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Kumru H, Ros-Alsina A, García Alén L, Vidal J, Gerasimenko Y, Hernandez A, Wrigth M. Improvement in Motor and Walking Capacity during Multisegmental Transcutaneous Spinal Stimulation in Individuals with Incomplete Spinal Cord Injury. Int J Mol Sci 2024; 25:4480. [PMID: 38674065 PMCID: PMC11050444 DOI: 10.3390/ijms25084480] [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: 03/28/2024] [Revised: 04/12/2024] [Accepted: 04/12/2024] [Indexed: 04/28/2024] Open
Abstract
Transcutaneous multisegmental spinal cord stimulation (tSCS) has shown superior efficacy in modulating spinal locomotor circuits compared to single-site stimulation in individuals with spinal cord injury (SCI). Building on these findings, we hypothesized that administering a single session of tSCS at multiple spinal segments may yield greater enhancements in muscle strength and gait function during stimulation compared to tSCS at only one or two segments. In our study, tSCS was applied at single segments (C5, L1, and Coc1), two segments (C5-L1, C5-Coc1, and L1-Coc1), or multisegments (C5-L1-Coc1) in a randomized order. We evaluated the 6-m walking test (6MWT) and maximum voluntary contraction (MVC) and assessed the Hmax/Mmax ratio during stimulation in ten individuals with incomplete motor SCI. Our findings indicate that multisegmental tSCS improved walking time and reduced spinal cord excitability, as measured by the Hmax/Mmax ratio, similar to some single or two-site tSCS interventions. However, only multisegmental tSCS resulted in increased tibialis anterior (TA) muscle strength. These results suggest that multisegmental tSCS holds promise for enhancing walking capacity, increasing muscle strength, and altering spinal cord excitability in individuals with incomplete SCI.
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Affiliation(s)
- Hatice Kumru
- Fundación Institut Guttmann, Institut Universitari de NeurorehabilitacióAdscrit a la UAB, 08916 Badalona, Spain; (A.R.-A.); (L.G.A.); (J.V.); (A.H.); (M.W.)
- Universitat Autònoma de Barcelona, 08193 Barcelona, Spain
- Fundació Institut d’Investigació en Ciències de la Salut Germans Trias i Pujol, 08916 Badalona, Spain
| | - Aina Ros-Alsina
- Fundación Institut Guttmann, Institut Universitari de NeurorehabilitacióAdscrit a la UAB, 08916 Badalona, Spain; (A.R.-A.); (L.G.A.); (J.V.); (A.H.); (M.W.)
| | - Loreto García Alén
- Fundación Institut Guttmann, Institut Universitari de NeurorehabilitacióAdscrit a la UAB, 08916 Badalona, Spain; (A.R.-A.); (L.G.A.); (J.V.); (A.H.); (M.W.)
- Universitat Autònoma de Barcelona, 08193 Barcelona, Spain
| | - Joan Vidal
- Fundación Institut Guttmann, Institut Universitari de NeurorehabilitacióAdscrit a la UAB, 08916 Badalona, Spain; (A.R.-A.); (L.G.A.); (J.V.); (A.H.); (M.W.)
- Universitat Autònoma de Barcelona, 08193 Barcelona, Spain
- Fundació Institut d’Investigació en Ciències de la Salut Germans Trias i Pujol, 08916 Badalona, Spain
| | - Yury Gerasimenko
- Pavlov Institute of Physiology, St. Petersburg 199034, Russia;
- Department of Physiology and Biophysics, University of Louisville, Louisville, KY 40292, USA
| | - Agusti Hernandez
- Fundación Institut Guttmann, Institut Universitari de NeurorehabilitacióAdscrit a la UAB, 08916 Badalona, Spain; (A.R.-A.); (L.G.A.); (J.V.); (A.H.); (M.W.)
- Universitat Autònoma de Barcelona, 08193 Barcelona, Spain
| | - Mark Wrigth
- Fundación Institut Guttmann, Institut Universitari de NeurorehabilitacióAdscrit a la UAB, 08916 Badalona, Spain; (A.R.-A.); (L.G.A.); (J.V.); (A.H.); (M.W.)
- Universitat Autònoma de Barcelona, 08193 Barcelona, Spain
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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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Hachmann JT, Yousak A, Wallner JJ, Gad PN, Edgerton VR, Gorgey AS. Epidural spinal cord stimulation as an intervention for motor recovery after motor complete spinal cord injury. J Neurophysiol 2021; 126:1843-1859. [PMID: 34669485 DOI: 10.1152/jn.00020.2021] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 10/12/2021] [Indexed: 12/19/2022] Open
Abstract
Spinal cord injury (SCI) commonly results in permanent loss of motor, sensory, and autonomic function. Recent clinical studies have shown that epidural spinal cord stimulation may provide a beneficial adjunct for restoring lower extremity and other neurological functions. Herein, we review the recent clinical advances of lumbosacral epidural stimulation for restoration of sensorimotor function in individuals with motor complete SCI and we discuss the putative neural pathways involved in this promising neurorehabilitative approach. We focus on three main sections: review recent clinical results for locomotor restoration in complete SCI; discuss the contemporary understanding of electrical neuromodulation and signal transduction pathways involved in spinal locomotor networks; and review current challenges of motor system modulation and future directions toward integrative neurorestoration. The current understanding is that initial depolarization occurs at the level of large diameter dorsal root proprioceptive afferents that when integrated with interneuronal and latent residual supraspinal translesional connections can recruit locomotor centers and augment downstream motor units. Spinal epidural stimulation can initiate excitability changes in spinal networks and supraspinal networks. Different stimulation parameters can facilitate standing or stepping, and it may also have potential for augmenting myriad other sensorimotor and autonomic functions. More comprehensive investigation of the mechanisms that mediate the transformation of dysfunctional spinal networks to higher functional states with a greater focus on integrated systems-based control system may reveal the key mechanisms underlying neurological augmentation and motor restoration after severe paralysis.
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Affiliation(s)
- Jan T Hachmann
- Department of Neurological Surgery, Virginia Commonwealth University, Richmond, Virginia
| | - Andrew Yousak
- Spinal Cord Injury and Disorders Center, Hunter Holmes McGuire VAMC, Richmond, Virginia
| | - Josephine J Wallner
- Spinal Cord Injury and Disorders Center, Hunter Holmes McGuire VAMC, Richmond, Virginia
| | - Parag N Gad
- Department of Neurobiology, University of California, Los Angeles, California
| | - V Reggie Edgerton
- Department of Neurobiology, University of California, Los Angeles, California
- Fundación Institut Guttmann, Institut Universitari de Neurorehabilitació Badalona, Barcelona, Spain
| | - Ashraf S Gorgey
- Spinal Cord Injury and Disorders Center, Hunter Holmes McGuire VAMC, Richmond, Virginia
- Physical Medicine and Rehabilitation, Virginia Commonwealth University, Richmond, Virginia
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Cao Y, Shi Y, Xiao Z, Chen X, Chen B, Yang B, Shu M, Yin Y, Wu S, Yin W, Fu X, Tan J, Zhou Q, Wu Z, Jiang X, Dai J. Contralateral Axon Sprouting but Not Ipsilateral Regeneration Is Responsible for Spontaneous Locomotor Recovery Post Spinal Cord Hemisection. Front Cell Neurosci 2021; 15:730348. [PMID: 34512270 PMCID: PMC8426601 DOI: 10.3389/fncel.2021.730348] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Accepted: 08/04/2021] [Indexed: 11/13/2022] Open
Abstract
Spinal cord injury (SCI) usually results in permanent functional impairment and is considered a worldwide medical problem. However, both motor and sensory functions can spontaneously recover to varying extents in humans and animals with incomplete SCI. This study observed a significant spontaneous hindlimb locomotor recovery in Sprague-Dawley rats at four weeks after post-right-side spinal cord hemisection at thoracic 8 (T8). To verify whether the above spontaneous recovery derives from the ipsilateral axonal or neuronal regeneration to reconnect the lesion site, we resected either the scar tissue or right side T7 spinal cord at five weeks post-T8 hemisected injury. The results showed that the spontaneously achieved right hindlimb locomotor function had little change after resection. Furthermore, when T7 left hemisection was performed five weeks after the initial injury, the spontaneously achieved right hindlimb locomotor function was dramatically abolished. A similar result could also be observed when T7 transection was performed after the initial hemisection. The results indicated that it might be the contralateral axonal remolding rather than the ipsilateral axonal or neuronal regeneration beyond the lesion site responsible for the spontaneous hindlimb locomotor recovery. The immunostaining analyses and corticospinal tracts (CSTs) tracing results confirmed this hypothesis. We detected no substantial neuronal and CST regeneration throughout the lesion site; however, significantly more CST fibers were observed to sprout from the contralateral side at the lumbar 4 (L4) spinal cord in the hemisection model rats than in intact ones. In conclusion, this study verified that contralateral CST sprouting, but not ipsilateral CST or neuronal regeneration, is primarily responsible for the spontaneous locomotor recovery in hemisection SCI rats.
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Affiliation(s)
- Yudong Cao
- Department of Neurosurgery, Xiangya Hospital, Central South University (CSU), Changsha, China
| | - Ya Shi
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Zhifeng Xiao
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Xi Chen
- Shigatse Branch, Xinqiao Hospital, Army Medical University (Third Military Medical University), Shigatse, China
| | - Bing Chen
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Bin Yang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Muya Shu
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Yanyun Yin
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Shuyu Wu
- Department of Neurosurgery, Xiangya Hospital, Central South University (CSU), Changsha, China
| | - Wen Yin
- Department of Neurosurgery, Xiangya Hospital, Central South University (CSU), Changsha, China
| | - Xianyong Fu
- Department of Neurosurgery, Xiangya Hospital, Central South University (CSU), Changsha, China
| | - Jun Tan
- Department of Neurosurgery, Xiangya Hospital, Central South University (CSU), Changsha, China
| | - Quanwei Zhou
- Department of Neurosurgery, Xiangya Hospital, Central South University (CSU), Changsha, China
| | - Zhaoping Wu
- Department of Neurosurgery, Xiangya Hospital, Central South University (CSU), Changsha, China
| | - Xingjun Jiang
- Department of Neurosurgery, Xiangya Hospital, Central South University (CSU), Changsha, China
| | - Jianwu Dai
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
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Malone IG, Nosacka RL, Nash MA, Otto KJ, Dale EA. Electrical epidural stimulation of the cervical spinal cord: implications for spinal respiratory neuroplasticity after spinal cord injury. J Neurophysiol 2021; 126:607-626. [PMID: 34232771 PMCID: PMC8409953 DOI: 10.1152/jn.00625.2020] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 06/07/2021] [Accepted: 06/27/2021] [Indexed: 01/15/2023] Open
Abstract
Traumatic cervical spinal cord injury (cSCI) can lead to damage of bulbospinal pathways to the respiratory motor nuclei and consequent life-threatening respiratory insufficiency due to respiratory muscle paralysis/paresis. Reports of electrical epidural stimulation (EES) of the lumbosacral spinal cord to enable locomotor function after SCI are encouraging, with some evidence of facilitating neural plasticity. Here, we detail the development and success of EES in recovering locomotor function, with consideration of stimulation parameters and safety measures to develop effective EES protocols. EES is just beginning to be applied in other motor, sensory, and autonomic systems; however, there has only been moderate success in preclinical studies aimed at improving breathing function after cSCI. Thus, we explore the rationale for applying EES to the cervical spinal cord, targeting the phrenic motor nucleus for the restoration of breathing. We also suggest cellular/molecular mechanisms by which EES may induce respiratory plasticity, including a brief examination of sex-related differences in these mechanisms. Finally, we suggest that more attention be paid to the effects of specific electrical parameters that have been used in the development of EES protocols and how that can impact the safety and efficacy for those receiving this therapy. Ultimately, we aim to inform readers about the potential benefits of EES in the phrenic motor system and encourage future studies in this area.
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Affiliation(s)
- Ian G Malone
- Department of Electrical and Computer Engineering, University of Florida, Gainesville, Florida
- Breathing Research and Therapeutics Center (BREATHE), University of Florida, Gainesville, Florida
| | - Rachel L Nosacka
- Department of Physiology and Functional Genomics, University of Florida, Gainesville, Florida
| | - Marissa A Nash
- Department of Physiology and Functional Genomics, University of Florida, Gainesville, Florida
| | - Kevin J Otto
- Department of Electrical and Computer Engineering, University of Florida, Gainesville, Florida
- Breathing Research and Therapeutics Center (BREATHE), University of Florida, Gainesville, Florida
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, Florida
- Department of Neuroscience, University of Florida, Gainesville, Florida
- Department of Neurology, University of Florida, Gainesville, Florida
- Department of Materials Science and Engineering, University of Florida, Gainesville, Florida
- McKnight Brain Institute, University of Florida, Gainesville, Florida
| | - Erica A Dale
- Breathing Research and Therapeutics Center (BREATHE), University of Florida, Gainesville, Florida
- Department of Physiology and Functional Genomics, University of Florida, Gainesville, Florida
- Department of Neuroscience, University of Florida, Gainesville, Florida
- McKnight Brain Institute, University of Florida, Gainesville, Florida
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Matzner H, Zelinger M, Cherniak M, Anglister L, Lev-Tov A. Rhythmogenic networks are potently modulated by activation of muscarinic acetylcholine receptors in the rodent spinal cord. J Neurochem 2021; 158:1263-1273. [PMID: 33735482 DOI: 10.1111/jnc.15354] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 03/10/2021] [Accepted: 03/11/2021] [Indexed: 02/02/2023]
Abstract
Electrical stimulation of the spinal cord is a potent means for activating mammalian stepping in the absence of the descending control from the brain. Previously, we have shown that stimulation of pain delivering (Aδ) sacrocaudal afferents (SCA) has a powerful capacity to activate the sacral and lumbar rhythmogenic networks in the neonatal rodent spinal cord. Relatively little is known about the neural pathways involved in activation of the locomotor networks by Aδ afferents, on their mechanism of action and on the possibility to modulate their activity. We have shown that elevation of the endogenous level of acetylcholine at the sacral cord by blocking cholinesterase could modulate the SCA-induced locomotor rhythm in a muscarinic receptor-dependent mechanism. Here, we review these and more recent findings and report that controlled stimulation of SCA in the presence of muscarine is a potent activator of the locomotor network. The possible mechanisms involved in the muscarinic modulation of the locomotor rhythm are discussed in terms of the differential projections of sacral relay neurons, activated by SCA stimulation, to the lumbar locomotor rhythm generators, and to their target motoneurons. Altogether, our studies show that manipulations of cholinergic networks offer a simple and powerful means to control the activity of locomotor networks in the absence of supraspinal control.
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Affiliation(s)
- Henry Matzner
- Department of Medical Neurobiology, Institute for Medical Research - Israel-Canada, IMRIC, Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Moshe Zelinger
- Department of Medical Neurobiology, Institute for Medical Research - Israel-Canada, IMRIC, Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Meir Cherniak
- Department of Medical Neurobiology, Institute for Medical Research - Israel-Canada, IMRIC, Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Lili Anglister
- Department of Medical Neurobiology, Institute for Medical Research - Israel-Canada, IMRIC, Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Aharon Lev-Tov
- Department of Medical Neurobiology, Institute for Medical Research - Israel-Canada, IMRIC, Hebrew University-Hadassah Medical School, Jerusalem, Israel
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Caron G, Bilchak JN, Côté MP. Direct evidence for decreased presynaptic inhibition evoked by PBSt group I muscle afferents after chronic SCI and recovery with step-training in rats. J Physiol 2020; 598:4621-4642. [PMID: 32721039 DOI: 10.1113/jp280070] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Accepted: 07/27/2020] [Indexed: 01/11/2023] Open
Abstract
KEY POINTS Presynaptic inhibition is modulated by supraspinal centres and primary afferents in order to filter sensory information, adjust spinal reflex excitability, and ensure smooth movement. After spinal cord injury (SCI), the supraspinal control of primary afferent depolarization (PAD) interneurons is disengaged, suggesting an increased role for sensory afferents. While increased H-reflex excitability in spastic individuals indicates a possible decrease in presynaptic inhibition, it remains unclear whether a decrease in sensory-evoked PAD contributes to this effect. We investigated whether the PAD evoked by hindlimb afferents contributes to the change in presynaptic inhibition of the H-reflex in a decerebrated rat preparation. We found that chronic SCI decreases presynaptic inhibition of the plantar H-reflex through a reduction in PAD evoked by posterior biceps-semitendinosus (PBSt) muscle group I afferents. We further found that step-training restored presynaptic inhibition of the plantar H-reflex evoked by PBSt, suggesting the presence of activity-dependent plasticity of PAD pathways activated by flexor muscle group I afferents. ABSTRACT Spinal cord injury (SCI) results in the disruption of supraspinal control of spinal networks and an increase in the relative influence of afferent feedback to sublesional neural networks, both of which contribute to enhancing spinal reflex excitability. Hyperreflexia occurs in ∼75% of individuals with a chronic SCI and critically hinders functional recovery and quality of life. It is suggested that it results from an increase in motoneuronal excitability and a decrease in presynaptic and postsynaptic inhibitory mechanisms. In contrast, locomotor training decreases hyperreflexia by restoring presynaptic inhibition. Primary afferent depolarization (PAD) is a powerful presynaptic inhibitory mechanism that selectively gates primary afferent transmission to spinal neurons to adjust reflex excitability and ensure smooth movement. However, the effect of chronic SCI and step-training on the reorganization of presynaptic inhibition evoked by hindlimb afferents, and the contribution of PAD has never been demonstrated. The objective of this study is to directly measure changes in presynaptic inhibition through dorsal root potentials (DRPs) and its association with plantar H-reflex inhibition. We provide direct evidence that H-reflex hyperexcitability is associated with a decrease in transmission of PAD pathways activated by posterior biceps-semitendinosus (PBSt) afferents after chronic SCI. More precisely, we illustrate that the pattern of inhibition evoked by PBSt group I muscle afferents onto both L4-DRPs and plantar H-reflexes evoked by the distal tibial nerve is impaired after chronic SCI. These changes are not observed in step-trained animals, suggesting a role for activity-dependent plasticity to regulate PAD pathways activated by flexor muscle group I afferents.
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Affiliation(s)
- Guillaume Caron
- Marion Murray Spinal Cord Research Center, Department of Neurobiology and Anatomy, Drexel University, Philadelphia, PA, 19129
| | - Jadwiga N Bilchak
- Marion Murray Spinal Cord Research Center, Department of Neurobiology and Anatomy, Drexel University, Philadelphia, PA, 19129
| | - Marie-Pascale Côté
- Marion Murray Spinal Cord Research Center, Department of Neurobiology and Anatomy, Drexel University, Philadelphia, PA, 19129
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Legg Ditterline B, Harkema SJ, Willhite A, Stills S, Ugiliweneza B, Rejc E. Epidural stimulation for cardiovascular function increases lower limb lean mass in individuals with chronic motor complete spinal cord injury. Exp Physiol 2020; 105:1684-1691. [PMID: 32749719 DOI: 10.1113/ep088876] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Accepted: 07/31/2020] [Indexed: 12/17/2022]
Abstract
NEW FINDINGS What is the central question of this study? Spinal cord injury results in paralysis and deleterious neuromuscular and autonomic adaptations. Lumbosacral epidural stimulation can modulate motor and/or autonomic functions. Does long-term epidural stimulation for normalizing cardiovascular function affect leg muscle properties? What is the main finding and its importance? Leg lean mass increased after long-term epidural stimulation for cardiovascular function, which was applied in the sitting position and did not activate the leg muscles. Leg muscle strength and fatigue resistance, assessed in a subgroup of individuals, also increased. These adaptations might support interventions for motor recovery and warrant further mechanistic investigation. ABSTRACT Chronic motor complete spinal cord injury (SCI) results in paralysis and deleterious neuromuscular and autonomic adaptations. Paralysed muscles demonstrate atrophy, loss of force and increased fatigability. Also, SCI-induced autonomic impairment results in persistently low resting blood pressure and heart rate, among other features. We previously reported that spinal cord epidural stimulation (scES) optimized for cardiovascular (CV) function (CV-scES), which is applied in sitting position and does not activate the leg muscles, can maintain systolic blood pressure within a normotensive range during quiet sitting and during orthostatic stress. In the present study, dual-energy X-ray absorptiometry collected from six individuals with chronic clinically motor complete SCI demonstrated that 88 ± 11 sessions of CV-scES (7 days week-1 ; 2 h day-1 in four individuals and 5 h day-1 in two individuals) over a period of ∼6 months significantly increased lower limb lean mass (by 0.67 ± 0.39 kg or 9.4 ± 8.1%; P < 0.001). Additionally, muscle strength and fatigability data elicited by neuromuscular electrical stimulation in three of these individuals demonstrated a general increase (57 ± 117%) in maximal torque output (between 2 and 44 N m in 14 of the 17 muscle groups tested overall) and torque-time integral during intermittent, fatiguing contractions (63 ± 71%; between 7 and 230% in 16 of the 17 muscle groups tested overall). In contrast, whole-body mass and composition did not change significantly. In conclusion, long-term use of CV-scES can have a significant impact on lower limb muscle properties after chronic motor complete SCI.
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Affiliation(s)
- Bonnie Legg Ditterline
- Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, KY, USA.,Department of Neurological Surgery, University of Louisville, Louisville, KY, USA
| | - Susan J Harkema
- Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, KY, USA.,Department of Neurological Surgery, University of Louisville, Louisville, KY, USA.,Frazier Rehabilitation Institute, University of Louisville Health, Louisville, KY, USA.,Department of Bioengineering, University of Louisville, Louisville, KY, USA
| | - Andrea Willhite
- Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, KY, USA
| | - Sean Stills
- Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, KY, USA
| | - Beatrice Ugiliweneza
- Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, KY, USA.,Department of Neurological Surgery, University of Louisville, Louisville, KY, USA
| | - Enrico Rejc
- Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, KY, USA.,Department of Neurological Surgery, University of Louisville, Louisville, KY, USA
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Emanuelsen A, Voigt M, Madeleine P, Hansen EA. Effect of Tapping Bout Duration During Freely Chosen and Passive Finger Tapping on Rate Enhancement. J Mot Behav 2020; 53:351-363. [PMID: 32525455 DOI: 10.1080/00222895.2020.1779021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
The present study investigated whether the duration of the first tapping bout, which could also be considered 'the priming', would play a role for the occurrence of the behavioral phenomenon termed repeated bout rate enhancement. Eighty-eight healthy individuals were recruited. Sixty-three of these demonstrated repeated bout rate enhancement and they were assigned to two different groups, which performed either active or passive tapping as priming. The durations of the first tapping bouts, which acted as priming, were 20, 60, 120, and 180 s. Following the first bout there was a 10 min rest and a subsequent 180 s tapping bout performed at freely chosen tapping rate. Vertical displacement and tapping force data were recorded. Rate enhancement was elicited independently of the duration of the first bout in both groups. Rate enhancement occurred without concurrent changes of the magnitude of vertical displacement, time to peak force, and duration of finger contact phase. The peak force was reduced when 180 s of tapping had been performed as priming. The increased tapping rate following priming by as little as 20 s active or passive tapping, as observed here, is suggested to be a result of increased net excitability of the nervous system.
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Affiliation(s)
- Anders Emanuelsen
- Department of Health Science and Technology, Sport Sciences - Performance and Technology, Aalborg University, Aalborg, Denmark
| | - Michael Voigt
- Department of Health Science and Technology, Sport Sciences - Performance and Technology, Aalborg University, Aalborg, Denmark
| | - Pascal Madeleine
- Department of Health Science and Technology, Sport Sciences - Performance and Technology, Aalborg University, Aalborg, Denmark
| | - Ernst Albin Hansen
- Department of Health Science and Technology, Sport Sciences - Performance and Technology, Aalborg University, Aalborg, Denmark
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Bonnet M, Alluin O, Trimaille T, Gigmes D, Marqueste T, Decherchi P. Delayed Injection of a Physically Cross-Linked PNIPAAm- g-PEG Hydrogel in Rat Contused Spinal Cord Improves Functional Recovery. ACS OMEGA 2020; 5:10247-10259. [PMID: 32426581 PMCID: PMC7226861 DOI: 10.1021/acsomega.9b03611] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/27/2019] [Accepted: 04/14/2020] [Indexed: 06/11/2023]
Abstract
Spinal cord injury is a main health issue, leading to multiple functional deficits with major consequences such as motor and sensitive impairment below the lesion. To date, all repair strategies remain ineffective. In line with the experiments showing that implanted hydrogels, immunologically inert biomaterials, from natural or synthetic origins, are promising tools and in order to reduce functional deficits, to increase locomotor recovery, and to reduce spasticity, we injected into the lesion area, 1 week after a severe T10 spinal cord contusion, a thermoresponsive physically cross-linked poly(N-isopropylacrylamide)-poly(ethylene glycol) copolymer hydrogel. The effect of postinjury intensive rehabilitation training was also studied. A group of male Sprague-Dawley rats receiving the hydrogel was enrolled in an 8 week program of physical activity (15 min/day, 5 days/week) in order to verify if the combination of a treadmill step-training and hydrogel could lead to better outcomes. The data obtained were compared to those obtained in animals with a spinal lesion alone receiving a saline injection with or without performing the same program of physical activity. Furthermore, in order to verify the biocompatibility of our designed biomaterial, an inflammatory reaction (interleukin-1β, interleukin-6, and tumor necrosis factor-α) was examined 15 days post-hydrogel injection. Functional recovery (postural and locomotor activities and sensorimotor coordination) was assessed from the day of injection, once a week, for 9 weeks. Finally, 9 weeks postinjection, the spinal reflexivity (rate-dependent depression of the H-reflex) was measured. The results indicate that the hydrogel did not induce an additional inflammation. Furthermore, we observed the same significant locomotor improvements in hydrogel-injected animals as in trained saline-injected animals. However, the combination of hydrogel with exercise did not show higher recovery compared to that evaluated by the two strategies independently. Finally, the H-reflex depression recovery was found to be induced by the hydrogel and, albeit to a lesser degree, exercise. However, no recovery was observed when the two strategies were combined. Our results highlight the effectiveness of our copolymer and its high therapeutic potential to preserve/repair the spinal cord after lesion.
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Affiliation(s)
- Maxime Bonnet
- Aix
Marseille Univ, CNRS, ISM, UMR 7287, Institut des Sciences du Mouvement:
Etienne-Jules MAREY, Equipe, Plasticité des Systèmes
Nerveux et Musculaire, (PSNM), Parc Scientifique et Technologique
de Luminy, Faculté des Sciences du Sport de Marseille, CC910—163 Avenue de Luminy, F-13288 Marseille Cedex 09, France
| | - Olivier Alluin
- Aix
Marseille Univ, CNRS, ISM, UMR 7287, Institut des Sciences du Mouvement:
Etienne-Jules MAREY, Equipe, Plasticité des Systèmes
Nerveux et Musculaire, (PSNM), Parc Scientifique et Technologique
de Luminy, Faculté des Sciences du Sport de Marseille, CC910—163 Avenue de Luminy, F-13288 Marseille Cedex 09, France
| | - Thomas Trimaille
- Aix
Marseille Univ, CNRS, ICR, UMR 7273, Institut de Chimie Radicalaire,
Equipe, Chimie Radicalaire Organique et Polymères de Spécialité,
(CROPS), Case 562—Avenue
Escadrille Normandie-Niemen, F-13397 Marseille Cedex 20, France
| | - Didier Gigmes
- Aix
Marseille Univ, CNRS, ICR, UMR 7273, Institut de Chimie Radicalaire,
Equipe, Chimie Radicalaire Organique et Polymères de Spécialité,
(CROPS), Case 562—Avenue
Escadrille Normandie-Niemen, F-13397 Marseille Cedex 20, France
| | - Tanguy Marqueste
- Aix
Marseille Univ, CNRS, ISM, UMR 7287, Institut des Sciences du Mouvement:
Etienne-Jules MAREY, Equipe, Plasticité des Systèmes
Nerveux et Musculaire, (PSNM), Parc Scientifique et Technologique
de Luminy, Faculté des Sciences du Sport de Marseille, CC910—163 Avenue de Luminy, F-13288 Marseille Cedex 09, France
| | - Patrick Decherchi
- Aix
Marseille Univ, CNRS, ISM, UMR 7287, Institut des Sciences du Mouvement:
Etienne-Jules MAREY, Equipe, Plasticité des Systèmes
Nerveux et Musculaire, (PSNM), Parc Scientifique et Technologique
de Luminy, Faculté des Sciences du Sport de Marseille, CC910—163 Avenue de Luminy, F-13288 Marseille Cedex 09, France
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11
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Propriospinal Neurons of L3-L4 Segments Involved in Control of the Rat External Urethral Sphincter. Neuroscience 2019; 425:12-28. [PMID: 31785359 DOI: 10.1016/j.neuroscience.2019.11.013] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 10/31/2019] [Accepted: 11/11/2019] [Indexed: 12/17/2022]
Abstract
Coordination of activity of external urethral sphincter (EUS) striated muscle and bladder (BL) smooth muscle is essential for efficient voiding. In this study we examined the morphological and electrophysiological properties of neurons in the L3/L4 spinal cord (SC) that are likely to have an important role in EUS-BL coordination in rats. EUS-related SC neurons were identified by retrograde transsynaptic tracing following injection of pseudorabies virus (PRV) co-expressing fluorescent markers into the EUS of P18-P20 male rats. Tracing revealed not only EUS motoneurons in L6/S1 but also interneurons in lamina X of the L6/S1 and L3/L4 SC. Physiological properties of fluorescently labeled neurons were assessed during whole-cell recordings in SC slices followed by reconstruction of biocytin-filled neurons. Reconstructions of neuronal processes from transverse or longitudinal slices showed that some L3/L4 neurons have axons projecting toward and into the ventro-medial funiculus (VMf) where axons extended caudally. Other neurons had axons projecting within laminae X and VII. Dendrites of L3/L4 neurons were distributed within laminae X and VII. The majority of L3/L4 neurons exhibited tonic firing in response to depolarizing currents. In transverse slices focal electrical stimulation (FES) in the VMf or in laminae X and VII elicited antidromic axonal spikes and/or excitatory synaptic responses in L3/L4 neurons; while in longitudinal slices FES elicited excitatory synaptic inputs from sites up to 400 μm along the central canal. Inhibitory inputs were rarely observed. These data suggest that L3/L4 EUS-related circuitry consists of at least two neuronal populations: segmental interneurons and propriospinal neurons projecting to L6/S1.
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12
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Serotonergic modulation of sacral dorsal root stimulation-induced locomotor output in newborn rat. Neuropharmacology 2019; 170:107815. [PMID: 31634501 DOI: 10.1016/j.neuropharm.2019.107815] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Revised: 10/14/2019] [Accepted: 10/15/2019] [Indexed: 12/22/2022]
Abstract
Descending neuromodulators from the brainstem play a major role in the development and regulation of spinal sensorimotor functions. Here, the contribution of serotonergic signaling in the lumbar spinal cord was investigated in the context of the generation of locomotor activity. Experiments were performed on in vitro spinal cord preparations from newborn rats (0-5 days). Rhythmic locomotor episodes (fictive locomotion) triggered by tonic electrical stimulations (2Hz, 30s) of a single sacral dorsal root were recorded from bilateral flexor-dominated (L2) and extensor-dominated (L5) ventral roots. We found that the activity pattern induced by sacral stimulation evolves over the 5 post-natal (P) day period. Although alternating rhythmic flexor-like motor bursts were expressed at all ages, the locomotor pattern of extensor-like bursting was progressively lost from P1 to P5. At later stages, serotonin (5-HT) and quipazine (5-HT2A receptor agonist) at concentrations sub-threshold for direct locomotor network activation promoted sacral stimulation-induced fictive locomotion. The 5-HT2A receptor antagonist ketanserin could reverse the agonist's action but was ineffective when fictive locomotion was already expressed in the absence of 5-HT (mainly before P2). Although inhibiting 5-HT7 receptors with SB266990 did not affect locomotor pattern organization, activating 5-HT1A receptors with 8-OH-DPAT specifically deteriorated extensor phase motor burst activity. We conclude that during the first 5 post-natal days in rat, serotonergic signaling in the lumbar cord becomes increasingly critical for the expression of fictive locomotion. Our findings therefore further underline the importance of both descending serotonergic and sensory afferent pathways in shaping locomotor activity during postnatal development. This article is part of the special issue entitled 'Serotonin Research: Crossing Scales and Boundaries'.
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Spinal Cord Epidural Stimulation for Lower Limb Motor Function Recovery in Individuals with Motor Complete Spinal Cord Injury. Phys Med Rehabil Clin N Am 2019; 30:337-354. [DOI: 10.1016/j.pmr.2018.12.009] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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14
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Gerasimenko Y, Preston C, Zhong H, Roy RR, Edgerton VR, Shah PK. Rostral lumbar segments are the key controllers of hindlimb locomotor rhythmicity in the adult spinal rat. J Neurophysiol 2019; 122:585-600. [PMID: 30943092 DOI: 10.1152/jn.00810.2018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The precise location and functional organization of the spinal neuronal locomotor-related networks in adult mammals remain unclear. Our recent neurophysiological findings provided empirical evidence that the rostral lumbar spinal cord segments play a critical role in the initiation and generation of the rhythmic activation patterns necessary for hindlimb locomotion in adult spinal rats. Since added epidural stimulation at the S1 segments significantly enhanced the motor output generated by L2 stimulation, these data also suggested that the sacral spinal cord provides a strong facilitory influence in rhythm initiation and generation. However, whether L2 will initiate hindlimb locomotion in the absence of S1 segments, and whether S1 segments can facilitate locomotion in the absence of L2 segments remain unknown. Herein, adult rats received complete spinal cord transections at T8 and then at either L2 or S1. Rats with spinal cord transections at T8 and S1 remained capable of generating coordinated hindlimb locomotion when receiving epidural stimulation at L2 and when ensembles of locomotor related loadbearing input were present. In contrast, minimal locomotion was observed when S1 stimulation was delivered after spinal cord transections at T8 and L2. Results were similar when the nonspecific serotonergic agonists were administered. These results demonstrate in adult rats that rostral lumbar segments are essential for the regulation of hindlimb locomotor rhythmicity. In addition, the more caudal spinal networks alone cannot control locomotion in the absence of the rostral segments around L2 even when loadbearing rhythmic proprioceptive afferent input is imposed.NEW & NOTEWORTHY The exact location of the spinal neuronal locomotor-related networks in adult mammals remains unknown. The present data demonstrate that when the rostral lumbar spinal segments (~L2) are completely eliminated in thoracic spinal adult rats, hindlimb stepping is not possible with neurochemical modulation of the lumbosacral cord. In contrast, eliminating the sacral cord retains stepping ability. These observations highlight the importance of rostral lumbar segments in generating effective mammalian locomotion.
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Affiliation(s)
- Yury Gerasimenko
- Pavlov Institute of Physiology, Russian Academy of Sciences, St. Petersburg, Russia.,Department of Integrative Biology and Physiology, University of California, Los Angeles, California
| | - Chet Preston
- Department of Physical Therapy, School of Health Technology and Management, Stony Brook University, Stony Brook, New York
| | - Hui Zhong
- Department of Integrative Biology and Physiology, University of California, Los Angeles, California
| | - Roland R Roy
- Department of Integrative Biology and Physiology, University of California, Los Angeles, California
| | - V Reggie Edgerton
- Department of Integrative Biology and Physiology, University of California, Los Angeles, California.,Department of Neurobiology, David Geffen School of Medicine at University of California, Los Angeles, California.,Department of Neurosurgery, David Geffen School of Medicine at University of California, Los Angeles, California.,Brain Research Institute, University of California, Los Angeles, California.,Institute Guttmann. Hospital de Neurorehabilitació, Institut Universitari Adscrit a la Universitat Autònoma de Barcelona, Badalona, Spain.,Centre for Neuroscience and Regenerative Medicine, Faculty of Science, University of Technology Sydney, Ultimo, New South Wales, Australia.,Department of Neurology, David Geffen School of Medicine at University of California, Los Angeles, California
| | - Prithvi K Shah
- Department of Physical Therapy, School of Health Technology and Management, Stony Brook University, Stony Brook, New York.,Department of Neurobiology, Stony Brook University, Stony Brook, New York
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15
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Emanuelsen A, Voigt M, Madeleine P, Kjær P, Dam S, Koefoed N, Hansen EA. Repeated Bout Rate Enhancement Is Elicited by Various Forms of Finger Tapping. Front Neurosci 2018; 12:526. [PMID: 30108479 PMCID: PMC6079229 DOI: 10.3389/fnins.2018.00526] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Accepted: 07/13/2018] [Indexed: 01/19/2023] Open
Abstract
Voluntary rhythmic movements, such as, for example, locomotion and other cyclic tasks, are fundamental during everyday life. Patients with impaired neural or motor function often take part in rehabilitation programs, which include rhythmic movements. Therefore, it is imperative to have the best possible understanding of control and behaviour of human voluntary rhythmic movements. A behavioural phenomenon termed repeated bout rate enhancement has been established as an increase of the freely chosen index finger tapping frequency during the second of two consecutive tapping bouts. The present study investigated whether the phenomenon would be elicited when the first bout consisted of imposed passive finger tapping or air tapping. These two forms of tapping were applied since they can be performed without descending drive (passive tapping) and without afferent feedback related to impact (air tapping) – as compared to tapping on a surface. Healthy individuals (n = 33) performed 3-min tapping bouts separated by 10 min rest. Surface electromyographic, kinetic, and kinematic data were recorded. Supportive experiments were made to measure, for example, the cortical sensory evoked potential (SEP) response during the three different forms of tapping. Results showed that tapping frequencies in the second of two consecutive bouts increased by 12.9 ± 14.8% (p < 0.001), 9.9 ± 6.0% (p = 0.001), and 16.8 ± 13.6% (p = 0.005) when the first bout had consisted of tapping, passive tapping, and air tapping, respectively. Rate enhancement occurred without increase in muscle activation. Besides, the rate enhancements occurred despite that tapping, as compared with passive tapping and air tapping, resulted in different cortical SEP responses. Based on the present findings, it can be suggested that sensory feedback in an initial bout increases the excitability of the spinal central pattern generators involved in finger tapping. This can eventually explain the phenomenon of repeated bout rate enhancement seen after a consecutive bout of finger tapping.
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Affiliation(s)
- Anders Emanuelsen
- Sport Sciences, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
| | - Michael Voigt
- Sport Sciences, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
| | - Pascal Madeleine
- Sport Sciences, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
| | - Pia Kjær
- Sport Sciences, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
| | - Sebastian Dam
- Sport Sciences, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
| | - Nikolaj Koefoed
- Sport Sciences, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
| | - Ernst A Hansen
- Sport Sciences, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
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16
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Brainstem Steering of Locomotor Activity in the Newborn Rat. J Neurosci 2018; 38:7725-7740. [PMID: 30037828 DOI: 10.1523/jneurosci.1074-18.2018] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Revised: 07/17/2018] [Accepted: 07/18/2018] [Indexed: 11/21/2022] Open
Abstract
Control of locomotion relies on motor loops conveying modulatory signals between brainstem and spinal motor circuits. We investigated the steering control of the brainstem reticular formation over the spinal locomotor networks using isolated brainstem-spinal cord preparations of male and female neonatal rats. First, we performed patch-clamp recordings of identified reticulospinal cells during episodes of fictive locomotion. This revealed that a spinal ascending phasic modulation of reticulospinal cell activity is already present at birth. Half of the cells exhibited tonic firing during locomotion, while the other half emitted phasic discharges of action potentials phase locked to ongoing activity. We next showed that mimicking the phasic activity of reticulospinal neurons by applying patterned electrical stimulation bilaterally at the ventral caudal medulla level triggered fictive locomotion efficiently. Moreover, the brainstem stimuli-induced locomotor rhythm was entrained in a one-to-one coupling over a range of cycle periods (2-6 s). Additionally, we induced turning like motor outputs by either increasing or decreasing the relative duration of the stimulation trains on one side of the brainstem compared to the other. The ability of the patterned descending command to control the locomotor output depended on the functional integrity of ventral reticulospinal pathways and the involvement of local spinal central pattern generator circuitry. Altogether, this study provides a mechanism by which brainstem reticulospinal neurons relay steering and speed commands to the spinal locomotor networks.SIGNIFICANCE STATEMENT Locomotor function allows the survival of most animal species while sustaining the expression of fundamental behaviors. Locomotor activities adapt from moment to moment to behavioral and environmental changes. We show that the brainstem can control the spinal locomotor network outputs through phasic descending commands that alternate bilaterally. Manipulating the periodicity and/or the relative durations of the left and right descending commands at the brainstem level is efficient to set the locomotor speed and sustain directional changes.
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17
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Taccola G, Sayenko D, Gad P, Gerasimenko Y, Edgerton VR. And yet it moves: Recovery of volitional control after spinal cord injury. Prog Neurobiol 2017; 160:64-81. [PMID: 29102670 PMCID: PMC5773077 DOI: 10.1016/j.pneurobio.2017.10.004] [Citation(s) in RCA: 114] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 10/09/2017] [Accepted: 10/21/2017] [Indexed: 12/12/2022]
Abstract
Preclinical and clinical neurophysiological and neurorehabilitation research has generated rather surprising levels of recovery of volitional sensory-motor function in persons with chronic motor paralysis following a spinal cord injury. The key factor in this recovery is largely activity-dependent plasticity of spinal and supraspinal networks. This key factor can be triggered by neuromodulation of these networks with electrical and pharmacological interventions. This review addresses some of the systems-level physiological mechanisms that might explain the effects of electrical modulation and how repetitive training facilitates the recovery of volitional motor control. In particular, we substantiate the hypotheses that: (1) in the majority of spinal lesions, a critical number and type of neurons in the region of the injury survive, but cannot conduct action potentials, and thus are electrically non-responsive; (2) these neuronal networks within the lesioned area can be neuromodulated to a transformed state of electrical competency; (3) these two factors enable the potential for extensive activity-dependent reorganization of neuronal networks in the spinal cord and brain, and (4) propriospinal networks play a critical role in driving this activity-dependent reorganization after injury. Real-time proprioceptive input to spinal networks provides the template for reorganization of spinal networks that play a leading role in the level of coordination of motor pools required to perform a given functional task. Repetitive exposure of multi-segmental sensory-motor networks to the dynamics of task-specific sensory input as occurs with repetitive training can functionally reshape spinal and supraspinal connectivity thus re-enabling one to perform complex motor tasks, even years post injury.
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Affiliation(s)
- G Taccola
- Department of Integrative Biology and Physiology, University of California, Los Angeles, CA 90095 USA; Neuroscience Department, International School for Advanced Studies (SISSA), Bonomea 265, Trieste, Italy
| | - D Sayenko
- Department of Integrative Biology and Physiology, University of California, Los Angeles, CA 90095 USA
| | - P Gad
- Department of Integrative Biology and Physiology, University of California, Los Angeles, CA 90095 USA
| | - Y Gerasimenko
- Department of Integrative Biology and Physiology, University of California, Los Angeles, CA 90095 USA; Pavlov Institute of Physiology, St. Petersburg 199034, Russia
| | - V R Edgerton
- Department of Integrative Biology and Physiology, University of California, Los Angeles, CA 90095 USA; Department of Neurobiology, University of California, Los Angeles, CA 90095 USA; Department of Neurosurgery, University of California, Los Angeles, CA 90095 USA; Brain Research Institute, University of California, Los Angeles, CA 90095 USA; The Centre for Neuroscience and Regenerative Medicine, Faculty of Science, University of Technology Sydney, Ultimo, 2007 NSW, Australia; Institut Guttmann, Hospital de Neurorehabilitació, Institut Universitari adscrit a la Universitat Autònoma de Barcelona, Barcelona, 08916 Badalona, Spain.
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18
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Anglister L, Cherniak M, Lev-Tov A. Ascending pathways that mediate cholinergic modulation of lumbar motor activity. J Neurochem 2017; 142 Suppl 2:82-89. [PMID: 28791705 DOI: 10.1111/jnc.14065] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 05/01/2017] [Accepted: 05/03/2017] [Indexed: 01/10/2023]
Abstract
Deciphering neuronal pathways that reactivate spinal central pattern generators (CPGs) and modulate the activity of spinal motoneurons in mammals in the absence of supraspinal control is important for understanding of neural control of movement and for developing novel therapeutic approaches to improve the mobility of spinal cord injury patients. Previously, we showed that the sacral and lumbar cholinergic system could potently modulate the locomotor CPGs in newborn rodents. Here, we review these and our more recent studies of sacral relay neurons with lumbar projections to the locomotor CPGs and to lumbar motoneurons and demonstrate that sacral and lumbar cholinergic components have the capacity to control the frequency of the locomotor CPGs and at the same time the motor output of the activated lumbar motoneurons during motor behavior. A model describing the suggested ascending sacro-lumbar connectivity involved in modulation of the locomotor rhythm by sacral cholinergic components is proposed and discussed. This is an article for the special issue XVth International Symposium on Cholinergic Mechanisms.
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Affiliation(s)
- Lili Anglister
- Department of Medical Neurobiology, IMRIC, the Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Meir Cherniak
- Department of Medical Neurobiology, IMRIC, the Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Aharon Lev-Tov
- Department of Medical Neurobiology, IMRIC, the Hebrew University-Hadassah Medical School, Jerusalem, Israel
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Shah PK, Lavrov I. Spinal Epidural Stimulation Strategies: Clinical Implications of Locomotor Studies in Spinal Rats. Neuroscientist 2017; 23:664-680. [PMID: 28345483 DOI: 10.1177/1073858417699554] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Significant advancements in spinal epidural stimulation (ES) strategies to enable volitional motor control in persons with a complete spinal cord injury (SCI) have generated much excitement in the field of neurorehabilitation. Still, an obvious gap lies in the ability of ES to effectively generate a robust locomotor stepping response after a complete SCI in rodents, but not in humans. In order to reveal potential discrepancies between rodent and human studies that account for this void, in this review, we summarize the findings of studies that have utilized ES strategies to enable successful hindlimb stepping in spinal rats. Recent clinical and preclinical evidence indicates that motor training with ES plays a crucial role in tuning spinal neural circuitry to generate meaningful motor output. Concurrently administered pharmacology can also facilitate the circuitry to provide near optimal motor performance in SCI rats. However, as of today, the evidence for pharmacological agents to enhance motor function in persons with complete SCI is insignificant. These and other recent findings discussed in this review provide insight into addressing the translational gap, guide the design of relevant preclinical experiments, and facilitate development of new approaches for motor recovery in patients with complete SCIs.
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Affiliation(s)
- Prithvi K Shah
- 1 Division of Rehabilitation Sciences, School of Health Technology and Management, Stony Brook University, Stony Brook, NY, USA.,2 Department of Neurobiology, Stony Brook University, Stony Brook, NY, USA
| | - Igor Lavrov
- 3 Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, USA.,4 Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN, USA.,5 Institute of Fundamental Medicine and Biology, Kazan Federal University, Kazan, Russia
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20
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Li LS, Yu H, Raynald R, Wang XD, Dai GH, Cheng HB, Liu XB, An YH. Anatomical mechanism of spontaneous recovery in regions caudal to thoracic spinal cord injury lesions in rats. PeerJ 2017; 5:e2865. [PMID: 28097067 PMCID: PMC5228130 DOI: 10.7717/peerj.2865] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Accepted: 12/05/2016] [Indexed: 11/23/2022] Open
Abstract
Background The nerve fibre circuits around a lesion play a major role in the spontaneous recovery process after spinal cord hemisection in rats. The aim of the present study was to answer the following question: in the re-control process, do all spinal cord nerves below the lesion site participate, or do the spinal cord nerves of only one vertebral segment have a role in repair? Methods First we made a T7 spinal cord hemisection in 50 rats. Eight weeks later, they were divided into three groups based on distinct second operations at T7: ipsilateral hemisection operation, contralateral hemisection, or transection. We then tested recovery of hindlimbs for another eight weeks. The first step was to confirm the lesion had role or not in the spontaneous recovery process. Secondly, we performed T7 spinal cord hemisections in 125 rats. Eight weeks later, we performed a second single hemisection on the ipsilateral side at T8–T12 and then tested hindlimb recovery for another six weeks. Results In the first part, the Basso, Beattie, Bresnahan (BBB) scores and the electrophysiology tests of both hindlimbs weren’t significantly different after the second hemisection of the ipsilateral side. In the second part, the closer the second hemisection was to T12, the more substantial the resulting impairment in BBB score tests and prolonged latency periods. Conclusions The nerve regeneration from the lesion area after hemisection has no effect on spontaneous recovery of the spinal cord. Repair is carried out by all vertebrae caudal and ipsilateral to the lesion, with T12 being most important.
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Affiliation(s)
- Lu-Sheng Li
- Department of Neurosurgery, Beijing Sanbo Brain Hospital, Capital Medical University, Beijing, China; Department of Neurosurgery, Beijing Chao-yang Hospital Affiliated with Capital Medical University, China
| | - Hao Yu
- Department of Neurosurgery, Beijing Sanbo Brain Hospital, Capital Medical University , Beijing , China
| | - Raynald Raynald
- Department of Functional Neurosurgery and Cytotherapy, General Hospital of Chinese People's Armed Police Forces , Beijing , China
| | - Xiao-Dong Wang
- Department of Functional Neurosurgery and Cytotherapy, General Hospital of Chinese People's Armed Police Forces , Beijing , China
| | - Guang-Hui Dai
- Department of Functional Neurosurgery and Cytotherapy, General Hospital of Chinese People's Armed Police Forces , Beijing , China
| | - Hong-Bin Cheng
- Department of Functional Neurosurgery and Cytotherapy, General Hospital of Chinese People's Armed Police Forces , Beijing , China
| | - Xue-Bin Liu
- Department of Functional Neurosurgery and Cytotherapy, General Hospital of Chinese People's Armed Police Forces , Beijing , China
| | - Yi-Hua An
- Department of Neurosurgery, Beijing Sanbo Brain Hospital, Capital Medical University, Beijing, China; Department of Functional Neurosurgery and Cytotherapy, General Hospital of Chinese People's Armed Police Forces, Beijing, China
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21
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Correction: Multi-site spinal stimulation strategies to enhance locomotion after paralysis. Neural Regen Res 2017; 12:161-162. [PMID: 28250764 PMCID: PMC5319224 DOI: 10.4103/1673-5374.199010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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22
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Shaping the Output of Lumbar Flexor Motoneurons by Sacral Neuronal Networks. J Neurosci 2016; 37:1294-1311. [PMID: 28025254 DOI: 10.1523/jneurosci.2213-16.2016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Revised: 12/11/2016] [Accepted: 12/14/2016] [Indexed: 12/27/2022] Open
Abstract
The ability to improve motor function in spinal cord injury patients by reactivating spinal central pattern generators (CPGs) requires the elucidation of neurons and pathways involved in activation and modulation of spinal networks in accessible experimental models. Previously we reported on adrenoceptor-dependent sacral control of lumbar flexor motoneuron firing in newborn rats. The current work focuses on clarification of the circuitry and connectivity involved in this unique modulation and its potential use. Using surgical manipulations of the spinal gray and white matter, electrophysiological recordings, and confocal microscopy mapping, we found that methoxamine (METH) activation of sacral networks within the ventral aspect of S2 segments was sufficient to produce alternating rhythmic bursting (0.15-1 Hz) in lumbar flexor motoneurons. This lumbar rhythm depended on continuity of the ventral funiculus (VF) along the S2-L2 segments. Interrupting the VF abolished the rhythm and replaced it by slow unstable bursting. Calcium imaging of S1-S2 neurons, back-labeled via the VF, revealed that ∼40% responded to METH, mostly by rhythmic firing. All uncrossed projecting METH responders and ∼70% of crossed projecting METH responders fired with the concurrent ipsilateral motor output, while the rest (∼30%) fired with the contralateral motor output. We suggest that METH-activated sacral CPGs excite ventral clusters of sacral VF neurons to deliver the ascending drive required for direct rhythmic activation of lumbar flexor motoneurons. The capacity of noradrenergic-activated sacral CPGs to modulate the activity of lumbar networks via sacral VF neurons provides a novel way to recruit rostral lumbar motoneurons and modulate the output required to execute various motor behaviors. SIGNIFICANCE STATEMENT Spinal central pattern generators (CPGs) produce the rhythmic output required for coordinating stepping and stabilizing the body axis during movements. Electrical stimulation and exogenous drugs can reactivate the spinal CPGs and improve the motor function in the absence of descending supraspinal control. Since the body-stabilizing sacral networks can activate and modulate the limb-moving lumbar circuitry, it is important to clarify the functional organization of sacral and lumbar networks and their linking pathways. Here we decipher the ascending circuitry linking adrenoceptor-activated sacral CPGs and lumbar flexor motoneurons, thereby providing novel insights into mechanisms by which sacral circuitry recruits lumbar flexors, and enhances the motor output during lumbar afferent-induced locomotor rhythms. Moreover, our findings might help to improve drug/electrical stimulation-based therapy to accelerate locomotor-based rehabilitation.
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Interactions between Dorsal and Ventral Root Stimulation on the Generation of Locomotor-Like Activity in the Neonatal Mouse Spinal Cord. eNeuro 2016; 3:eN-NWR-0101-16. [PMID: 27419215 PMCID: PMC4937207 DOI: 10.1523/eneuro.0101-16.2016] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Revised: 05/24/2016] [Accepted: 05/31/2016] [Indexed: 12/23/2022] Open
Abstract
We investigated whether dorsal (DR) and ventral root (VR) stimulus trains engage common postsynaptic components to activate the central pattern generator (CPG) for locomotion in the neonatal mouse spinal cord. VR stimulation did not activate the first order interneurons mediating the activation of the locomotor CPG by sacrocaudal afferent stimulation. Simultaneous stimulation of adjacent dorsal or ventral root pairs, subthreshold for evoking locomotor-like activity, did not summate to activate the CPG. This suggests that locomotor-like activity is triggered when a critical class of efferent or afferent axons is stimulated and does not depend on the number of stimulated axons or activated postsynaptic neurons. DR- and VR-evoked episodes exhibited differences in the coupling between VR pairs. In DR-evoked episodes, the coupling between the ipsilateral and contralateral flexor/extensor roots was similar and stronger than the bilateral extensor roots. In VR-evoked episodes, ipsilateral flexor/extensor coupling was stronger than both the contralateral flexor/extensor and the bilateral extensor coupling. For both types of stimulation, the coupling was greatest between the bilateral L1/L2 flexor-dominated roots. This indicates that the recruitment and/or the firing pattern of motoneurons differed in DR and VR-evoked episodes. However, the DR and VR trains do not appear to activate distinct CPGs because trains of DR and VR stimuli at frequencies too low to evoke locomotor-like activity did so when they were interleaved. These results indicate that the excitatory actions of VR stimulation converge onto the CPG through an unknown pathway that is not captured by current models of the locomotor CPG.
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Shah PK, Sureddi S, Alam M, Zhong H, Roy RR, Edgerton VR, Gerasimenko Y. Unique Spatiotemporal Neuromodulation of the Lumbosacral Circuitry Shapes Locomotor Success after Spinal Cord Injury. J Neurotrauma 2016; 33:1709-23. [PMID: 26792233 DOI: 10.1089/neu.2015.4256] [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] [Indexed: 11/12/2022] Open
Abstract
Spinal cord epidural stimulation has resulted in the initiation of voluntary leg movements and improvement in postural, bladder, and sexual function. However, one of the limitations in reaching the full potential of epidural stimulation for therapeutic purposes in humans has been the identification of optimal stimulation configurations that can neuromodulate the spinal cord for stepping. In the present work, we investigated the mechanisms underlying the specificity of interaction between the rostral and caudal spinal cord circuitries in enabling locomotion in spinal rats (n = 10) by epidural spinal cord stimulation. By using unique spatiotemporal epidural stimulation parameters of the lumbar and sacral spinal cords, a robust stepping pattern in spinal rats was observed with only six training sessions and as early as 3 weeks post-injury. Electrophysiological evidence reveals that in addition to frequency of stimulation pulses at the stimulation sites, the relative timing between stimulation pulses applied at the lumbar (L2) and sacral (S1) segments of the spinal cord heavily impacted stepping performance. Best stepping was established at a higher stimulation frequency (40 Hz vs. 5, 10, 15, and 20Hz) and at specific relative time-intervals between the stimulation pulses (L2 pulse applied at 18-25 msec after the onset of the S1 pulse; S1 pulse applied 0-7 msec after the L2 pulse). Our data suggest that controlling pulse-to-pulse timing at multiple stimulation sources provides a novel strategy to optimize spinal stepping by fine-tuning the physiological state of the locomotor networks. These findings hold direct relevance to the clinician who will incorporate electrical stimulation strategies for optimizing control of locomotion after complete paralysis.
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Affiliation(s)
- Prithvi K Shah
- 1 Division of Rehabilitation Sciences, School of Health Technology and Management, Stony Brook University , Stony Brook, New York.,2 Department of Neurobiology, Stony Brook University , Stony Brook, New York
| | - Shakthi Sureddi
- 3 Department of Neuroscience, University of California , Los Angeles, California
| | - Monzurul Alam
- 4 Department of Neurosurgery, University of California , Los Angeles, California
| | - Hui Zhong
- 5 Department of Integrative Biology and Physiology, University of California , Los Angeles, California
| | - Roland R Roy
- 5 Department of Integrative Biology and Physiology, University of California , Los Angeles, California.,6 Brain Research Institute, University of California , Los Angeles, California
| | - V Reggie Edgerton
- 4 Department of Neurosurgery, University of California , Los Angeles, California.,5 Department of Integrative Biology and Physiology, University of California , Los Angeles, California.,6 Brain Research Institute, University of California , Los Angeles, California.,7 Department of Neurobiology, University of California , Los Angeles, California
| | - Yury Gerasimenko
- 5 Department of Integrative Biology and Physiology, University of California , Los Angeles, California.,8 Pavlov Institute of Physiology, St. Petersburg, Russia .,9 Institute of Fundamental Medicine and Biology, Kazan Federal University , Kazan, Russia
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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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Shah PK, Gerasimenko Y. Multi-site spinal stimulation strategies to enhance locomotion after paralysis. Neural Regen Res 2016; 11:1926-1927. [PMID: 28197186 PMCID: PMC5270428 DOI: 10.4103/1673-5374.197131] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Prithvi K Shah
- Division of Rehabilitation Sciences, School of Health Technology and Management, Stony Brook University, Stony Brook, NY, USA; Department of Neurobiology, Life Science Building, Stony Brook University, Stony Brook, NY, USA
| | - Yury Gerasimenko
- Department of Integrative Biology and Physiology, Charles E Young Dr, University of California, Los Angeles, CA, USA; Pavlov Institute of Physiology, St. Petersburg, Russia; Institute of Fundamental Medicine and Biology, Kazan Federal University, Kazan, Russia
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Veeraraghavan P, Nistri A. Modulatory effects by CB1 receptors on rat spinal locomotor networks after sustained application of agonists or antagonists. Neuroscience 2015; 303:16-33. [DOI: 10.1016/j.neuroscience.2015.06.045] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Revised: 06/19/2015] [Accepted: 06/19/2015] [Indexed: 10/23/2022]
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Alluin O, Delivet-Mongrain H, Rossignol S. Inducing hindlimb locomotor recovery in adult rat after complete thoracic spinal cord section using repeated treadmill training with perineal stimulation only. J Neurophysiol 2015; 114:1931-46. [PMID: 26203108 PMCID: PMC4579296 DOI: 10.1152/jn.00416.2015] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Accepted: 07/20/2015] [Indexed: 01/18/2023] Open
Abstract
Although a complete thoracic spinal cord section in various mammals induces paralysis of voluntary movements, the spinal lumbosacral circuitry below the lesion retains its ability to generate hindlimb locomotion. This important capacity may contribute to the overall locomotor recovery after partial spinal cord injury (SCI). In rats, it is usually triggered by pharmacological and/or electrical stimulation of the cord while a robot sustains the animals in an upright posture. In the present study we daily trained a group of adult spinal (T7) rats to walk with the hindlimbs for 10 wk (10 min/day for 5 days/wk), using only perineal stimulation. Kinematic analysis and terminal electromyographic recordings revealed a strong effect of training on the reexpression of hindlimb locomotion. Indeed, trained animals gradually improved their locomotion while untrained animals worsened throughout the post-SCI period. Kinematic parameters such as averaged and instant swing phase velocity, step cycle variability, foot drag duration, off period duration, and relationship between the swing features returned to normal values only in trained animals. The present results clearly demonstrate that treadmill training alone, in a normal horizontal posture, elicited by noninvasive perineal stimulation is sufficient to induce a persistent hindlimb locomotor recovery without the need for more complex strategies. This provides a baseline level that should be clearly surpassed if additional locomotor-enabling procedures are added. Moreover, it has a clinical value since intrinsic spinal reorganization induced by training should contribute to improve locomotor recovery together with afferent feedback and supraspinal modifications in patients with incomplete SCI.
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Affiliation(s)
- Olivier Alluin
- Department of Neuroscience and Groupe de Recherche sur le Système Nerveux Central (GRSNC), Faculty of Medicine, Université de Montréal, Montreal, Quebec, Canada; and SensoriMotor Rehabilitation Research Team, Canadian Institutes of Health Research, Montreal, Quebec, Canada
| | - Hugo Delivet-Mongrain
- Department of Neuroscience and Groupe de Recherche sur le Système Nerveux Central (GRSNC), Faculty of Medicine, Université de Montréal, Montreal, Quebec, Canada; and SensoriMotor Rehabilitation Research Team, Canadian Institutes of Health Research, Montreal, Quebec, Canada
| | - Serge Rossignol
- Department of Neuroscience and Groupe de Recherche sur le Système Nerveux Central (GRSNC), Faculty of Medicine, Université de Montréal, Montreal, Quebec, Canada; and SensoriMotor Rehabilitation Research Team, Canadian Institutes of Health Research, Montreal, Quebec, Canada
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Rejc E, Angeli C, Harkema S. Effects of Lumbosacral Spinal Cord Epidural Stimulation for Standing after Chronic Complete Paralysis in Humans. PLoS One 2015. [PMID: 26207623 PMCID: PMC4514797 DOI: 10.1371/journal.pone.0133998] [Citation(s) in RCA: 123] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Sensory and motor complete spinal cord injury (SCI) has been considered functionally complete resulting in permanent paralysis with no recovery of voluntary movement, standing or walking. Previous findings demonstrated that lumbosacral spinal cord epidural stimulation can activate the spinal neural networks in one individual with motor complete, but sensory incomplete SCI, who achieved full body weight-bearing standing with independent knee extension, minimal self-assistance for balance and minimal external assistance for facilitating hip extension. In this study, we showed that two clinically sensory and motor complete participants were able to stand over-ground bearing full body-weight without any external assistance, using their hands to assist balance. The two clinically motor complete, but sensory incomplete participants also used minimal external assistance for hip extension. Standing with the least amount of assistance was achieved with individual-specific stimulation parameters, which promoted overall continuous EMG patterns in the lower limbs’ muscles. Stimulation parameters optimized for one individual resulted in poor standing and additional need of external assistance for hip and knee extension in the other participants. During sitting, little or negligible EMG activity of lower limb muscles was induced by epidural stimulation, showing that the weight-bearing related sensory information was needed to generate sufficient EMG patterns to effectively support full weight-bearing standing. In general, electrode configurations with cathodes selected in the caudal region of the array at relatively higher frequencies (25–60 Hz) resulted in the more effective EMG patterns for standing. These results show that human spinal circuitry can generate motor patterns effective for standing in the absence of functional supraspinal connections; however the appropriate selection of stimulation parameters is critical.
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Affiliation(s)
- Enrico Rejc
- Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, Kentucky, United States of America
| | - Claudia Angeli
- Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, Kentucky, United States of America
- Frazier Rehab Institute, Kentucky One Health, Louisville, Kentucky, United States of America
| | - Susan Harkema
- Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, Kentucky, United States of America
- Frazier Rehab Institute, Kentucky One Health, Louisville, Kentucky, United States of America
- * E-mail:
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Neurons in the lateral part of the lumbar spinal cord show distinct novel axon trajectories and are excited by short propriospinal ascending inputs. Brain Struct Funct 2015; 221:2343-60. [PMID: 25912439 DOI: 10.1007/s00429-015-1046-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Accepted: 04/15/2015] [Indexed: 10/23/2022]
Abstract
The role of spinal dorsal horn propriospinal connections in nociceptive processing is not yet established. Recently described, rostrocaudally oriented axon collaterals of lamina I projection and local-circuit neurons (PNs and LCNs) running in the dorsolateral funiculus (DLF) may serve as the anatomical substrate for intersegmental processing. Putative targets of these axons include lateral dendrites of superficial dorsal horn neurons, including PNs, and also neurons in the lateral spinal nucleus (LSN) that are thought to be important integrator units receiving, among others, visceral sensory information. Here we used an intact spinal cord preparation to study intersegmental connections within the lateral part of the superficial dorsal horn. We detected brief monosynaptic and prolonged polysynaptic excitation of lamina I and LSN neurons when stimulating individual dorsal horn neurons located caudally, even in neighboring spinal cord segments. These connections, however, were infrequent. We also revealed that some projection neurons outside the dorsal grey matter and in the LSN have distinct, previously undescribed course of their projection axon. Our findings indicate that axon collaterals of lamina I PNs and LCNs in the DLF rarely form functional connections with other lamina I and LSN neurons and that the majority of their targets are on other elements of the dorsal horn. The unique axon trajectories of neurons in the dorsolateral aspect of the spinal cord, including the LSN do not fit our present understanding of midline axon guidance and suggest that their function and development differ from the neurons inside lamina I. These findings emphasize the importance of understanding the connectivity matrix of the superficial dorsal horn in order to decipher spinal sensory information processing.
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Cherniak M, Etlin A, Strauss I, Anglister L, Lev-Tov A. The sacral networks and neural pathways used to elicit lumbar motor rhythm in the rodent spinal cord. Front Neural Circuits 2014; 8:143. [PMID: 25520624 PMCID: PMC4253665 DOI: 10.3389/fncir.2014.00143] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Accepted: 11/11/2014] [Indexed: 01/17/2023] Open
Abstract
Identification of neural networks and pathways involved in activation and modulation of spinal central pattern generators (CPGs) in the absence of the descending control from the brain is important for further understanding of neural control of movement and for developing innovative therapeutic approaches to improve the mobility of spinal cord injury patients. Activation of the hindlimb innervating segments by sacrocaudal (SC) afferent input and by specific application of neurochemicals to the sacral networks is feasible in the isolated spinal cord preparation of the newborn rat. Here we review our recent studies of sacral relay neurons with lumbar projections and evaluate their role in linking the sacral and thoracolumbar (TL) networks during different motor behaviors. Our major findings show that: (1) heterogeneous groups of dorsal, intermediate and ventral sacral-neurons with ventral and lateral ascending funicular projections mediate the activation of the locomotor CPGs through sacral sensory input; and (2) rhythmic excitation of lumbar flexor motoneurons, produced by bath application of alpha-1 adrenoceptor agonists to the sacral segments is mediated exclusively by ventral clusters of sacral-neurons with lumbar projections through the ventral funiculus.
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Affiliation(s)
- Meir Cherniak
- Department of Medical Neurobiology, Institute for Medical Research-Israel-Canada, IMRIC, The Hebrew University Medical School Jerusalem, Israel
| | - Alex Etlin
- Department of Medical Neurobiology, Institute for Medical Research-Israel-Canada, IMRIC, The Hebrew University Medical School Jerusalem, Israel
| | - Ido Strauss
- Department of Medical Neurobiology, Institute for Medical Research-Israel-Canada, IMRIC, The Hebrew University Medical School Jerusalem, Israel
| | - Lili Anglister
- Department of Medical Neurobiology, Institute for Medical Research-Israel-Canada, IMRIC, The Hebrew University Medical School Jerusalem, Israel
| | - Aharon Lev-Tov
- Department of Medical Neurobiology, Institute for Medical Research-Israel-Canada, IMRIC, The Hebrew University Medical School Jerusalem, Israel
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32
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Hadas Y, Etlin A, Falk H, Avraham O, Kobiler O, Panet A, Lev-Tov A, Klar A. A 'tool box' for deciphering neuronal circuits in the developing chick spinal cord. Nucleic Acids Res 2014; 42:e148. [PMID: 25147209 PMCID: PMC4231727 DOI: 10.1093/nar/gku750] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The genetic dissection of spinal circuits is an essential new means for understanding the neural basis of mammalian behavior. Molecular targeting of specific neuronal populations, a key instrument in the genetic dissection of neuronal circuits in the mouse model, is a complex and time-demanding process. Here we present a circuit-deciphering 'tool box' for fast, reliable and cheap genetic targeting of neuronal circuits in the developing spinal cord of the chick. We demonstrate targeting of motoneurons and spinal interneurons, mapping of axonal trajectories and synaptic targeting in both single and populations of spinal interneurons, and viral vector-mediated labeling of pre-motoneurons. We also demonstrate fluorescent imaging of the activity pattern of defined spinal neurons during rhythmic motor behavior, and assess the role of channel rhodopsin-targeted population of interneurons in rhythmic behavior using specific photoactivation.
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Affiliation(s)
- Yoav Hadas
- Department of Medical Neurobiology, IMRIC, Hebrew University Medical School, Jerusalem, Israel
| | - Alex Etlin
- Department of Medical Neurobiology, IMRIC, Hebrew University Medical School, Jerusalem, Israel
| | - Haya Falk
- Department of Medical Neurobiology, IMRIC, Hebrew University Medical School, Jerusalem, Israel
| | - Oshri Avraham
- Department of Medical Neurobiology, IMRIC, Hebrew University Medical School, Jerusalem, Israel
| | - Oren Kobiler
- Department of Clinical Microbiology and Immunology, Sackler School of Medicine, Tel Aviv University, Ramat Aviv, Israel
| | - Amos Panet
- Department of Biochemistry, IMRIC, Hebrew University Medical School, Jerusalem, Israel
| | - Aharon Lev-Tov
- Department of Medical Neurobiology, IMRIC, Hebrew University Medical School, Jerusalem, Israel
| | - Avihu Klar
- Department of Medical Neurobiology, IMRIC, Hebrew University Medical School, Jerusalem, Israel
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Sławińska U, Miazga K, Jordan LM. 5-HT₂ and 5-HT₇ receptor agonists facilitate plantar stepping in chronic spinal rats through actions on different populations of spinal neurons. Front Neural Circuits 2014; 8:95. [PMID: 25191231 PMCID: PMC4137449 DOI: 10.3389/fncir.2014.00095] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Accepted: 07/21/2014] [Indexed: 01/13/2023] Open
Abstract
There is considerable evidence from research in neonatal and adult rat and mouse preparations to warrant the conclusion that activation of 5-HT2 and 5-HT1A/7 receptors leads to activation of the spinal cord circuitry for locomotion. These receptors are involved in control of locomotor movements, but it is not clear how they are implicated in the responses to 5-HT agonists observed after spinal cord injury. Here we used agonists that are efficient in promoting locomotor recovery in paraplegic rats, 8-hydroxy-2-(di-n-propylamino)-tetralin (8-OHDPAT) (acting on 5-HT1A/7 receptors) and quipazine (acting on 5-HT2 receptors), to examine this issue. Analysis of intra- and interlimb coordination confirmed that the locomotor performance was significantly improved by either drug, but the data revealed marked differences in their mode of action. Interlimb coordination was significantly better after 8-OHDPAT application, and the activity of the extensor soleus muscle was significantly longer during the stance phase of locomotor movements enhanced by quipazine. Our results show that activation of both receptors facilitates locomotion, but their effects are likely exerted on different populations of spinal neurons. Activation of 5-HT2 receptors facilitates the output stage of the locomotor system, in part by directly activating motoneurons, and also through activation of interneurons of the locomotor central pattern generator (CPG). Activation of 5-HT7/1A receptors facilitates the activity of the locomotor CPG, without direct actions on the output components of the locomotor system, including motoneurons. Although our findings show that the combined use of these two drugs results in production of well-coordinated weight supported locomotion with a reduced need for exteroceptive stimulation, they also indicate that there might be some limitations to the utility of combined treatment. Sensory feedback and some intraspinal circuitry recruited by the drugs can conflict with the locomotor activation.
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Affiliation(s)
- Urszula Sławińska
- Department of Neurophysiology, Nencki Institute of Experimental Biology PAS Warsaw, Poland
| | - Krzysztof Miazga
- Department of Neurophysiology, Nencki Institute of Experimental Biology PAS Warsaw, Poland
| | - Larry M Jordan
- Department of Physiology, Spinal Cord Research Centre, University of Manitoba Winnipeg, MB, Canada
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Etlin A, Finkel E, Cherniak M, Lev-Tov A, Anglister L. The motor output of hindlimb innervating segments of the spinal cord is modulated by cholinergic activation of rostrally projecting sacral relay neurons. J Mol Neurosci 2014; 53:517-24. [PMID: 24973872 DOI: 10.1007/s12031-014-0351-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Accepted: 06/05/2014] [Indexed: 10/25/2022]
Abstract
Cholinergic networks have been shown to be involved in generation and modulation of the locomotor rhythmic pattern produced by the mammalian central pattern generators. Here, we show that changes in the endogenous levels of acetylcholine in the sacral segments of the isolated spinal cord of the neonatal rat modulate the locomotor-related output produced by stimulation of sacrocaudal afferents in muscarinic receptor-dependent mechanisms. Cholinergic components we found on sacral relay neurons with lumbar projections through the ventral and lateral funiculi are suggested to mediate this ascending cholinergic modulation. Our findings, possible mechanisms accounting for them, and their potential implications are discussed.
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Affiliation(s)
- Alex Etlin
- Department of Medical Neurobiology, IMRIC, The Hebrew University Medical School, Jerusalem, 9112102, Israel
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Finkel E, Etlin A, Cherniak M, Mor Y, Lev-Tov A, Anglister L. Neuroanatomical basis for cholinergic modulation of locomotor networks by sacral relay neurons with ascending lumbar projections. J Comp Neurol 2014; 522:3437-55. [DOI: 10.1002/cne.23613] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2013] [Revised: 04/10/2014] [Accepted: 04/14/2014] [Indexed: 12/28/2022]
Affiliation(s)
- Eran Finkel
- Department of Medical Neurobiology, IMRIC; Hebrew University-Hadassah Medical School; Jerusalem 91120 Israel
| | - Alex Etlin
- Department of Medical Neurobiology, IMRIC; Hebrew University-Hadassah Medical School; Jerusalem 91120 Israel
| | - Meir Cherniak
- Department of Medical Neurobiology, IMRIC; Hebrew University-Hadassah Medical School; Jerusalem 91120 Israel
| | - Yoav Mor
- Department of Medical Neurobiology, IMRIC; Hebrew University-Hadassah Medical School; Jerusalem 91120 Israel
| | - Aharon Lev-Tov
- Department of Medical Neurobiology, IMRIC; Hebrew University-Hadassah Medical School; Jerusalem 91120 Israel
| | - Lili Anglister
- Department of Medical Neurobiology, IMRIC; Hebrew University-Hadassah Medical School; Jerusalem 91120 Israel
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Mandadi S, Hong P, Tran MA, Bráz JM, Colarusso P, Basbaum AI, Whelan PJ. Identification of multisegmental nociceptive afferents that modulate locomotor circuits in the neonatal mouse spinal cord. J Comp Neurol 2014; 521:2870-87. [PMID: 23436436 DOI: 10.1002/cne.23321] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2012] [Revised: 02/08/2013] [Accepted: 02/11/2013] [Indexed: 11/06/2022]
Abstract
Compared to proprioceptive afferent collateral projections, less is known about the anatomical, neurochemical, and functional basis of nociceptive collateral projections modulating lumbar central pattern generators (CPG). Quick response times are critical to ensure rapid escape from aversive stimuli. Furthermore, sensitization of nociceptive afferent pathways can contribute to a pathological activation of motor circuits. We investigated the extent and role of collaterals of capsaicin-sensitive nociceptive sacrocaudal afferent (nSCA) nerves that directly ascend several spinal segments in Lissauer's tract and the dorsal column and regulate motor activity. Anterograde tracing demonstrated direct multisegmental projections of the sacral dorsal root 4 (S4) afferent collaterals in Lissauer's tract and in the dorsal column. Subsets of the traced S4 afferent collaterals expressed transient receptor potential vanilloid 1 (TRPV1), which transduces a nociceptive response to capsaicin. Electrophysiological data revealed that S4 dorsal root stimulation could evoke regular rhythmic bursting activity, and our data suggested that capsaicin-sensitive collaterals contribute to CPG activation across multiple segments. Capsaicin's effect on S4-evoked locomotor activity was potent until the lumbar 5 (L5) segments, and diminished in rostral segments. Using calcium imaging we found elevated calcium transients within Lissauer's tract and dorsal column at L5 segments when compared to the calcium transients only within the dorsal column at the lumbar 2 (L2) segments, which were desensitized by capsaicin. We conclude that lumbar locomotor networks in the neonatal mouse spinal cord are targets for modulation by direct multisegmental nSCA, subsets of which express TRPV1 in Lissauer's tract and the dorsal column. J. Comp. Neurol. 521:2870-2887, 2013. © 2013 Wiley Periodicals, Inc.
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Affiliation(s)
- Sravan Mandadi
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, T2N 4N1, Canada; Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, T2N 4N1, Canada
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Characterization of sacral interneurons that mediate activation of locomotor pattern generators by sacrocaudal afferent input. J Neurosci 2013; 33:734-47. [PMID: 23303951 DOI: 10.1523/jneurosci.4390-12.2013] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Identification of the neural pathways involved in retraining the spinal central pattern generators (CPGs) by afferent input in the absence of descending supraspinal control is feasible in isolated rodent spinal cords where the locomotor CPGs are potently activated by sacrocaudal afferent (SCA) input. Here we study the involvement of sacral neurons projecting rostrally through the ventral funiculi (VF) in activation of the CPGs by sensory stimulation. Fluorescent labeling and immunostaining showed that VF neurons are innervated by primary afferents immunoreactive for vesicular glutamate transporters 1 and 2 and by intraspinal neurons. Calcium imaging revealed that 55% of the VF neurons were activated by SCA stimulation. The activity of VF neurons and the sacral and lumbar CPGs was abolished when non-NMDA receptors in the sacral segments were blocked by the antagonist CNQX. When sacral NMDA receptors were blocked by APV, the sacral CPGs were suppressed, VF neurons with nonrhythmic activity were recruited and a moderate-drive locomotor rhythm developed during SCA stimulation. In contrast, when the sacral CPGs were activated by SCA stimulation, rhythmic and nonrhythmic VF neurons were recruited and the locomotor rhythm was most powerful. The activity of 73 and 27% of the rhythmic VF neurons was in-phase with the ipsilateral and contralateral motor output, respectively. Collectively, our studies indicate that sacral VF neurons serve as a major link between SCA and the hindlimb CPGs and that the ability of SCA to induce stepping can be enhanced by the sacral CPGs. The nature of the ascending drive to lumbar CPGs, the identity of subpopulations of VF neurons, and their potential role in activating the locomotor rhythm are discussed.
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Gad P, Choe J, Nandra MS, Zhong H, Roy RR, Tai YC, Edgerton VR. Development of a multi-electrode array for spinal cord epidural stimulation to facilitate stepping and standing after a complete spinal cord injury in adult rats. J Neuroeng Rehabil 2013; 10:2. [PMID: 23336733 PMCID: PMC3599040 DOI: 10.1186/1743-0003-10-2] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Accepted: 01/07/2013] [Indexed: 01/07/2023] Open
Abstract
Background Stimulation of the spinal cord has been shown to have great potential for improving function after motor deficits caused by injury or pathological conditions. Using a wide range of animal models, many studies have shown that stimulation applied to the neural networks intrinsic to the spinal cord can result in a dramatic improvement of motor ability, even allowing an animal to step and stand after a complete spinal cord transection. Clinical use of this technology, however, has been slow to develop due to the invasive nature of the implantation procedures, the lack of versatility in conventional stimulation technology, and the difficulty of ascertaining specific sites of stimulation that would provide optimal amelioration of the motor deficits. Moreover, the development of tools available to control precise stimulation chronically via biocompatible electrodes has been limited. In this paper, we outline the development of this technology and its use in the spinal rat model, demonstrating the ability to identify and stimulate specific sites of the spinal cord to produce discrete motor behaviors in spinal rats using this array. Methods We have designed a chronically implantable, rapidly switchable, high-density platinum based multi-electrode array that can be used to stimulate at 1–100 Hz and 1–10 V in both monopolar and bipolar configurations to examine the electrophysiological and behavioral effects of spinal cord epidural stimulation in complete spinal cord transected rats. Results In this paper, we have demonstrated the effectiveness of using high-resolution stimulation parameters in the context of improving motor recovery after a spinal cord injury. We observed that rats whose hindlimbs were paralyzed can stand and step when specific sets of electrodes of the array are stimulated tonically (40 Hz). Distinct patterns of stepping and standing were produced by stimulation of different combinations of electrodes on the array located at specific spinal cord levels and by specific stimulation parameters, i.e., stimulation frequency and intensity, and cathode/anode orientation. The array also was used to assess functional connectivity between the cord dorsum to interneuronal circuits and specific motor pools via evoked potentials induced at 1 Hz stimulation in the absence of any anesthesia. Conclusions Therefore the high density electrode array allows high spatial resolution and the ability to selectively activate different neural pathways within the lumbosacral region of the spinal cord to facilitate standing and stepping in adult spinal rats and provides the capability to evoke motor potentials and thus a means for assessing connectivity between sensory circuits and specific motor pools and muscles.
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Affiliation(s)
- Parag Gad
- Biomedical Engineering IDP, University of California, Los Angeles, CA 90095, USA
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Dose F, Taccola G. Coapplication of noisy patterned electrical stimuli and NMDA plus serotonin facilitates fictive locomotion in the rat spinal cord. J Neurophysiol 2012; 108:2977-90. [DOI: 10.1152/jn.00554.2012] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
A new stimulating protocol [fictive locomotion-induced stimulation (FL istim)], consisting of intrinsically variable weak waveforms applied to a single dorsal root is very effective (though not optimal as it eventually wanes away) in activating the locomotor program of the isolated rat spinal cord. The present study explored whether combination of FL istim with low doses of pharmacological agents that raise network excitability might further improve the functional outcome, using this in vitro model. FL istim was applied together with N-methyl-d-aspartate (NMDA) + serotonin, while fictive locomotion (FL) was electrophysiologically recorded from lumbar ventral roots. Superimposing FL istim on FL evoked by these neurochemicals persistently accelerated locomotor-like cycles to a set periodicity and modulated cycle amplitude depending on FL istim rate. Trains of stereotyped rectangular pulses failed to replicate this phenomenon. The GABAB agonist baclofen dose dependently inhibited, in a reversible fashion, FL evoked by either FL istim or square pulses. Sustained episodes of FL emerged when FL istim was delivered, at an intensity subthreshold for FL, in conjunction with subthreshold pharmacological stimulation. Such an effect was, however, not found when high potassium solution instead of NMDA + serotonin was used. These results suggest that the combined action of subthreshold FL istim (e.g., via epidural stimulation) and neurochemicals should be tested in vivo to improve locomotor rehabilitation after injury. In fact, reactivation of spinal locomotor circuits by conventional electrical stimulation of afferent fibers is difficult, while pharmacological activation of spinal networks is clinically impracticable due to concurrent unwanted effects. We speculate that associating subthreshold chemical and electrical inputs might decrease side effects when attempting to evoke human locomotor patterns.
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Affiliation(s)
- Francesco Dose
- Neuroscience Area International School for Advanced Studies, Trieste, Italy; and
- Spinal Person Injury Neurorehabilitation Applied Laboratory, Istituto di Medicina Fisica e Riabilitazione, Udine, Italy
| | - Giuliano Taccola
- Neuroscience Area International School for Advanced Studies, Trieste, Italy; and
- Spinal Person Injury Neurorehabilitation Applied Laboratory, Istituto di Medicina Fisica e Riabilitazione, Udine, Italy
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Clemens S, Belin-Rauscent A, Simmers J, Combes D. Opposing modulatory effects of D1- and D2-like receptor activation on a spinal central pattern generator. J Neurophysiol 2012; 107:2250-9. [DOI: 10.1152/jn.00366.2011] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The role of dopamine in regulating spinal cord function is receiving increasing attention, but its actions on spinal motor networks responsible for rhythmic behaviors remain poorly understood. Here, we have explored the modulatory influence of dopamine on locomotory central pattern generator (CPG) circuitry in the spinal cord of premetamorphic Xenopus laevis tadpoles. Bath application of exogenous dopamine to isolated brain stem-spinal cords exerted divergent dose-dependent effects on spontaneous episodic patterns of locomotory-related activity recorded extracellularly from spinal ventral roots. At low concentration (2 μM), dopamine reduced the occurrence of bursts and fictive swim episodes and increased episode cycle periods. In contrast, at high concentration (50 μM) dopamine reversed its actions on fictive swimming, now increasing both burst and swim episode occurrences while reducing episode periods. The low-dopamine effects were mimicked by the D2-like receptor agonists bromocriptine and quinpirole, whereas the D1-like receptor agonist SKF 38393 reproduced the effects of high dopamine. Furthermore, the motor response to the D1-like antagonist SCH 23390 resembled that to the D2 agonists, whereas the D2-like antagonist raclopride mimicked the effects of the D1 agonist. Together, these findings indicate that dopamine plays an important role in modulating spinal locomotor activity. Moreover, the transmitter's opposing influences on the same target CPG are likely to be accomplished by a specific, concentration-dependent recruitment of independent D2- and D1-like receptor signaling pathways that differentially mediate inhibitory and excitatory actions.
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Affiliation(s)
- S. Clemens
- Brody School of Medicine, Department of Physiology, East Carolina University, Greenville, North Carolina; and
| | - A. Belin-Rauscent
- Université de Bordeaux, CNRS, Institut de Neurosciences Cognitives et Intégratives d'Aquitaine (INCIA), UMR 5287, Bordeaux, France
| | - J. Simmers
- Université de Bordeaux, CNRS, Institut de Neurosciences Cognitives et Intégratives d'Aquitaine (INCIA), UMR 5287, Bordeaux, France
| | - D. Combes
- Université de Bordeaux, CNRS, Institut de Neurosciences Cognitives et Intégratives d'Aquitaine (INCIA), UMR 5287, Bordeaux, France
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Schnell L, Hunanyan AS, Bowers WJ, Horner PJ, Federoff HJ, Gullo M, Schwab ME, Mendell LM, Arvanian VL. Combined delivery of Nogo-A antibody, neurotrophin-3 and the NMDA-NR2d subunit establishes a functional 'detour' in the hemisected spinal cord. Eur J Neurosci 2011; 34:1256-67. [PMID: 21995852 PMCID: PMC3195885 DOI: 10.1111/j.1460-9568.2011.07862.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
To encourage re-establishment of functional innervation of ipsilateral lumbar motoneurons by descending fibers after an intervening lateral thoracic (T10) hemisection (Hx), we treated adult rats with the following agents: (i) anti-Nogo-A antibodies to neutralize the growth-inhibitor Nogo-A; (ii) neurotrophin-3 (NT-3) via engineered fibroblasts to promote neuron survival and plasticity; and (iii) the NMDA-receptor 2d (NR2d) subunit via an HSV-1 amplicon vector to elevate NMDA receptor function by reversing the Mg2+ block, thereby enhancing synaptic plasticity and promoting the effects of NT-3. Synaptic responses evoked by stimulation of the ventrolateral funiculus ipsilateral and rostral to the Hx were recorded intracellularly from ipsilateral lumbar motoneurons. In uninjured adult rats short-latency (1.7-ms) monosynaptic responses were observed. After Hx these monosynaptic responses were abolished. In the Nogo-Ab + NT-3 + NR2d group, long-latency (approximately 10 ms), probably polysynaptic, responses were recorded and these were not abolished by re-transection of the spinal cord through the Hx area. This suggests that these novel responses resulted from new connections established around the Hx. Anterograde anatomical tracing from the cervical grey matter ipsilateral to the Hx revealed increased numbers of axons re-crossing the midline below the lesion in the Nogo-Ab + NT-3 + NR2d group. The combined treatment resulted in slightly better motor function in the absence of adverse effects (e.g. pain). Together, these results suggest that the combination treatment with Nogo-Ab + NT-3 + NR2d can produce a functional ‘detour’ around the lesion in a laterally hemisected spinal cord. This novel combination treatment may help to improve function of the damaged spinal cord.
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Affiliation(s)
- Lisa Schnell
- Brain Research Institute, University and ETH of Zurich, Zurich, Switzerland
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Taccola G. The locomotor central pattern generator of the rat spinal cord in vitro is optimally activated by noisy dorsal root waveforms. J Neurophysiol 2011; 106:872-84. [DOI: 10.1152/jn.00170.2011] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The spinal cord contains an intrinsic locomotor program driven by a central pattern generator that rhythmically activates flexor and extensor limb motor pools. Although long-lasting locomotor activity can be generated pharmacologically, trains of afferent stimuli trigger only few locomotor cycles. The present study investigated whether a new electrical stimulation protocol (termed FL istim) could elicit long-lasting fictive locomotion (FL) in the rat spinal cord in vitro. Thus, after first inducing FL by bath application of N-methyl-d-aspartate and serotonin, the recorded waveform obtained from a lumbar ventral root was digitized and then applied to either a lumbar dorsal root or the cauda equina following washout of pharmacological agents. Two FL istim cycles were the threshold input to evoke an episode of FL from ventral roots. Longer cycles (up to 1 min) induced sustained FL (up to 1 min) with stereotyped periodicity (2.2 ± 0.5 s), despite changing frequency (2–4 s) or cycle amplitude of FL istim. Gradual filtering out of the noise from FL istim trace concomitantly decreased the efficiency of FL so that stimulation with equivalent pure sinusoids produced asynchronous, irregular discharges only that could not be converted to FL by adding spontaneous basal activity. This study is the first demonstration that epochs of rhythmic locomotor-like oscillations applied to a dorsal root represent an efficient stimulus to evoke FL as long as they contain the electrophysiological noise produced within FL cycles. These observations suggest novel strategies to improve the efficiency of electrical stimulation delivered by clinical devices for neurorehabilitation after spinal injury.
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Affiliation(s)
- Giuliano Taccola
- Neurobiology Sector, International School for Advanced Studies, Trieste; and
- Spinal Person Injury Neurorehabilitation Applied Laboratory, Istituto di Medicina Fisica e Riabilitazione, Udine, Italy
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Abstract
Neuronal networks within the spinal cord of mammals are responsible for generating various rhythmic movements, such as walking, running, swimming, and scratching. The ability to generate multiple rhythmic movements highlights the complexity and flexibility of the mammalian spinal circuitry. The present review describes features of some rhythmic motor behaviors generated by the mammalian spinal cord and discusses how the spinal circuitry is able to produce different rhythmic movements with their own sets of goals and demands.
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Affiliation(s)
- Alain Frigon
- Department of Physiology and Biophysics, Université de Sherbrooke, Sherbrooke, Quebec, Canada
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Côté MP, Azzam GA, Lemay MA, Zhukareva V, Houlé JD. Activity-dependent increase in neurotrophic factors is associated with an enhanced modulation of spinal reflexes after spinal cord injury. J Neurotrauma 2011; 28:299-309. [PMID: 21083432 DOI: 10.1089/neu.2010.1594] [Citation(s) in RCA: 136] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Activity-based therapies such as passive bicycling and step-training on a treadmill contribute to motor recovery after spinal cord injury (SCI), leading to a greater number of steps performed, improved gait kinematics, recovery of phase-dependent modulation of spinal reflexes, and prevention of decrease in muscle mass. Both tasks consist of alternating movements that rhythmically stretch and shorten hindlimb muscles. However, the paralyzed hindlimbs are passively moved by a motorized apparatus during bike-training, whereas locomotor movements during step-training are generated by spinal networks triggered by afferent feedback. Our objective was to compare the task-dependent effect of bike- and step-training after SCI on physiological measures of spinal cord plasticity in relation to changes in levels of neurotrophic factors. Thirty adult female Sprague-Dawley rats underwent complete spinal transection at a low thoracic level (T12). The rats were assigned to one of three groups: bike-training, step-training, or no training. The exercise regimen consisted of 15 min/d, 5 days/week, for 4 weeks, beginning 5 days after SCI. During a terminal experiment, H-reflexes were recorded from interosseus foot muscles following stimulation of the tibial nerve at 0.3, 5, or 10 Hz. The animals were sacrificed and the spinal cords were harvested for Western blot analysis of the expression of neurotrophic factors in the lumbar spinal cord. We provide evidence that bike- and step-training significantly increase the levels of brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), and NT-4 in the lumbar enlargement of SCI rats, whereas only step-training increased glial cell-derived neurotrophic factor (GDNF) levels. An increase in neurotrophic factor protein levels that positively correlated with the recovery of H-reflex frequency-dependent depression suggests a role for neurotrophic factors in reflex normalization.
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Affiliation(s)
- Marie-Pascale Côté
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania 19129, USA
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