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Mari S, Lecomte CG, Merlet AN, Audet J, Yassine S, Arab RA, Harnie J, Rybak IA, Prilutsky BI, Frigon A. Changes in intra- and interlimb reflexes from forelimb cutaneous afferents after staggered thoracic lateral hemisections during locomotion in cats. J Physiol 2024. [PMID: 39340178 DOI: 10.1113/jp286808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2024] [Accepted: 09/05/2024] [Indexed: 09/30/2024] Open
Abstract
In quadrupeds, such as cats, cutaneous afferents from the forepaw dorsum signal external perturbations and send inputs to spinal circuits to co-ordinate the activity in muscles of all four limbs. How these cutaneous reflex pathways from forelimb afferents are reorganized after an incomplete spinal cord injury is not clear. Using a staggered thoracic lateral hemisections paradigm, we investigated changes in intralimb and interlimb reflex pathways by electrically stimulating the left and right superficial radial nerves in seven adult cats and recording reflex responses in five forelimb and ten hindlimb muscles. After the first (right T5-T6) and second (left T10-T11) hemisections, forelimb-hindlimb co-ordination was altered and weakened. After the second hemisection, cats required balance assistance to perform quadrupedal locomotion. Short-, mid- and long-latency homonymous and crossed reflex responses in forelimb muscles and their phase modulation remained largely unaffected after staggered hemisections. The occurrence of homolateral and diagonal mid- and long-latency responses in hindlimb muscles evoked with left and right superficial radial nerve stimulation was significantly reduced at the first time point after the first hemisection, but partially recovered at the second time point with left superficial radial nerve stimulation. These responses were lost or reduced after the second hemisection. When present, all reflex responses, including homolateral and diagonal, maintained their phase-dependent modulation. Therefore, our results show a considerable loss in cutaneous reflex transmission from cervical to lumbar levels after incomplete spinal cord injury, albeit with preservation of phase modulation, probably affecting functional responses to external perturbations. KEY POINTS: Cutaneous afferent inputs co-ordinate muscle activity in the four limbs during locomotion when the forepaw dorsum contacts an obstacle. Thoracic spinal cord injury disrupts communication between spinal locomotor centres located at cervical and lumbar levels, impairing balance and limb co-ordination. We investigated cutaneous reflexes from forelimb afferents during quadrupedal locomotion by electrically stimulating the superficial radial nerve bilaterally, before and after staggered lateral thoracic hemisections in cats. We showed a loss/reduction of mid- and long-latency homolateral and diagonal reflex responses in hindlimb muscles early after the first hemisection that partially recovered with left superficial radial nerve stimulation, before being reduced after the second hemisection. Targeting cutaneous reflex pathways from forelimb afferents projecting to the four limbs could help develop therapeutic approaches aimed at restoring transmission in ascending and descending spinal pathways.
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Affiliation(s)
- Stephen Mari
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Centre de recherche du Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, QC, Canada
| | - Charly G Lecomte
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Centre de recherche du Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, QC, Canada
| | - Angèle N Merlet
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Centre de recherche du Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, QC, Canada
| | - Johannie Audet
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Centre de recherche du Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, QC, Canada
| | - Sirine Yassine
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Centre de recherche du Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, QC, Canada
| | - Rasha Al Arab
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Centre de recherche du Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, QC, Canada
| | - Jonathan Harnie
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Centre de recherche du Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, QC, Canada
| | - Ilya A Rybak
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, USA
| | - Boris I Prilutsky
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA
| | - Alain Frigon
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Centre de recherche du Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, QC, Canada
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Shepard CT, Brown BL, Van Rijswijck MA, Zalla RM, Burke DA, Morehouse JR, Riegler AS, Whittemore SR, Magnuson DSK. Silencing long-descending inter-enlargement propriospinal neurons improves hindlimb stepping after contusive spinal cord injuries. eLife 2023; 12:e82944. [PMID: 38099572 PMCID: PMC10776087 DOI: 10.7554/elife.82944] [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: 08/30/2022] [Accepted: 12/13/2023] [Indexed: 01/10/2024] Open
Abstract
Spinal locomotor circuitry is comprised of rhythm generating centers, one for each limb, that are interconnected by local and long-distance propriospinal neurons thought to carry temporal information necessary for interlimb coordination and gait control. We showed previously that conditional silencing of the long ascending propriospinal neurons (LAPNs) that project from the lumbar to the cervical rhythmogenic centers (L1/L2 to C6), disrupts right-left alternation of both the forelimbs and hindlimbs without significantly disrupting other fundamental aspects of interlimb and speed-dependent coordination (Pocratsky et al., 2020). Subsequently, we showed that silencing the LAPNs after a moderate thoracic contusive spinal cord injury (SCI) resulted in better recovered locomotor function (Shepard et al., 2021). In this research advance, we focus on the descending equivalent to the LAPNs, the long descending propriospinal neurons (LDPNs) that have cell bodies at C6 and terminals at L2. We found that conditional silencing of the LDPNs in the intact adult rat resulted in a disrupted alternation of each limb pair (forelimbs and hindlimbs) and after a thoracic contusion SCI significantly improved locomotor function. These observations lead us to speculate that the LAPNs and LDPNs have similar roles in the exchange of temporal information between the cervical and lumbar rhythm generating centers, but that the partial disruption of the pathway after SCI limits the independent function of the lumbar circuitry. Silencing the LAPNs or LDPNs effectively permits or frees-up the lumbar circuitry to function independently.
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Affiliation(s)
- Courtney T Shepard
- Interdisciplinary Program in Translational Neuroscience, School of Interdisciplinary and Graduate Studies, University of LouisvilleLouisvilleUnited States
- Department of Anatomical Sciences and Neurobiology, University of LouisvilleLouisvilleUnited States
- Kentucky Spinal Cord Injury Research Center, University of LouisvilleLouisvilleUnited States
| | - Brandon L Brown
- Interdisciplinary Program in Translational Neuroscience, School of Interdisciplinary and Graduate Studies, University of LouisvilleLouisvilleUnited States
- Department of Anatomical Sciences and Neurobiology, University of LouisvilleLouisvilleUnited States
- Kentucky Spinal Cord Injury Research Center, University of LouisvilleLouisvilleUnited States
| | - Morgan A Van Rijswijck
- Kentucky Spinal Cord Injury Research Center, University of LouisvilleLouisvilleUnited States
- Speed School of Engineering, University of LouisvilleLouisvilleUnited States
| | - Rachel M Zalla
- Kentucky Spinal Cord Injury Research Center, University of LouisvilleLouisvilleUnited States
- Speed School of Engineering, University of LouisvilleLouisvilleUnited States
| | - Darlene A Burke
- Kentucky Spinal Cord Injury Research Center, University of LouisvilleLouisvilleUnited States
| | - Johnny R Morehouse
- Kentucky Spinal Cord Injury Research Center, University of LouisvilleLouisvilleUnited States
| | - Amberly S Riegler
- Kentucky Spinal Cord Injury Research Center, University of LouisvilleLouisvilleUnited States
| | - Scott R Whittemore
- Interdisciplinary Program in Translational Neuroscience, School of Interdisciplinary and Graduate Studies, University of LouisvilleLouisvilleUnited States
- Department of Anatomical Sciences and Neurobiology, University of LouisvilleLouisvilleUnited States
- Kentucky Spinal Cord Injury Research Center, University of LouisvilleLouisvilleUnited States
- Department of Neurological Surgery, University of LouisvilleLouisvilleUnited States
| | - David SK Magnuson
- Interdisciplinary Program in Translational Neuroscience, School of Interdisciplinary and Graduate Studies, University of LouisvilleLouisvilleUnited States
- Department of Anatomical Sciences and Neurobiology, University of LouisvilleLouisvilleUnited States
- Kentucky Spinal Cord Injury Research Center, University of LouisvilleLouisvilleUnited States
- Speed School of Engineering, University of LouisvilleLouisvilleUnited States
- Department of Neurological Surgery, University of LouisvilleLouisvilleUnited States
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3
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Kuehn N, Schwarz A, Beretta CA, Schwarte Y, Schmitt F, Motsch M, Weidner N, Puttagunta R. Intermediate gray matter interneurons in the lumbar spinal cord play a critical and necessary role in coordinated locomotion. PLoS One 2023; 18:e0291740. [PMID: 37906544 PMCID: PMC10617729 DOI: 10.1371/journal.pone.0291740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2023] [Accepted: 09/05/2023] [Indexed: 11/02/2023] Open
Abstract
Locomotion is a complex task involving excitatory and inhibitory circuitry in spinal gray matter. While genetic knockouts examine the function of individual spinal interneuron (SpIN) subtypes, the phenotype of combined SpIN loss remains to be explored. We modified a kainic acid lesion to damage intermediate gray matter (laminae V-VIII) in the lumbar spinal enlargement (spinal L2-L4) in female rats. A thorough, tailored behavioral evaluation revealed deficits in gross hindlimb function, skilled walking, coordination, balance and gait two weeks post-injury. Using a Random Forest algorithm, we combined these behavioral assessments into a highly predictive binary classification system that strongly correlated with structural deficits in the rostro-caudal axis. Machine-learning quantification confirmed interneuronal damage to laminae V-VIII in spinal L2-L4 correlates with hindlimb dysfunction. White matter alterations and lower motoneuron loss were not observed with this KA lesion. Animals did not regain lost sensorimotor function three months after injury, indicating that natural recovery mechanisms of the spinal cord cannot compensate for loss of laminae V-VIII neurons. As gray matter damage accounts for neurological/walking dysfunction in instances of spinal cord injury affecting the cervical or lumbar enlargement, this research lays the groundwork for new neuroregenerative therapies to replace these lost neuronal pools vital to sensorimotor function.
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Affiliation(s)
- Naëmi Kuehn
- Laboratory for Experimental Neuroregeneration, Spinal Cord Injury Center, Heidelberg University Hospital, Heidelberg, Germany
| | - Andreas Schwarz
- Laboratory for Experimental Neurorehabilitation, Spinal Cord Injury Center, Heidelberg University Hospital, Heidelberg, Germany
| | - Carlo Antonio Beretta
- Department of Functional Neuroanatomy, Institute for Anatomy and Cell Biology, Heidelberg University, Heidelberg, Germany
- Institute of Pharmacology, Heidelberg University, Heidelberg, Germany
| | - Yvonne Schwarte
- Laboratory for Experimental Neuroregeneration, Spinal Cord Injury Center, Heidelberg University Hospital, Heidelberg, Germany
| | - Francesca Schmitt
- Laboratory for Experimental Neuroregeneration, Spinal Cord Injury Center, Heidelberg University Hospital, Heidelberg, Germany
| | - Melanie Motsch
- Laboratory for Experimental Neuroregeneration, Spinal Cord Injury Center, Heidelberg University Hospital, Heidelberg, Germany
| | - Norbert Weidner
- Spinal Cord Injury Center, Heidelberg University Hospital, Heidelberg, Germany
| | - Radhika Puttagunta
- Laboratory for Experimental Neuroregeneration, Spinal Cord Injury Center, Heidelberg University Hospital, Heidelberg, Germany
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Audet J, Yassine S, Lecomte CG, Mari S, Soucy F, Morency C, Merlet AN, Harnie J, Beaulieu C, Gendron L, Rybak IA, Prilutsky BI, Frigon A. Spinal Sensorimotor Circuits Play a Prominent Role in Hindlimb Locomotor Recovery after Staggered Thoracic Lateral Hemisections but Cannot Restore Posture and Interlimb Coordination during Quadrupedal Locomotion in Adult Cats. eNeuro 2023; 10:ENEURO.0191-23.2023. [PMID: 37328297 PMCID: PMC10288532 DOI: 10.1523/eneuro.0191-23.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Revised: 06/05/2023] [Accepted: 06/06/2023] [Indexed: 06/18/2023] Open
Abstract
Spinal sensorimotor circuits interact with supraspinal and peripheral inputs to generate quadrupedal locomotion. Ascending and descending spinal pathways ensure coordination between the forelimbs and hindlimbs. Spinal cord injury (SCI) disrupts these pathways. To investigate the control of interlimb coordination and hindlimb locomotor recovery, we performed two lateral thoracic hemisections on opposite sides of the cord (right T5-T6 and left T10-T11) at an interval of approximately two months in eight adult cats. In three cats, the spinal cord was transected at T12-T13. We collected electromyography (EMG) and kinematic data during quadrupedal and hindlimb-only locomotion before and after spinal lesions. We show that (1) cats spontaneously recover quadrupedal locomotion following staggered hemisections but require balance assistance after the second one, (2) coordination between the forelimbs and hindlimbs displays 2:1 patterns (two cycles of one forelimb within one hindlimb cycle) and becomes weaker and more variable after both hemisections, (3) left-right asymmetries in hindlimb stance and swing durations appear after the first hemisection and reverse after the second, and (4) support periods reorganize after staggered hemisections to favor support involving both forelimbs and diagonal limbs. Cats expressed hindlimb locomotion the day following spinal transection, indicating that lumbar sensorimotor circuits play a prominent role in hindlimb locomotor recovery after staggered hemisections. These results reflect a series of changes in spinal sensorimotor circuits that allow cats to maintain and recover some level of quadrupedal locomotor functionality with diminished motor commands from the brain and cervical cord, although the control of posture and interlimb coordination remains impaired.
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Affiliation(s)
- Johannie Audet
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada
| | - Sirine Yassine
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada
| | - Charly G Lecomte
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada
| | - Stephen Mari
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada
| | - Félix Soucy
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada
| | - Caroline Morency
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada
| | - Angèle N Merlet
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada
| | - Jonathan Harnie
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada
| | - Claudie Beaulieu
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada
| | - Louis Gendron
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada
| | - Ilya A Rybak
- Department of Neurobiology and Anatomy, College of Medicine, Drexel University, Philadelphia, PA 19129
| | - Boris I Prilutsky
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332
| | - Alain Frigon
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada
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Sousa CS, Lima R, Cibrão JR, Gomes ED, Fernandes LS, Pinho TS, Silva D, Campos J, Salgado AJ, Silva NA. Pre-Clinical Assessment of Roflumilast Therapy in a Thoracic Model of Spinal Cord Injury. Pharmaceutics 2023; 15:1556. [PMID: 37242797 PMCID: PMC10222626 DOI: 10.3390/pharmaceutics15051556] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 05/14/2023] [Accepted: 05/17/2023] [Indexed: 05/28/2023] Open
Abstract
The failure of axons to regenerate after a spinal cord injury (SCI) remains one of the greatest challenges in neuroscience. The initial mechanical trauma is followed by a secondary injury cascade, creating a hostile microenvironment, which not only is not permissive to regeneration but also leads to further damage. One of the most promising approaches for promoting axonal regeneration is to maintain the levels of cyclic adenosine monophosphate (cAMP), specifically by a phosphodiesterase-4 (PDE4) inhibitor expressed in neural tissues. Therefore, in our study, we evaluated the therapeutic effect of an FDA-approved PDE4 inhibitor, Roflumilast (Rof), in a thoracic contusion rat model. Results indicate that the treatment was effective in promoting functional recovery. Rof-treated animals showed improvements in both gross and fine motor function. Eight weeks post-injury, the animals significantly recovered by achieving occasional weight-supported plantar steps. Histological assessment revealed a significant decrease in cavity size, less reactive microglia, as well as higher axonal regeneration in treated animals. Molecular analysis revealed that IL-10 and IL-13 levels, as well as VEGF, were increased in the serum of Rof-treated animals. Overall, Roflumilast promotes functional recovery and supports neuroregeneration in a severe thoracic contusion injury model and may be important in SCI treatment.
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Affiliation(s)
- Carla S Sousa
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, 4710-057 Braga, Portugal
- ICVS/3B's Associate Lab, PT Government Associated Lab, 4805-017 Guimarães, Portugal
- Department of Neurosurgery, Hospital Garcia de Orta, 2805-267 Almada, Portugal
| | - Rui Lima
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, 4710-057 Braga, Portugal
- ICVS/3B's Associate Lab, PT Government Associated Lab, 4805-017 Guimarães, Portugal
| | - Jorge R Cibrão
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, 4710-057 Braga, Portugal
- ICVS/3B's Associate Lab, PT Government Associated Lab, 4805-017 Guimarães, Portugal
| | - Eduardo D Gomes
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, 4710-057 Braga, Portugal
- ICVS/3B's Associate Lab, PT Government Associated Lab, 4805-017 Guimarães, Portugal
| | - Luís S Fernandes
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, 4710-057 Braga, Portugal
- ICVS/3B's Associate Lab, PT Government Associated Lab, 4805-017 Guimarães, Portugal
| | - Tiffany S Pinho
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, 4710-057 Braga, Portugal
- ICVS/3B's Associate Lab, PT Government Associated Lab, 4805-017 Guimarães, Portugal
| | - Deolinda Silva
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, 4710-057 Braga, Portugal
- ICVS/3B's Associate Lab, PT Government Associated Lab, 4805-017 Guimarães, Portugal
| | - Jonas Campos
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, 4710-057 Braga, Portugal
- ICVS/3B's Associate Lab, PT Government Associated Lab, 4805-017 Guimarães, Portugal
| | - António J Salgado
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, 4710-057 Braga, Portugal
- ICVS/3B's Associate Lab, PT Government Associated Lab, 4805-017 Guimarães, Portugal
| | - Nuno A Silva
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, 4710-057 Braga, Portugal
- ICVS/3B's Associate Lab, PT Government Associated Lab, 4805-017 Guimarães, Portugal
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Nakajima T, Fortier-Lebel N, Drew T. A secondary motor area contributing to interlimb coordination during visually guided locomotion in the cat. Cereb Cortex 2022; 33:290-315. [PMID: 35259760 PMCID: PMC9837607 DOI: 10.1093/cercor/bhac068] [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: 08/24/2021] [Revised: 02/01/2022] [Accepted: 02/01/2022] [Indexed: 01/19/2023] Open
Abstract
We investigated the contribution of cytoarchitectonic cortical area 4δc, in the caudal bank of the cruciate sulcus of the cat, to the control of visually guided locomotion. To do so, we recorded the activity of 114 neurons in 4δc while cats walked on a treadmill and stepped over an obstacle that advanced toward them. A total of 84/114 (74%) cells were task-related and 68/84 (81%) of these cells showed significant modulation of their discharge frequency when the contralateral limbs were the first to step over the obstacle. These latter cells included a substantial proportion (27/68 40%) that discharged between the passage of the contralateral forelimb and the contralateral hindlimb over the obstacle, suggesting a contribution of this area to interlimb coordination. We further compared the discharge in area 4δc with the activity patterns of cells in the rostral division of the same cytoarchitectonic area (4δr), which has been suggested to be a separate functional region. Despite some differences in the patterns of activity in the 2 subdivisions, we suggest that activity in each is compatible with a contribution to interlimb coordination and that they should be considered as a single functional area that contributes to both forelimb-forelimb and forelimb-hindlimb coordination.
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Affiliation(s)
- Toshi Nakajima
- Department of Integrative Neuroscience, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan
| | - Nicolas Fortier-Lebel
- Département de Neurosciences, Centre Interdisciplinaire de Recherche sur le Cerveau et l'Apprentissage (CIRCA) Groupe de recherche sur la signalisation neurale et la circuiterie (SNC), Université de Montréal, Pavillon Paul-G. Desmarais, C.P. 6128, Succursale Centre-ville, Montréal, QC H3C 3J7, Canada
| | - Trevor Drew
- Département de Neurosciences, Centre Interdisciplinaire de Recherche sur le Cerveau et l'Apprentissage (CIRCA) Groupe de recherche sur la signalisation neurale et la circuiterie (SNC), Université de Montréal, Pavillon Paul-G. Desmarais, C.P. 6128, Succursale Centre-ville, Montréal, QC H3C 3J7, Canada
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Lecomte CG, Mari S, Audet J, Merlet AN, Harnie J, Beaulieu C, Abdallah K, Gendron L, Rybak IA, Prilutsky BI, Frigon A. Modulation of the gait pattern during split-belt locomotion after lateral spinal cord hemisection in adult cats. J Neurophysiol 2022; 128:1593-1616. [PMID: 36382895 PMCID: PMC9744650 DOI: 10.1152/jn.00230.2022] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 11/10/2022] [Accepted: 11/10/2022] [Indexed: 11/17/2022] Open
Abstract
Most previous studies investigated the recovery of locomotion in animals and people with incomplete spinal cord injury (SCI) during relatively simple tasks (e.g., walking in a straight line on a horizontal surface or a treadmill). We know less about the recovery of locomotion after incomplete SCI in left-right asymmetric conditions, such as turning or stepping along circular trajectories. To investigate this, we collected kinematic and electromyography data during split-belt locomotion at different left-right speed differences before and after a right thoracic lateral spinal cord hemisection in nine adult cats. After hemisection, although cats still performed split-belt locomotion, we observed several changes in the gait pattern compared with the intact state at early (1-2 wk) and late (7-8 wk) time points. Cats with larger lesions showed new coordination patterns between the fore- and hindlimbs, with the forelimbs taking more steps. Despite this change in fore-hind coordination, cats maintained consistent phasing between the fore- and hindlimbs. Adjustments in cycle and phase (stance and swing) durations between the slow and fast sides allowed animals to maintain 1:1 left-right coordination. Periods of triple support involving the right (ipsilesional) hindlimb decreased in favor of quad support and triple support involving the other limbs. Step and stride lengths decreased with concurrent changes in the right fore- and hindlimbs, possibly to avoid interference. The above adjustments in the gait pattern allowed cats to retain the ability to locomote in asymmetric conditions after incomplete SCI. We discuss potential plastic neuromechanical mechanisms involved in locomotor recovery in these conditions.NEW & NOTEWORTHY Everyday locomotion often involves left-right asymmetries, when turning, walking along circular paths, stepping on uneven terrains, etc. To show how incomplete spinal cord injury affects locomotor control in asymmetric conditions, we collected data before and after a thoracic lateral spinal hemisection on a split-belt treadmill with one side stepping faster than the other. We show that adjustments in kinematics and muscle activity allowed cats to retain the ability to perform asymmetric locomotion after hemisection.
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Affiliation(s)
- Charly G Lecomte
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Stephen Mari
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Johannie Audet
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Angèle N Merlet
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Jonathan Harnie
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Claudie Beaulieu
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Khaled Abdallah
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Louis Gendron
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Ilya A Rybak
- Department of Neurobiology and Anatomy, College of Medicine, Drexel University, Philadelphia, Pennsylvania
| | - Boris I Prilutsky
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia
| | - Alain Frigon
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec, Canada
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Audet J, Harnie J, Lecomte CG, Mari S, Merlet AN, Prilutsky BI, Rybak IA, Frigon A. Control of Forelimb and Hindlimb Movements and Their Coordination during Quadrupedal Locomotion across Speeds in Adult Spinal Cats. J Neurotrauma 2022; 39:1113-1131. [PMID: 35343245 PMCID: PMC9347373 DOI: 10.1089/neu.2022.0042] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Coordinating the four limbs is critical for terrestrial mammalian locomotion. Thoracic spinal transection abolishes neural communication between the brain and spinal networks controlling hindlimb/leg movements. Several studies have shown that animal models of spinal transection (spinalization), such as mice, rats, cats, and dogs recover hindlimb locomotion with the forelimbs stationary or suspended. We know less on the ability to generate quadrupedal locomotion after spinal transection, however. We collected kinematic and electromyography data in four adult cats during quadrupedal locomotion at five treadmill speeds before (intact cats) and after low-thoracic spinal transection (spinal cats). We show that adult spinal cats performed quadrupedal treadmill locomotion and modulated their speed from 0.4 m/sec to 0.8 m/sec but required perineal stimulation. During quadrupedal locomotion, several compensatory strategies occurred, such as postural adjustments of the head and neck and the appearance of new coordination patterns between the forelimbs and hindlimbs, where the hindlimbs took more steps than the forelimbs. We also observed temporal changes, such as shorter forelimb cycle/swing durations and shorter hindlimb cycle/stance durations in the spinal state. Forelimb double support periods occupied a greater proportion of the cycle in the spinal state, and hindlimb stride length was shorter. Coordination between the forelimbs and hindlimbs was weakened and more variable in the spinal state. Changes in muscle activity reflected spatiotemporal changes in the locomotor pattern. Despite important changes in the pattern, our results indicate that biomechanical properties of the musculoskeletal system play an important role in quadrupedal locomotion and offset some of the loss in neural communication between networks controlling the forelimbs and hindlimbs after spinal transection.
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Affiliation(s)
- Johannie Audet
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Jonathan Harnie
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Charly G. Lecomte
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Stephen Mari
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Angèle N. Merlet
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Boris I. Prilutsky
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Ilya A. Rybak
- Department of Neurobiology and Anatomy, College of Medicine, Drexel University, Philadelphia, Pennsylvania, USA
| | - Alain Frigon
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec, Canada
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9
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Quantitative electrophysiological assessments as predictive markers of lower limb motor recovery after spinal cord injury: a pilot study with an adaptive trial design. Spinal Cord Ser Cases 2022; 8:26. [PMID: 35210402 PMCID: PMC8873458 DOI: 10.1038/s41394-022-00491-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 01/27/2022] [Accepted: 02/01/2022] [Indexed: 11/13/2022] Open
Abstract
Study design Observational, cohort study. Objectives (1) Determine the feasibility and relevance of assessing corticospinal, sensory, and spinal pathways early after traumatic spinal cord injury (SCI) in a rehabilitation setting. (2) Validate whether electrophysiological and magnetic resonance imaging (MRI) measures taken early after SCI could identify preserved neural pathways, which could then guide therapy. Setting Intensive functional rehabilitation hospital (IFR). Methods Five individuals with traumatic SCI and eight controls were recruited. The lower extremity motor score (LEMS), electrical perceptual threshold (EPT) at the S2 dermatome, soleus (SOL) H-reflex, and motor evoked potentials (MEPs) in the tibialis anterior (TA) muscle were assessed during the stay in IFR and in the chronic stage (>6 months post-SCI). Control participants were only assessed once. Feasibility criteria included the absence of adverse events, adequate experimental session duration, and complete dataset gathering. The relationship between electrophysiological data collected in IFR and LEMS in the chronic phase was studied. The admission MRI was used to calculate the maximal spinal cord compression (MSCC). Results No adverse events occurred, but a complete dataset could not be collected for all subjects due to set-up configuration limitations and time constraints. EPT measured at IFR correlated with LEMS in the chronic phases (r = −0.67), whereas SOL H/M ratio, H latency, MEPs and MSCC did not. Conclusions Adjustments are necessary to implement electrophysiological assessments in an IFR setting. Combining MRI and electrophysiological measures may lead to better assessment of neuronal deficits early after SCI.
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Dougherty JB, Disse GD, Bridges NR, Moxon KA. Effect of spinal cord injury on neural encoding of spontaneous postural perturbations in the hindlimb sensorimotor cortex. J Neurophysiol 2021; 126:1555-1567. [PMID: 34379540 PMCID: PMC8782649 DOI: 10.1152/jn.00727.2020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 07/02/2021] [Accepted: 07/02/2021] [Indexed: 11/22/2022] Open
Abstract
Supraspinal signals play a significant role in compensatory responses to postural perturbations. Although the cortex is not necessary for basic postural tasks in intact animals, its role in responding to unexpected postural perturbations after spinal cord injury (SCI) has not been studied. To better understand how SCI impacts cortical encoding of postural perturbations, the activity of single neurons in the hindlimb sensorimotor cortex (HLSMC) was recorded in the rat during unexpected tilts before and after a complete midthoracic spinal transection. In a subset of animals, limb ground reaction forces were also collected. HLSMC activity was strongly modulated in response to different tilt profiles. As the velocity of the tilt increased, more information was conveyed by the HLSMC neurons about the perturbation due to increases in both the number of recruited neurons and the magnitude of their responses. SCI led to attenuated and delayed hindlimb ground reaction forces. However, HLSMC neurons remained responsive to tilts after injury but with increased latencies and decreased tuning to slower tilts. Information conveyed by cortical neurons about the tilts was therefore reduced after SCI, requiring more cells to convey the same amount of information as before the transection. Given that reorganization of the hindlimb sensorimotor cortex in response to therapy after complete midthoracic SCI is necessary for behavioral recovery, this sustained encoding of information after SCI could be a substrate for the reorganization that uses sensory information from above the lesion to control trunk muscles that permit weight-supported stepping and postural control.NEW & NOTEWORTHY The role of cortical circuits in the encoding of posture and balance is of interest for developing therapies for spinal cord injury. This work demonstrated that unexpected postural perturbations are encoded in the hindlimb sensorimotor cortex even in the absence of hindlimb sensory feedback. In fact, the hindlimb sensorimotor cortex continues to encode for postural perturbations after complete spinal transection.
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Affiliation(s)
- Jaimie B Dougherty
- School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, Pennsylvania
| | - Gregory D Disse
- Department of Biomedical Engineering, University of California at Davis, Davis, California
| | - Nathaniel R Bridges
- Air Force Research Laboratory, Wright-Patterson Air Force Base, Dayton, Ohio
| | - Karen A Moxon
- School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, Pennsylvania
- Department of Biomedical Engineering, University of California at Davis, Davis, California
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11
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Fortier-Lebel N, Nakajima T, Yahiaoui N, Drew T. Microstimulation of the Premotor Cortex of the Cat Produces Phase-Dependent Changes in Locomotor Activity. Cereb Cortex 2021; 31:5411-5434. [PMID: 34289039 DOI: 10.1093/cercor/bhab167] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 05/20/2021] [Accepted: 05/20/2021] [Indexed: 11/14/2022] Open
Abstract
To determine the functional organization of premotor areas in the cat pericruciate cortex we applied intracortical microstimulation (ICMS) within multiple cytoarchitectonically identified subregions of areas 4 and 6 in the awake cat, both at rest and during treadmill walking. ICMS in most premotor areas evoked clear twitch responses in the limbs and/or head at rest. During locomotion, these same areas produced phase-dependent modifications of muscle activity. ICMS in the primary motor cortex (area 4γ) produced large phase-dependent responses, mostly restricted to the contralateral forelimb or hindlimb. Stimulation in premotor areas also produced phase-dependent responses that, in some cases, were as large as those evoked from area 4γ. However, responses from premotor areas had more widespread effects on multiple limbs, including the ipsilateral limbs, than did stimulation in 4γ. During locomotion, responses in both forelimb and hindlimb muscles were evoked from cytoarchitectonic areas 4γ, 4δ, 6aα, and 6aγ. However, the prevalence of effects in a given limb varied from one area to another. The results suggest that premotor areas may contribute to the production, modification, and coordination of activity in the limbs during locomotion and may be particularly pertinent during modifications of gait.
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Affiliation(s)
- Nicolas Fortier-Lebel
- Département de Neurosciences, Centre Interdisciplinaire de Recherche sur le Cerveau et l'Apprentissage (CIRCA) Groupe de recherche sur le système nerveux central (GRSNC), Université de Montréal, Québec H3C 3J7, Canada
| | - Toshi Nakajima
- Department of Integrative Neuroscience, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama 930-0194, Japan
| | - Nabiha Yahiaoui
- Département de Neurosciences, Centre Interdisciplinaire de Recherche sur le Cerveau et l'Apprentissage (CIRCA) Groupe de recherche sur le système nerveux central (GRSNC), Université de Montréal, Québec H3C 3J7, Canada
| | - Trevor Drew
- Département de Neurosciences, Centre Interdisciplinaire de Recherche sur le Cerveau et l'Apprentissage (CIRCA) Groupe de recherche sur le système nerveux central (GRSNC), Université de Montréal, Québec H3C 3J7, Canada
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12
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Levetiracetam treatment leads to functional recovery after thoracic or cervical injuries of the spinal cord. NPJ Regen Med 2021; 6:11. [PMID: 33654068 PMCID: PMC7977146 DOI: 10.1038/s41536-021-00121-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Accepted: 02/01/2021] [Indexed: 01/31/2023] Open
Abstract
Spinal cord injury (SCI) leads to dramatic impairments of motor, sensory, and autonomic functions of affected individuals. Following the primary injury, there is an increased release of glutamate that leads to excitotoxicity and further neuronal death. Therefore, modulating glutamate excitotoxicity seems to be a promising target to promote neuroprotection during the acute phase of the injury. In this study, we evaluated the therapeutic effect of a FDA approved antiepileptic drug (levetiracetam-LEV), known for binding to the synaptic vesicle protein SV2A in the brain and spinal cord. LEV therapy was tested in two models of SCI-one affecting the cervical and other the thoracic level of the spinal cord. The treatment was effective on both SCI models. Treated animals presented significant improvements on gross and fine motor functions. The histological assessment revealed a significant decrease of cavity size, as well as higher neuronal and oligodendrocyte survival on treated animals. Molecular analysis revealed that LEV acts by stabilizing the astrocytes allowing an effective uptake of the excess glutamate from the extracellular space. Overall, our results demonstrate that Levetiracetam may be a promising drug for acute management of SCI.
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13
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Fouad K, Popovich PG, Kopp MA, Schwab JM. The neuroanatomical-functional paradox in spinal cord injury. Nat Rev Neurol 2021; 17:53-62. [PMID: 33311711 PMCID: PMC9012488 DOI: 10.1038/s41582-020-00436-x] [Citation(s) in RCA: 73] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/11/2020] [Indexed: 12/13/2022]
Abstract
Although lesion size is widely considered to be the most reliable predictor of outcome after CNS injury, lesions of comparable size can produce vastly different magnitudes of functional impairment and subsequent recovery. This neuroanatomical-functional paradox is likely to contribute to the many failed attempts to independently replicate findings from animal models of neurotrauma. In humans, the analogous clinical-radiological paradox could explain why individuals with similar injuries can respond differently to rehabilitation. We describe the neuroanatomical-functional paradox in the context of traumatic spinal cord injury (SCI) and discuss the underlying mechanisms of the paradox, including the concepts of lesion-affected and recovery-related networks. We also consider the various secondary complications that further limit the accuracy of outcome prediction in SCI and provide suggestions for how to increase the predictive, translational value of preclinical SCI models.
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Affiliation(s)
- Karim Fouad
- Department of Physical Therapy, Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, AB, Canada
- Institute for Neuroscience and Mental Health, University of Alberta, Edmonton, AB, Canada
| | - Phillip G Popovich
- Belford Center for Spinal Cord Injury, The Ohio State University, Wexner Medical Center, Columbus, OH, USA
- Center for Brain and Spinal Cord Repair, The Ohio State University, Wexner Medical Center, Columbus, OH, USA
- Department of Neuroscience, The Ohio State University, Wexner Medical Center, Columbus, OH, USA
- The Neurological Institute, The Ohio State University, Wexner Medical Center, Columbus, OH, USA
| | - Marcel A Kopp
- Clinical & Experimental Spinal Cord Injury Research, Department of Neurology with Experimental Neurology, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
- Berlin Institute of Health (QUEST-Center for Transforming Biomedical Research), Berlin, Germany
| | - Jan M Schwab
- Belford Center for Spinal Cord Injury, The Ohio State University, Wexner Medical Center, Columbus, OH, USA.
- Center for Brain and Spinal Cord Repair, The Ohio State University, Wexner Medical Center, Columbus, OH, USA.
- Department of Neuroscience, The Ohio State University, Wexner Medical Center, Columbus, OH, USA.
- The Neurological Institute, The Ohio State University, Wexner Medical Center, Columbus, OH, USA.
- Clinical & Experimental Spinal Cord Injury Research, Department of Neurology with Experimental Neurology, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany.
- Spinal Cord Injury Medicine (Neuroplegiology), Department of Neurology, The Ohio State University, Wexner Medical Center, Columbus, OH, USA.
- Department of Physical Medicine and Rehabilitation, The Ohio State University, Wexner Medical Center, Columbus, OH, USA.
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14
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Fouad K, Ng C, Basso DM. Behavioral testing in animal models of spinal cord injury. Exp Neurol 2020; 333:113410. [PMID: 32735871 PMCID: PMC8325780 DOI: 10.1016/j.expneurol.2020.113410] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 07/13/2020] [Accepted: 07/17/2020] [Indexed: 01/08/2023]
Abstract
This review is based on a lecture presented at the Craig H. Neilsen Foundation sponsored Spinal Cord Injury Training Program at Ohio State University. We discuss the advantages and challenges of injury models in rodents and theory relation to various behavioral outcome measures. We offer strategies and advice on experimental design, behavioral testing, and on the challenges, one will encounter with animal testing. This review is designed to guide those entering the field of spinal cord injury and/or involved with in vivo animal testing.
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Affiliation(s)
- K Fouad
- University of Alberta, Faculty of Rehabilitation Medicine, Dept of Physical Therapy, 3-48 Corbett Hall, Edmonton T6G 2G4, Canada; University of Alberta, Neuroscience and Mental Health Institute, 2-132 Li Ka Shing, Edmonton T6G 2E1, Canada.
| | - C Ng
- University of Alberta, Neuroscience and Mental Health Institute, 2-132 Li Ka Shing, Edmonton T6G 2E1, Canada
| | - D M Basso
- Ohio State University, College of Medicine, School of Health and Rehabilitation Sciences, 106A Atwell Hall, 453 W. 10th Ave, Columbus, OH 43210, USA
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15
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Boakye M, Morehouse J, Ethridge J, Burke DA, Khattar NK, Kumar C, Manouchehri N, Streijger F, Reed R, Magnuson DS, Sherwood L, Kwon BK, Howland DR. Treadmill-Based Gait Kinematics in the Yucatan Mini Pig. J Neurotrauma 2020; 37:2277-2291. [PMID: 32605423 PMCID: PMC9836690 DOI: 10.1089/neu.2020.7050] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Yucatan miniature pigs (YMPs) are similar to humans in spinal cord size as well as physiological and neuroanatomical features, making them a useful model for human spinal cord injury. However, little is known regarding pig gait kinematics, especially on a treadmill. In this study, 12 healthy YMPs were assessed during bipedal and/or quadrupedal stepping on a treadmill at six speeds (1.0, 1.5, 2.0, 2.5, 3.0, and 3.5 km/h). Kinematic parameters, including limb coordination and proximal and distal limb angles, were measured. Findings indicate that YMPs use a lateral sequence footfall pattern across all speeds. Stride and stance durations decreased with increasing speed whereas swing duration showed no significant change. Across all speeds assessed, no significant differences were noted between hindlimb stepping parameters for bipedal or quadrupedal gait with the exception of distal limb angular kinematics. Specifically, significant differences were observed between locomotor tasks during maximum flexion (quadrupedal > bipedal), total excursion (bipedal > quadrupedal), and the phase relationship between the timing of maximum extension between the right and left hindlimbs (bipedal > quadrupedal). Speed also impacted maximum flexion and right-left phase relationships given that significant differences were found between the fastest speed (3.5 km/h) relative to each of the other speeds. This study establishes a methodology for bipedal and quadrupedal treadmill-based kinematic testing in healthy YMPs. The treadmill approach used was effective in recruiting primarily the spinal circuitry responsible for the basic stepping patterns as has been shown in cats. We recommend 2.5 km/h (0.7 m/sec) as a target walking gait for pre-clinical studies using YMPs, which is similar to that used in cats.
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Affiliation(s)
- Maxwell Boakye
- Department of Neurological Surgery and Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, Kentucky, USA
| | - Johnny Morehouse
- Department of Neurological Surgery and Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, Kentucky, USA
| | - Jay Ethridge
- Department of Neurological Surgery and Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, Kentucky, USA
| | - Darlene A. Burke
- Department of Neurological Surgery and Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, Kentucky, USA
| | - Nicolas K. Khattar
- Department of Neurological Surgery and Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, Kentucky, USA
| | - Chitra Kumar
- Department of Neurological Surgery and Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, Kentucky, USA
| | - Neda Manouchehri
- International Collaboration on Repair Discoveries, Department of Orthopedics, University of British Columbia (UBC), Vancouver, British Columbia, Canada
| | - Femke Streijger
- International Collaboration on Repair Discoveries, Department of Orthopedics, University of British Columbia (UBC), Vancouver, British Columbia, Canada
| | - Robert Reed
- Department of Neurological Surgery and Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, Kentucky, USA
| | - David S.K. Magnuson
- Department of Neurological Surgery and Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, Kentucky, USA
| | - Leslie Sherwood
- Research Resources Facilities, University of Louisville, Louisville, Kentucky, USA
| | - Brian K. Kwon
- International Collaboration on Repair Discoveries, Department of Orthopedics, University of British Columbia (UBC), Vancouver, British Columbia, Canada
- Vancouver Spine Surgery Institute, Department of Orthopedics, University of British Columbia (UBC), Vancouver, British Columbia, Canada
| | - Dena R. Howland
- Department of Neurological Surgery and Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, Kentucky, USA
- Research Service, Robley Rex Veterans Affairs Medical Center, Louisville, Kentucky, USA
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16
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Delivet-Mongrain H, Dea M, Gossard JP, Rossignol S. Recovery of locomotion in cats after severe contusion of the low thoracic spinal cord. J Neurophysiol 2020; 123:1504-1525. [PMID: 32101502 DOI: 10.1152/jn.00498.2019] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Large bilateral contusions of the T10 thoracic spinal cord were performed in 16 adult cats using a calibrated impactor. EMG and video recordings allowed weekly assessments of key locomotor parameters during treadmill training for 5 wk. Thirty-five days postcontusion, several hindlimb locomotor parameters were very similar to the prelesion ones despite some long-term deficits such as paw drag and disrupted fore-hindlimb coupling. Nine out of ten tested cats could step over obstacles placed on the treadmill. Acute electrophysiological experiments showed viable connectivity between segments rostral and caudal to the contusion. At the fifth postcontusion week, a complete spinalization was performed at T13 in 10 cats and all expressed remarkable bilateral hindlimb locomotion within 24-72 h. From our histological evaluation, we concluded that only a small percentage (~10%) of spinal cord pathways was necessary to initiate and maintain a voluntary quadrupedal locomotor pattern on a treadmill and even to negotiate obstacles. Our findings suggest that hindlimb stepping largely resulted from the activity of spinal locomotor circuits, which gradually recovered autonomy week after week. Our histological and electrophysiological evidence indicated that the persistence of specific deficits or else the maintenance of specific functions was related to the integrity of specific supraspinal and propriospinal pathways. The conclusion is that the recovery of locomotion after large spinal contusions depends on a homeostatic recalibration of a tripartite control system involving interactions between spinal circuits (central pattern generator), supraspinal influences, and sensory feedback activated through locomotor training.NEW & NOTEWORTHY The recovery of quadrupedal treadmill locomotion after a large bilateral contusion at the low thoracic T10 spinal level and the ability to negotiate obstacles were studied for 5 wk in 16 cats. Ten cats were further completely spinalized at T13 and were found to walk with the hindlimbs within 24-72 h. We conclude that the extent of locomotor recovery after large spinal contusions hinges both on remnant supraspinal pathways and on a spinal pattern generator.
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Affiliation(s)
- Hugo Delivet-Mongrain
- Department of Neuroscience, Groupe de Recherche sur le Système Nerveux Central (GRSNC of FRQ-S), Faculty of Medicine, Université de Montréal, Montreal, Canada
| | - Melvin Dea
- Department of Neuroscience, Groupe de Recherche sur le Système Nerveux Central (GRSNC of FRQ-S), Faculty of Medicine, Université de Montréal, Montreal, Canada
| | - Jean-Pierre Gossard
- Department of Neuroscience, Groupe de Recherche sur le Système Nerveux Central (GRSNC of FRQ-S), Faculty of Medicine, Université de Montréal, Montreal, Canada
| | - Serge Rossignol
- Department of Neuroscience, Groupe de Recherche sur le Système Nerveux Central (GRSNC of FRQ-S), Faculty of Medicine, Université de Montréal, Montreal, Canada
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Laliberte AM, Goltash S, Lalonde NR, Bui TV. Propriospinal Neurons: Essential Elements of Locomotor Control in the Intact and Possibly the Injured Spinal Cord. Front Cell Neurosci 2019; 13:512. [PMID: 31798419 PMCID: PMC6874159 DOI: 10.3389/fncel.2019.00512] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Accepted: 10/29/2019] [Indexed: 12/22/2022] Open
Abstract
Propriospinal interneurons (INs) communicate information over short and long distances within the spinal cord. They act to coordinate different parts of the body by linking motor circuits that control muscles across the forelimbs, trunk, and hindlimbs. Their role in coordinating locomotor circuits near and far may be invaluable to the recovery of locomotor function lost due to injury to the spinal cord where the flow of motor commands from the brain and brainstem to spinal motor circuits is disrupted. The formation and activation of circuits established by spared propriospinal INs may promote the re-emergence of locomotion. In light of progress made in animal models of spinal cord injury (SCI) and in human patients, we discuss the role of propriospinal INs in the intact spinal cord and describe recent studies investigating the assembly and/or activation of propriospinal circuits to promote recovery of locomotion following SCI.
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Affiliation(s)
- Alex M Laliberte
- Department of Biology, Faculty of Science, Brain and Mind Research Institute, University of Ottawa, Ottawa, ON, Canada
| | - Sara Goltash
- Department of Biology, Faculty of Science, Brain and Mind Research Institute, University of Ottawa, Ottawa, ON, Canada
| | - Nicolas R Lalonde
- Department of Biology, Faculty of Science, Brain and Mind Research Institute, University of Ottawa, Ottawa, ON, Canada
| | - Tuan Vu Bui
- Department of Biology, Faculty of Science, Brain and Mind Research Institute, University of Ottawa, Ottawa, ON, Canada
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18
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Steuer I, Guertin PA. Central pattern generators in the brainstem and spinal cord: an overview of basic principles, similarities and differences. Rev Neurosci 2019; 30:107-164. [PMID: 30543520 DOI: 10.1515/revneuro-2017-0102] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 03/30/2018] [Indexed: 12/11/2022]
Abstract
Central pattern generators (CPGs) are generally defined as networks of neurons capable of enabling the production of central commands, specifically controlling stereotyped, rhythmic motor behaviors. Several CPGs localized in brainstem and spinal cord areas have been shown to underlie the expression of complex behaviors such as deglutition, mastication, respiration, defecation, micturition, ejaculation, and locomotion. Their pivotal roles have clearly been demonstrated although their organization and cellular properties remain incompletely characterized. In recent years, insightful findings about CPGs have been made mainly because (1) several complementary animal models were developed; (2) these models enabled a wide variety of techniques to be used and, hence, a plethora of characteristics to be discovered; and (3) organizations, functions, and cell properties across all models and species studied thus far were generally found to be well-preserved phylogenetically. This article aims at providing an overview for non-experts of the most important findings made on CPGs in in vivo animal models, in vitro preparations from invertebrate and vertebrate species as well as in primates. Data about CPG functions, adaptation, organization, and cellular properties will be summarized with a special attention paid to the network for locomotion given its advanced level of characterization compared with some of the other CPGs. Similarities and differences between these networks will also be highlighted.
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Affiliation(s)
- Inge Steuer
- Neuroscience Unit, Laval University Medical Center (CHUL - CHU de Québec), 2705 Laurier Blvd, Quebec City, Quebec G1V 4G2, Canada
| | - Pierre A Guertin
- Neuroscience Unit, Laval University Medical Center (CHUL - CHU de Québec), 2705 Laurier Blvd, Quebec City, Quebec G1V 4G2, Canada
- Faculty of Medicine, Department of Psychiatry and Neurosciences, Laval University, Quebec City, Quebec G1V 0A6, Canada
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19
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Parallel descending dopaminergic connectivity of A13 cells to the brainstem locomotor centers. Sci Rep 2018; 8:7972. [PMID: 29789702 PMCID: PMC5964077 DOI: 10.1038/s41598-018-25908-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Accepted: 04/30/2018] [Indexed: 12/20/2022] Open
Abstract
The mesencephalic locomotor region (MLR) is an important integrative area for the initiation and modulation of locomotion. Recently it has been realized that dopamine (DA) projections from the substantia nigra pars compacta project to the MLR. Here we explore DA projections from an area of the medial zona incerta (ZI) known for its role in motor control onto the MLR. We provide evidence that dopaminergic (DAergic) A13 neurons have connectivity to the cuneiform nucleus (CnF) and pedunculopontine tegmental nucleus (PPTg) of the MLR. No ascending connectivity to the dorsolateral striatum was observed. On the other hand, DAergic A13 projections to the medullary reticular formation (MRF) and the lumbar spinal cord were sparse. A small number of non-DAergic neurons within the medial ZI projected to the lumbar spinal cord. We then characterized the DA A13 cells and report that these cells differ from canonical DA neurons since they lack the Dopamine Transporter (DAT). The lack of DAT expression, and possibly the lack of a dopamine reuptake mechanism, points to a longer time of action compared to typical dopamine neurons. Collectively our data suggest a parallel descending DAergic pathway from the A13 neurons of the medial ZI to the MLR, which we expect is important for modulating movement.
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Kim LH, Sharma S, Sharples SA, Mayr KA, Kwok CHT, Whelan PJ. Integration of Descending Command Systems for the Generation of Context-Specific Locomotor Behaviors. Front Neurosci 2017; 11:581. [PMID: 29093660 PMCID: PMC5651258 DOI: 10.3389/fnins.2017.00581] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Accepted: 10/04/2017] [Indexed: 11/23/2022] Open
Abstract
Over the past decade there has been a renaissance in our understanding of spinal cord circuits; new technologies are beginning to provide key insights into descending circuits which project onto spinal cord central pattern generators. By integrating work from both the locomotor and animal behavioral fields, we can now examine context-specific control of locomotion, with an emphasis on descending modulation arising from various regions of the brainstem. Here we examine approach and avoidance behaviors and the circuits that lead to the production and arrest of locomotion.
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Affiliation(s)
- Linda H Kim
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada.,Department of Neuroscience, University of Calgary, Calgary, AB, Canada
| | - Sandeep Sharma
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada.,Department of Comparative Biology and Experimental Medicine, University of Calgary, Calgary, AB, Canada
| | - Simon A Sharples
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada.,Department of Neuroscience, University of Calgary, Calgary, AB, Canada
| | - Kyle A Mayr
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada.,Department of Neuroscience, University of Calgary, Calgary, AB, Canada
| | - Charlie H T Kwok
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada.,Department of Comparative Biology and Experimental Medicine, University of Calgary, Calgary, AB, Canada
| | - Patrick J Whelan
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada.,Department of Neuroscience, University of Calgary, Calgary, AB, Canada.,Department of Comparative Biology and Experimental Medicine, University of Calgary, Calgary, AB, Canada
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21
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Gu M, Gao Z, Li X, Zhao F, Guo L, Liu J, He X. Feasibility of Diffusion Tensor Imaging for Assessing Functional Recovery in Rats with Olfactory Ensheathing Cell Transplantation After Contusive Spinal Cord Injury (SCI). Med Sci Monit 2017. [PMID: 28623671 PMCID: PMC5484594 DOI: 10.12659/msm.902126] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Background Olfactory ensheathing cell transplantation is a promising treatment for spinal cord injury. Diffusion tensor imaging has been applied to assess various kinds of spinal cord injury. However, it has rarely been used to evaluate the beneficial effects of olfactory ensheathing cell transplantation. This study aimed to explore the feasibility of diffusion tensor imaging in the evaluation of functional recovery in rats with olfactory ensheathing cell transplantation after contusive spinal cord injury. Material/Methods Immunofluorescence staining was performed to determine the purity of olfactory ensheathing cells. Rats received cell transplantation at week 1 after injury. Basso, Beattie, and Bresnahan score was used to assess the functional recovery. Magnetic resonance imaging was applied weekly, including diffusion tensor imaging. Diffusion tensor tractography was reconstructed to visualize the repair process. Results The results showed that olfactory ensheathing cell transplantation increased the functional and histological recovery and restrained the secondary injury process after the initial spinal cord injury. The fractional anisotropy values in rats with cell transplantation were significantly higher than those in the control group, while the apparent diffusion coefficient values were significantly lower. Basso, Beattie, and Bresnahan score was positively and linearly correlated with fractional anisotropy value, and it was negatively and linearly correlated with apparent diffusion coefficient value. Conclusions These findings suggest that diffusion tensor imaging parameters are sensitive biomarker indices for olfactory ensheathing cell transplantation interventions, and diffusion tensor imaging scan can reflect the functional recovery promoted by the olfactory ensheathing cell transplantation after contusive spinal cord injury.
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Affiliation(s)
- Mengchao Gu
- Department of Othopaedics, Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi, China (mainland)
| | - Zhengchao Gao
- Department of Othopaedics, Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi, China (mainland)
| | - Xiaohui Li
- Department of Radiology, Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi, China (mainland)
| | - Feng Zhao
- Department of Orthopaedics, Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi, China (mainland)
| | - Lei Guo
- Department of Orthopaedics, Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi, China (mainland)
| | - Jiantao Liu
- Department of Orthopaedics, Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi, China (mainland)
| | - Xijing He
- Department of Orthopaedics, Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi, China (mainland)
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22
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Leonard AV, Menendez JY, Pat BM, Hadley MN, Floyd CL. Localization of the corticospinal tract within the porcine spinal cord: Implications for experimental modeling of traumatic spinal cord injury. Neurosci Lett 2017; 648:1-7. [PMID: 28323088 DOI: 10.1016/j.neulet.2017.03.020] [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: 09/19/2016] [Revised: 02/15/2017] [Accepted: 03/14/2017] [Indexed: 11/24/2022]
Abstract
Spinal cord injury (SCI) researchers have predominately utilized rodents for SCI modeling and experimentation. Unfortunately, a large number of novel therapies developed in rodent models have failed to demonstrate efficacy in human clinical trials which suggests that improved animal models are an important translational tool. Recently, porcine models of SCI have been identified as a valuable intermediary model for preclinical evaluation of promising therapies to aid clinical translation. However, the localization of the major spinal tracts in pigs has not yet been described. Given that significant differences exist in the location of the corticospinal tract (CST) between rodents and humans, determining its location in pigs will provide important information related to the translational potential of the porcine pre-clinical model of SCI. Thus, the goal of this study is to investigate the localization of the CST within the porcine spinal cord. Mature female domestic pigs (n=4, 60kg) received microinjections of fluorescent dextran tracers (Alexa Fluor, 10,000MW) into the primary motor cortex, using image-guided navigation (StealthStation®), to label the CST. At 5 weeks post-tracer injection animals were euthanized, the entire neuroaxis harvested and processed for histological examination. Serial sections of the brain and spinal cord were prepared and imaged using confocal microscopy to observe the location of the CST in pigs. Results demonstrate that the CST of pigs is located in the lateral white matter, signifying greater similarity to human anatomical structure compared to that of rodents. We conclude that the corticospinal tract in pigs demonstrates anatomical similarity to human, suggesting that the porcine model has importance as a translational intermediary pre-clinical model.
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Affiliation(s)
- Anna Victoria Leonard
- Spain Rehabilitation Center, Department of Physical Medicine and Rehabilitation, School of Medicine, The University of Alabama at Birmingham, USA; Discipline of Anatomy and Pathology, School of Medicine, The University of Adelaide, Australia.
| | - Joshua York Menendez
- Department of Neurosurgery, School of Medicine, The University of Alabama at Birmingham, USA.
| | - Betty Maki Pat
- Spain Rehabilitation Center, Department of Physical Medicine and Rehabilitation, School of Medicine, The University of Alabama at Birmingham, USA.
| | - Mark N Hadley
- Department of Neurosurgery, School of Medicine, The University of Alabama at Birmingham, USA.
| | - Candace Lorraine Floyd
- Spain Rehabilitation Center, Department of Physical Medicine and Rehabilitation, School of Medicine, The University of Alabama at Birmingham, USA.
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Frigon A. The neural control of interlimb coordination during mammalian locomotion. J Neurophysiol 2017; 117:2224-2241. [PMID: 28298308 DOI: 10.1152/jn.00978.2016] [Citation(s) in RCA: 101] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Revised: 03/02/2017] [Accepted: 03/15/2017] [Indexed: 01/06/2023] Open
Abstract
Neuronal networks within the spinal cord directly control rhythmic movements of the arms/forelimbs and legs/hindlimbs during locomotion in mammals. For an effective locomotion, these networks must be flexibly coordinated to allow for various gait patterns and independent use of the arms/forelimbs. This coordination can be accomplished by mechanisms intrinsic to the spinal cord, somatosensory feedback from the limbs, and various supraspinal pathways. Incomplete spinal cord injury disrupts some of the pathways and structures involved in interlimb coordination, often leading to a disruption in the coordination between the arms/forelimbs and legs/hindlimbs in animal models and in humans. However, experimental spinal lesions in animal models to uncover the mechanisms coordinating the limbs have limitations due to compensatory mechanisms and strategies, redundant systems of control, and plasticity within remaining circuits. The purpose of this review is to provide a general overview and critical discussion of experimental studies that have investigated the neural mechanisms involved in coordinating the arms/forelimbs and legs/hindlimbs during mammalian locomotion.
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Affiliation(s)
- Alain Frigon
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada
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24
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Benthall KN, Hough RA, McClellan AD. Descending propriospinal neurons mediate restoration of locomotor function following spinal cord injury. J Neurophysiol 2017; 117:215-229. [PMID: 27760818 PMCID: PMC5209543 DOI: 10.1152/jn.00544.2016] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Accepted: 10/17/2016] [Indexed: 12/30/2022] Open
Abstract
Following spinal cord injury (SCI) in the lamprey, there is virtually complete recovery of locomotion within a few weeks, but interestingly, axonal regeneration of reticulospinal (RS) neurons is mostly limited to short distances caudal to the injury site. To explain this situation, we hypothesize that descending propriospinal (PS) neurons relay descending drive from RS neurons to indirectly activate spinal central pattern generators (CPGs). In the present study, the contributions of PS neurons to locomotor recovery were tested in the lamprey following SCI. First, long RS neuron projections were interrupted by staggered spinal hemitransections on the right side at 10% body length (BL; normalized from the tip of the oral hood) and on the left side at 30% BL. For acute recovery conditions (≤1 wk) and before axonal regeneration, swimming muscle burst activity was relatively normal, but with some deficits in coordination. Second, lampreys received two spaced complete spinal transections, one at 10% BL and one at 30% BL, to interrupt long-axon RS neuron projections. At short recovery times (3-5 wk), RS and PS neurons will have regenerated their axons for short distances and potentially established a polysynaptic descending command pathway. At these short recovery times, swimming muscle burst activity had only minor coordination deficits. A computer model that incorporated either of the two spinal lesions could mimic many aspects of the experimental data. In conclusion, descending PS neurons are a viable mechanism for indirect activation of spinal locomotor CPGs, although there can be coordination deficits of locomotor activity. NEW & NOTEWORTHY In the lamprey following spinal lesion-mediated interruption of long axonal projections of reticulospinal (RS) neurons, sensory stimulation still elicited relatively normal locomotor muscle burst activity, but with some coordination deficits. Computer models incorporating the spinal lesions could mimic many aspects of the experimental results. Thus, after disruption of long-axon projections from RS neurons in the lamprey, descending propriospinal (PS) neurons appear to be a viable compensatory mechanism for indirect activation of spinal locomotor networks.
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Affiliation(s)
- Katelyn N Benthall
- Division of Biological Sciences, University of Missouri, Columbia, Missouri; and
| | - Ryan A Hough
- Division of Biological Sciences, University of Missouri, Columbia, Missouri; and
| | - Andrew D McClellan
- Division of Biological Sciences, University of Missouri, Columbia, Missouri; and
- Interdisciplinary Neuroscience Program, University of Missouri, Columbia, Missouri
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25
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Côté MP, Murray M, Lemay MA. Rehabilitation Strategies after Spinal Cord Injury: Inquiry into the Mechanisms of Success and Failure. J Neurotrauma 2016; 34:1841-1857. [PMID: 27762657 DOI: 10.1089/neu.2016.4577] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
Body-weight supported locomotor training (BWST) promotes recovery of load-bearing stepping in lower mammals, but its efficacy in individuals with a spinal cord injury (SCI) is limited and highly dependent on injury severity. While animal models with complete spinal transections recover stepping with step-training, motor complete SCI individuals do not, despite similarly intensive training. In this review, we examine the significant differences between humans and animal models that may explain this discrepancy in the results obtained with BWST. We also summarize the known effects of SCI and locomotor training on the muscular, motoneuronal, interneuronal, and supraspinal systems in human and non-human models of SCI and address the potential causes for failure to translate to the clinic. The evidence points to a deficiency in neuronal activation as the mechanism of failure, rather than muscular insufficiency. While motoneuronal and interneuronal systems cannot be directly probed in humans, the changes brought upon by step-training in SCI animal models suggest a beneficial re-organization of the systems' responsiveness to descending and afferent feedback that support locomotor recovery. The literature on partial lesions in humans and animal models clearly demonstrate a greater dependency on supraspinal input to the lumbar cord in humans than in non-human mammals for locomotion. Recent results with epidural stimulation that activates the lumbar interneuronal networks and/or increases the overall excitability of the locomotor centers suggest that these centers are much more dependent on the supraspinal tonic drive in humans. Sensory feedback shapes the locomotor output in animal models but does not appear to be sufficient to drive it in humans.
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Affiliation(s)
- Marie-Pascale Côté
- 1 Department of Neurobiology and Anatomy, Drexel University College of Medicine , Philadelphia, Pennsylvania
| | - Marion Murray
- 1 Department of Neurobiology and Anatomy, Drexel University College of Medicine , Philadelphia, Pennsylvania
| | - Michel A Lemay
- 2 Department of Bioengineering, Temple University , Philadelphia, Pennsylvania
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Thibaudier Y, Hurteau MF, Dambreville C, Chraibi A, Goetz L, Frigon A. Interlimb Coordination during Tied-Belt and Transverse Split-Belt Locomotion before and after an Incomplete Spinal Cord Injury. J Neurotrauma 2016; 34:1751-1765. [PMID: 27219842 DOI: 10.1089/neu.2016.4421] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Coordination between the arms/forelimbs and legs/hindlimbs is often impaired in humans and quadrupedal mammals after incomplete spinal cord injury. In quadrupeds, the forelimbs often take more steps than the hindlimbs, producing a two-to-one forelimb-hindlimb (2-1 FL-HL) coordination. In locomotor performance scales, this is generally considered a loss of FL-HL coordination. Here, FL-HL coordination was quantified before and 8 weeks after a lateral spinal hemisection at the sixth thoracic segment in six adult cats. Cats were tested during tied-belt locomotion (equal front and rear speeds) and transverse split-belt locomotion with the forelimbs or hindlimbs stepping faster. The results show that consistent phasing between forelimb and hindlimb movements was maintained after hemisection, even with the appearance of 2-1 FL-HL coordination, indicating that new stable forms of coordination emerge. Moreover, transverse split-belt locomotion potently modulated interlimb coordination and was capable of restoring a one-to-one FL-HL coordination with a faster treadmill speed for the hindlimbs. In conclusion, the results suggest that neural communication persists after an incomplete spinal cord injury, despite an unequal number of steps between the forelimbs and hindlimbs, and that interlimb coordination can be modulated by having the forelimbs or hindlimbs move at a faster frequency. We propose that locomotor recovery scales incorporate more sensitive methods to quantify FL-HL coordination, to better reflect residual functional capacity and possible cervicolumbar neural communication. Lastly, devising training protocols that make use of the bidirectional influences of the cervical and lumbar locomotor pattern generators could strengthen interlimb coordination and promote locomotor recovery.
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Affiliation(s)
- Yann Thibaudier
- 1 Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du CHUS, Université de Sherbrooke , Sherbrooke, Quebec, Canada
| | - Marie-France Hurteau
- 1 Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du CHUS, Université de Sherbrooke , Sherbrooke, Quebec, Canada
| | - Charline Dambreville
- 1 Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du CHUS, Université de Sherbrooke , Sherbrooke, Quebec, Canada
| | - Anass Chraibi
- 1 Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du CHUS, Université de Sherbrooke , Sherbrooke, Quebec, Canada
| | - Laurent Goetz
- 2 Centre de Recherche de l'Institut Universitaire en Santé Mentale de Québec , Quebec, Canada
| | - Alain Frigon
- 1 Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du CHUS, Université de Sherbrooke , Sherbrooke, Quebec, Canada
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Training-Induced Functional Gains following SCI. Neural Plast 2016; 2016:4307694. [PMID: 27403345 PMCID: PMC4926009 DOI: 10.1155/2016/4307694] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Accepted: 04/27/2016] [Indexed: 12/30/2022] Open
Abstract
We previously demonstrated that daily, hour-long training sessions significantly improved both locomotor (limb kinematics, gait, and hindlimb flexor-extensor bursting patterns) and nonlocomotor (bladder function and at-level mechanical allodynia) functions following a moderate contusive spinal cord injury. The amount of training needed to achieve this recovery is unknown. Furthermore, whether this recovery is induced primarily by neuronal activity below the lesion or other aspects related to general exercise is unclear. Therefore, the current study objectives were to (1) test the efficacy of 30 minutes of step training for recovery following a clinically relevant contusion injury in male Wistar rats and (2) test the efficacy of training without hindlimb engagement. The results indicate that as little as 30 minutes of step training six days per week enhances overground locomotion in male rats with contusive spinal cord injury but does not alter allodynia or bladder function. Thirty minutes of forelimb-only exercise did not alter locomotion, allodynia, or bladder function, and neither training protocol altered the amount of in-cage activity. Taken together, locomotor improvements were facilitated by hindlimb step training for 30 minutes, but longer durations of training are required to affect nonlocomotor systems.
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Tamoxifen Promotes Axonal Preservation and Gait Locomotion Recovery after Spinal Cord Injury in Cats. J Vet Med 2016; 2016:9561968. [PMID: 27006979 PMCID: PMC4781988 DOI: 10.1155/2016/9561968] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2015] [Accepted: 01/14/2016] [Indexed: 01/01/2023] Open
Abstract
We performed experiments in cats with a spinal cord penetrating hemisection at T13-L1 level, with and without tamoxifen treatment. The results showed that the numbers of the ipsilateral and contralateral ventral horn neurons were reduced to less than half in the nontreated animals compared with the treated ones. Also, axons myelin sheet was preserved to almost normal values in treated cats. On the contrary, in the untreated animals, their myelin sheet was reduced to 28% at 30 days after injury (DAI), in both the ipsilateral and contralateral regions of the spinal cord. Additionally, we made hindlimb kinematics experiments to study the effects of tamoxifen on cat locomotion after the injury: at 4, 16, and 30 DAI. We observed that the ipsilateral hindlimb angular displacement (AD) of the pendulum-like movements (PLM) during gait locomotion was recovered to almost normal values in treated cats. Contralateral PLM acquired similar values to those obtained in intact cats. At 4 DAI, untreated animals showed a compensatory increment of PLM occurring in the contralateral hindlimb, which was partially recovered at 30 DAI. Our findings indicate that tamoxifen exerts a neuroprotective effect and preserves or produces myelinated axons, which could benefit the locomotion recovery in injured cats.
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Dillenseger A, Schulze S, Martens H, Schmidt MJ. [Central pattern generators in the spinal cord of the cat and their relevance in rehabilitation after spinal lesion]. TIERAERZTLICHE PRAXIS AUSGABE KLEINTIERE HEIMTIERE 2015; 44:39-46. [PMID: 26530110 DOI: 10.15654/tpk-140729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Accepted: 10/01/2015] [Indexed: 11/13/2022]
Abstract
The ability of the spinal cord to recover after partial or complete transection, and even reinitiate motor function, was investigated in several studies in cats. It has been shown that even after a complete spinalisation at the level of T12/T13, the possibility of restoration of hind-limb function is good. Central pattern generators (CPGs), located in the spinal cord, play an important role in this situation. Although CPGs alone are unable to restore function, the combination of CPGs with targeted and consistent mobility training and, in some cases, hind-limb sensory stimulation is essential to improve function. These result in a reorganisation of the CPGs and neuronal networks in the spinal cord. The age of the animal at the time of injury and the extent and localisation of lesions, play a crucial role in recovery. A new focus of research is the influence of neurotransmitters/neuromodulators on spinal-cord regeneration. How and to what extent these factors support locomotor training remains for further clinical investigation.
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Affiliation(s)
- A Dillenseger
- Anja Dillenseger, Holbeinstraße 90, 01309 Dresden, E-Mail:
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Rossignol S, Martinez M, Escalona M, Kundu A, Delivet-Mongrain H, Alluin O, Gossard JP. The "beneficial" effects of locomotor training after various types of spinal lesions in cats and rats. PROGRESS IN BRAIN RESEARCH 2015; 218:173-98. [PMID: 25890137 DOI: 10.1016/bs.pbr.2014.12.009] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
This chapter reviews a number of experiments on the recovery of locomotion after various types of spinal lesions and locomotor training mainly in cats. We first recall the major evidence on the recovery of hindlimb locomotion in completely spinalized cats at the T13 level and the role played by the spinal locomotor network, also known as the central pattern generator, as well as the beneficial effects of locomotor training on this recovery. Having established that hindlimb locomotion can recover, we raise the issue as to whether spinal plastic changes could also contribute to the recovery after partial spinal lesions such as unilateral hemisections. We found that after such hemisection at T10, cats could recover quadrupedal locomotion and that deficits could be improved by training. We further showed that, after a complete spinalization a few segments below the first hemisection (at T13, i.e., the level of previous studies on spinalization), cats could readily walk with the hindlimbs within hours of completely severing the remaining spinal tracts and not days as is usually the case with only a single complete spinalization. This suggests that neuroplastic changes occurred below the first hemisection so that the cat was already primed to walk after the spinalization subsequent to the hemispinalization 3 weeks before. Of interest is the fact that some characteristic kinematic features in trained or untrained hemispinalized cats could remain after complete spinalization, suggesting that spinal changes induced by training could also be durable. Other studies on reflexes and on the pattern of "fictive" locomotion recorded after curarization corroborate this view. More recent work deals with training cats in more demanding situations such as ladder treadmill (vs. flat treadmill) to evaluate how the locomotor training regimen can influence the spinal cord. Finally, we report our recent studies in rats using compressive lesions or surgical complete spinalization and find that some principles of locomotor recovery in cats also apply to rats when adequate locomotor training is provided.
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Affiliation(s)
- Serge Rossignol
- Department of Neuroscience and Groupe de Recherche sur le Système Nerveux Central (GRSNC), Faculty of Medicine, Université de Montréal, P.O. Box 6128, Montreal, Quebec, Canada; SensoriMotor Rehabilitation Research Team of the Canadian Institute of Health Research, Montreal, Quebec, Canada.
| | - Marina Martinez
- Department of Neuroscience and Groupe de Recherche sur le Système Nerveux Central (GRSNC), Faculty of Medicine, Université de Montréal, P.O. Box 6128, Montreal, Quebec, Canada; SensoriMotor Rehabilitation Research Team of the Canadian Institute of Health Research, Montreal, Quebec, Canada
| | - Manuel Escalona
- Department of Neuroscience and Groupe de Recherche sur le Système Nerveux Central (GRSNC), Faculty of Medicine, Université de Montréal, P.O. Box 6128, Montreal, Quebec, Canada
| | - Aritra Kundu
- Department of Neuroscience and Groupe de Recherche sur le Système Nerveux Central (GRSNC), Faculty of Medicine, Université de Montréal, P.O. Box 6128, 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, P.O. Box 6128, Montreal, Quebec, Canada
| | - Olivier Alluin
- Department of Neuroscience and Groupe de Recherche sur le Système Nerveux Central (GRSNC), Faculty of Medicine, Université de Montréal, P.O. Box 6128, Montreal, Quebec, Canada; SensoriMotor Rehabilitation Research Team of the Canadian Institute of Health Research, Montreal, Quebec, Canada
| | - Jean-Pierre Gossard
- Department of Neuroscience and Groupe de Recherche sur le Système Nerveux Central (GRSNC), Faculty of Medicine, Université de Montréal, P.O. Box 6128, Montreal, Quebec, Canada; SensoriMotor Rehabilitation Research Team of the Canadian Institute of Health Research, Montreal, Quebec, Canada
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Impact of treatment duration and lesion size on effectiveness of chondroitinase treatment post-SCI. Exp Neurol 2015; 267:64-77. [PMID: 25725355 DOI: 10.1016/j.expneurol.2015.02.028] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Revised: 02/17/2015] [Accepted: 02/18/2015] [Indexed: 12/30/2022]
Abstract
The effects of 2weeks of intralesional chondroitinase abc (ch'abc) treatment on anatomical plasticity and behavioral recovery are examined in adult cats and compared to results achieved with 4weeks of treatment following tightly controlled lateral hemisection injuries. Analyses also were completed using 35 cats with a range of hemisection magnitudes to assess relationships between treatment duration, lesion size and functional recovery. Results indicate that both 2 and 4weeks of treatment significantly increased the number of rubrospinal tract (RuST) neurons with axons below the lesion, but neither affected the number of corticospinal tract neurons. Similarly, both treatment periods also accelerated recovery of select motor tasks, which carries considerable importance with respect to human health care and rehabilitation. Four weeks of treatment promoted recovery beyond that seen with 2weeks in its significant impact on accuracy of movement critical for placement of the ipsilateral hindlimb onto small support surfaces during the most challenging locomotor tasks. Analyses, which extended to a larger group of cats with a range of lesion magnitudes, indicate that 4weeks of ch'abc treatment promoted earlier recovery as well as significantly greater targeting accuracy even in cats with larger lesions. Together, these results support the potential for ch'abc to promote anatomical and behavioral recovery and suggest that intraspinal treatment with ch'abc continues to enhance motor recovery and performance beyond the subacute injury period and diminishes the impact of lesion size.
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Wyart C, Knafo S. Sensorimotor Integration in the Spinal Cord, from Behaviors to Circuits: New Tools to Close the Loop? BIOLOGICAL AND MEDICAL PHYSICS, BIOMEDICAL ENGINEERING 2015. [DOI: 10.1007/978-3-319-12913-6_8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Cowley KC, MacNeil BJ, Chopek JW, Sutherland S, Schmidt BJ. Neurochemical excitation of thoracic propriospinal neurons improves hindlimb stepping in adult rats with spinal cord lesions. Exp Neurol 2014; 264:174-87. [PMID: 25527257 DOI: 10.1016/j.expneurol.2014.12.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2014] [Revised: 12/01/2014] [Accepted: 12/07/2014] [Indexed: 01/07/2023]
Abstract
Using an in vitro neonatal rat brainstem-spinal cord preparation, we previously showed that cervicothoracic propriospinal neurons contribute to descending transmission of the bulbospinal locomotor command signal, and neurochemical excitation of these neurons facilitates signal propagation. The present study examined the relevance of these observations to adult rats in vivo. The first aim was to determine the extent to which rats are able to spontaneously recover hindlimb locomotor function in the presence of staggered contralateral hemisections (left T2-4 and right T9-11) designed to abolish all long direct bulbospinal projections. The second aim was to determine whether neurochemical excitation of thoracic propriospinal neurons in such animals facilitates hindlimb stepping. In the absence of intrathecal drug injection, all animals (n=24) displayed some degree of hindlimb recovery ranging from weak ankle movements to brief periods of unsupported hindlimb stepping on the treadmill. The effect of boluses of neurochemicals delivered via an intrathecal catheter (tip placed midway between the rostral and caudal thoracic hemisections) was examined at post-lesion weeks 3, 6 and 9. Quipazine was particularly effective facilitating hindlimb stepping. Subsequent complete transection above the rostral (n=3) or caudal (n=2) hemisections at week 9 had no consistent effect on drug-free locomotor performance, but the facilitatory effect of drug injection decreased in 4/5 animals. Two animals underwent complete transection at T3 as the first and only surgery and implantation of two intrathecal catheters targeted to the mid-thoracic and lumbar regions, respectively. A similar facilitatory effect on stepping was observed in response to drugs administered via either catheter. The results indicate that partial spontaneous recovery of stepping occurs in adult rats after abolishing all long direct bulbospinal connections, in contrast to previous studies suggesting that hindlimb stepping after dual hemisections either does not occur or is observed only if the second hemisection surgery is delayed relative to the first. The results support the hypothesis that artificial modulation of propriospinal neuron excitability may facilitate recovery of motor function after spinal cord injury. However, whether this facilitation is due to enhanced transmission of a descending locomotor signal or is the result of excitation of thoracolumbar circuits independent of supraspinal influence, requires further study.
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Affiliation(s)
- Kristine C Cowley
- Department of Physiology and Pathophysiology, College of Medicine, Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, R3E 3J7, Canada
| | - Brian J MacNeil
- Department of Physical Therapy, College of Rehabilitation Sciences, Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, R3E 3J7, Canada
| | - Jeremy W Chopek
- Department of Physiology and Pathophysiology, College of Medicine, Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, R3E 3J7, Canada
| | - Scott Sutherland
- Department of Radiology, College of Medicine, Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, R3E 3J7, Canada
| | - Brian J Schmidt
- Department of Physiology and Pathophysiology, College of Medicine, Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, R3E 3J7, Canada; Department of Internal Medicine, Section of Neurology, College of Medicine, Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, R3E 3J7, Canada.
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Thibaudier Y, Frigon A. Spatiotemporal control of interlimb coordination during transverse split-belt locomotion with 1:1 or 2:1 coupling patterns in intact adult cats. J Neurophysiol 2014; 112:2006-18. [PMID: 25057143 DOI: 10.1152/jn.00236.2014] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Interlimb coordination must be flexible to adjust to an ever-changing environment. Here adjustments in interlimb coordination were quantified during tied-belt (equal speed of the fore- and hindlimbs) and transverse split-belt (unequal speed of the fore- and hindlimbs) locomotion in five intact adult cats. Cats performed tied-belt locomotion at 0.4 m/s and 0.8 m/s. For transverse split-belt locomotion, the forelimbs stepped at 0.4 m/s and 0.8 m/s while the hindlimbs stepped at 0.8 m/s (4F8H condition) and 0.4 m/s (8F4H condition), respectively. In the 8F4H condition, the forelimbs could take two steps within one hindlimb cycle, or a 2:1 forelimb-hindlimb relationship. The sequence of limbs contacting the ground and the duration of support periods were differentially modified if the forelimbs stepped faster or slower than the hindlimbs. During transverse split-belt locomotion, the hindlimbs performed longer strides when the forelimbs took shorter strides. In the 8F4H condition with a 2:1 forelimb-hindlimb relationship, phase and gap intervals for the first and second steps were found around certain values and were not randomly distributed, indicating that a new coupling pattern was established. However, temporal and spatial coordination indexes revealed that bilateral coordination between hindlimbs was less accurate and more variable with a 2:1 coupling pattern. Importantly, the animals did not stumble, indicating that spatial and temporal adjustments in interlimb coordination allowed the animals to maintain dynamic stability. The results provide a better understanding of the spatiotemporal adjustments that take place among the four limbs during locomotion when interlimb coordination is challenged.
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Affiliation(s)
- Yann Thibaudier
- Department of Physiology and Biophysics, Faculty of Medicine and Health Sciences, Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Alain Frigon
- Department of Physiology and Biophysics, Faculty of Medicine and Health Sciences, Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Quebec, Canada
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Silva NA, Sousa N, Reis RL, Salgado AJ. From basics to clinical: a comprehensive review on spinal cord injury. Prog Neurobiol 2013; 114:25-57. [PMID: 24269804 DOI: 10.1016/j.pneurobio.2013.11.002] [Citation(s) in RCA: 526] [Impact Index Per Article: 47.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Revised: 11/12/2013] [Accepted: 11/12/2013] [Indexed: 12/15/2022]
Abstract
Spinal cord injury (SCI) is a devastating neurological disorder that affects thousands of individuals each year. Over the past decades an enormous progress has been made in our understanding of the molecular and cellular events generated by SCI, providing insights into crucial mechanisms that contribute to tissue damage and regenerative failure of injured neurons. Current treatment options for SCI include the use of high dose methylprednisolone, surgical interventions to stabilize and decompress the spinal cord, and rehabilitative care. Nonetheless, SCI is still a harmful condition for which there is yet no cure. Cellular, molecular, rehabilitative training and combinatorial therapies have shown promising results in animal models. Nevertheless, work remains to be done to ascertain whether any of these therapies can safely improve patient's condition after human SCI. This review provides an extensive overview of SCI research, as well as its clinical component. It starts covering areas from physiology and anatomy of the spinal cord, neuropathology of the SCI, current clinical options, neuronal plasticity after SCI, animal models and techniques to assess recovery, focusing the subsequent discussion on a variety of promising neuroprotective, cell-based and combinatorial therapeutic approaches that have recently moved, or are close, to clinical testing.
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Affiliation(s)
- Nuno A Silva
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Nuno Sousa
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Rui L Reis
- ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal; 3B's Research Group - Biomaterials, Biodegradables and Biomimetics, University of Minho, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, AvePark, 4806-909 Caldas das Taipas, Guimarães, Portugal
| | - António J Salgado
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal.
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Sledge J, Graham WA, Westmoreland S, Sejdic E, Miller A, Hoggatt A, Nesathurai S. Spinal cord injury models in non human primates: are lesions created by sharp instruments relevant to human injuries? Med Hypotheses 2013; 81:747-8. [PMID: 23948598 DOI: 10.1016/j.mehy.2013.07.040] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Revised: 07/18/2013] [Accepted: 07/22/2013] [Indexed: 12/01/2022]
Abstract
The worldwide incidence of traumatic spinal cord injury (SCI) is approximated at 180,000 new cases per year. Experiments using nonhuman primates (NHP) are often used to replicate the human condition in order to advance the understanding of SCI and to assist in the development of new treatments. Experimental spinal cord lesions in NHP have been created by a number of methods including blunt trauma, epidural balloons, circumferential cuffs, and dropping a precision weight over the spinal cord. As well, experimental lesions have been created with sharp instruments after opening the dura mater. However, spinal cord lesions that are created with a sharp instrument in NHP experiments may not replicate the clinical and pathological features of human spinal cord injury. Researchers should recognize the challenges associated with making clinical inferences in human SCIs based on NHP experiments that created experimental lesions with a sharp surgical instrument.
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Affiliation(s)
- J Sledge
- Lafayette Bone and Joint Clinic, Lafayette, LA, USA
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Fouad K, Tse A. Adaptive changes in the injured spinal cord and their role in promoting functional recovery. Neurol Res 2013; 30:17-27. [DOI: 10.1179/016164107x251781] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Martinez M, Rossignol S. A dual spinal cord lesion paradigm to study spinal locomotor plasticity in the cat. Ann N Y Acad Sci 2013; 1279:127-34. [PMID: 23531010 DOI: 10.1111/j.1749-6632.2012.06823.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
After a complete spinal cord injury (SCI) at the lowest thoracic level (T13), adult cats trained to walk on a treadmill can recover hindlimb locomotion within 2-3 weeks, resulting from the activity of a spinal circuitry termed the central pattern generator (CPG). The role of this spinal circuitry in the recovery of locomotion after partial SCIs, when part of descending pathways can still access the CPG, is not yet fully understood. Using a dual spinal lesion paradigm (first hemisection at T10 followed three weeks after by a complete spinalization at T13), we showed that major changes occurred in this locomotor spinal circuitry. These plastic changes at the spinal cord level could participate in the recovery of locomotion after partial SCI. This short review describes the main findings of this paradigm in adult cats.
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Affiliation(s)
- Marina Martinez
- Department of Physiology, Université de Montréal, Montréal, Québec, Canada
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Rangasamy SB. Locomotor recovery after spinal cord hemisection/contusion injures in bonnet monkeys: footprint testing--a minireview. Synapse 2013; 67:427-53. [PMID: 23401170 DOI: 10.1002/syn.21645] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Accepted: 02/01/2013] [Indexed: 12/12/2022]
Abstract
Spinal cord injuries usually produce loss or impairment of sensory, motor and reflex function below the level of damage. In the absence of functional regeneration or manipulations that promote regeneration, spontaneous improvements in motor functions occur due to the activation of multiple compensatory mechanisms in animals and humans following the partial spinal cord injury. Many studies were performed on quantitative evaluation of locomotor recovery after induced spinal cord injury in animals using behavioral tests and scoring techniques. Although few studies on rodents have led to clinical trials, it would appear imperative to use nonhuman primates such as macaque monkeys in order to relate the research outcomes to recovery of functions in humans. In this review, we will discuss some of our research evidences concerning the degree of spontaneous recovery in bipedal locomotor functions of bonnet monkeys that underwent spinal cord hemisection/contusion lesions. To our knowledge, this is the first report to discuss on the extent of spontaneous recovery in bipedal locomotion of macaque monkeys through the application of footprint analyzing technique. In addition, the results obtained were compared with the published data on recovery of quadrupedal locomotion of spinally injured rodents. We propose that the mechanisms underlying spontaneous recovery of functions in spinal cord lesioned monkeys may be correlated to the mature function of spinal pattern generator for locomotion under the impact of residual descending and afferent connections. Moreover, based on analysis of motor functions observed in locomotion in these subjected monkeys, we understand that spinal automatism and development of responses by afferent stimuli from outside the cord could possibly contribute to recovery of paralyzed hindlimbs. This report also emphasizes the functional contribution of progressive strengthening of undamaged nerve fibers through a collateral sprouts/synaptic plasticity formed in partially lesioned cord of monkeys.
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Affiliation(s)
- Suresh Babu Rangasamy
- Department of Neurological Sciences, Rush University Medical Center, Chicago, Illinois, 60612, USA.
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López-Dolado E, Lucas-Osma AM, Collazos-Castro JE. Dynamic motor compensations with permanent, focal loss of forelimb force after cervical spinal cord injury. J Neurotrauma 2013; 30:191-210. [PMID: 23249275 PMCID: PMC3565556 DOI: 10.1089/neu.2012.2530] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Incomplete cervical lesion is the most common type of human spinal cord injury (SCI) and causes permanent paresis of arm muscles, a phenomenon still incompletely understood in physiopathological and neuroanatomical terms. We performed spinal cord hemisection in adult rats at the caudal part of the segment C6, just rostral to the bulk of triceps brachii motoneurons, and analyzed the forces and kinematics of locomotion up to 4 months postlesion to determine the nature of motor function loss and recovery. A dramatic (50%), immediate and permanent loss of extensor force occurred in the forelimb but not in the hind limb of the injured side, accompanied by elbow and wrist kinematic impairments and early adaptations of whole-body movements that initially compensated the balance but changed continuously over the follow-up period to allow effective locomotion. Overuse of both contralateral legs and ipsilateral hind leg was evidenced since 5 days postlesion. Ipsilateral foreleg deficits resulted mainly from interruption of axons that innervate the spinal cord segments caudal to the lesion, because chronic loss (about 35%) of synapses was detected at C7 while only 14% of triceps braquii motoneurons died, as assessed by synaptophysin immunohistochemistry and retrograde neural tracing, respectively. We also found a large pool of propriospinal neurons projecting from C2-C5 to C7 in normal rats, with topographical features similar to the propriospinal premotoneuronal system of cats and primates. Thus, concurrent axotomy at C6 of brain descending axons and cervical propriospinal axons likely hampered spontaneous recovery of the focal neurological impairments.
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Affiliation(s)
- Elisa López-Dolado
- Neural Repair Laboratory, Hospital Nacional de Parapléjicos, Toledo, Spain
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42
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Cervical response among ascending ventrolateral funiculus pathways of the neonatal rat. Brain Res 2013; 1491:136-46. [DOI: 10.1016/j.brainres.2012.11.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2012] [Revised: 10/02/2012] [Accepted: 11/04/2012] [Indexed: 12/28/2022]
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Effect of locomotor training in completely spinalized cats previously submitted to a spinal hemisection. J Neurosci 2012; 32:10961-70. [PMID: 22875930 DOI: 10.1523/jneurosci.1578-12.2012] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
After a spinal hemisection in cats, locomotor plasticity occurring at the spinal level can be revealed by performing, several weeks later, a complete spinalization below the first hemisection. Using this paradigm, we recently demonstrated that the hemisection induces durable changes in the symmetry of locomotor kinematics that persist after spinalization. Can this asymmetry be changed again in the spinal state by interventions such as treadmill locomotor training started within a few days after the spinalization? We performed, in 9 adult cats, a spinal hemisection at thoracic level 10 and then a complete spinalization at T13, 3 weeks later. Cats were not treadmill trained during the hemispinal period. After spinalization, 5 of 9 cats were not trained and served as control while 4 of 9 cats were trained on the treadmill for 20 min, 5 d a week for 3 weeks. Using detailed kinematic analyses, we showed that, without training, the asymmetrical state of locomotion induced by the hemisection was retained durably after the subsequent spinalization. By contrast, training cats after spinalization induced a reversal of the left/right asymmetries, suggesting that new plastic changes occurred within the spinal cord through locomotor training. Moreover, training was shown to improve the kinematic parameters and the performance of the hindlimb on the previously hemisected side. These results indicate that spinal locomotor circuits, previously modified by past experience such as required for adaptation to the hemisection, can remarkably respond to subsequent locomotor training and improve bilateral locomotor kinematics, clearly showing the benefits of locomotor training in the spinal state.
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Hansen CN, Linklater W, Santiago R, Fisher LC, Moran S, Buford JA, Michele Basso D. Characterization of recovered walking patterns and motor control after contusive spinal cord injury in rats. Brain Behav 2012; 2:541-52. [PMID: 23139900 PMCID: PMC3489807 DOI: 10.1002/brb3.71] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Revised: 05/10/2012] [Accepted: 05/14/2012] [Indexed: 11/25/2022] Open
Abstract
Currently, complete recovery is unattainable for most individuals with spinal cord injury (SCI). Instead, recovery is typically accompanied by persistent sensory and motor deficits. Restoration of preinjury function will likely depend on improving plasticity and integration of these impaired systems. Eccentric muscle actions require precise integration of sensorimotor signals and are predominant during the yield (E2) phase of locomotion. Motor neuron activation and control during eccentric contractions is impaired across a number of central nervous system (CNS) disorders, but remains unexamined after SCI. Therefore, we characterized locomotor recovery after contusive SCI using hindlimb (HL) kinematics and electromyographic (EMG) recordings with specific consideration of eccentric phases of treadmill (TM) walking. Deficits in E2 and a caudal shift of locomotor subphases persisted throughout the 3-week recovery period. EMG records showed notable deficits in the semitendinosus (ST) during yield. Unlike other HL muscles, recruitment of ST changed with recovery. At 7 days, the typical dual-burst pattern of ST was lost and the second burst (ST2) was indistinct. By 21 days, the dual-burst pattern returned, but latencies remained impaired. We show that ST2 burst duration is highly predictive of open field Basso, Beattie, Bresnahan (BBB) scores. Moreover, we found that simple changes in locomotor specificity which enhance eccentric actions result in new motor patterns after SCI. Our findings identify a caudal shift in stepping kinematics, irregularities in E2, and aberrant ST2 bursting as markers of incomplete recovery. These residual impairments may provide opportunities for targeted rehabilitation.
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Affiliation(s)
- Christopher N Hansen
- Neuroscience Graduate Studies Program, The Ohio State University Columbus, Ohio ; Center for Brain and Spinal Cord Repair (CBSCR), The Ohio State University Columbus, Ohio
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Côté MP, Detloff MR, Wade RE, Lemay MA, Houlé JD. Plasticity in ascending long propriospinal and descending supraspinal pathways in chronic cervical spinal cord injured rats. Front Physiol 2012; 3:330. [PMID: 22934078 PMCID: PMC3429098 DOI: 10.3389/fphys.2012.00330] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Accepted: 07/28/2012] [Indexed: 11/29/2022] Open
Abstract
The high clinical relevance of models of incomplete cervical spinal cord injury (SCI) creates a need to address the spontaneous neuroplasticity that underlies changes in functional activity that occur over time after SCI. There is accumulating evidence supporting long projecting propriospinal neurons as suitable targets for therapeutic intervention after SCI, but focus has remained primarily oriented toward study of descending pathways. Long ascending axons from propriospinal neurons at lower thoracic and lumbar levels that form inter-enlargement pathways are involved in forelimb-hindlimb coordination during locomotion and are capable of modulating cervical motor output. We used non-invasive magnetic stimulation to assess how a unilateral cervical (C5) spinal contusion might affect transmission in intact, long ascending propriospinal pathways, and influence spinal cord plasticity. Our results show that transmission is facilitated in this pathway on the ipsilesional side as early as 1 week post-SCI. We also probed for descending magnetic motor evoked potentials (MMEPs) and found them absent or greatly reduced on the ipsilesional side as expected. The frequency-dependent depression (FDD) of the H-reflex recorded from the forelimb triceps brachii was bilaterally decreased although Hmax/Mmax was increased only on the ipsilesional side. Behaviorally, stepping recovered, but there were deficits in forelimb–hindlimb coordination as detected by BBB and CatWalk measures. Importantly, epicenter sparing correlated to the amplitude of the MMEPs and locomotor recovery but it was not significantly associated with the inter-enlargement or segmental H-reflex. In summary, our results indicate that complex plasticity occurs after a C5 hemicontusion injury, leading to differential changes in ascending vs. descending pathways, ipsi- vs. contralesional sides even though the lesion was unilateral as well as cervical vs. lumbar local spinal networks.
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Affiliation(s)
- Marie-Pascale Côté
- Department of Neurobiology and Anatomy, Drexel University College of Medicine Philadelphia, PA, USA
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Martinez M, Delivet-Mongrain H, Leblond H, Rossignol S. Incomplete spinal cord injury promotes durable functional changes within the spinal locomotor circuitry. J Neurophysiol 2012; 108:124-34. [PMID: 22490556 DOI: 10.1152/jn.00073.2012] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
While walking in a straight path, changes in speed result mainly from adjustments in the duration of the stance phase while the swing phase remains relatively invariant, a basic feature of the spinal central pattern generator (CPG). To produce a broad range of locomotor behaviors, the CPG has to integrate modulatory inputs from the brain and the periphery and alter these swing/stance characteristics. In the present work we raise the issue as to whether the CPG can adapt or reorganize in response to a chronic change of supraspinal inputs, as is the case after spinal cord injury (SCI). Kinematic data obtained from six adult cats walking at different treadmill speeds were collected to calculate the cycle and subphase duration at different stages after a first spinal hemisection at T(10) and after a subsequent complete SCI at T(13) respectively aimed at disconnecting unilaterally and then totally the spinal cord from its supraspinal inputs. The results show, first, that the neural control of locomotion is flexible and responsive to a partial or total loss of supraspinal inputs. Second, we demonstrate that a hemisection induces durable plastic changes within the spinal locomotor circuitry below the lesion. In addition, this study gives new insights into the organization of the spinal CPG for locomotion such that phases of the step cycle (swing, stance) can be independently regulated for adapting to speed and also that the CPGs controlling the left and right hindlimbs can, up to a point, be regulated independently.
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Affiliation(s)
- Marina Martinez
- Groupe de Recherche sur le Système Nerveux Central (FRSQ), Department of Physiology, Université de Montréal, Montreal, Quebec, Canada
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Suresh Babu R, Sunandhini RL, Sridevi D, Periasamy P, Namasivayam A. Locomotor behavior of bonnet monkeys after spinal contusion injury: footprint study. Synapse 2012; 66:509-21. [PMID: 22237918 DOI: 10.1002/syn.21537] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2011] [Accepted: 01/04/2012] [Indexed: 11/11/2022]
Abstract
Analysis of gait functions following spinal cord injury has been widely studied in rats, mice but limited in primates. This investigation was performed to quantitatively analyze the degree of functional recovery in bipedal locomotion in bonnet monkeys after induced spinal cord contusion. The degree of locomotor recovery was examined by measuring four gait variables, viz., tip of opposite foot (TOF), print-length (PL), toe-spread (TS), and intermediary toe-spread (IT) from the recorded hindlimb prints of monkeys using ink and paper technique. Contusion was induced in spinal cord at T12-L1 level in anaesthetized monkeys by using the Allen's weight drop technique. Postoperatively, all spinal contused animals initially showed a significant decrease in TOF, which then gradually increased for longer duration and attained the near normal values by the sixth month. On the other hand, PL, TS, and IT variables in hindlimb prints of contused animals were found to dramatically increase initially and then slowly decrease subsequently. Later there was a recovery to insignificant levels which differed from the corresponding preoperative values by the fifth month. The observations of this study suggest that the functional contributions of the spared fibers, especially in ventral and ventrolateral funiculi, through collateral sprouts or synaptic plasticity that were formed in the contused spinal cord may be responsible for substantial recovery of hindlimb movements. Moreover, based on analysis of footprint variables observed in locomotion in these subjected monkeys, we understand that spinal automatism and development of responses by afferent stimuli from outside the cord could possibly contribute to recovery of the paralyzed hindlimbs.
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Affiliation(s)
- R Suresh Babu
- Department of Cellular Biology and Anatomy, Georgia Health Sciences University, Augusta, Georgia 30912, USA.
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Alluin O, Karimi-Abdolrezaee S, Delivet-Mongrain H, Leblond H, Fehlings MG, Rossignol S. Kinematic study of locomotor recovery after spinal cord clip compression injury in rats. J Neurotrauma 2011; 28:1963-81. [PMID: 21770755 DOI: 10.1089/neu.2011.1840] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
After spinal cord injury (SCI), precise assessment of motor recovery is essential to evaluate the outcome of new therapeutic approaches. Very little is known on the recovery of kinematic parameters after clinically-relevant severe compressive/contusive incomplete spinal cord lesions in experimental animal models. In the present study we evaluated the time-course of kinematic parameters during a 6-week period in rats walking on a treadmill after a severe thoracic clip compression SCI. The effect of daily treadmill training was also assessed. During the recovery period, a significant amount of spontaneous locomotor recovery occurred in 80% of the rats with a return of well-defined locomotor hindlimb pattern, regular plantar stepping, toe clearance and homologous hindlimb coupling. However, substantial residual abnormalities persisted up to 6 weeks after SCI including postural deficits, a bias of the hindlimb locomotor cycle toward the back of the animals with overextension at the swing/stance transition, loss of lateral balance and impairment of weight bearing. Although rats never recovered the antero-posterior (i.e. homolateral) coupling, different levels of decoupling between the fore and hindlimbs were measured. We also showed that treadmill training increased the swing duration variability during locomotion suggesting an activity-dependent compensatory mechanism of the motor control system. However, no effect of training was observed on the main locomotor parameters probably due to a ceiling effect of self-training in the cage. These findings constitute a kinematic baseline of locomotor recovery after clinically relevant SCI in rats and should be taken into account when evaluating various therapeutic strategies aimed at improving locomotor function.
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Affiliation(s)
- Olivier Alluin
- Multidisciplinary Team in Locomotor Rehabilitation of the Canadian Institutes of Health Research and Groupe de Recherche sur le Système Nerveux Central of the Fonds de la Recherche en Santé du Québec, Canada Research Chair on the Spinal Cord, Department of Physiology, University of Montreal, Montreal, Quebec, Canada
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Rossignol S, Frigon A. Recovery of Locomotion After Spinal Cord Injury: Some Facts and Mechanisms. Annu Rev Neurosci 2011; 34:413-40. [PMID: 21469957 DOI: 10.1146/annurev-neuro-061010-113746] [Citation(s) in RCA: 222] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Serge Rossignol
- Groupe de Recherche sur le Système Nerveux Central (FRSQ), Department of Physiology, and Multidisciplinary Team in Locomotor Rehabilitation of the Canadian Institutes for Health Research, Université de Montréal, Montreal H3C 3J7, Canada;
| | - Alain Frigon
- Groupe de Recherche sur le Système Nerveux Central (FRSQ), Department of Physiology, and Multidisciplinary Team in Locomotor Rehabilitation of the Canadian Institutes for Health Research, Université de Montréal, Montreal H3C 3J7, Canada;
- Department of Physiology and Biophysics, Université de Sherbrooke, Sherbrooke JIH 5N4, Canada
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Martinez M, Delivet-Mongrain H, Leblond H, Rossignol S. Recovery of hindlimb locomotion after incomplete spinal cord injury in the cat involves spontaneous compensatory changes within the spinal locomotor circuitry. J Neurophysiol 2011; 106:1969-84. [PMID: 21775717 DOI: 10.1152/jn.00368.2011] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
After incomplete spinal cord injury (SCI), compensatory changes occur throughout the whole neuraxis, including the spinal cord below the lesion, as suggested by previous experiments using a dual SCI paradigm. Indeed, cats submitted to a lateral spinal hemisection at T10-T11 and trained on a treadmill for 3-14 wk re-expressed bilateral hindlimb locomotion as soon as 24 h after spinalization, a process that normally takes 2-3 wk when a complete spinalization is performed without a prior hemisection. In this study, we wanted to ascertain whether similar effects could occur spontaneously without training between the two SCIs and within a short period of 3 wk in 11 cats. One day after the complete spinalization, 9 of the 11 cats were able to re-express hindlimb locomotion either bilaterally (n = 6) or unilaterally on the side of the previous hemisection (n = 3). In these 9 cats, the hindlimb on the side of the previous hemisection (left hindlimb) performed better than the right side in contrast to that observed during the hemispinal period itself. Cats re-expressing the best bilateral hindlimb locomotion after spinalization had the largest initial hemilesion and the most prominent locomotor deficits after this first SCI. These results provide evidence that 1) marked reorganization of the spinal locomotor circuitry can occur without specific locomotor training and within a short period of 3 wk; 2) the spinal cord can reorganize in a more or less symmetrical way; and 3) the ability to walk after spinalization depends on the degree of deficits and adaptation observed in the hemispinal period.
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Affiliation(s)
- Marina Martinez
- Groupe de Recherche sur le Système Nerveux Central, Faculté de Médecine, Université de Montréal, Département de Physiologie, Pavillon Paul-G.-Desmarais, 2960 Chemin de la Tour, Montréal, QC, Canada
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