brainstem muscarinoceptive neurons in lampreys (Petromyzon marinus) that received parallel inputs from the MLR and projected back to reticulospinal cells to amplify and extend the duration of locomotor output. These cells responded to muscarine with extended periods of excitation, received direct muscarinic excitation from the MLR and projected glutamatergic excitation to reticulospinal neurons. Targeted blockade of muscarine receptors over these neurons profoundly reduced MLR-induced excitation of reticulospinal neurons and markedly slowed MLR-evoked locomotion. The presence of these neurons forces us to rethink the organization of supraspinal locomotor control, to include a sustained feedforward loop that boosts locomotor output.
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