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Dai Y, Cheng Y, Ge R, Chen K, Yang L. Exercise-induced adaptation of neurons in the vertebrate locomotor system. JOURNAL OF SPORT AND HEALTH SCIENCE 2024; 13:160-171. [PMID: 37914153 PMCID: PMC10980905 DOI: 10.1016/j.jshs.2023.10.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 09/20/2023] [Accepted: 10/07/2023] [Indexed: 11/03/2023]
Abstract
Vertebrate neurons are highly dynamic cells that undergo several alterations in their functioning and physiologies in adaptation to various external stimuli. In particular, how these neurons respond to physical exercise has long been an area of active research. Studies of the vertebrate locomotor system's adaptability suggest multiple mechanisms are involved in the regulation of neuronal activity and properties during exercise. In this brief review, we highlight recent results and insights from the field with a focus on the following mechanisms: (a) alterations in neuronal excitability during acute exercise; (b) alterations in neuronal excitability after chronic exercise; (c) exercise-induced changes in neuronal membrane properties via modulation of ion channel activity; (d) exercise-enhanced dendritic plasticity; and (e) exercise-induced alterations in neuronal gene expression and protein synthesis. Our hope is to update the community with a cellular and molecular understanding of the recent mechanisms underlying the adaptability of the vertebrate locomotor system in response to both acute and chronic physical exercise.
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Affiliation(s)
- Yue Dai
- Key Lab of Adolescent Health Assessment and Exercise Intervention of Ministry of Education, College of Physical Education and Health Care, East China Normal University, Shanghai 200241, China; Shanghai Key Laboratory of Multidimensional Information Processing, School of Communication and Electronic Engineering, East China Normal University, Shanghai 200241, China.
| | - Yi Cheng
- Key Lab of Adolescent Health Assessment and Exercise Intervention of Ministry of Education, College of Physical Education and Health Care, East China Normal University, Shanghai 200241, China
| | - Renkai Ge
- School of Physical Education and Health Care, East China Jiaotong University, Nanchang 330013, China
| | - Ke Chen
- Key Laboratory of High Confidence Software Technologies of Ministry of Education, School of Computer Science, Peking University, Beijing 100871, China
| | - Liming Yang
- Key Lab of Adolescent Health Assessment and Exercise Intervention of Ministry of Education, College of Physical Education and Health Care, East China Normal University, Shanghai 200241, China
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2
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Zhou K, Wei W, Yang D, Zhang H, Yang W, Zhang Y, Nie Y, Hao M, Wang P, Ruan H, Zhang T, Wang S, Liu Y. Dual electrical stimulation at spinal-muscular interface reconstructs spinal sensorimotor circuits after spinal cord injury. Nat Commun 2024; 15:619. [PMID: 38242904 PMCID: PMC10799086 DOI: 10.1038/s41467-024-44898-9] [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: 01/12/2023] [Accepted: 01/09/2024] [Indexed: 01/21/2024] Open
Abstract
The neural signals produced by varying electrical stimulation parameters lead to characteristic neural circuit responses. However, the characteristics of neural circuits reconstructed by electrical signals remain poorly understood, which greatly limits the application of such electrical neuromodulation techniques for the treatment of spinal cord injury. Here, we develop a dual electrical stimulation system that combines epidural electrical and muscle stimulation to mimic feedforward and feedback electrical signals in spinal sensorimotor circuits. We demonstrate that a stimulus frequency of 10-20 Hz under dual stimulation conditions is required for structural and functional reconstruction of spinal sensorimotor circuits, which not only activates genes associated with axonal regeneration of motoneurons, but also improves the excitability of spinal neurons. Overall, the results provide insights into neural signal decoding during spinal sensorimotor circuit reconstruction, suggesting that the combination of epidural electrical and muscle stimulation is a promising method for the treatment of spinal cord injury.
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Affiliation(s)
- Kai Zhou
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and Institute of Neuroscience, Soochow University; Clinical Research Center of Neurological Disease, The Second Affiliated Hospital of Soochow University, Suzhou, 215123, China
- Co-innovation Center of Neuroregeneration, Nantong University, Nantong, 226001, China
| | - Wei Wei
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and Institute of Neuroscience, Soochow University; Clinical Research Center of Neurological Disease, The Second Affiliated Hospital of Soochow University, Suzhou, 215123, China
| | - Dan Yang
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and Institute of Neuroscience, Soochow University; Clinical Research Center of Neurological Disease, The Second Affiliated Hospital of Soochow University, Suzhou, 215123, China
- Department of Anatomy, School of Basic Medical Science, Guizhou Medical University, Guiyang, 550025, China
| | - Hui Zhang
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and Institute of Neuroscience, Soochow University; Clinical Research Center of Neurological Disease, The Second Affiliated Hospital of Soochow University, Suzhou, 215123, China
| | - Wei Yang
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and Institute of Neuroscience, Soochow University; Clinical Research Center of Neurological Disease, The Second Affiliated Hospital of Soochow University, Suzhou, 215123, China
| | - Yunpeng Zhang
- Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou, Jiangsu, 215163, China
| | - Yingnan Nie
- Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai, 200433, China
| | - Mingming Hao
- i-Lab, Key Laboratory of Multifunctional Nanomaterials and Smart Systems, Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Suzhou, Jiangsu, 215123, China
- Ningbo Medical Centre Lihuili Hospital, Ningbo, Zhejiang, 315048, China
| | - Pengcheng Wang
- Institutes of Biology and Medical Sciences, Soochow University, Suzhou, Jiangsu, 215123, China
| | - Hang Ruan
- Institutes of Biology and Medical Sciences, Soochow University, Suzhou, Jiangsu, 215123, China
| | - Ting Zhang
- i-Lab, Key Laboratory of Multifunctional Nanomaterials and Smart Systems, Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Suzhou, Jiangsu, 215123, China
| | - Shouyan Wang
- Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai, 200433, China
| | - Yaobo Liu
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and Institute of Neuroscience, Soochow University; Clinical Research Center of Neurological Disease, The Second Affiliated Hospital of Soochow University, Suzhou, 215123, China.
- Co-innovation Center of Neuroregeneration, Nantong University, Nantong, 226001, China.
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3
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Kohler M, Röhrbein F, Knoll A, Albu-Schäffer A, Jörntell H. The Bcm rule allows a spinal cord model to learn rhythmic movements. BIOLOGICAL CYBERNETICS 2023; 117:275-284. [PMID: 37594531 PMCID: PMC10600281 DOI: 10.1007/s00422-023-00970-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2022] [Accepted: 07/28/2023] [Indexed: 08/19/2023]
Abstract
Currently, it is accepted that animal locomotion is controlled by a central pattern generator in the spinal cord. Experiments and models show that rhythm generating neurons and genetically determined network properties could sustain oscillatory output activity suitable for locomotion. However, current central pattern generator models do not explain how a spinal cord circuitry, which has the same basic genetic plan across species, can adapt to control the different biomechanical properties and locomotion patterns existing in these species. Here we demonstrate that rhythmic and alternating movements in pendulum models can be learned by a monolayer spinal cord circuitry model using the Bienenstock-Cooper-Munro learning rule, which has been previously proposed to explain learning in the visual cortex. These results provide an alternative theory to central pattern generator models, because rhythm generating neurons and genetically defined connectivity are not required in our model. Though our results are not in contradiction to current models, as existing neural mechanism and structures, not used in our model, can be expected to facilitate the kind of learning demonstrated here. Therefore, our model could be used to augment existing models.
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Affiliation(s)
- Matthias Kohler
- Department of Informatics, Technical University of Munich, Boltzmannstraße 3, 85748, Garching, Bavaria, Germany.
| | - Florian Röhrbein
- Department of Computer Science, Chemnitz University of Technology, Straße der Nationen 62, 09111, Chemnitz, Saxony, Germany
| | - Alois Knoll
- Department of Informatics, Technical University of Munich, Boltzmannstraße 3, 85748, Garching, Bavaria, Germany
| | - Alin Albu-Schäffer
- Department of Informatics, Technical University of Munich, Boltzmannstraße 3, 85748, Garching, Bavaria, Germany
- Institute of Robotics and Mechatronics, German Aerospace Center, Münchener Straße 20, 82234, Weßling, Bavaria, Germany
| | - Henrik Jörntell
- Department of Experimental Medical Science, Lund University, Sölvegatan 19, 22184, Lund, Scania, Sweden
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4
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Paulson OB, Schousboe A, Hultborn H. The history of Danish neuroscience. Eur J Neurosci 2023; 58:2893-2960. [PMID: 37477973 DOI: 10.1111/ejn.16062] [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: 11/22/2022] [Revised: 05/04/2023] [Accepted: 05/29/2023] [Indexed: 07/22/2023]
Abstract
The history of Danish neuroscience starts with an account of impressive contributions made at the 17th century. Thomas Bartholin was the first Danish neuroscientist, and his disciple Nicolaus Steno became internationally one of the most prominent neuroscientists in this period. From the start, Danish neuroscience was linked to clinical disciplines. This continued in the 19th and first half of the 20th centuries with new initiatives linking basic neuroscience to clinical neurology and psychiatry in the same scientific environment. Subsequently, from the middle of the 20th century, basic neuroscience was developing rapidly within the preclinical university sector. Clinical neuroscience continued and was even reinforced during this period with important translational research and a close co-operation between basic and clinical neuroscience. To distinguish 'history' from 'present time' is not easy, as many historical events continue in present time. Therefore, we decided to consider 'History' as new major scientific developments in Denmark, which were launched before the end of the 20th century. With this aim, scientists mentioned will have been born, with a few exceptions, no later than the early 1960s. However, we often refer to more recent publications in documenting the developments of initiatives launched before the end of the last century. In addition, several scientists have moved to Denmark after the beginning of the present century, and they certainly are contributing to the present status of Danish neuroscience-but, again, this is not the History of Danish neuroscience.
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Affiliation(s)
- Olaf B Paulson
- Neurobiology Research Unit, Department of Neurology, Rigshospitalet, 9 Blegdamsvej, Copenhagen, Denmark
- Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Arne Schousboe
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Hans Hultborn
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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5
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Mohammadshirazi A, Apicella R, Zylberberg BA, Mazzone GL, Taccola G. Suprapontine Structures Modulate Brainstem and Spinal Networks. Cell Mol Neurobiol 2023:10.1007/s10571-023-01321-z. [PMID: 36732488 DOI: 10.1007/s10571-023-01321-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Accepted: 01/19/2023] [Indexed: 02/04/2023]
Abstract
Several spinal motor output and essential rhythmic behaviors are controlled by supraspinal structures, although their contribution to neuronal networks for respiration and locomotion at birth still requires better characterization. As preparations of isolated brainstem and spinal networks only focus on local circuitry, we introduced the in vitro central nervous system (CNS) from neonatal rodents to simultaneously record a stable respiratory rhythm from both cervical and lumbar ventral roots (VRs).Electrical pulses supplied to multiple sites of brainstem evoked distinct VR responses with staggered onset in the rostro-caudal direction. Stimulation of ventrolateral medulla (VLM) resulted in higher events from homolateral VRs. Stimulating a lumbar dorsal root (DR) elicited responses even from cervical VRs, albeit small and delayed, confirming functional ascending pathways. Oximetric assessments detected optimal oxygen levels on brainstem and cortical surfaces, and histological analysis of internal brain structures indicated preserved neuron viability without astrogliosis. Serial ablations showed precollicular decerebration reducing respiratory burst duration and frequency and diminishing the area of lumbar DR and VR potentials elicited by DR stimulation, while pontobulbar transection increased the frequency and duration of respiratory bursts. Keeping legs attached allows for expressing a respiratory rhythm during hindlimb stimulation. Trains of pulses evoked episodes of fictive locomotion (FL) when delivered to VLM or to a DR, the latter with a slightly better FL than in isolated cords.In summary, suprapontine centers regulate spontaneous respiratory rhythms, as well as electrically evoked reflexes and spinal network activity. The current approach contributes to clarifying modulatory brain influences on the brainstem and spinal microcircuits during development. Novel preparation of the entire isolated CNS from newborn rats unveils suprapontine modulation on brainstem and spinal networks. Preparation views (A) with and without legs attached (B). Successful fictive respiration occurs with fast dissection from P0-P2 rats (C). Decerebration speeds up respiratory rhythm (D) and reduces spinal reflexes derived from both ventral and dorsal lumbar roots (E).
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Affiliation(s)
- Atiyeh Mohammadshirazi
- Neuroscience Department, International School for Advanced Studies (SISSA), Via Bonomea 265, 34136, Trieste, Italy.,Applied Neurophysiology and Neuropharmacology Lab, Istituto di Medicina Fisica e Riabilitazione (IMFR), Via Gervasutta 48, Udine, UD, Italy
| | - Rosamaria Apicella
- Neuroscience Department, International School for Advanced Studies (SISSA), Via Bonomea 265, 34136, Trieste, Italy.,Applied Neurophysiology and Neuropharmacology Lab, Istituto di Medicina Fisica e Riabilitazione (IMFR), Via Gervasutta 48, Udine, UD, Italy
| | - Benjamín A Zylberberg
- Instituto de Investigaciones en Medicina Traslacional (IIMT)-CONICET - Universidad Austral, Av. Pte. Perón 1500, Pilar, Buenos Aires, Argentina
| | - Graciela L Mazzone
- Instituto de Investigaciones en Medicina Traslacional (IIMT)-CONICET - Universidad Austral, Av. Pte. Perón 1500, Pilar, Buenos Aires, Argentina
| | - Giuliano Taccola
- Neuroscience Department, International School for Advanced Studies (SISSA), Via Bonomea 265, 34136, Trieste, Italy. .,Applied Neurophysiology and Neuropharmacology Lab, Istituto di Medicina Fisica e Riabilitazione (IMFR), Via Gervasutta 48, Udine, UD, Italy.
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6
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Jonaitis J, MacLeod J, Pulver SR. Localization of muscarinic acetylcholine receptor-dependent rhythm-generating modules in the Drosophila larval locomotor network. J Neurophysiol 2022; 127:1098-1116. [PMID: 35294308 PMCID: PMC9018013 DOI: 10.1152/jn.00106.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Revised: 03/09/2022] [Accepted: 03/10/2022] [Indexed: 11/22/2022] Open
Abstract
Mechanisms of rhythm generation have been extensively studied in motor systems that control locomotion over terrain in limbed animals; however, much less is known about rhythm generation in soft-bodied terrestrial animals. Here we explored how muscarinic acetylcholine receptor (mAChR)-modulated rhythm-generating networks are distributed in the central nervous system (CNS) of soft-bodied Drosophila larvae. We measured fictive motor patterns in isolated CNS preparations, using a combination of Ca2+ imaging and electrophysiology while manipulating mAChR signaling pharmacologically. Bath application of the mAChR agonist oxotremorine potentiated bilaterally asymmetric activity in anterior thoracic regions and promoted bursting in posterior abdominal regions. Application of the mAChR antagonist scopolamine suppressed rhythm generation in these regions and blocked the effects of oxotremorine. Oxotremorine triggered fictive forward crawling in preparations without brain lobes. Oxotremorine also potentiated rhythmic activity in isolated posterior abdominal CNS segments as well as isolated anterior brain and thoracic regions, but it did not induce rhythmic activity in isolated anterior abdominal segments. Bath application of scopolamine to reduced preparations lowered baseline Ca2+ levels and abolished rhythmic activity. Overall, these results suggest that mAChR signaling plays a role in enabling rhythm generation at multiple sites in the larval CNS. This work furthers our understanding of motor control in soft-bodied locomotion and provides a foundation for study of rhythm-generating networks in an emerging genetically tractable locomotor system.NEW & NOTEWORTHY Using a combination of pharmacology, electrophysiology, and Ca2+ imaging, we find that signaling through mACh receptors plays a critical role in rhythmogenesis in different regions of the Drosophila larval CNS. mAChR-dependent rhythm generators reside in distal regions of the larval CNS and provide functional substrates for central pattern-generating networks (CPGs) underlying headsweep behavior and forward locomotion. This provides new insights into locomotor CPG operation in soft-bodied animals that navigate over terrain.
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Affiliation(s)
- Julius Jonaitis
- School of Psychology and Neuroscience, University of St Andrews, St Andrews, United Kingdom
| | - James MacLeod
- School of Psychology and Neuroscience, University of St Andrews, St Andrews, United Kingdom
| | - Stefan R Pulver
- School of Psychology and Neuroscience, University of St Andrews, St Andrews, United Kingdom
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7
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Koning HK, Ahemaiti A, Boije H. A deep-dive into fictive locomotion - a strategy to probe cellular activity during speed transitions in fictively swimming zebrafish larvae. Biol Open 2022; 11:274799. [PMID: 35188534 PMCID: PMC8966775 DOI: 10.1242/bio.059167] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Accepted: 02/14/2022] [Indexed: 11/20/2022] Open
Abstract
Fictive locomotion is frequently used to study locomotor output in paralyzed animals. We have evaluated the character of swim episodes elicited by different strategies in zebrafish. Motor output was measured on both sides of a body segment using electrodes and a pipeline for synchronizing stimulation and recording, denoising data and peak-finding was developed. The optomotor response generated swims most equivalent to spontaneous activity, while electrical stimulation and NMDA application caused various artefacts. Our optimal settings, optomotor stimulation using 5-day-old larvae, were combined with calcium imaging and optogenetics to validate the setup's utility. Expression of GCaMP5G by the mnx1 promoter allowed correlation of calcium traces of dozens of motor neurons to the fictive locomotor output. Activation of motor neurons through channelrhodopsin produced aberrant locomotor episodes. This strategy can be used to investigate novel neuronal populations in a high-throughput manner to reveal their role in shaping motor output. This article has an associated First Person interview with the first author of the paper. Summary: This approach combines fictive locomotion, elicited through the optomotor response, and calcium imaging or optogenetics, to investigate the role of neuronal populations in shaping motor output.
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Affiliation(s)
- Harmen Kornelis Koning
- Department of Immunology, Genetics and Pathology, Uppsala University, S-751 08, Uppsala, Sweden
| | - Aikeremu Ahemaiti
- Department of Immunology, Genetics and Pathology, Uppsala University, S-751 08, Uppsala, Sweden
| | - Henrik Boije
- Department of Immunology, Genetics and Pathology, Uppsala University, S-751 08, Uppsala, Sweden
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8
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Chalif JI, de Lourdes Martínez-Silva M, Pagiazitis JG, Murray AJ, Mentis GZ. Control of mammalian locomotion by ventral spinocerebellar tract neurons. Cell 2022; 185:328-344.e26. [PMID: 35063074 PMCID: PMC8852337 DOI: 10.1016/j.cell.2021.12.014] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 11/09/2021] [Accepted: 12/13/2021] [Indexed: 01/22/2023]
Abstract
Locomotion is a complex behavior required for animal survival. Vertebrate locomotion depends on spinal interneurons termed the central pattern generator (CPG), which generates activity responsible for the alternation of flexor and extensor muscles and the left and right side of the body. It is unknown whether multiple or a single neuronal type is responsible for the control of mammalian locomotion. Here, we show that ventral spinocerebellar tract neurons (VSCTs) drive generation and maintenance of locomotor behavior in neonatal and adult mice. Using mouse genetics, physiological, anatomical, and behavioral assays, we demonstrate that VSCTs exhibit rhythmogenic properties and neuronal circuit connectivity consistent with their essential role in the locomotor CPG. Importantly, optogenetic activation and chemogenetic silencing reveals that VSCTs are necessary and sufficient for locomotion. These findings identify VSCTs as critical components for mammalian locomotion and provide a paradigm shift in our understanding of neural control of complex behaviors.
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Affiliation(s)
- Joshua I. Chalif
- Center for Motor Neuron Biology and Disease, Columbia University, New York, NY 10032, USA,Dept. of Neurology, Columbia University, New York, NY 10032, USA
| | - María de Lourdes Martínez-Silva
- Center for Motor Neuron Biology and Disease, Columbia University, New York, NY 10032, USA,Dept. of Neurology, Columbia University, New York, NY 10032, USA
| | - John G. Pagiazitis
- Center for Motor Neuron Biology and Disease, Columbia University, New York, NY 10032, USA,Dept. of Neurology, Columbia University, New York, NY 10032, USA
| | - Andrew J. Murray
- Sainsbury Wellcome Centre, University College London, 25 Howland Street, London W1T 4JG, UK
| | - George Z. Mentis
- Center for Motor Neuron Biology and Disease, Columbia University, New York, NY 10032, USA,Dept. of Neurology, Columbia University, New York, NY 10032, USA,Dept. of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA,Corresponding author & Lead contact: Tel: +1-212-305-9846,
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Falgairolle M, O'Donovan MJ. Motoneuronal Regulation of Central Pattern Generator and Network Function. ADVANCES IN NEUROBIOLOGY 2022; 28:259-280. [PMID: 36066829 DOI: 10.1007/978-3-031-07167-6_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
This chapter reviews recent work showing that vertebrate motoneurons can trigger spontaneous rhythmic activity in the developing spinal cord and can modulate the function of several different central pattern generators later in development. In both the embryonic chick and the fetal mouse spinal cords, antidromic activation of motoneurons can trigger bouts of rhythmic activity. In the neonatal mouse, optogenetic manipulation of motoneuron firing can modulate the frequency of fictive locomotion activated by a drug cocktail. In adult animals, motoneurons have been shown to regulate swimming in the zebrafish, and vocalization in fish and frogs. We discuss the significance of these findings and the degree to which motoneurons may be considered a part of these central pattern generators.
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10
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Biological data questions the support of the self inhibition required for pattern generation in the half center model. PLoS One 2020; 15:e0238586. [PMID: 32915814 PMCID: PMC7485810 DOI: 10.1371/journal.pone.0238586] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2020] [Accepted: 08/19/2020] [Indexed: 11/19/2022] Open
Abstract
Locomotion control in mammals has been hypothesized to be governed by a central pattern generator (CPG) located in the circuitry of the spinal cord. The most common model of the CPG is the half center model, where two pools of neurons generate alternating, oscillatory activity. In this model, the pools reciprocally inhibit each other ensuring alternating activity. There is experimental support for reciprocal inhibition. However another crucial part of the half center model is a self inhibitory mechanism which prevents the neurons of each individual pool from infinite firing. Self-inhibition is hence necessary to obtain alternating activity. But critical parts of the experimental bases for the proposed mechanisms for self-inhibition were obtained in vitro, in preparations of juvenile animals. The commonly used adaptation of spike firing does not appear to be present in adult animals in vivo. We therefore modeled several possible self inhibitory mechanisms for locomotor control. Based on currently published data, previously proposed hypotheses of the self inhibitory mechanism, necessary to support the CPG hypothesis, seems to be put into question by functional evaluation tests or by in vivo data. This opens for alternative explanations of how locomotion activity patterns in the adult mammal could be generated.
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11
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Christensen NR, De Luca M, Lever MB, Richner M, Hansen AB, Noes-Holt G, Jensen KL, Rathje M, Jensen DB, Erlendsson S, Bartling CR, Ammendrup-Johnsen I, Pedersen SE, Schönauer M, Nissen KB, Midtgaard SR, Teilum K, Arleth L, Sørensen AT, Bach A, Strømgaard K, Meehan CF, Vaegter CB, Gether U, Madsen KL. A high-affinity, bivalent PDZ domain inhibitor complexes PICK1 to alleviate neuropathic pain. EMBO Mol Med 2020; 12:e11248. [PMID: 32352640 PMCID: PMC7278562 DOI: 10.15252/emmm.201911248] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Revised: 04/01/2020] [Accepted: 04/07/2020] [Indexed: 12/13/2022] Open
Abstract
Maladaptive plasticity involving increased expression of AMPA-type glutamate receptors is involved in several pathologies, including neuropathic pain, but direct inhibition of AMPARs is associated with side effects. As an alternative, we developed a cell-permeable, high-affinity (~2 nM) peptide inhibitor, Tat-P4 -(C5)2 , of the PDZ domain protein PICK1 to interfere with increased AMPAR expression. The affinity is obtained partly from the Tat peptide and partly from the bivalency of the PDZ motif, engaging PDZ domains from two separate PICK1 dimers to form a tetrameric complex. Bivalent Tat-P4 -(C5)2 disrupts PICK1 interaction with membrane proteins on supported cell membrane sheets and reduce the interaction of AMPARs with PICK1 and AMPA-receptor surface expression in vivo. Moreover, Tat-P4 -(C5)2 administration reduces spinal cord transmission and alleviates mechanical hyperalgesia in the spared nerve injury model of neuropathic pain. Taken together, our data reveal Tat-P4 -(C5)2 as a novel promising lead for neuropathic pain treatment and expand the therapeutic potential of bivalent inhibitors to non-tandem protein-protein interaction domains.
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Affiliation(s)
- Nikolaj R Christensen
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, Faculty of Health and Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Marta De Luca
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Michael B Lever
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Mette Richner
- Danish Research Institute of Translational Neuroscience (DANDRITE), Nordic-EMBL Partnership for Molecular Medicine, Department of Biomedicine, Aarhus University, Aarhus C, Denmark
| | - Astrid B Hansen
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Gith Noes-Holt
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Kathrine L Jensen
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Mette Rathje
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Dennis Bo Jensen
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Simon Erlendsson
- Structural biology and NMR Laboratory, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Christian Ro Bartling
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, Faculty of Health and Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Ina Ammendrup-Johnsen
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Sofie E Pedersen
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Michèle Schönauer
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, Faculty of Health and Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Klaus B Nissen
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, Faculty of Health and Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Søren R Midtgaard
- Structural Biophysics, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
| | - Kaare Teilum
- Structural biology and NMR Laboratory, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Lise Arleth
- Structural Biophysics, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
| | - Andreas T Sørensen
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Anders Bach
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, Faculty of Health and Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Kristian Strømgaard
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, Faculty of Health and Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Claire F Meehan
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Christian B Vaegter
- Danish Research Institute of Translational Neuroscience (DANDRITE), Nordic-EMBL Partnership for Molecular Medicine, Department of Biomedicine, Aarhus University, Aarhus C, Denmark
| | - Ulrik Gether
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Kenneth L Madsen
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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12
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Develle Y, Leblond H. Biphasic Effect of Buspirone on the H-Reflex in Acute Spinal Decerebrated Mice. Front Cell Neurosci 2020; 13:573. [PMID: 32009904 PMCID: PMC6974439 DOI: 10.3389/fncel.2019.00573] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Accepted: 12/12/2019] [Indexed: 11/13/2022] Open
Abstract
Pharmacological treatment facilitating locomotor expression will also have some effects on reflex expression through the modulation of spinal circuitry. Buspirone, a partial serotonin receptor agonist (5-HT1 A), was recently shown to facilitate and even trigger locomotor movements in mice after complete spinal lesion (Tx). Here, we studied its effect on the H-reflex after acute Tx in adult mice. To avoid possible impacts of anesthetics on H-reflex depression, experiments were performed after decerebration in un-anesthetized mice (N = 20). The H-reflex in plantar muscles of the hind paw was recorded after tibial nerve stimulation 2 h after Tx at the 8th thoracic vertebrae and was compared before and every 10 min after buspirone (8 mg/kg, i.p.) for 60 min (N = 8). Frequency-dependent depression (FDD) of the H-reflex was assessed before and 60 min after buspirone. Before buspirone, a stable H-reflex could be elicited in acute spinal mice and FDD of the H-reflex was observed at 5 and 10 Hz relative to 0.2 Hz, FDD was still present 60 min after buspirone. Early after buspirone, the H-reflex was significantly decreased to 69% of pre-treatment, it then increased significantly 30-60 min after treatment, reaching 170% 60 min after injection. This effect was not observed in a control group (saline, N = 5) and was blocked when a 5-HT1 A antagonist (NAD-299) was administered with buspirone (N = 7). Altogether results suggest that the reported pro-locomotor effect of buspirone occurs at a time where there is a 5-HT1 A receptors mediated reflex depression followed by a second phase marked by enhancement of reflex excitability.
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Affiliation(s)
- Yann Develle
- Department of Anatomy, CogNAC Research Group, Université du Québec à Trois-Rivières, Trois-Rivières, QC, Canada
| | - Hugues Leblond
- Department of Anatomy, CogNAC Research Group, Université du Québec à Trois-Rivières, Trois-Rivières, QC, Canada
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Liu D, Li X, Xiao Z, Yin W, Zhao Y, Tan J, Chen B, Jiang X, Dai J. Different functional bio-scaffolds share similar neurological mechanism to promote locomotor recovery of canines with complete spinal cord injury. Biomaterials 2019; 214:119230. [PMID: 31174066 DOI: 10.1016/j.biomaterials.2019.119230] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Revised: 05/22/2019] [Accepted: 05/27/2019] [Indexed: 12/27/2022]
Abstract
Many studies have shown that rodents exhibit a certain degree of spontaneous motor function recovery even if they suffer from spinal cord complete transection injury. However, the characteristics of spontaneous locomotor recovery and its associated neurobiological mechanisms are unclear. In this study, we observed that spontaneous locomotor function recovery of hind limbs could also be detected in a canine thoracic (T8) spinal cord complete transection model. In addition, the spontaneous locomotor recovery of canines could be further promoted by chronic implantation of Taxol- or human bone marrow mesenchymal stem cell-modified bio-scaffolds. Moreover, functional bio-scaffolds implantation promoted locomotor outcome could be significantly weakened (drop to the spontaneous recovery level) but not totally abolished by resection in the lesion site. The neurological mechanism for functional bio-scaffolds improved locomotor outcome was primarily dependent on the formation of neuronal bridging but not the long-distance regeneration of descending motor axons throughout the lesion gap. Besides that, we found that spontaneously achieved locomotor recovery of hind limbs was unable to be weaken by repetitive resection of the lesion area, indicating the mechanism for spontaneous locomotor recovery was independent on functional neurological bridging throughout the lesion gap.
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Affiliation(s)
- Dingyang Liu
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha 410008, Hunan Province, China
| | - Xing Li
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha 410008, Hunan Province, China; Key Laboratory of Organ Injury, Aging and Regenerative Medicine of Hunan Province, Changsha 410008, Hunan Province, China; Department of Spine Surgery, Xiangya Hospital, Central South University, Changsha 410008, Hunan Province, China.
| | - Zhifeng Xiao
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Wen Yin
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha 410008, Hunan Province, China
| | - Yannan Zhao
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Jun Tan
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha 410008, Hunan Province, China
| | - Bing Chen
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Xingjun Jiang
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha 410008, Hunan Province, China.
| | - Jianwu Dai
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
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Manuel M, Zytnicki D. Molecular and electrophysiological properties of mouse motoneuron and motor unit subtypes. CURRENT OPINION IN PHYSIOLOGY 2018; 8:23-29. [PMID: 32551406 DOI: 10.1016/j.cophys.2018.11.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The field of motoneuron and motor unit physiology in mammals has deeply evolved the last decade thanks to the parallel development of mouse genetics and transcriptomic analysis and of in vivo mouse preparations that allow intracellular electrophysiological recordings of motoneurons. We review the efforts made to investigate the electrophysiological properties of the different functional subtypes of mouse motoneurons, to decipher the mosaic of molecular markers specifically expressed in each subtype, and to elucidate which of those factors drive the identity of motoneurons.
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Affiliation(s)
- Marin Manuel
- Center for Neurophysics, Physiology and Pathology, Paris Descartes University, CNRS UMR 8119, Paris, France
| | - Daniel Zytnicki
- Center for Neurophysics, Physiology and Pathology, Paris Descartes University, CNRS UMR 8119, Paris, France
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15
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Jeffrey-Gauthier R, Piché M, Leblond H. H-reflex disinhibition by lumbar muscle inflammation in a mouse model of spinal cord injury. Neurosci Lett 2018; 690:36-41. [PMID: 30292718 DOI: 10.1016/j.neulet.2018.10.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Revised: 09/05/2018] [Accepted: 10/03/2018] [Indexed: 12/27/2022]
Abstract
Inflammation is a common comorbidity in patients with traumatic spinal cord injury (SCI). Recent reports indicate that inflammation hinders functional recovery in animal models of SCI. However, the spinal mechanisms underlying this alteration are currently unknown. Considering that spinal plasticity is a therapeutic target in patients and animal models of SCI, these mechanisms remain to be clarified. Using injections of complete Freund's adjuvant (CFA) in lumbar muscles as a model of persistent inflammation, the objective of this study was to assess the impact of inflammation on spinal reflex excitability after a complete midthoracic spinal transection in mice. To this end, the excitability of spinal reflexes was examined by measuring H-reflex frequency-dependent depression (FDD) on days 7, 14 and 28 following a complete spinal transection. H-reflex parameters were compared between spinal mice with CFA and control spinal mice. On day 7, lumbar muscle inflammation disinhibited the H-reflex, reflected by an attenuation of H-reflex FDD (p < 0.01), although this effect did not persist later on, either on day 14 or day 28. These results indicate that lumbar muscle inflammation alters spinal reflex excitability transiently in spinal mice. Considering that changes in spinal reflex excitability are associated with poor functional recovery after SCI, this implies that inflammation should be treated effectively to promote optimal recovery following SCI.
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Affiliation(s)
- Renaud Jeffrey-Gauthier
- Department of Anatomy, Université du Québec à Trois-Rivières (UQTR), 3351 boul. des Forges, C.P. 500, Trois-Rivières, QC, G9A 5H7, Canada; CogNAC Research Group, Université du Québec à Trois-Rivières, 3351 boul. des Forges, C.P. 500, Trois-Rivières, QC, G9A 5H7, Canada
| | - Mathieu Piché
- CogNAC Research Group, Université du Québec à Trois-Rivières, 3351 boul. des Forges, C.P. 500, Trois-Rivières, QC, G9A 5H7, Canada; Department of Chiropractic, Université du Québec à Trois-Rivières, 3351 boul. des Forges, C.P. 500, Trois-Rivières, QC, G9A 5H7, Canada
| | - Hugues Leblond
- Department of Anatomy, Université du Québec à Trois-Rivières (UQTR), 3351 boul. des Forges, C.P. 500, Trois-Rivières, QC, G9A 5H7, Canada; CogNAC Research Group, Université du Québec à Trois-Rivières, 3351 boul. des Forges, C.P. 500, Trois-Rivières, QC, G9A 5H7, Canada.
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16
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Jean-Xavier C, Perreault MC. Influence of Brain Stem on Axial and Hindlimb Spinal Locomotor Rhythm Generating Circuits of the Neonatal Mouse. Front Neurosci 2018; 12:53. [PMID: 29479302 PMCID: PMC5811543 DOI: 10.3389/fnins.2018.00053] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2017] [Accepted: 01/23/2018] [Indexed: 12/18/2022] Open
Abstract
The trunk plays a pivotal role in limbed locomotion. Yet, little is known about how the brain stem controls trunk activity during walking. In this study, we assessed the spatiotemporal activity patterns of axial and hindlimb motoneurons (MNs) during drug-induced fictive locomotor-like activity (LLA) in an isolated brain stem-spinal cord preparation of the neonatal mouse. We also evaluated the extent to which these activity patterns are affected by removal of brain stem. Recordings were made in the segments T7, L2, and L5 using calcium imaging from individual axial MNs in the medial motor column (MMC) and hindlimb MNs in lateral motor column (LMC). The MN activities were analyzed during both the rhythmic and the tonic components of LLA, the tonic component being used as a readout of generalized increase in excitability in spinal locomotor networks. The most salient effect of brain stem removal was an increase in locomotor rhythm frequency and a concomitant reduction in burst durations in both MMC and LMC MNs. The lack of effect on the tonic component of LLA indicated specificity of action during the rhythmic component. Cooling-induced silencing of the brain stem reproduced the increase in rhythm frequency and accompanying decrease in burst durations in L2 MMC and LMC, suggesting a dependency on brain stem neuron activity. The work supports the idea that the brain stem locomotor circuits are operational already at birth and further suggests an important role in modulating trunk activity. The brain stem may influence the axial and hindlimb spinal locomotor rhythm generating circuits by extending their range of operation. This may represent a critical step of locomotor development when learning how to walk in different conditions and environments is a major endeavor.
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Affiliation(s)
| | - Marie-Claude Perreault
- Department of Physiology, Emory University School of Medicine, Atlanta, GA, United States
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17
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Züchner M, Kondratskaya E, Sylte CB, Glover JC, Boulland JL. Rapid recovery and altered neurochemical dependence of locomotor central pattern generation following lumbar neonatal spinal cord injury. J Physiol 2017; 596:281-303. [PMID: 29086918 DOI: 10.1113/jp274484] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Accepted: 10/25/2017] [Indexed: 01/30/2023] Open
Abstract
KEY POINTS Spinal compression injury targeted to the neonatal upper lumbar spinal cord, the region of highest hindlimb locomotor rhythmogenicity, leads to an initial paralysis of the hindlimbs. Behavioural recovery is evident within a few days and approaches normal function within about 3 weeks. Fictive locomotion in the isolated injured spinal cord cannot be elicited by a neurochemical cocktail containing NMDA, dopamine and serotonin 1 day post-injury, but can 3 days post-injury as readily as in the uninjured spinal cord. Low frequency coordinated rhythmic activity can be elicited in the isolated uninjured spinal cord by NMDA + dopamine (without serotonin), but not in the isolated injured spinal cord. In both the injured and uninjured spinal cord, eliciting bona fide fictive locomotion requires the additional presence of serotonin. ABSTRACT Following incomplete compression injury in the thoracic spinal cord of neonatal mice 1 day after birth (P1), we previously reported that virtually normal hindlimb locomotor function is recovered within about 3 weeks despite substantial permanent thoracic tissue loss. Here, we asked whether similar recovery occurs following lumbar injury that impacts more directly on the locomotor central pattern generator (CPG). As in thoracic injuries, lumbar injuries caused about 90% neuronal loss at the injury site and increased serotonergic innervation below the injury. Motor recovery was slower after lumbar than thoracic injury, but virtually normal function was attained by P25 in both cases. Locomotor CPG status was tested by eliciting fictive locomotion in isolated spinal cords using a widely used neurochemical cocktail (NMDA, dopamine, serotonin). No fictive locomotion could be elicited 1 day post-injury, but could within 3 days post-injury as readily as in age-matched uninjured control spinal cords. Burst patterning and coordination were largely similar in injured and control spinal cords but there were differences. Notably, in both groups there were two main locomotor frequencies, but injured spinal cords exhibited a shift towards the higher frequency. Injury also altered the neurochemical dependence of locomotor CPG output, such that injured spinal cords, unlike control spinal cords, were incapable of generating low frequency rhythmic coordinated activity in the presence of NMDA and dopamine alone. Thus, the neonatal spinal cord also exhibits remarkable functional recovery after lumbar injuries, but the neurochemical sensitivity of locomotor circuitry is modified in the process.
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Affiliation(s)
- Mark Züchner
- Laboratory of Neural Development and Optical Recording (NDEVOR), Division of Physiology, Department of Molecular Medicine, University of Oslo, Oslo, Norway.,Norwegian Centre for Stem Cell Research, Oslo University Hospital, Oslo, Norway.,Department of Neurosurgery, Oslo University Hospital, Oslo, Norway
| | - Elena Kondratskaya
- Laboratory of Neural Development and Optical Recording (NDEVOR), Division of Physiology, Department of Molecular Medicine, University of Oslo, Oslo, Norway.,Norwegian Centre for Stem Cell Research, Oslo University Hospital, Oslo, Norway
| | - Camilla B Sylte
- Laboratory of Neural Development and Optical Recording (NDEVOR), Division of Physiology, Department of Molecular Medicine, University of Oslo, Oslo, Norway
| | - Joel C Glover
- Laboratory of Neural Development and Optical Recording (NDEVOR), Division of Physiology, Department of Molecular Medicine, University of Oslo, Oslo, Norway.,Norwegian Centre for Stem Cell Research, Oslo University Hospital, Oslo, Norway
| | - Jean-Luc Boulland
- Laboratory of Neural Development and Optical Recording (NDEVOR), Division of Physiology, Department of Molecular Medicine, University of Oslo, Oslo, Norway.,Norwegian Centre for Stem Cell Research, Oslo University Hospital, Oslo, Norway
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18
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Jeffrey-Gauthier R, Piché M, Leblond H. Lumbar muscle inflammation alters spinally mediated locomotor recovery induced by training in a mouse model of complete spinal cord injury. Neuroscience 2017; 359:69-81. [DOI: 10.1016/j.neuroscience.2017.07.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Revised: 06/30/2017] [Accepted: 07/06/2017] [Indexed: 02/07/2023]
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19
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Abstract
BACKGROUND Genetic techniques rendering murine models a popular choice for neuroscience research has led to important insights on neural networks controlling locomotor function. Using genetically altered mouse models for in vivo, electrophysiological studies in the adult state could validate key principles of locomotor network organization that have been described in neonatal, in vitro preparations. NEW METHOD The experimental model presented here describes a decerebrate, in vivo adult mouse preparation in which focal, electrical midbrain stimulation was combined with monitoring lumbar neural activity and motor output after pre-collicular decerebration and neuromuscular blockade. RESULTS Lumbar cord dorsum potentials (in 9/10 animals) and motoneuron output (in 3/5 animals) including fictive locomotion, was achieved by focal midbrain stimulation. The stimulation electrode locations could be reconstructed (in 6/7 animals) thereby allowing anatomical identification of the stimulated supraspinal regions. COMPARISON WITH EXISTING METHODS This preparation allows for concomitant recording or stimulation in the spinal cord and in the mid/hindbrain of adult mice. It differs from other methods used in the past with adult mice as it does not require pharmacological manipulation of neural excitability in order to generate motor output. CONCLUSIONS Midbrain stimulation can consistently be used for inducing lumbar neural activity in adult mice under neuromuscular blockade. This model is suited for examination of brain-spinal connectivity and it may benefit a wide range of fields depending on the features of the genetically modified mouse models used in combination with the presented methods.
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Affiliation(s)
- Katinka Stecina
- Department of Physiology and Pathophysiology, Rady Faculty of Health Sciences, University of Manitoba, 745 Bannatyne Ave., BMSB-436, Winnipeg, MB, R3E0J9, Canada.
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20
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Jaiswal PB, English AW. Chemogenetic enhancement of functional recovery after a sciatic nerve injury. Eur J Neurosci 2017; 45:1252-1257. [PMID: 28244163 DOI: 10.1111/ejn.13550] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Revised: 02/15/2017] [Accepted: 02/22/2017] [Indexed: 11/28/2022]
Abstract
Designer receptors exclusively activated by designer drugs (DREADDs) are chemogenetic tools used to modulate neuronal excitability. We hypothesized that activation of excitatory (Gq) DREADD by its designer ligand, clozapine-N-oxide (CNO), would increase the excitability of neurons whose axons have been transected following peripheral nerve injury, and that this increase will lead to an enhanced functional recovery. The lateral gastrocnemius (LG) muscle of adult female Lewis rats was injected unilaterally with AAV9- hsyn- hM3Dq-mCherry (7.6 × 109 viral genomes/μL) to transduce Gq-DREADD expression in LG neurons. The contralateral LG muscle served as an uninjected control. No significant changes in either spontaneous EMG activity or electrically evoked direct muscle (M) responses were found in either muscle after injection of CNO (1 mg/kg, i.p.). The amplitude of monosynaptic H-reflexes in LG was increased after CNO treatment exclusively in muscles previously injected with virus, suggesting that Gq-DREADD activation increased neuronal excitability. After bilateral sciatic nerve transection and repair, additional rats were treated similarly with CNO for up to three days after injury. Electrophysiological data were collected at 2, 4 and 6 weeks after injury. Evoked EMG responses were observed as early as 2 weeks after injury only in Gq-DREADD expressing virus injected LG muscle. By 4 weeks after injury, both M-response and H-reflex amplitudes were significantly greater in muscles previously injected with viral vector than contralateral, uninjected muscles. Increases in the excitability of injured neurons produced by this novel use of Gq-DREADD were sufficient to promote an enhancement in functional recovery after a sciatic nerve injury.
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Affiliation(s)
- Poonam B Jaiswal
- Department of Cell Biology, Emory University, 615 Michael St, Atlanta, GA, 30322, USA
| | - Arthur W English
- Department of Cell Biology, Emory University, 615 Michael St, Atlanta, GA, 30322, USA
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21
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Frigon A. The neural control of interlimb coordination during mammalian locomotion. J Neurophysiol 2017; 117:2224-2241. [PMID: 28298308 DOI: 10.1152/jn.00978.2016] [Citation(s) in RCA: 101] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Revised: 03/02/2017] [Accepted: 03/15/2017] [Indexed: 01/06/2023] Open
Abstract
Neuronal networks within the spinal cord directly control rhythmic movements of the arms/forelimbs and legs/hindlimbs during locomotion in mammals. For an effective locomotion, these networks must be flexibly coordinated to allow for various gait patterns and independent use of the arms/forelimbs. This coordination can be accomplished by mechanisms intrinsic to the spinal cord, somatosensory feedback from the limbs, and various supraspinal pathways. Incomplete spinal cord injury disrupts some of the pathways and structures involved in interlimb coordination, often leading to a disruption in the coordination between the arms/forelimbs and legs/hindlimbs in animal models and in humans. However, experimental spinal lesions in animal models to uncover the mechanisms coordinating the limbs have limitations due to compensatory mechanisms and strategies, redundant systems of control, and plasticity within remaining circuits. The purpose of this review is to provide a general overview and critical discussion of experimental studies that have investigated the neural mechanisms involved in coordinating the arms/forelimbs and legs/hindlimbs during mammalian locomotion.
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Affiliation(s)
- Alain Frigon
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada
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22
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Abstract
The adult decerebrate mouse model (a mouse with the cerebrum removed) enables the study of sensory-motor integration and motor output from the spinal cord for several hours without compromising these functions with anesthesia. For example, the decerebrate mouse is ideal for examining locomotor behavior using intracellular recording approaches, which would not be possible using current anesthetized preparations. This protocol describes the steps required to achieve a low-blood-loss decerebration in the mouse and approaches for recording signals from spinal cord neurons with a focus on motoneurons. The protocol also describes an example application for the protocol: the evocation of spontaneous and actively driven stepping, including optimization of these behaviors in decerebrate mice. The time taken to prepare the animal and perform a decerebration takes ∼2 h, and the mice are viable for up to 3-8 h, which is ample time to perform most short-term procedures. These protocols can be modified for those interested in cardiovascular or respiratory function in addition to motor function and can be performed by trainees with some previous experience in animal surgery.
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23
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Cabaj AM, Majczyński H, Couto E, Gardiner PF, Stecina K, Sławińska U, Jordan LM. Serotonin controls initiation of locomotion and afferent modulation of coordination via 5-HT 7 receptors in adult rats. J Physiol 2016; 595:301-320. [PMID: 27393215 DOI: 10.1113/jp272271] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Accepted: 06/30/2016] [Indexed: 12/16/2022] Open
Abstract
KEY POINTS Experiments on neonatal rodent spinal cord showed that serotonin (5-HT), acting via 5-HT7 receptors, is required for initiation of locomotion and for controlling the action of interneurons responsible for inter- and intralimb coordination, but the importance of the 5-HT system in adult locomotion is not clear. Blockade of spinal 5-HT7 receptors interfered with voluntary locomotion in adult rats and fictive locomotion in paralysed decerebrate rats with no afferent feedback, consistent with a requirement for activation of descending 5-HT neurons for production of locomotion. The direct control of coordinating interneurons by 5-HT7 receptors observed in neonatal animals was not found during fictive locomotion, revealing a developmental shift from direct control of locomotor interneurons in neonates to control of afferent input from the moving limb in adults. An understanding of the afferents controlled by 5-HT during locomotion is required for optimal use of rehabilitation therapies involving the use of serotonergic drugs. ABSTRACT Serotonergic pathways to the spinal cord are implicated in the control of locomotion based on studies using serotonin type 7 (5-HT7 ) receptor agonists and antagonists and 5-HT7 receptor knockout mice. Blockade of these receptors is thought to interfere with the activity of coordinating interneurons, a conclusion derived primarily from in vitro studies on isolated spinal cord of neonatal rats and mice. Developmental changes in the effects of serotonin (5-HT) on spinal neurons have recently been described, and there is increasing data on control of sensory input by 5-HT7 receptors on dorsal root ganglion cells and/or dorsal horn neurons, leading us to determine the effects of 5-HT7 receptor blockade on voluntary overground locomotion and on locomotion without afferent input from the moving limb (fictive locomotion) in adult animals. Intrathecal injections of the selective 5-HT7 antagonist SB269970 in adult intact rats suppressed locomotion by partial paralysis of hindlimbs. This occurred without a direct effect on motoneurons as revealed by an investigation of reflex activity. The antagonist disrupted intra- and interlimb coordination during locomotion in all intact animals but not during fictive locomotion induced by stimulation of the mesencephalic locomotor region (MLR). MLR-evoked fictive locomotion was transiently blocked, then the amplitude and frequency of rhythmic activity were reduced by SB269970, consistent with the notion that the MLR activates 5-HT neurons, leading to excitation of central pattern generator neurons with 5-HT7 receptors. Effects on coordination in adults required the presence of afferent input, suggesting a switch to 5-HT7 receptor-mediated control of sensory pathways during development.
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Affiliation(s)
- Anna M Cabaj
- Department of Neurophysiology, Nencki Institute of Experimental Biology PAS, 02-093, Warsaw, Poland.,Department of Nerve-Muscle Engineering, Institute of Biocybernetics and Biomedical Engineering PAS, 02-109, Warsaw, Poland
| | - Henryk Majczyński
- Department of Neurophysiology, Nencki Institute of Experimental Biology PAS, 02-093, Warsaw, Poland
| | - Erika Couto
- Department of Physiology & Pathophysiology, Spinal Cord Research Centre, University of Manitoba, Winnipeg, MB, R3E 0J9, Canada
| | - Phillip F Gardiner
- Department of Physiology & Pathophysiology, Spinal Cord Research Centre, University of Manitoba, Winnipeg, MB, R3E 0J9, Canada
| | - Katinka Stecina
- Department of Physiology & Pathophysiology, Spinal Cord Research Centre, University of Manitoba, Winnipeg, MB, R3E 0J9, Canada
| | - Urszula Sławińska
- Department of Neurophysiology, Nencki Institute of Experimental Biology PAS, 02-093, Warsaw, Poland
| | - Larry M Jordan
- Department of Physiology & Pathophysiology, Spinal Cord Research Centre, University of Manitoba, Winnipeg, MB, R3E 0J9, Canada
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Dose F, Taccola G. Two Distinct Stimulus Frequencies Delivered Simultaneously at Low Intensity Generate Robust Locomotor Patterns. Neuromodulation 2016; 19:563-75. [PMID: 26968869 DOI: 10.1111/ner.12402] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Revised: 12/21/2015] [Accepted: 12/29/2015] [Indexed: 12/25/2022]
Abstract
OBJECTIVES Explore the primary characteristics of afferent noisy stimuli, which optimally activate locomotor patterns at low intensity. MATERIALS AND METHODS Intracellular and extracellular electrophysiological traces were derived from single motoneurons and from ventral roots, respectively. From these recordings, we obtained noisy stimulating protocols, delivered to a dorsal root (DR) of an isolated neonatal rat spinal cord, while recording fictive locomotion (FL) from ventral roots. RESULTS We decreased complexity of efficient noisy stimulating protocols down to single cell spikes. Then, we identified four main components within the power spectrum of these signals and used them to construct a basic multifrequency protocol of rectangular impulses, able to induce FL. Further disassembling generated the minimum stimulation paradigm that activated FL, which consisted of a pair of 35 and 172 Hz frequency pulse trains, strongly effective at low intensity when delivered either jointly to one lumbosacral DR or as single simultaneous trains to two distinct DRs. This simplified pulse schedule always activated a locomotor rhythm, even when delivered for a very short time (500 ms). One prerequisite for the two-frequency protocol to activate FL at low intensity when applied to sacrocaudal afferents was the ability to induce ascending volleys of greater amplitude. CONCLUSION Multifrequency protocols can support future studies in defining the most effective characteristics for electrical stimulation to reactivate stepping following motor injury.
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Affiliation(s)
- Francesco Dose
- Neuroscience Area, International School for Advanced Studies (SISSA), Trieste, TS, Italy.,SPINAL (Spinal Person Injury Neurorehabilitation Applied Laboratory), Istituto di Medicina Fisica e Riabilitazione (IMFR), Udine, UD, Italy
| | - Giuliano Taccola
- Neuroscience Area, International School for Advanced Studies (SISSA), Trieste, TS, Italy.,SPINAL (Spinal Person Injury Neurorehabilitation Applied Laboratory), Istituto di Medicina Fisica e Riabilitazione (IMFR), Udine, UD, Italy
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Lemieux M, Josset N, Roussel M, Couraud S, Bretzner F. Speed-Dependent Modulation of the Locomotor Behavior in Adult Mice Reveals Attractor and Transitional Gaits. Front Neurosci 2016; 10:42. [PMID: 26941592 PMCID: PMC4763020 DOI: 10.3389/fnins.2016.00042] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Accepted: 02/01/2016] [Indexed: 01/21/2023] Open
Abstract
Locomotion results from an interplay between biomechanical constraints of the muscles attached to the skeleton and the neuronal circuits controlling and coordinating muscle activities. Quadrupeds exhibit a wide range of locomotor gaits. Given our advances in the genetic identification of spinal and supraspinal circuits important to locomotion in the mouse, it is now important to get a better understanding of the full repertoire of gaits in the freely walking mouse. To assess this range, young adult C57BL/6J mice were trained to walk and run on a treadmill at different locomotor speeds. Instead of using the classical paradigm defining gaits according to their footfall pattern, we combined the inter-limb coupling and the duty cycle of the stance phase, thus identifying several types of gaits: lateral walk, trot, out-of-phase walk, rotary gallop, transverse gallop, hop, half-bound, and full-bound. Out-of-phase walk, trot, and full-bound were robust and appeared to function as attractor gaits (i.e., a state to which the network flows and stabilizes) at low, intermediate, and high speeds respectively. In contrast, lateral walk, hop, transverse gallop, rotary gallop, and half-bound were more transient and therefore considered transitional gaits (i.e., a labile state of the network from which it flows to the attractor state). Surprisingly, lateral walk was less frequently observed. Using graph analysis, we demonstrated that transitions between gaits were predictable, not random. In summary, the wild-type mouse exhibits a wider repertoire of locomotor gaits than expected. Future locomotor studies should benefit from this paradigm in assessing transgenic mice or wild-type mice with neurotraumatic injury or neurodegenerative disease affecting gait.
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Affiliation(s)
- Maxime Lemieux
- Centre de Recherche du CHU de Québec, CHUL-Neurosciences Québec, QC, Canada
| | - Nicolas Josset
- Centre de Recherche du CHU de Québec, CHUL-Neurosciences Québec, QC, Canada
| | - Marie Roussel
- Centre de Recherche du CHU de Québec, CHUL-Neurosciences Québec, QC, Canada
| | - Sébastien Couraud
- Centre de Recherche du CHU de Québec, CHUL-Neurosciences Québec, QC, Canada
| | - Frédéric Bretzner
- Centre de Recherche du CHU de Québec, CHUL-NeurosciencesQuébec, QC, Canada; Department of Psychiatry and Neurosciences, Faculty of Medicine, Université LavalQuébec, QC, Canada
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26
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English AW, Wilhelm JC, Ward PJ. Exercise, neurotrophins, and axon regeneration in the PNS. Physiology (Bethesda) 2015; 29:437-45. [PMID: 25362637 DOI: 10.1152/physiol.00028.2014] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Electrical stimulation and exercise are treatments to enhance recovery from peripheral nerve injuries. Brain-derived neurotrophic factor and androgen receptor signaling are requirements for the effectiveness of these treatments. Increased neuronal activity is adequate to promote regeneration in injured nerves, but the dosing of activity and its relationship to neurotrophins and sex steroid hormones is less clear. Translation of these therapies will require principles associated with their cellular mechanisms.
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Affiliation(s)
- Arthur W English
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia; and
| | - Jennifer C Wilhelm
- Department of Psychology, College of Charleston, Charleston, South Carolina
| | - Patricia J Ward
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia; and
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27
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Danner SM, Hofstoetter US, Freundl B, Binder H, Mayr W, Rattay F, Minassian K. Human spinal locomotor control is based on flexibly organized burst generators. Brain 2015; 138:577-88. [PMID: 25582580 PMCID: PMC4408427 DOI: 10.1093/brain/awu372] [Citation(s) in RCA: 102] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Revised: 10/01/2014] [Accepted: 11/05/2014] [Indexed: 12/27/2022] Open
Abstract
Constant drive provided to the human lumbar spinal cord by epidural electrical stimulation can cause local neural circuits to generate rhythmic motor outputs to lower limb muscles in people paralysed by spinal cord injury. Epidural spinal cord stimulation thus allows the study of spinal rhythm and pattern generating circuits without their configuration by volitional motor tasks or task-specific peripheral feedback. To reveal spinal locomotor control principles, we studied the repertoire of rhythmic patterns that can be generated by the functionally isolated human lumbar spinal cord, detected as electromyographic activity from the legs, and investigated basic temporal components shared across these patterns. Ten subjects with chronic, motor-complete spinal cord injury were studied. Surface electromyographic responses to lumbar spinal cord stimulation were collected from quadriceps, hamstrings, tibialis anterior, and triceps surae in the supine position. From these data, 10-s segments of rhythmic activity present in the four muscle groups of one limb were extracted. Such samples were found in seven subjects. Physiologically adequate cycle durations and relative extension- and flexion-phase durations similar to those needed for locomotion were generated. The multi-muscle activation patterns exhibited a variety of coactivation, mixed-synergy and locomotor-like configurations. Statistical decomposition of the electromyographic data across subjects, muscles and samples of rhythmic patterns identified three common temporal components, i.e. basic or shared activation patterns. Two of these basic patterns controlled muscles to contract either synchronously or alternatingly during extension- and flexion-like phases. The third basic pattern contributed to the observed muscle activities independently from these extensor- and flexor-related basic patterns. Each bifunctional muscle group was able to express both extensor- and flexor-patterns, with variable ratios across the samples of rhythmic patterns. The basic activation patterns can be interpreted as central drives implemented by spinal burst generators that impose specific spatiotemporally organized activation on the lumbosacral motor neuron pools. Our data thus imply that the human lumbar spinal cord circuits can form burst-generating elements that flexibly combine to obtain a wide range of locomotor outputs from a constant, repetitive input. It may be possible to use this flexibility to incorporate specific adaptations to gait and stance to improve locomotor control, even after severe central nervous system damage.
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Affiliation(s)
- Simon M Danner
- 1 Institute for Analysis and Scientific Computing, Vienna University of Technology, Vienna, Austria 2 Centre for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Ursula S Hofstoetter
- 2 Centre for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | | | - Heinrich Binder
- 3 Neurological Centre, Otto Wagner Hospital, Vienna, Austria
| | - Winfried Mayr
- 2 Centre for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Frank Rattay
- 1 Institute for Analysis and Scientific Computing, Vienna University of Technology, Vienna, Austria
| | - Karen Minassian
- 2 Centre for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
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28
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Wienecke J, Enríquez Denton M, Stecina K, Kirkwood PA, Hultborn H. Modulation of spontaneous locomotor and respiratory drives to hindlimb motoneurons temporally related to sympathetic drives as revealed by Mayer waves. Front Neural Circuits 2015; 9:1. [PMID: 25713515 PMCID: PMC4322721 DOI: 10.3389/fncir.2015.00001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Accepted: 01/05/2015] [Indexed: 12/12/2022] Open
Abstract
In this study we investigated how the networks mediating respiratory and locomotor drives to lumbar motoneurons interact and how this interaction is modulated in relation to periodic variations in blood pressure (Mayer waves). Seven decerebrate cats, under neuromuscular blockade, were used to study central respiratory drive potentials (CRDPs, usually enhanced by added CO2) and spontaneously occurring locomotor drive potentials (LDPs) in hindlimb motoneurons, together with hindlimb and phrenic nerve discharges. In four of the cats both drives and their voltage-dependent amplification were absent or modest, but in the other three, one or other of these drives was common and the voltage-dependent amplification was frequently strong. Moreover, in these three cats the blood pressure showed marked periodic variation (Mayer waves), with a slow rate (periods 9–104 s, mean 39 ± 17 SD). Profound modulation, synchronized with the Mayer waves was seen in the occurrence and/or in the amplification of the CRDPs or LDPs. In one animal, where CRDPs were present in most cells and the amplification was strong, the CRDP consistently triggered sustained plateaux at one phase of the Mayer wave cycle. In the other two animals, LDPs were common, and the occurrence of the locomotor drive was gated by the Mayer wave cycle, sometimes in alternation with the respiratory drive. Other interactions between the two drives involved respiration providing leading events, including co-activation of flexors and extensors during post-inspiration or a locomotor drive gated or sometimes entrained by respiration. We conclude that the respiratory drive in hindlimb motoneurons is transmitted via elements of the locomotor central pattern generator. The rapid modulation related to Mayer waves suggests the existence of a more direct and specific descending modulatory control than has previously been demonstrated.
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Affiliation(s)
- Jacob Wienecke
- Department of Neuroscience and Pharmacology, The Panum Institute, University of Copenhagen Copenhagen, Denmark ; Department of Nutrition, Exercise and Sports, The Panum Institute, University of Copenhagen Copenhagen, Denmark
| | - Manuel Enríquez Denton
- Department of Neuroscience and Pharmacology, The Panum Institute, University of Copenhagen Copenhagen, Denmark ; Sobell Department for Motor Neuroscience and Movement Disorders, University College London Institute of Neurology London, UK ; Universidad del Valle de México Mexico City, Mexico
| | - Katinka Stecina
- Department of Neuroscience and Pharmacology, The Panum Institute, University of Copenhagen Copenhagen, Denmark ; Department of Physiology and Pathophysiology, University of Manitoba Winnipeg, MB, Canada
| | - Peter A Kirkwood
- Sobell Department for Motor Neuroscience and Movement Disorders, University College London Institute of Neurology London, UK
| | - Hans Hultborn
- Department of Neuroscience and Pharmacology, The Panum Institute, University of Copenhagen Copenhagen, Denmark
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29
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Ghosh M, Pearse DD. The role of the serotonergic system in locomotor recovery after spinal cord injury. Front Neural Circuits 2015; 8:151. [PMID: 25709569 PMCID: PMC4321350 DOI: 10.3389/fncir.2014.00151] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Accepted: 12/28/2014] [Indexed: 11/30/2022] Open
Abstract
Serotonin (5-HT), a monoamine neurotransmitter synthesized in various populations of brainstem neurons, plays an important role in modulating the activity of spinal networks involved in vertebrate locomotion. Following spinal cord injury (SCI) there is a disruption of descending serotonergic projections to spinal motor areas, which results in a subsequent depletion in 5-HT, the dysregulation of 5-HT transporters as well as the elevated expression, super-sensitivity and/or constitutive auto-activation of specific 5-HT receptors. These changes in the serotonergic system can produce varying degrees of locomotor dysfunction through to paralysis. To date, various approaches targeting the different components of the serotonergic system have been employed to restore limb coordination and improve locomotor function in experimental models of SCI. These strategies have included pharmacological modulation of serotonergic receptors, through the administration of specific 5-HT receptor agonists, or by elevating the 5-HT precursor 5-hydroxytryptophan, which produces a global activation of all classes of 5-HT receptors. Stimulation of these receptors leads to the activation of the locomotor central pattern generator (CPG) below the site of injury to facilitate or improve the quality and frequency of movements, particularly when used in concert with the activation of other monoaminergic systems or coupled with electrical stimulation. Another approach has been to employ cell therapeutics to replace the loss of descending serotonergic input to the CPG, either through transplanted fetal brainstem 5-HT neurons at the site of injury that can supply 5-HT to below the level of the lesion or by other cell types to provide a substrate at the injury site for encouraging serotonergic axon regrowth across the lesion to the caudal spinal cord for restoring locomotion.
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Affiliation(s)
- Mousumi Ghosh
- The Miami Project to Cure Paralysis, University of Miami Miller School of Medicine Miami, FL, USA ; Department of Neurological Surgery, University of Miami Miller School of Medicine Miami, FL, USA
| | - Damien D Pearse
- The Miami Project to Cure Paralysis, University of Miami Miller School of Medicine Miami, FL, USA ; Department of Neurological Surgery, University of Miami Miller School of Medicine Miami, FL, USA ; The Neuroscience Program, University of Miami Miller School of Medicine Miami, FL, USA ; The Interdisciplinary Stem Cell Institute, University of Miami Miller School of Medicine Miami, FL, USA
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30
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Schomburg ED, Kalezic I, Dibaj P, Steffens H. Reflex transmission to lumbar α-motoneurones in the mouse similar and different to those in the cat. Neurosci Res 2013; 76:133-40. [PMID: 23562791 DOI: 10.1016/j.neures.2013.03.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Revised: 03/26/2013] [Accepted: 03/26/2013] [Indexed: 11/15/2022]
Abstract
Investigation and interpretation of defective motor circuitries in transgenic mice required further basic results from wild-type mice. Therefore, we investigated the lumbar motor reflex pattern in anaesthetised mice using intracellular motoneuronal recording and monosynaptic reflex testing. Thresholds and latencies in mice were similar to those in cats: thresholds for monosynaptic (group I) EPSPs were slightly above 1T (T=threshold for the lowest threshold fibres), around 1.5T for group II EPSPs and above 10T for group III EPSPs; group I EPSPs were maximal with a stimulus strength around 2T, group II EPSPs were maximal with 5-8T; latencies to the group I incoming volley were below 1ms for monosynaptic group I EPSPs, around 3ms for polysynaptic group II EPSPs and above 4ms for polysynaptic group III EPSPs. In contrast to reflex actions in the cat, monosynaptic gastrocnemius-soleus reflexes were facilitated by conditioning stimulation of the peroneal, sural and tibial nerves, i.e. by a variety of different, probably flexor reflex afferents. This facilitation persisted after high lumbar spinalisation indicating an independency to supraspinal influences. Nociceptive muscle afferents facilitated the peroneal monosynaptic reflex while nociceptive cutaneous afferents from the foot sole inhibited the ipsilateral but facilitated the contralateral peroneal reflex.
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Affiliation(s)
- Eike D Schomburg
- Institute of Physiology, University of Göttingen, Göttingen, Germany.
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31
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Manuel M, Marin M, Heckman CJ. Simultaneous intracellular recording of a lumbar motoneuron and the force produced by its motor unit in the adult mouse in vivo. J Vis Exp 2012:e4312. [PMID: 23242236 DOI: 10.3791/4312] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
The spinal motoneuron has long been a good model system for studying neural function because it is a neuron of the central nervous system with the unique properties of (1) having readily identifiable targets (the muscle fibers) and therefore having a very well-known function (to control muscle contraction); (2) being the convergent target of many spinal and descending networks, hence the name of "final common pathway"; and (3) having a large soma which makes it possible to penetrate them with sharp intracellular electrodes. Furthermore, when studied in vivo, it is possible to record simultaneously the electrical activity of the motoneurons and the force developed by their muscle targets. Performing intracellular recordings of motoneurons in vivo therefore put the experimentalist in the unique position of being able to study, at the same time, all the compartments of the "motor unit" (the name given to the motoneuron, its axon, and the muscle fibers it innervates(1)): the inputs impinging on the motoneuron, the electrophysiological properties of the motoneuron, and the impact of these properties on the physiological function of the motoneurons, i.e. the force produced by its motor unit. However, this approach is very challenging because the preparation cannot be paralyzed and thus the mechanical stability for the intracellular recording is reduced. Thus, this kind of experiments has only been achieved in cats and in rats. However, the study of spinal motor systems could make a formidable leap if it was possible to perform similar experiments in normal and genetically modified mice. For technical reasons, the study of the spinal networks in mice has mostly been limited to neonatal in vitro preparations, where the motoneurons and the spinal networks are immature, the motoneurons are separated from their targets, and when studied in slices, the motoneurons are separated from most of their inputs. Until recently, only a few groups had managed to perform intracellular recordings of motoneurons in vivo(2-4 ), including our team who published a new preparation which allowed us to obtain very stable recordings of motoneurons in vivo in adult mice(5,6). However, these recordings were obtained in paralyzed animals, i.e. without the possibility to record the force output of these motoneurons. Here we present an extension of this original preparation in which we were able to obtain simultaneous recordings of the electrophysiological properties of the motoneurons and of the force developed by their motor unit. This is an important achievement, as it allows us to identify the different types of motoneurons based on their force profile, and thereby revealing their function. Coupled with genetic models disturbing spinal segmental circuitry(7-9), or reproducting human disease(10,11), we expect this technique to be an essential tool for the study of spinal motor system.
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Affiliation(s)
- Marin Manuel
- Department of Physiology, Northwestern University Feinberg School of Medicine.
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32
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Peng J, Charron F. Lateralization of motor control in the human nervous system: genetics of mirror movements. Curr Opin Neurobiol 2012; 23:109-18. [PMID: 22989473 DOI: 10.1016/j.conb.2012.08.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2012] [Revised: 08/21/2012] [Accepted: 08/26/2012] [Indexed: 01/10/2023]
Abstract
Mirror movements (MM) are a peculiar motor defect in humans where the intended unilateral movement of a body part results in involuntary movement of the same body part on the opposite side. This loss in the lateralization of motor control can be caused by genetic mutations that result in an aberrant projection of the corticospinal tract. However, recent evidence suggests that the same genes controlling corticospinal tract development also play roles in the development of other circuits involved in motor control, including local spinal circuits and the corpus callosum. These recent studies in humans and mouse models of MM will be discussed to provide an overview of the basis of MM and the molecular mechanisms underlying the lateralization of motor control.
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Affiliation(s)
- Jimmy Peng
- Molecular Biology of Neural Development, Institut de Recherches Cliniques de Montréal, Montréal, QC, Canada
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Abstract
Surgical methods currently employed for the mechanical decerebration of a rat are only briefly described in the literature; hence, an information void exists for researchers wishing to adopt this technique successfully. Decerebration can lead to a high rate of mortality owing to cranial bleeding, particularly if the operator is inexperienced and uninformed. The illustrated methodology presented here describes, in detail, steps in the decerebration process and indicates effective approaches, such as reversible occlusion of a carotid artery, the combined use of tissue adhesive and haemostatic sponge, and perisurgical monitoring of blood pressure, by which to control blood loss and thus maintain mean postsurgical blood pressure within acceptable physiological parameters. By using this methodology, animal losses can be minimized, particularly in the early stages of adoption of the technique, ultimately reducing the numbers required for a study of this nature.
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Affiliation(s)
- K L Dobson
- Division of Animal Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, Leicestershire LE12 5RD, UK.
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