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Brown BL, Anil N, States G, Whittemore SR, Magnuson DSK. Long ascending propriospinal neurons are heterogenous and subject to spinal cord injury induced anatomic plasticity. Exp Neurol 2024; 373:114631. [PMID: 38070723 PMCID: PMC10922963 DOI: 10.1016/j.expneurol.2023.114631] [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: 09/08/2023] [Revised: 11/15/2023] [Accepted: 11/29/2023] [Indexed: 12/21/2023]
Abstract
Long ascending propriospinal neurons (LAPNs) are a subset of spinal interneurons that provide direct connectivity between distant spinal segments. Here, we focus specifically on an anatomically defined population of "inter-enlargement" LAPNs with cell bodies at L2/3 and terminals at C5/6. Previous studies showed that silencing LAPNs in awake and freely moving animals disrupted interlimb coordination of the hindlimbs, forelimbs, and heterolateral limb pairs. Surprisingly, despite a proportion of LAPNs being anatomically intact post- spinal cord injury (SCI), silencing them improved locomotor function but only influenced coordination of the hindlimb pair. Given the functional significance of LAPNs pre- and post-SCI, we characterized their anatomy and SCI-induced anatomical plasticity. This detailed anatomical characterization revealed three morphologically distinct subsets of LAPNs that differ in soma size, neurite complexity and/or neurite orientation. Following a mild thoracic contusive SCI there was a marked shift in neurite orientation in two of the LAPN subsets to a more dorsoventral orientation, and collateral densities decreased in the cervical enlargement but increased just caudal to the injury epicenter. These post-SCI anatomical changes potentially reflect maladaptive plasticity and an effort to establish new functional inputs from sensory afferents that sprout post-SCI to achieve circuitry homeostasis.
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Affiliation(s)
- Brandon L Brown
- Interdisciplinary Program in Translational Neuroscience, University of Louisville, Louisville, KY, United States; Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, KY, United States; Department of Anatomical Sciences and Neurobiology, School of Medicine, University of Louisville, Louisville, KY, United States
| | - Neha Anil
- Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, KY, United States; Department of Bioengineering, J.B. Speed School of Engineering, University of Louisville, Louisville, KY, United States
| | - Gregory States
- Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, KY, United States; Department of Anatomical Sciences and Neurobiology, School of Medicine, University of Louisville, Louisville, KY, United States
| | - Scott R Whittemore
- Interdisciplinary Program in Translational Neuroscience, University of Louisville, Louisville, KY, United States; Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, KY, United States; Department of Anatomical Sciences and Neurobiology, School of Medicine, University of Louisville, Louisville, KY, United States; Department of Neurological Surgery, School of Medicine, University of Louisville, Louisville, KY, United States
| | - David S K Magnuson
- Interdisciplinary Program in Translational Neuroscience, University of Louisville, Louisville, KY, United States; Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, KY, United States; Department of Anatomical Sciences and Neurobiology, School of Medicine, University of Louisville, Louisville, KY, United States; Department of Bioengineering, J.B. Speed School of Engineering, University of Louisville, Louisville, KY, United States; Department of Neurological Surgery, School of Medicine, University of Louisville, Louisville, KY, United States.
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2
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Grau JW, Hudson KE, Johnston DT, Partipilo SR. Updating perspectives on spinal cord function: motor coordination, timing, relational processing, and memory below the brain. Front Syst Neurosci 2024; 18:1184597. [PMID: 38444825 PMCID: PMC10912355 DOI: 10.3389/fnsys.2024.1184597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2023] [Accepted: 01/29/2024] [Indexed: 03/07/2024] Open
Abstract
Those studying neural systems within the brain have historically assumed that lower-level processes in the spinal cord act in a mechanical manner, to relay afferent signals and execute motor commands. From this view, abstracting temporal and environmental relations is the province of the brain. Here we review work conducted over the last 50 years that challenges this perspective, demonstrating that mechanisms within the spinal cord can organize coordinated behavior (stepping), induce a lasting change in how pain (nociceptive) signals are processed, abstract stimulus-stimulus (Pavlovian) and response-outcome (instrumental) relations, and infer whether stimuli occur in a random or regular manner. The mechanisms that underlie these processes depend upon signal pathways (e.g., NMDA receptor mediated plasticity) analogous to those implicated in brain-dependent learning and memory. New data show that spinal cord injury (SCI) can enable plasticity within the spinal cord by reducing the inhibitory effect of GABA. It is suggested that the signals relayed to the brain may contain information about environmental relations and that spinal cord systems can coordinate action in response to descending signals from the brain. We further suggest that the study of stimulus processing, learning, memory, and cognitive-like processing in the spinal cord can inform our views of brain function, providing an attractive model system. Most importantly, the work has revealed new avenues of treatment for those that have suffered a SCI.
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Affiliation(s)
- James W. Grau
- Lab of Dr. James Grau, Department of Psychological and Brain Sciences, Cellular and Behavioral Neuroscience, Texas A&M University, College Station, TX, United States
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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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4
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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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Danner SM, Shepard CT, Hainline C, Shevtsova NA, Rybak IA, Magnuson DSK. Spinal control of locomotion before and after spinal cord injury. Exp Neurol 2023; 368:114496. [PMID: 37499972 PMCID: PMC10529867 DOI: 10.1016/j.expneurol.2023.114496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2023] [Revised: 07/10/2023] [Accepted: 07/23/2023] [Indexed: 07/29/2023]
Abstract
Thoracic spinal cord injury affects long propriospinal neurons that interconnect the cervical and lumbar enlargements. These neurons are crucial for coordinating forelimb and hindlimb locomotor movements in a speed-dependent manner. However, recovery from spinal cord injury is usually studied over a very limited range of speeds that may not fully expose circuitry dysfunction. To overcome this limitation, we investigated overground locomotion in rats trained to move over an extended distance with a wide range of speeds both pre-injury and after recovery from thoracic hemisection or contusion injuries. In this experimental context, intact rats expressed a speed-dependent continuum of alternating (walk and trot) and non-alternating (canter, gallop, half-bound gallop, and bound) gaits. After a lateral hemisection injury, rats recovered the ability to locomote over a wide range of speeds but lost the ability to use the highest-speed gaits (half-bound gallop and bound) and predominantly used the limb contralateral to the injury as lead during canter and gallop. A moderate contusion injury caused a greater reduction in maximal speed, loss of all non-alternating gaits, and emergence of novel alternating gaits. These changes resulted from weak fore-hind coupling together with appropriate control of left-right alternation. After hemisection, animals expressed a subset of intact gaits with appropriate interlimb coordination even on the side of the injury, where the long propriospinal connections were severed. These observations highlight how investigating locomotion over the full range of speeds can reveal otherwise hidden aspects of spinal locomotor control and post-injury recovery.
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Affiliation(s)
- Simon M Danner
- Department of Neurobiology and Anatomy, College of Medicine, Drexel University, Philadelphia, PA, USA.
| | - Courtney T Shepard
- Interdisciplinary Program in Translational Neuroscience, University of Louisville School of Medicine, Health Sciences Campus, Louisville, KY, USA
| | - Casey Hainline
- Speed School of Engineering, University of Louisville School of Medicine, Health Sciences Campus, Louisville, KY, USA
| | - Natalia A Shevtsova
- Department of Neurobiology and Anatomy, College of Medicine, Drexel University, Philadelphia, PA, USA
| | - Ilya A Rybak
- Department of Neurobiology and Anatomy, College of Medicine, Drexel University, Philadelphia, PA, USA
| | - David S K Magnuson
- Department of Neurological Surgery, University of Louisville School of Medicine, Health Sciences Campus, Louisville, KY, USA; Kentucky Spinal Cord Injury Research Center, University of Louisville School of Medicine, Health Sciences Campus, Louisville, KY, USA
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Pocratsky AM, Nascimento F, Özyurt MG, White IJ, Sullivan R, O’Callaghan BJ, Smith CC, Surana S, Beato M, Brownstone RM. Pathophysiology of Dyt1- Tor1a dystonia in mice is mediated by spinal neural circuit dysfunction. Sci Transl Med 2023; 15:eadg3904. [PMID: 37134150 PMCID: PMC7614689 DOI: 10.1126/scitranslmed.adg3904] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Accepted: 04/14/2023] [Indexed: 05/05/2023]
Abstract
Dystonia, a neurological disorder defined by abnormal postures and disorganized movements, is considered to be a neural circuit disorder with dysfunction arising within and between multiple brain regions. Given that spinal neural circuits constitute the final pathway for motor control, we sought to determine their contribution to this movement disorder. Focusing on the most common inherited form of dystonia in humans, DYT1-TOR1A, we generated a conditional knockout of the torsin family 1 member A (Tor1a) gene in the mouse spinal cord and dorsal root ganglia (DRG). We found that these mice recapitulated the phenotype of the human condition, developing early-onset generalized torsional dystonia. Motor signs emerged early in the mouse hindlimbs before spreading caudo-rostrally to affect the pelvis, trunk, and forelimbs throughout postnatal maturation. Physiologically, these mice bore the hallmark features of dystonia, including spontaneous contractions at rest and excessive and disorganized contractions, including cocontractions of antagonist muscle groups, during voluntary movements. Spontaneous activity, disorganized motor output, and impaired monosynaptic reflexes, all signs of human dystonia, were recorded from isolated mouse spinal cords from these conditional knockout mice. All components of the monosynaptic reflex arc were affected, including motor neurons. Given that confining the Tor1a conditional knockout to DRG did not lead to early-onset dystonia, we conclude that the pathophysiological substrate of this mouse model of dystonia lies in spinal neural circuits. Together, these data provide new insights into our current understanding of dystonia pathophysiology.
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Affiliation(s)
- Amanda M. Pocratsky
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London; London, WC1N 3BG, UK
| | - Filipe Nascimento
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London; London, WC1N 3BG, UK
| | - M. Görkem Özyurt
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London; London, WC1N 3BG, UK
| | - Ian J. White
- Laboratory for Molecular Cell Biology, University College London; London, WC1E 6BT, UK
| | - Roisin Sullivan
- Department of Molecular Neuroscience, UCL Queen Square Institute of Neurology, University College London; London, WC1N 3BG, UK
| | - Benjamin J. O’Callaghan
- Department of Molecular Neuroscience, UCL Queen Square Institute of Neurology, University College London; London, WC1N 3BG, UK
| | - Calvin C. Smith
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London; London, WC1N 3BG, UK
| | - Sunaina Surana
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London; London, WC1N 3BG, UK
- UK Dementia Research Institute, University College London; London, WC1E 6BT, UK
| | - Marco Beato
- Department of Neuroscience, Physiology, and Pharmacology, University College London; London, WC1E 6BT, UK
| | - Robert M. Brownstone
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London; London, WC1N 3BG, UK
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7
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Danner SM, Shepard CT, Hainline C, Shevtsova NA, Rybak IA, Magnuson DS. Spinal control of locomotion before and after spinal cord injury. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.22.533794. [PMID: 36993490 PMCID: PMC10055332 DOI: 10.1101/2023.03.22.533794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 04/13/2023]
Abstract
Thoracic spinal cord injury affects long propriospinal neurons that interconnect the cervical and lumbar enlargements. These neurons are crucial for coordinating forelimb and hindlimb movements in a speed-dependent manner. At the same time, recovery from spinal cord injury is usually studied over a very limited range of speeds. To overcome this limitation, we investigated overground locomotion in rats over the full range of speeds pre-injury and after recovery from thoracic hemisection or contusion injuries. Intact rats expressed a speed-dependent continuum of alternating (walk and trot) and non-alternating (canter, gallop, half-bound gallop, and bound) gaits. After a lateral hemisection injury, rats recovered the ability to locomote over a wide range of speeds but lost the ability to move using the highest-speed gaits (half-bound gallop and bound) and predominantly used the limb contralateral to injury as lead during canter and gallop. A moderate contusion injury resulted in a greater reduction in maximal speed, loss of non-alternating gaits, and emergence of novel alternating gaits. Analysis of the gait structure in phase space and the variability of limb coupling suggests substantial reorganization of intraspinal pathways mediating interlimb coordination following recovery of locomotion after lateral hemisection or midline contusion injuries. This reorganization appears as an increased reliance on local enlargement circuitry and suggests that speed-dependent gait changes in the forelimbs rely on ascending information from the lumbar circuitry that is impaired post-injury. These observations highlight how investigating the full repertoire of locomotor speeds can reveal otherwise hidden aspects of spinal circuitry and post-injury reorganization.
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Affiliation(s)
- Simon M. Danner
- Department of Neurobiology and Anatomy, College of Medicine, Drexel University, Philadelphia, PA, USA
- For correspondence:
| | - Courtney T. Shepard
- Interdisciplinary Program in Translational Neuroscience, University of Louisville School of Medicine, Health Sciences Campus, Louisville, Kentucky, USA
| | - Casey Hainline
- Speed School of Engineering, University of Louisville School of Medicine, Health Sciences Campus, Louisville, Kentucky, USA
| | - Natalia A. Shevtsova
- Department of Neurobiology and Anatomy, College of Medicine, Drexel University, Philadelphia, PA, USA
| | - Ilya A. Rybak
- Department of Neurobiology and Anatomy, College of Medicine, Drexel University, Philadelphia, PA, USA
| | - David S.K. Magnuson
- Department of Neurological Surgery, University of Louisville School of Medicine, Health Sciences Campus, Louisville, Kentucky, USA
- Kentucky Spinal Cord Injury Research Center, University of Louisville School of Medicine, Health Sciences Campus, Louisville, Kentucky, USA
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Hayashi M, Gullo M, Senturk G, Di Costanzo S, Nagasaki SC, Kageyama R, Imayoshi I, Goulding M, Pfaff SL, Gatto G. A spinal synergy of excitatory and inhibitory neurons coordinates ipsilateral body movements. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.21.533603. [PMID: 36993220 PMCID: PMC10055247 DOI: 10.1101/2023.03.21.533603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/31/2023]
Abstract
Innate and goal-directed movements require a high-degree of trunk and appendicular muscle coordination to preserve body stability while ensuring the correct execution of the motor action. The spinal neural circuits underlying motor execution and postural stability are finely modulated by propriospinal, sensory and descending feedback, yet how distinct spinal neuron populations cooperate to control body stability and limb coordination remains unclear. Here, we identified a spinal microcircuit composed of V2 lineage-derived excitatory (V2a) and inhibitory (V2b) neurons that together coordinate ipsilateral body movements during locomotion. Inactivation of the entire V2 neuron lineage does not impair intralimb coordination but destabilizes body balance and ipsilateral limb coupling, causing mice to adopt a compensatory festinating gait and be unable to execute skilled locomotor tasks. Taken together our data suggest that during locomotion the excitatory V2a and inhibitory V2b neurons act antagonistically to control intralimb coordination, and synergistically to coordinate forelimb and hindlimb movements. Thus, we suggest a new circuit architecture, by which neurons with distinct neurotransmitter identities employ a dual-mode of operation, exerting either synergistic or opposing functions to control different facets of the same motor behavior.
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Affiliation(s)
- Marito Hayashi
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
- Howard Hughes Medical Institute, Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Miriam Gullo
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Gokhan Senturk
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
- Biological Sciences Graduate Program, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92037, USA
| | - Stefania Di Costanzo
- Biological Sciences Graduate Program, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92037, USA
- Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Shinji C. Nagasaki
- Research Center for Dynamic Living Systems, Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan
- Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto 606-8507, Japan
| | - Ryoichiro Kageyama
- Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto 606-8507, Japan
- RIKEN Center for Brain Science, Wako 351-0198, Japan
| | - Itaru Imayoshi
- Research Center for Dynamic Living Systems, Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan
- Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto 606-8507, Japan
| | - Martyn Goulding
- Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Samuel L. Pfaff
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Graziana Gatto
- Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
- Neurology Department, University Hospital of Cologne, Cologne, 50937, Germany
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9
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Janssen P, Isa T, Lanciego J, Leech K, Logothetis N, Poo MM, Mitchell AS. Visualizing advances in the future of primate neuroscience research. CURRENT RESEARCH IN NEUROBIOLOGY 2022; 4:100064. [PMID: 36582401 PMCID: PMC9792703 DOI: 10.1016/j.crneur.2022.100064] [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: 02/17/2022] [Revised: 09/30/2022] [Accepted: 11/24/2022] [Indexed: 12/15/2022] Open
Abstract
Future neuroscience and biomedical projects involving non-human primates (NHPs) remain essential in our endeavors to understand the complexities and functioning of the mammalian central nervous system. In so doing, the NHP neuroscience researcher must be allowed to incorporate state-of-the-art technologies, including the use of novel viral vectors, gene therapy and transgenic approaches to answer continuing and emerging research questions that can only be addressed in NHP research models. This perspective piece captures these emerging technologies and some specific research questions they can address. At the same time, we highlight some current caveats to global NHP research and collaborations including the lack of common ethical and regulatory frameworks for NHP research, the limitations involving animal transportation and exports, and the ongoing influence of activist groups opposed to NHP research.
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Affiliation(s)
- Peter Janssen
- Laboratory for Neuro- and Psychophysiology, KU Leuven, Belgium
| | - Tadashi Isa
- Graduate School of Medicine, Kyoto University, Japan
| | - Jose Lanciego
- Department Neurosciences, Center for Applied Medical Research (CIMA), University of Navarra, CiberNed., Pamplona, Spain
| | - Kirk Leech
- European Animal Research Association, United Kingdom
| | - Nikos Logothetis
- International Center for Primate Brain Research, Shanghai, China
| | - Mu-Ming Poo
- International Center for Primate Brain Research, Shanghai, China
| | - Anna S. Mitchell
- School of Psychology, Speech and Hearing, University of Canterbury, Christchurch, New Zealand,Department of Experimental Psychology, University of Oxford, United Kingdom,Corresponding author. School of Psychology, Speech and Hearing, University of Canterbury, Christchurch, New Zealand.
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Orem BC, Morehouse JR, Ames S, Burke DA, Magnuson DS, Stirling DP. Direct Ryanodine Receptor-2 Knockout in Primary Afferent Fibers Modestly Affects Neurological Recovery after Contusive Spinal Cord Injury. Neurotrauma Rep 2022; 3:433-446. [PMID: 36337076 PMCID: PMC9622210 DOI: 10.1089/neur.2022.0044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Neuronal ryanodine receptors (RyR) release calcium from internal stores and play a key role in synaptic plasticity, learning, and memory. Dysregulation of RyR function contributes to neurodegeneration and negatively impacts neurological recovery after spinal cord injury (SCI). However, the individual role of RyR isoforms and the underlying mechanisms remain poorly understood. To determine whether RyR2 plays a direct role in axonal fate and functional recovery after SCI, we bred Advillin-Cre: tdTomato (Ai9) reporter mice with "floxed" RyR2 mice to directly knock out (KO) RyR2 function in dorsal root ganglion neurons and their spinal projections. Adult 6- to 8-week-old RyR2KO and littermate controls were subjected to a contusive SCI and their dorsal column axons were imaged in vivo using two-photon excitation microscopy. We found that direct RyR2KO in dorsal column primary afferents did not significantly alter secondary axonal degeneration after SCI. We next assessed behavioral recovery after SCI and found that direct RyR2KO in primary afferents worsened open-field locomotor scores (Basso Mouse Scale subscore) compared to littermate controls. However, both TreadScan™ gait analysis and overground kinematic gait analysis tests revealed subtle, but no fundamental, differences in gait patterns between the two groups after SCI. Subsequent removal of spared afferent fibers using a dorsal column crush revealed similar outcomes in both groups. Analysis of primary afferents at the lumbar (L3-L5) level similarly revealed no noticeable differences between groups. Together, our results support a modest contribution of dorsal column primary afferent RyR2 in neurological recovery after SCI.
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Affiliation(s)
- Ben C. Orem
- Kentucky Spinal Cord Injury Research Center, University of Louisville, School of Medicine, Louisville, Kentucky, USA.,Department of Anatomical Sciences and Neurobiology, University of Louisville, School of Medicine, Louisville, Kentucky, USA
| | - Johnny R. Morehouse
- Kentucky Spinal Cord Injury Research Center, University of Louisville, School of Medicine, Louisville, Kentucky, USA
| | - Spencer Ames
- Kentucky Spinal Cord Injury Research Center, University of Louisville, School of Medicine, Louisville, Kentucky, USA
| | - Darlene A. Burke
- Kentucky Spinal Cord Injury Research Center, University of Louisville, School of Medicine, Louisville, Kentucky, USA
| | - David S.K. Magnuson
- Kentucky Spinal Cord Injury Research Center, University of Louisville, School of Medicine, Louisville, Kentucky, USA.,Department of Neurological Surgery, University of Louisville, School of Medicine, Louisville, Kentucky, USA.,Department of Anatomical Sciences and Neurobiology, University of Louisville, School of Medicine, Louisville, Kentucky, USA
| | - David P. Stirling
- Kentucky Spinal Cord Injury Research Center, University of Louisville, School of Medicine, Louisville, Kentucky, USA.,Department of Neurological Surgery, University of Louisville, School of Medicine, Louisville, Kentucky, USA.,Department of Anatomical Sciences and Neurobiology, University of Louisville, School of Medicine, Louisville, Kentucky, USA.,Department of Microbiology and Immunology, University of Louisville, School of Medicine, Louisville, Kentucky, USA.,*Address correspondence to: David P. Stirling, PhD, Departments of Neurological Surgery, Microbiology and Immunology, and Anatomical Sciences and Neurobiology, KY Spinal Cord Injury Research Center, University of Louisville, 511 South Floyd Street, MDR Building, Room 608, Louisville, KY 40202, USA.
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11
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Grau JW, Hudson KE, Tarbet MM, Strain MM. Behavioral studies of spinal conditioning: The spinal cord is smarter than you think it is. JOURNAL OF EXPERIMENTAL PSYCHOLOGY. ANIMAL LEARNING AND COGNITION 2022; 48:435-457. [PMID: 35901417 PMCID: PMC10391333 DOI: 10.1037/xan0000332] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In 1988 Robert Rescorla published an article in the Annual Review of Neuroscience that addressed the circumstances under which learning occurs, some key methodological issues, and what constitutes an example of learning. The article has inspired a generation of neuroscientists, opening the door to a wider range of learning phenomena. After reviewing the historical context for his article, its key points are briefly reviewed. The perspective outlined enabled the study of learning in simpler preparations, such as the spinal cord. The period after 1988 revealed that pain (nociceptive) stimuli can induce a lasting sensitization of spinal cord circuits, laying down a kind of memory mediated by signal pathways analogous to those implicated in brain dependent learning and memory. Evidence suggests that the spinal cord is sensitive to instrumental response-outcome (R-O) relations, that learning can induce a peripheral modification (muscle memory) that helps maintain the learned response, and that learning can promote adaptive plasticity (a form of metaplasticity). Conversely, exposure to uncontrollable stimulation disables the capacity to learn. Spinal cord neurons can also abstract that stimuli occur in a regular (predictable) manner, a capacity that appears linked to a neural oscillator (central pattern generator). Disrupting communication with the brain has been shown to transform how GABA affects neuronal function (an example of ionic plasticity), releasing a brake that enables plasticity. We conclude by presenting a framework for understanding these findings and the implications for the broader study of learning. (PsycInfo Database Record (c) 2022 APA, all rights reserved).
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Affiliation(s)
- James W. Grau
- Cellular and Behavioral Neuroscience, Department of Psychology, Texas A&M University, College Station, TX, 77843 USA
| | - Kelsey E. Hudson
- Cellular and Behavioral Neuroscience, Department of Psychology, Texas A&M University, College Station, TX, 77843 USA
| | - Megan M. Tarbet
- McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX
| | - Misty M. Strain
- Department of Cellular and Integrative Physiology, University of Texas Health San Antonio, San Antonio, TX 78229
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12
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Kawai K, Tazoe T, Yanai T, Kanosue K, Nishimura Y. Activation of human spinal locomotor circuitry using transvertebral magnetic stimulation. Front Hum Neurosci 2022; 16:1016064. [PMID: 36211130 PMCID: PMC9537552 DOI: 10.3389/fnhum.2022.1016064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Accepted: 08/31/2022] [Indexed: 11/16/2022] Open
Abstract
Transvertebral magnetic stimulation (TVMS) of the human lumbar spinal cord can evoke bilateral rhythmic leg movements, as in walking, supposedly through the activation of spinal locomotor neural circuitry. However, an appropriate stimulus intensity that can effectively drive the human spinal locomotor circuitry to evoke walking-like movements has not been determined. To address this issue, TVMS was delivered over an intervertebral space of the lumbar cord (L1–L3) at different stimulus intensities (10–70% of maximum stimulator output) in healthy human adults. In a stimulus intensity-dependent manner, TVMS evoked two major patterns of rhythmic leg movements in which the left-right movement cycles were coordinated with different phase relationships: hopping-like movements, in which both legs moved in the same direction in phase, and walking-like movements, in which both legs moved alternatively in anti-phase; uncategorized movements were also observed which could not be categorized as either movement type. Even at the same stimulation site, the stimulus-evoked rhythmic movements changed from hopping-like movements to walking-like movements as stimulus intensity was increased. Different leg muscle activation patterns were engaged in the induction of the hopping- and walking-like movements. The magnitude of the evoked hopping- and walking-like movements was positively correlated with stimulus intensity. The human spinal neural circuitry required a higher intensity of magnetic stimulation to produce walking-like leg movements than to produce hopping-like movements. These results suggest that TVMS activates distinct neural modules in the human spinal cord to generate hopping- and walking-like movements.
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Affiliation(s)
- Kazutake Kawai
- College of Sports Sciences, Nihon University, Tokyo, Japan
- Neural Prosthetics Project, Department of Brain and Neuroscience, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
- Faculty of Sport Sciences, Waseda University, Saitama, Japan
| | - Toshiki Tazoe
- Neural Prosthetics Project, Department of Brain and Neuroscience, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| | - Toshimasa Yanai
- Faculty of Sport Sciences, Waseda University, Saitama, Japan
| | - Kazuyuki Kanosue
- Faculty of Sport Sciences, Waseda University, Saitama, Japan
- Institute of Health and Sports Science and Medicine, Juntendo University, Chiba, Japan
| | - Yukio Nishimura
- Neural Prosthetics Project, Department of Brain and Neuroscience, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
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13
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Isa T. Double viral vector intersectional approaches for pathway-selective manipulation of motor functions and compensatory mechanisms. Exp Neurol 2021; 349:113959. [PMID: 34953894 DOI: 10.1016/j.expneurol.2021.113959] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 12/13/2021] [Accepted: 12/18/2021] [Indexed: 12/16/2022]
Abstract
Selective manipulation of particular subcomponent of neural circuits is crucial for understanding the functional architecture of neural systems and for development of the future therapeutic strategies against neurological disorders. In this article, I review how the intersectional approaches with double viral vector technique was introduced for the pathway-selective manipulation of spinal circuits. In this technique, a retrograde gene transfer vector is injected into the terminal area of the targeted neurons and an anterograde vector is injected at the location of their somata. Either by using the Tet-transactivator or Cre-loxP system, the experimenter can chemogenetically or optogenetically manipulate the transmission of the target pathway originated from the double-infected neurons. This technique was first developed for manipulation of spinal cord interneurons in the macaque monkeys by selective expression of tetanus neurotoxin and successfully affected the dexterous hand movements. Currently, this technique is widely used on a variety of neural pathways both in rodents and primates in combination with a variety of retrograde vectors and a variety of optogenetic and chemogenetic tools. The advantage of this technique is that it is not necessary to generate transgenic animals. Knowledge of the cell-type specific promotors is not needed. Manipulation is achieved primarily by injection of two viral vectors based on the anatomical knowledge and it is applicable in a variety of animal species including primates. The pros, cons and future direction of this technique are discussed.
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Affiliation(s)
- Tadashi Isa
- Department of Neuroscience, Graduate School of Medicine, Kyoto University, Japan; Institute for the Advanced Study of Human Biology (WPI-ASHBi), Japan; Human Brain Research Center, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan.
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14
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Deng L, Ravenscraft B, Xu XM. Exploring propriospinal neuron-mediated neural circuit plasticity using recombinant viruses after spinal cord injury. Exp Neurol 2021; 349:113962. [PMID: 34953895 DOI: 10.1016/j.expneurol.2021.113962] [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: 06/07/2021] [Revised: 12/16/2021] [Accepted: 12/19/2021] [Indexed: 11/04/2022]
Abstract
Propriospinal neurons (PSNs) play a crucial role in motor control and sensory processing and contribute to plastic reorganization of spinal circuits responsible for recovery from spinal cord injury (SCI). Due to their scattered distribution and various intersegmental projection patterns, it is challenging to dissect the function of PSNs within the neuronal network. New genetically encoded tools, particularly cell-type-specific transgene expression methods using recombinant viral vectors combined with other genetic, pharmacologic, and optogenetic approaches, have enormous potential for visualizing PSNs in the neuronal circuits and monitoring and manipulating their activity. Furthermore, recombinant viral tools have been utilized to promote the intrinsic regenerative capacities of PSNs, towards manipulating the 'hostile' microenvironment for improving functional regeneration of PSNs. Here we summarize the latest development in this fast-moving field and provide a perspective for using this technology to dissect PSN physiological role in contributing to recovery of function after SCI.
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Affiliation(s)
- Lingxiao Deng
- Spinal Cord and Brain Injury Research Group, Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN 46202, United States; Department of Neurological Surgery, Indiana University School of Medicine, Indianapolis, IN 46202, United States
| | - Baylen Ravenscraft
- Spinal Cord and Brain Injury Research Group, Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN 46202, United States
| | - Xiao-Ming Xu
- Spinal Cord and Brain Injury Research Group, Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN 46202, United States; Department of Neurological Surgery, Indiana University School of Medicine, Indianapolis, IN 46202, United States.
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15
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Shepard CT, Pocratsky AM, Brown BL, Van Rijswijck MA, Zalla RM, Burke DA, Morehouse JR, Riegler AS, Whittemore SR, Magnuson DSK. Silencing long ascending propriospinal neurons after spinal cord injury improves hindlimb stepping in the adult rat. eLife 2021; 10:e70058. [PMID: 34854375 PMCID: PMC8639151 DOI: 10.7554/elife.70058] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 11/23/2021] [Indexed: 12/11/2022] Open
Abstract
Long ascending propriospinal neurons (LAPNs) are a subpopulation of spinal cord interneurons that directly connect the lumbar and cervical enlargements. Previously we showed, in uninjured animals, that conditionally silencing LAPNs disrupted left-right coordination of the hindlimbs and forelimbs in a context-dependent manner, demonstrating that LAPNs secure alternation of the fore- and hindlimb pairs during overground stepping. Given the ventrolateral location of LAPN axons in the spinal cord white matter, many likely remain intact following incomplete, contusive, thoracic spinal cord injury (SCI), suggesting a potential role in the recovery of stepping. Thus, we hypothesized that silencing LAPNs after SCI would disrupt recovered locomotion. Instead, we found that silencing spared LAPNs post-SCI improved locomotor function, including paw placement order and timing, and a decrease in the number of dorsal steps. Silencing also restored left-right hindlimb coordination and normalized spatiotemporal features of gait such as stance and swing time. However, hindlimb-forelimb coordination was not restored. These data indicate that the temporal information carried between the spinal enlargements by the spared LAPNs post-SCI is detrimental to recovered hindlimb locomotor function. These findings are an illustration of a post-SCI neuroanatomical-functional paradox and have implications for the development of neuronal- and axonal-protective therapeutic strategies and the clinical study/implementation of neuromodulation strategies.
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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 Louisville, LouisvilleLouisvilleUnited States
- Kentucky Spinal Cord Injury Research Center, University of LouisvilleLouisvilleUnited States
| | - Amanda M Pocratsky
- Department of Anatomical Sciences and Neurobiology, University of Louisville, 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 Louisville, 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
- Department of Neurological Surgery, University of LouisvilleLouisvilleUnited States
| | - Johnny R Morehouse
- Kentucky Spinal Cord Injury Research Center, University of LouisvilleLouisvilleUnited States
- Department of Neurological Surgery, University of LouisvilleLouisvilleUnited States
| | - Amberley S Riegler
- Kentucky Spinal Cord Injury Research Center, University of LouisvilleLouisvilleUnited States
- Department of Neurological Surgery, 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 Louisville, 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 Louisville, 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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16
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Blackmore M, Batsel E, Tsoulfas P. Widening spinal injury research to consider all supraspinal cell types: Why we must and how we can. Exp Neurol 2021; 346:113862. [PMID: 34520726 PMCID: PMC8805209 DOI: 10.1016/j.expneurol.2021.113862] [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: 06/30/2021] [Revised: 08/19/2021] [Accepted: 09/08/2021] [Indexed: 01/05/2023]
Abstract
The supraspinal connectome consists of dozens of neuronal populations that project axons from the brain to the spinal cord to influence a wide range of motor, autonomic, and sensory functions. The complexity and wide distribution of supraspinal neurons present significant technical challenges, leading most spinal cord injury research to focus on a handful of major pathways such as the corticospinal, rubrospinal, and raphespinal. Much less is known about many additional populations that carry information to modulate or compensate for these main pathways, or which carry pre-autonomic and other information of high value to individuals with spinal injury. A confluence of technical developments, however, now enables a whole-connectome study of spinal cord injury. Improved viral labeling, tissue clearing, and automated registration to 3D atlases can quantify supraspinal neurons throughout the murine brain, offering a practical means to track responses to injury and treatment on an unprecedented scale. Here we discuss the need for expanded connectome-wide analyses in spinal injury research, illustrate the potential by discussing a new web-based resource for brain-wide study of supraspinal neurons, and highlight future prospects for connectome analyses.
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Affiliation(s)
- Murray Blackmore
- Department of Biomedical Sciences, Marquette University, 53201, United States of America.
| | - Elizabeth Batsel
- Department of Biomedical Sciences, Marquette University, 53201, United States of America
| | - Pantelis Tsoulfas
- Department of Neurological Surgery, Miami Project to Cure Paralysis, University of Miami Miller School of Medicine, Miami, FL 33136, United States of America
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17
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McCreedy DA, Jalufka FL, Platt ME, Min SW, Kirchhoff MA, Pritchard AL, Reid SK, Manlapaz R, Mihaly E, Butts JC, Iyer NR, Sakiyama-Elbert SE, Crone SA, McDevitt TC. Passive Clearing and 3D Lightsheet Imaging of the Intact and Injured Spinal Cord in Mice. Front Cell Neurosci 2021; 15:684792. [PMID: 34408627 PMCID: PMC8366232 DOI: 10.3389/fncel.2021.684792] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Accepted: 07/07/2021] [Indexed: 12/18/2022] Open
Abstract
The spinal cord contains a diverse array of sensory and motor circuits that are essential for normal function. Spinal cord injury (SCI) permanently disrupts neural circuits through initial mechanical damage, as well as a cascade of secondary injury events that further expand the spinal cord lesion, resulting in permanent paralysis. Tissue clearing and 3D imaging have recently emerged as promising techniques to improve our understanding of the complex neural circuitry of the spinal cord and the changes that result from damage due to SCI. However, the application of this technology for studying the intact and injured spinal cord remains limited. Here, we optimized the passive CLARITY technique (PACT) to obtain gentle and efficient clearing of the murine spinal cord without the need for specialized equipment. We demonstrate that PACT clearing enables 3D imaging of multiple fluorescent labels in the spinal cord to assess molecularly defined neuronal populations, acute inflammation, long-term tissue damage, and cell transplantation. Collectively, these procedures provide a framework for expanding the utility of tissue clearing to enhance the study of spinal cord neural circuits, as well as cellular- and tissue-level changes that occur following SCI.
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Affiliation(s)
- Dylan A. McCreedy
- Department of Biology, Texas A&M University, College Station, TX, United States
- Gladstone Institutes, San Francisco, CA, United States
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, United States
- Texas A&M Institute for Neuroscience, College Station, TX, United States
| | - Frank L. Jalufka
- Department of Biology, Texas A&M University, College Station, TX, United States
| | - Madison E. Platt
- Department of Biology, Texas A&M University, College Station, TX, United States
| | - Sun Won Min
- Department of Biology, Texas A&M University, College Station, TX, United States
| | - Megan A. Kirchhoff
- Department of Biology, Texas A&M University, College Station, TX, United States
| | - Anna L. Pritchard
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, United States
| | - Shelby K. Reid
- Texas A&M Institute for Neuroscience, College Station, TX, United States
| | | | - Eszter Mihaly
- Gladstone Institutes, San Francisco, CA, United States
| | | | - Nisha R. Iyer
- Wisconsin Institute for Discovery, University of Wisconsin-Madison, Madison, WI, United States
| | | | - Steven A. Crone
- Division of Neurosurgery, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, United States
- Division of Developmental Biology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, United States
- Department of Neurosurgery, College of Medicine, University of Cincinnati, Cincinnati, OH, United States
| | - Todd C. McDevitt
- Gladstone Institutes, San Francisco, CA, United States
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA, United States
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18
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Abstract
Spinal cord injury (SCI) triggers a complex cascade of molecular and cellular events that leads to progressive cell loss and tissue damage. In this review, the authors outline the temporal profile of SCI pathogenesis, focusing on key mediators of the secondary injury, and highlight cutting edge insights on the alterations in neural circuits that largely define the chronic injury environment. They bridge these important basic science concepts with clinical implications for informing novel experimental therapies. Furthermore, emerging concepts in the study of SCI pathogenesis that are transforming fundamental research into innovative clinical treatment paradigms are outlined.
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Affiliation(s)
- Laureen D Hachem
- Division of Neurosurgery, Department of Surgery, University of Toronto, 149 College Street, Toronto, Ontario M5T 1P5, Canada; Division of Neurosurgery, Toronto Western Hospital, University Health Network, 399 Bathurst Street, Suite 4W-449, Toronto, Ontario M5T 2S8, Canada
| | - Michael G Fehlings
- Division of Neurosurgery, Department of Surgery, University of Toronto, 149 College Street, Toronto, Ontario M5T 1P5, Canada; Division of Neurosurgery, Toronto Western Hospital, University Health Network, 399 Bathurst Street, Suite 4W-449, Toronto, Ontario M5T 2S8, Canada.
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19
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Islam MA, Pulverenti TS, Knikou M. Neuronal Actions of Transspinal Stimulation on Locomotor Networks and Reflex Excitability During Walking in Humans With and Without Spinal Cord Injury. Front Hum Neurosci 2021; 15:620414. [PMID: 33679347 PMCID: PMC7930001 DOI: 10.3389/fnhum.2021.620414] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Accepted: 01/25/2021] [Indexed: 12/03/2022] Open
Abstract
This study investigated the neuromodulatory effects of transspinal stimulation on soleus H-reflex excitability and electromyographic (EMG) activity during stepping in humans with and without spinal cord injury (SCI). Thirteen able-bodied adults and 5 individuals with SCI participated in the study. EMG activity from both legs was determined for steps without, during, and after a single-pulse or pulse train transspinal stimulation delivered during stepping randomly at different phases of the step cycle. The soleus H-reflex was recorded in both subject groups under control conditions and following single-pulse transspinal stimulation at an individualized exactly similar positive and negative conditioning-test interval. The EMG activity was decreased in both subject groups at the steps during transspinal stimulation, while intralimb and interlimb coordination were altered only in SCI subjects. At the steps immediately after transspinal stimulation, the physiological phase-dependent EMG modulation pattern remained unaffected in able-bodied subjects. The conditioned soleus H-reflex was depressed throughout the step cycle in both subject groups. Transspinal stimulation modulated depolarization of motoneurons over multiple segments, limb coordination, and soleus H-reflex excitability during assisted stepping. The soleus H-reflex depression may be the result of complex spinal inhibitory interneuronal circuits activated by transspinal stimulation and collision between orthodromic and antidromic volleys in the peripheral mixed nerve. The soleus H-reflex depression by transspinal stimulation suggests a potential application for normalization of spinal reflex excitability after SCI.
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Affiliation(s)
- Md. Anamul Islam
- Klab4Recovery Research Laboratory, Department of Physical Therapy, College of Staten Island, The City University of New York, Staten Island, NY, United States
| | - Timothy S. Pulverenti
- Klab4Recovery Research Laboratory, Department of Physical Therapy, College of Staten Island, The City University of New York, Staten Island, NY, United States
| | - Maria Knikou
- Klab4Recovery Research Laboratory, Department of Physical Therapy, College of Staten Island, The City University of New York, Staten Island, NY, United States
- PhD Program in Biology and Collaborative Neuroscience Program, Graduate Center of the City University of New York and College of Staten Island, New York, NY, United States
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20
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Zholudeva LV, Abraira VE, Satkunendrarajah K, McDevitt TC, Goulding MD, Magnuson DSK, Lane MA. Spinal Interneurons as Gatekeepers to Neuroplasticity after Injury or Disease. J Neurosci 2021; 41:845-854. [PMID: 33472820 PMCID: PMC7880285 DOI: 10.1523/jneurosci.1654-20.2020] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 12/15/2020] [Accepted: 12/17/2020] [Indexed: 12/15/2022] Open
Abstract
Spinal interneurons are important facilitators and modulators of motor, sensory, and autonomic functions in the intact CNS. This heterogeneous population of neurons is now widely appreciated to be a key component of plasticity and recovery. This review highlights our current understanding of spinal interneuron heterogeneity, their contribution to control and modulation of motor and sensory functions, and how this role might change after traumatic spinal cord injury. We also offer a perspective for how treatments can optimize the contribution of interneurons to functional improvement.
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Affiliation(s)
| | - Victoria E Abraira
- Department of Cell Biology & Neuroscience, Rutgers University, The State University of New Jersey, New Jersey, 08854
| | - Kajana Satkunendrarajah
- Departments of Neurosurgery and Physiology, Medical College of Wisconsin, Wisconsin, 53226
- Clement J. Zablocki Veterans Affairs Medical Center, Milwaukee, Wisconsin, 53295
| | - Todd C McDevitt
- Gladstone Institutes, San Francisco, California, 94158
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, California, 94143
| | | | - David S K Magnuson
- University of Louisville, Kentucky Spinal Cord Injury Research Center, Louisville, Kentucky, 40208
| | - Michael A Lane
- Department of Neurobiology and Anatomy, and the Marion Murray Spinal Cord Research Center, Drexel University, Philadelphia, Pennsylvania, 19129
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21
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Ronzano R, Lancelin C, Bhumbra GS, Brownstone RM, Beato M. Proximal and distal spinal neurons innervating multiple synergist and antagonist motor pools. eLife 2021; 10:70858. [PMID: 34727018 PMCID: PMC8631798 DOI: 10.7554/elife.70858] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 11/01/2021] [Indexed: 11/13/2022] Open
Abstract
Motoneurons (MNs) control muscle contractions, and their recruitment by premotor circuits is tuned to produce accurate motor behaviours. To understand how these circuits coordinate movement across and between joints, it is necessary to understand whether spinal neurons pre-synaptic to motor pools have divergent projections to more than one MN population. Here, we used modified rabies virus tracing in mice to investigate premotor interneurons projecting to synergist flexor or extensor MNs, as well as those projecting to antagonist pairs of muscles controlling the ankle joint. We show that similar proportions of premotor neurons diverge to synergist and antagonist motor pools. Divergent premotor neurons were seen throughout the spinal cord, with decreasing numbers but increasing proportion with distance from the hindlimb enlargement. In the cervical cord, divergent long descending propriospinal neurons were found in contralateral lamina VIII, had large somata, were neither glycinergic, nor cholinergic, and projected to both lumbar and cervical MNs. We conclude that distributed spinal premotor neurons coordinate activity across multiple motor pools and that there are spinal neurons mediating co-contraction of antagonist muscles.
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Affiliation(s)
- Remi Ronzano
- Department of Neuromuscular Diseases, University College LondonLondonUnited Kingdom
| | - Camille Lancelin
- Department of Neuromuscular Diseases, University College LondonLondonUnited Kingdom
| | - Gardave Singh Bhumbra
- Department of Neuroscience Physiology and Pharmacology, University College LondonLondonUnited Kingdom
| | - Robert M Brownstone
- Department of Neuromuscular Diseases, University College LondonLondonUnited Kingdom
| | - Marco Beato
- Neuroscience, Physiology and Pharmacology, University College LondonLondonUnited Kingdom
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22
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Pocratsky AM, Shepard CT, Morehouse JR, Burke DA, Riegler AS, Hardin JT, Beare JE, Hainline C, States GJR, Brown BL, Whittemore SR, Magnuson DSK. Long ascending propriospinal neurons provide flexible, context-specific control of interlimb coordination. eLife 2020; 9:e53565. [PMID: 32902379 PMCID: PMC7527236 DOI: 10.7554/elife.53565] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Accepted: 09/08/2020] [Indexed: 11/13/2022] Open
Abstract
Within the cervical and lumbar spinal enlargements, central pattern generator (CPG) circuitry produces the rhythmic output necessary for limb coordination during locomotion. Long propriospinal neurons that inter-connect these CPGs are thought to secure hindlimb-forelimb coordination, ensuring that diagonal limb pairs move synchronously while the ipsilateral limb pairs move out-of-phase during stepping. Here, we show that silencing long ascending propriospinal neurons (LAPNs) that inter-connect the lumbar and cervical CPGs disrupts left-right limb coupling of each limb pair in the adult rat during overground locomotion on a high-friction surface. These perturbations occurred independent of the locomotor rhythm, intralimb coordination, and speed-dependent (or any other) principal features of locomotion. Strikingly, the functional consequences of silencing LAPNs are highly context-dependent; the phenotype was not expressed during swimming, treadmill stepping, exploratory locomotion, or walking on an uncoated, slick surface. These data reveal surprising flexibility and context-dependence in the control of interlimb coordination during locomotion.
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Affiliation(s)
- Amanda M Pocratsky
- Department of Anatomical Sciences and Neurobiology, University of LouisvilleLouisvilleUnited States
- Kentucky Spinal Cord Injury Research Center, University of LouisvilleLouisvilleUnited States
| | - Courtney T Shepard
- Department of Anatomical Sciences and Neurobiology, University of LouisvilleLouisvilleUnited States
- Kentucky Spinal Cord Injury Research Center, University of LouisvilleLouisvilleUnited States
| | - Johnny R Morehouse
- Kentucky Spinal Cord Injury Research Center, University of LouisvilleLouisvilleUnited States
- Department of Neurological Surgery, University of LouisvilleLouisvilleUnited States
| | - Darlene A Burke
- Kentucky Spinal Cord Injury Research Center, University of LouisvilleLouisvilleUnited States
- Department of Neurological Surgery, University of LouisvilleLouisvilleUnited States
| | - Amberley S Riegler
- Kentucky Spinal Cord Injury Research Center, University of LouisvilleLouisvilleUnited States
- Department of Neurological Surgery, University of LouisvilleLouisvilleUnited States
| | - Josiah T Hardin
- Speed School of Engineering, University of LouisvilleLouisvilleUnited States
| | - Jason E Beare
- Kentucky Spinal Cord Injury Research Center, University of LouisvilleLouisvilleUnited States
- Cardiovascular Innovation Institute, Department of Physiology and Biophysics, University of LouisvilleLouisvilleUnited States
| | - Casey Hainline
- Speed School of Engineering, University of LouisvilleLouisvilleUnited States
| | - Gregory JR States
- Department of Anatomical Sciences and Neurobiology, University of LouisvilleLouisvilleUnited States
- Kentucky Spinal Cord Injury Research Center, University of LouisvilleLouisvilleUnited States
| | - Brandon L Brown
- Kentucky Spinal Cord Injury Research Center, University of LouisvilleLouisvilleUnited States
| | - Scott R Whittemore
- 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
- 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
- Speed School of Engineering, University of LouisvilleLouisvilleUnited States
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23
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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: 38] [Impact Index Per Article: 7.6] [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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24
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Deska-Gauthier D, Zhang Y. The functional diversity of spinal interneurons and locomotor control. CURRENT OPINION IN PHYSIOLOGY 2019. [DOI: 10.1016/j.cophys.2019.01.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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25
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Spejo AB, Teles CB, Zuccoli GDS, Oliveira ALRD. Synapse preservation and decreased glial reactions following ventral root crush (VRC) and treatment with 4‐hydroxy‐tempo (TEMPOL). J Neurosci Res 2018; 97:520-534. [DOI: 10.1002/jnr.24365] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Revised: 11/20/2018] [Accepted: 11/20/2018] [Indexed: 11/06/2022]
Affiliation(s)
- Aline Barroso Spejo
- Department of Structural and Functional Biology, Institute of Biology University of Campinas (UNICAMP) Campinas Brazil
| | - Caroline Brandão Teles
- Department of Structural and Functional Biology, Institute of Biology University of Campinas (UNICAMP) Campinas Brazil
| | - Giuliana da Silva Zuccoli
- Department of Structural and Functional Biology, Institute of Biology University of Campinas (UNICAMP) Campinas Brazil
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26
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The Neuroplastic and Therapeutic Potential of Spinal Interneurons in the Injured Spinal Cord. Trends Neurosci 2018; 41:625-639. [PMID: 30017476 DOI: 10.1016/j.tins.2018.06.004] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Revised: 06/06/2018] [Accepted: 06/12/2018] [Indexed: 12/25/2022]
Abstract
The central nervous system is not a static, hard-wired organ. Examples of neuroplasticity, whether at the level of the synapse, the cell, or within and between circuits, can be found during development, throughout the progression of disease, or after injury. One essential component of the molecular, anatomical, and functional changes associated with neuroplasticity is the spinal interneuron (SpIN). Here, we draw on recent multidisciplinary studies to identify and interrogate subsets of SpINs and their roles in locomotor and respiratory circuits. We highlight some of the recent progress that elucidates the importance of SpINs in circuits affected by spinal cord injury (SCI), especially those within respiratory networks; we also discuss potential ways that spinal neuroplasticity can be therapeutically harnessed for recovery.
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27
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Côté MP, Murray LM, Knikou M. Spinal Control of Locomotion: Individual Neurons, Their Circuits and Functions. Front Physiol 2018; 9:784. [PMID: 29988534 PMCID: PMC6026662 DOI: 10.3389/fphys.2018.00784] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 06/05/2018] [Indexed: 12/31/2022] Open
Abstract
Systematic research on the physiological and anatomical characteristics of spinal cord interneurons along with their functional output has evolved for more than one century. Despite significant progress in our understanding of these networks and their role in generating and modulating movement, it has remained a challenge to elucidate the properties of the locomotor rhythm across species. Neurophysiological experimental evidence indicates similarities in the function of interneurons mediating afferent information regarding muscle stretch and loading, being affected by motor axon collaterals and those mediating presynaptic inhibition in animals and humans when their function is assessed at rest. However, significantly different muscle activation profiles are observed during locomotion across species. This difference may potentially be driven by a modified distribution of muscle afferents at multiple segmental levels in humans, resulting in an altered interaction between different classes of spinal interneurons. Further, different classes of spinal interneurons are likely activated or silent to some extent simultaneously in all species. Regardless of these limitations, continuous efforts on the function of spinal interneuronal circuits during mammalian locomotion will assist in delineating the neural mechanisms underlying locomotor control, and help develop novel targeted rehabilitation strategies in cases of impaired bipedal gait in humans. These rehabilitation strategies will include activity-based therapies and targeted neuromodulation of spinal interneuronal circuits via repetitive stimulation delivered to the brain and/or spinal cord.
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Affiliation(s)
- Marie-Pascale Côté
- CÔTÉ Lab, Spinal Cord Research Center, Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, United States
| | - Lynda M. Murray
- Motor Control and NeuroRecovery Research Laboratory (Klab4Recovery), Department of Physical Therapy, College of Staten Island, City University of New York, New York, NY, United States
- Graduate Center, Ph.D. Program in Biology, City University of New York, New York, NY, United States
| | - Maria Knikou
- Motor Control and NeuroRecovery Research Laboratory (Klab4Recovery), Department of Physical Therapy, College of Staten Island, City University of New York, New York, NY, United States
- Graduate Center, Ph.D. Program in Biology, City University of New York, New York, NY, United States
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