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Evaluation of the effects of the Arm Light Exoskeleton on movement execution and muscle activities: a pilot study on healthy subjects. J Neuroeng Rehabil 2016; 13:9. [PMID: 26801620 PMCID: PMC4724067 DOI: 10.1186/s12984-016-0117-x] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Accepted: 01/18/2016] [Indexed: 11/17/2022] Open
Abstract
Background Exoskeletons for lower and upper extremities have been introduced in neurorehabilitation because they can guide the patient’s limb following its anatomy, covering many degrees of freedom and most of its natural workspace, and allowing the control of the articular joints. The aims of this study were to evaluate the possible use of a novel exoskeleton, the Arm Light Exoskeleton (ALEx), for robot-aided neurorehabilitation and to investigate the effects of some rehabilitative strategies adopted in robot-assisted training. Methods We studied movement execution and muscle activities of 16 upper limb muscles in six healthy subjects, focusing on end-effector and joint kinematics, muscle synergies, and spinal maps. The subjects performed three dimensional point-to-point reaching movements, without and with the exoskeleton in different assistive modalities and control strategies. Results The results showed that ALEx supported the upper limb in all modalities and control strategies: it reduced the muscular activity of the shoulder’s abductors and it increased the activity of the elbow flexors. The different assistive modalities favored kinematics and muscle coordination similar to natural movements, but the muscle activity during the movements assisted by the exoskeleton was reduced with respect to the movements actively performed by the subjects. Moreover, natural trajectories recorded from the movements actively performed by the subjects seemed to promote an activity of muscles and spinal circuitries more similar to the natural one. Conclusions The preliminary analysis on healthy subjects supported the use of ALEx for post-stroke upper limb robotic assisted rehabilitation, and it provided clues on the effects of different rehabilitative strategies on movement and muscle coordination.
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Wenger N, Moraud EM, Gandar J, Musienko P, Capogrosso M, Baud L, Le Goff CG, Barraud Q, Pavlova N, Dominici N, Minev IR, Asboth L, Hirsch A, Duis S, Kreider J, Mortera A, Haverbeck O, Kraus S, Schmitz F, DiGiovanna J, van den Brand R, Bloch J, Detemple P, Lacour SP, Bézard E, Micera S, Courtine G. Spatiotemporal neuromodulation therapies engaging muscle synergies improve motor control after spinal cord injury. Nat Med 2016; 22:138-45. [PMID: 26779815 PMCID: PMC5061079 DOI: 10.1038/nm.4025] [Citation(s) in RCA: 209] [Impact Index Per Article: 26.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2014] [Accepted: 12/08/2015] [Indexed: 12/17/2022]
Abstract
Electrical neuromodulation of lumbar segments improves motor control after spinal cord injury in animal models and humans. However, the physiological principles underlying the effect of this intervention remain poorly understood, which has limited this therapeutic approach to continuous stimulation applied to restricted spinal cord locations. Here, we developed novel stimulation protocols that reproduce the natural dynamics of motoneuron activation during locomotion. For this, we computed the spatiotemporal activation pattern of muscle synergies during locomotion in healthy rats. Computer simulations identified optimal electrode locations to target each synergy through the recruitment of proprioceptive feedback circuits. This framework steered the design of spatially selective spinal implants and real–time control software that modulate extensor versus flexor synergies with precise temporal resolution. Spatiotemporal neuromodulation therapies improved gait quality, weight–bearing capacities, endurance and skilled locomotion in multiple rodent models of spinal cord injury. These new concepts are directly translatable to strategies to improve motor control in humans.
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Affiliation(s)
- Nikolaus Wenger
- International Paraplegic Foundation Chair in Spinal Cord Repair, Center for Neuroprosthetics and Brain Mind Institute, School of Life Sciences, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland.,Department of Neurology with Experimental Neurology, Charité-Universitätsmedizin Berlin, Berlin, Germany.,Center for Stroke Research Berlin, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Eduardo Martin Moraud
- Bertarelli Foundation Chair in Translational Neuroengineering, Center for Neuroprosthetics and Institute of Bioengineering, School of Bioengineering, EPFL, Lausanne, Switzerland
| | - Jerome Gandar
- International Paraplegic Foundation Chair in Spinal Cord Repair, Center for Neuroprosthetics and Brain Mind Institute, School of Life Sciences, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland
| | - Pavel Musienko
- International Paraplegic Foundation Chair in Spinal Cord Repair, Center for Neuroprosthetics and Brain Mind Institute, School of Life Sciences, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland.,Motor Physiology Laboratory, Pavlov Institute of Physiology, St. Petersburg, Russia.,Laboratory of Neuroprosthetics, Institute of Translational Biomedicine, St. Petersburg State University, St. Petersburg, Russia.,Lab of Neurophysiology and Experimental Neurorehabilitation, Children's Surgery and Orthopedic Clinic, Department of Nonpulmonary Tuberculosis, Institute of Physiopulmonology, St. Petersburg, Russia
| | - Marco Capogrosso
- Bertarelli Foundation Chair in Translational Neuroengineering, Center for Neuroprosthetics and Institute of Bioengineering, School of Bioengineering, EPFL, Lausanne, Switzerland.,The BioRobotics Institute, Scuola Superiore Sant'Anna, Pisa, Italy
| | - Laetitia Baud
- International Paraplegic Foundation Chair in Spinal Cord Repair, Center for Neuroprosthetics and Brain Mind Institute, School of Life Sciences, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland
| | - Camille G Le Goff
- International Paraplegic Foundation Chair in Spinal Cord Repair, Center for Neuroprosthetics and Brain Mind Institute, School of Life Sciences, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland
| | - Quentin Barraud
- International Paraplegic Foundation Chair in Spinal Cord Repair, Center for Neuroprosthetics and Brain Mind Institute, School of Life Sciences, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland
| | - Natalia Pavlova
- International Paraplegic Foundation Chair in Spinal Cord Repair, Center for Neuroprosthetics and Brain Mind Institute, School of Life Sciences, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland.,Motor Physiology Laboratory, Pavlov Institute of Physiology, St. Petersburg, Russia
| | - Nadia Dominici
- International Paraplegic Foundation Chair in Spinal Cord Repair, Center for Neuroprosthetics and Brain Mind Institute, School of Life Sciences, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland.,MOVE Research Institute Amsterdam, Faculty of Behavioural and Movement Sciences, VU University Amsterdam, Amsterdam, the Netherlands
| | - Ivan R Minev
- Bertarelli Foundation Chair in Neuroprosthetic Technology, Center for Neuroprosthetics and Institute of Bioengineering, EPFL, Lausanne, Switzerland
| | - Leonie Asboth
- International Paraplegic Foundation Chair in Spinal Cord Repair, Center for Neuroprosthetics and Brain Mind Institute, School of Life Sciences, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland
| | - Arthur Hirsch
- Bertarelli Foundation Chair in Neuroprosthetic Technology, Center for Neuroprosthetics and Institute of Bioengineering, EPFL, Lausanne, Switzerland
| | - Simone Duis
- International Paraplegic Foundation Chair in Spinal Cord Repair, Center for Neuroprosthetics and Brain Mind Institute, School of Life Sciences, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland
| | - Julie Kreider
- International Paraplegic Foundation Chair in Spinal Cord Repair, Center for Neuroprosthetics and Brain Mind Institute, School of Life Sciences, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland
| | - Andrea Mortera
- Bertarelli Foundation Chair in Translational Neuroengineering, Center for Neuroprosthetics and Institute of Bioengineering, School of Bioengineering, EPFL, Lausanne, Switzerland
| | | | | | - Felix Schmitz
- Fraunhofer Institute for Chemical Technology-Mainz Institute for Microtechnology (ICT-IMM), Mainz, Germany
| | - Jack DiGiovanna
- Bertarelli Foundation Chair in Translational Neuroengineering, Center for Neuroprosthetics and Institute of Bioengineering, School of Bioengineering, EPFL, Lausanne, Switzerland
| | - Rubia van den Brand
- International Paraplegic Foundation Chair in Spinal Cord Repair, Center for Neuroprosthetics and Brain Mind Institute, School of Life Sciences, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland
| | - Jocelyne Bloch
- Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne, Switzerland
| | - Peter Detemple
- Fraunhofer Institute for Chemical Technology-Mainz Institute for Microtechnology (ICT-IMM), Mainz, Germany
| | - Stéphanie P Lacour
- Bertarelli Foundation Chair in Neuroprosthetic Technology, Center for Neuroprosthetics and Institute of Bioengineering, EPFL, Lausanne, Switzerland
| | - Erwan Bézard
- Motac Neuroscience Inc., Beijing, China.,University of Bordeaux, Institut des Maladies Neurodégénératives, Bordeaux, France.,CNRS, Institut des Maladies Neurodégénératives, Bordeaux, France
| | - Silvestro Micera
- Bertarelli Foundation Chair in Translational Neuroengineering, Center for Neuroprosthetics and Institute of Bioengineering, School of Bioengineering, EPFL, Lausanne, Switzerland.,The BioRobotics Institute, Scuola Superiore Sant'Anna, Pisa, Italy
| | - Grégoire Courtine
- International Paraplegic Foundation Chair in Spinal Cord Repair, Center for Neuroprosthetics and Brain Mind Institute, School of Life Sciences, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland.,Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne, Switzerland
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Hinckley CA, Alaynick WA, Gallarda BW, Hayashi M, Hilde KL, Driscoll SP, Dekker JD, Tucker HO, Sharpee TO, Pfaff SL. Spinal Locomotor Circuits Develop Using Hierarchical Rules Based on Motorneuron Position and Identity. Neuron 2015; 87:1008-21. [PMID: 26335645 DOI: 10.1016/j.neuron.2015.08.005] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Revised: 07/29/2015] [Accepted: 08/03/2015] [Indexed: 11/28/2022]
Abstract
The coordination of multi-muscle movements originates in the circuitry that regulates the firing patterns of spinal motorneurons. Sensory neurons rely on the musculotopic organization of motorneurons to establish orderly connections, prompting us to examine whether the intraspinal circuitry that coordinates motor activity likewise uses cell position as an internal wiring reference. We generated a motorneuron-specific GCaMP6f mouse line and employed two-photon imaging to monitor the activity of lumbar motorneurons. We show that the central pattern generator neural network coordinately drives rhythmic columnar-specific motorneuron bursts at distinct phases of the locomotor cycle. Using multiple genetic strategies to perturb the subtype identity and orderly position of motorneurons, we found that neurons retained their rhythmic activity-but cell position was decoupled from the normal phasing pattern underlying flexion and extension. These findings suggest a hierarchical basis of motor circuit formation that relies on increasingly stringent matching of neuronal identity and position.
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Affiliation(s)
- Christopher A Hinckley
- Gene Expression Laboratory and the Howard Hughes Medical Institute, Salk Institute for Biological Studies, 10010 North Torrey Pines, La Jolla, CA 92037, USA
| | - William A Alaynick
- Gene Expression Laboratory and the Howard Hughes Medical Institute, Salk Institute for Biological Studies, 10010 North Torrey Pines, La Jolla, CA 92037, USA
| | - Benjamin W Gallarda
- Gene Expression Laboratory and the Howard Hughes Medical Institute, Salk Institute for Biological Studies, 10010 North Torrey Pines, La Jolla, CA 92037, USA
| | - Marito Hayashi
- Gene Expression Laboratory and the Howard Hughes Medical Institute, Salk Institute for Biological Studies, 10010 North Torrey Pines, La Jolla, CA 92037, USA
| | - Kathryn L Hilde
- Gene Expression Laboratory and the Howard Hughes Medical Institute, Salk Institute for Biological Studies, 10010 North Torrey Pines, La Jolla, CA 92037, USA
| | - Shawn P Driscoll
- Gene Expression Laboratory and the Howard Hughes Medical Institute, Salk Institute for Biological Studies, 10010 North Torrey Pines, La Jolla, CA 92037, USA
| | - Joseph D Dekker
- Institute of Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712, USA
| | - Haley O Tucker
- Institute of Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712, USA
| | - Tatyana O Sharpee
- Gene Expression Laboratory and the Howard Hughes Medical Institute, Salk Institute for Biological Studies, 10010 North Torrey Pines, La Jolla, CA 92037, USA; Computational Neurobiology Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines, La Jolla, CA 92037, USA
| | - Samuel L Pfaff
- Gene Expression Laboratory and the Howard Hughes Medical Institute, Salk Institute for Biological Studies, 10010 North Torrey Pines, La Jolla, CA 92037, USA.
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54
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Synergy temporal sequences and topography in the spinal cord: evidence for a traveling wave in frog locomotion. Brain Struct Funct 2015; 221:3869-3890. [PMID: 26501407 DOI: 10.1007/s00429-015-1133-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 10/08/2015] [Indexed: 12/27/2022]
Abstract
Locomotion is produced by a central pattern generator. Its spinal cord organization is generally considered to be distributed, with more rhythmogenic rostral lumbar segments. While this produces a rostrocaudally traveling wave in undulating species, this is not thought to occur in limbed vertebrates, with the exception of the interneuronal traveling wave demonstrated in fictive cat scratching (Cuellar et al. J Neurosci 29:798-810, 2009). Here, we reexamine this hypothesis in the frog, using the seven muscle synergies A to G previously identified with intraspinal NMDA (Saltiel et al. J Neurophysiol 85:605-619, 2001). We find that locomotion consists of a sequence of synergy activations (A-B-G-A-F-E-G). The same sequence is observed when focal NMDA iontophoresis in the spinal cord elicits a caudal extension-lateral force-flexion cycle (flexion onset without the C synergy). Examining the early NMDA-evoked motor output at 110 sites reveals a rostrocaudal topographic organization of synergy encoding by the lumbar cord. Each synergy is preferentially activated from distinct regions, which may be multiple, and partially overlap between different synergies. Comparing the sequence of synergy activation in locomotion with their spinal cord topography suggests that the locomotor output is achieved by a rostrocaudally traveling wave of activation in the swing-stance cycle. A two-layer circuitry model, based on this topography and a traveling wave reproduces this output and explores its possible modifications under different afferent inputs. Our results and simulations suggest that a rostrocaudally traveling wave of excitation takes advantage of the topography of interneuronal regions encoding synergies, to activate them in the proper sequence for locomotion.
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55
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Britz O, Zhang J, Grossmann KS, Dyck J, Kim JC, Dymecki S, Gosgnach S, Goulding M. A genetically defined asymmetry underlies the inhibitory control of flexor-extensor locomotor movements. eLife 2015; 4. [PMID: 26465208 PMCID: PMC4604447 DOI: 10.7554/elife.04718] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Accepted: 08/29/2015] [Indexed: 11/13/2022] Open
Abstract
V1 and V2b interneurons (INs) are essential for the production of an alternating flexor–extensor motor output. Using a tripartite genetic system to selectively ablate either V1 or V2b INs in the caudal spinal cord and assess their specific functions in awake behaving animals, we find that V1 and V2b INs function in an opposing manner to control flexor–extensor-driven movements. Ablation of V1 INs results in limb hyperflexion, suggesting that V1 IN-derived inhibition is needed for proper extension movements of the limb. The loss of V2b INs results in hindlimb hyperextension and a delay in the transition from stance phase to swing phase, demonstrating V2b INs are required for the timely initiation and execution of limb flexion movements. Our findings also reveal a bias in the innervation of flexor- and extensor-related motor neurons by V1 and V2b INs that likely contributes to their differential actions on flexion–extension movements. DOI:http://dx.doi.org/10.7554/eLife.04718.001 Although there are many different movements an animal can make with its limbs—from reaching to walking—they all basically involve two sets of muscles that act as opposing levers around each joint. ‘Flexor’ muscles contract to bend the limb, and ‘extensor’ muscles contract to extend the limb. When an animal is walking these two sets of muscles contract repeatedly, one after the other. Inhibitory neurons in the spinal cord coordinate these walking movements by preventing the flexor or extensor muscles from contracting at the same time. In 2014, researchers discovered that two groups of inhibitory neurons, known as the V1 and V2b interneurons, are essential for this alternating pattern of flexing and extending of the limbs of newborn mice. However, these experiments were not able to assess the particular contribution that the V1 and V2b neurons each make to limb movements. Now, Britz et al.—including several of the researchers involved in the 2014 study—have used a sophisticated genetic technique in mice to investigate the role that each group of neurons plays separately. This involved introducing a gene into either the V1 or V2b neurons that makes them susceptible to being killed with the diphtheria toxin. Injecting the mice with diphtheria toxin selectively removed these cells from the regions of the spinal cord that controls hindlimb movements. Britz et al. found that removing either group of neurons prevented the mice from walking normally. Eliminating the V1 neurons caused extreme flexing of the hindlimbs, revealing that the V1 neurons are needed to extend the limb by inhibiting the motor neurons that contract the flexor muscles. In contrast, the loss of V2b neurons caused exaggerated hindlimb extension, indicating that the V2b neurons inhibit the motor neurons that innervate extensor muscles. Both the V1 and V2b groups of neurons contain a wide range of different cell types. Future studies will therefore need to explore how these different cells are involved in coordinating the motions involved in walking. DOI:http://dx.doi.org/10.7554/eLife.04718.002
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Affiliation(s)
- Olivier Britz
- Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, La Jolla, United States
| | - Jingming Zhang
- Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, La Jolla, United States
| | - Katja S Grossmann
- Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, La Jolla, United States
| | - Jason Dyck
- Department of Physiology, University of Alberta, Edmonton, Canada
| | - Jun C Kim
- Department of Genetics, Harvard Medical School, Boston, United States
| | - Susan Dymecki
- Department of Genetics, Harvard Medical School, Boston, United States
| | - Simon Gosgnach
- Department of Physiology, University of Alberta, Edmonton, Canada
| | - Martyn Goulding
- Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, La Jolla, United States
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56
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Machado TA, Pnevmatikakis E, Paninski L, Jessell TM, Miri A. Primacy of Flexor Locomotor Pattern Revealed by Ancestral Reversion of Motor Neuron Identity. Cell 2015; 162:338-350. [PMID: 26186188 PMCID: PMC4540486 DOI: 10.1016/j.cell.2015.06.036] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Revised: 04/01/2015] [Accepted: 05/21/2015] [Indexed: 02/07/2023]
Abstract
Spinal circuits can generate locomotor output in the absence of sensory or descending input, but the principles of locomotor circuit organization remain unclear. We sought insight into these principles by considering the elaboration of locomotor circuits across evolution. The identity of limb-innervating motor neurons was reverted to a state resembling that of motor neurons that direct undulatory swimming in primitive aquatic vertebrates, permitting assessment of the role of motor neuron identity in determining locomotor pattern. Two-photon imaging was coupled with spike inference to measure locomotor firing in hundreds of motor neurons in isolated mouse spinal cords. In wild-type preparations, we observed sequential recruitment of motor neurons innervating flexor muscles controlling progressively more distal joints. Strikingly, after reversion of motor neuron identity, virtually all firing patterns became distinctly flexor like. Our findings show that motor neuron identity directs locomotor circuit wiring and indicate the evolutionary primacy of flexor pattern generation.
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Affiliation(s)
- Timothy A Machado
- Departments of Neuroscience and Biochemistry and Molecular Biophysics, Howard Hughes Medical Institute, Kavli Institute of Brain Science, Columbia University, New York, NY 10032, USA; Department of Statistics, Center for Theoretical Neuroscience and Grossman Center for the Statistics of Mind, Columbia University, New York, NY 10027, USA.
| | - Eftychios Pnevmatikakis
- Department of Statistics, Center for Theoretical Neuroscience and Grossman Center for the Statistics of Mind, Columbia University, New York, NY 10027, USA; Simons Center for Data Analysis, Simons Foundation, New York, NY 10010, USA
| | - Liam Paninski
- Department of Statistics, Center for Theoretical Neuroscience and Grossman Center for the Statistics of Mind, Columbia University, New York, NY 10027, USA
| | - Thomas M Jessell
- Departments of Neuroscience and Biochemistry and Molecular Biophysics, Howard Hughes Medical Institute, Kavli Institute of Brain Science, Columbia University, New York, NY 10032, USA.
| | - Andrew Miri
- Departments of Neuroscience and Biochemistry and Molecular Biophysics, Howard Hughes Medical Institute, Kavli Institute of Brain Science, Columbia University, New York, NY 10032, USA
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57
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Wang H, Liu NK, Zhang YP, Deng L, Lu QB, Shields CB, Walker MJ, Li J, Xu XM. Treadmill training induced lumbar motoneuron dendritic plasticity and behavior recovery in adult rats after a thoracic contusive spinal cord injury. Exp Neurol 2015; 271:368-78. [PMID: 26164199 DOI: 10.1016/j.expneurol.2015.07.004] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Revised: 07/01/2015] [Accepted: 07/04/2015] [Indexed: 12/17/2022]
Abstract
Spinal cord injury (SCI) is devastating, causing sensorimotor impairments and paralysis. Persisting functional limitations on physical activity negatively affect overall health in individuals with SCI. Physical training may improve motor function by affecting cellular and molecular responses of motor pathways in the central nervous system (CNS) after SCI. Although motoneurons form the final common path for motor output from the CNS, little is known concerning the effect of exercise training on spared motoneurons below the level of injury. Here we examined the effect of treadmill training on morphological, trophic, and synaptic changes in the lumbar motoneuron pool and on behavior recovery after a moderate contusive SCI inflicted at the 9th thoracic vertebral level (T9) using an Infinite Horizon (IH, 200 kDyne) impactor. We found that treadmill training significantly improved locomotor function, assessed by Basso-Beattie-Bresnahan (BBB) locomotor rating scale, and reduced foot drops, assessed by grid walking performance, as compared with non-training. Additionally, treadmill training significantly increased the total neurite length per lumbar motoneuron innervating the soleus and tibialis anterior muscles of the hindlimbs as compared to non-training. Moreover, treadmill training significantly increased the expression of a neurotrophin brain-derived neurotrophic factor (BDNF) in the lumbar motoneurons as compared to non-training. Finally, treadmill training significantly increased synaptic density, identified by synaptophysin immunoreactivity, in the lumbar motoneuron pool as compared to non-training. However, the density of serotonergic terminals in the same regions did not show a significant difference between treadmill training and non-training. Thus, our study provides a biological basis for exercise training as an effective medical practice to improve recovery after SCI. Such an effect may be mediated by synaptic plasticity, and neurotrophic modification in the spared lumbar motoneuron pool caudal to a thoracic contusive SCI.
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Affiliation(s)
- Hongxing Wang
- Department of Rehabilitation Medicine, First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu 210029, PR China; Spinal Cord and Brain Injury Research Group, Stark Neurosciences Research Institute, Department of Neurological Surgery, Goodman Campbell Brain and Spine, Indiana University School of Medicine, Indianapolis, IN 46202, United States
| | - Nai-Kui Liu
- Spinal Cord and Brain Injury Research Group, Stark Neurosciences Research Institute, Department of Neurological Surgery, Goodman Campbell Brain and Spine, Indiana University School of Medicine, Indianapolis, IN 46202, United States
| | - Yi Ping Zhang
- Norton Neuroscience Institute, Norton Healthcare, Louisville, KY 40202, United States
| | - Lingxiao Deng
- Spinal Cord and Brain Injury Research Group, Stark Neurosciences Research Institute, Department of Neurological Surgery, Goodman Campbell Brain and Spine, Indiana University School of Medicine, Indianapolis, IN 46202, United States
| | - Qing-Bo Lu
- Spinal Cord and Brain Injury Research Group, Stark Neurosciences Research Institute, Department of Neurological Surgery, Goodman Campbell Brain and Spine, Indiana University School of Medicine, Indianapolis, IN 46202, United States
| | - Christopher B Shields
- Norton Neuroscience Institute, Norton Healthcare, Louisville, KY 40202, United States
| | - Melissa J Walker
- Spinal Cord and Brain Injury Research Group, Stark Neurosciences Research Institute, Department of Neurological Surgery, Goodman Campbell Brain and Spine, Indiana University School of Medicine, Indianapolis, IN 46202, United States
| | - Jianan Li
- Department of Rehabilitation Medicine, First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu 210029, PR China.
| | - Xiao-Ming Xu
- Spinal Cord and Brain Injury Research Group, Stark Neurosciences Research Institute, Department of Neurological Surgery, Goodman Campbell Brain and Spine, Indiana University School of Medicine, Indianapolis, IN 46202, United States.
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58
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Buschmann T, Ewald A, von Twickel A, Büschges A. Controlling legs for locomotion-insights from robotics and neurobiology. BIOINSPIRATION & BIOMIMETICS 2015; 10:041001. [PMID: 26119450 DOI: 10.1088/1748-3190/10/4/041001] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Walking is the most common terrestrial form of locomotion in animals. Its great versatility and flexibility has led to many attempts at building walking machines with similar capabilities. The control of walking is an active research area both in neurobiology and robotics, with a large and growing body of work. This paper gives an overview of the current knowledge on the control of legged locomotion in animals and machines and attempts to give walking control researchers from biology and robotics an overview of the current knowledge in both fields. We try to summarize the knowledge on the neurobiological basis of walking control in animals, emphasizing common principles seen in different species. In a section on walking robots, we review common approaches to walking controller design with a slight emphasis on biped walking control. We show where parallels between robotic and neurobiological walking controllers exist and how robotics and biology may benefit from each other. Finally, we discuss where research in the two fields diverges and suggest ways to bridge these gaps.
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Affiliation(s)
- Thomas Buschmann
- Technische Universität München, Institute of Applied Mechanics, Boltzmannstrasse 15, D-85747 Garching, Germany
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59
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Mendelsohn AI, Simon CM, Abbott LF, Mentis GZ, Jessell TM. Activity Regulates the Incidence of Heteronymous Sensory-Motor Connections. Neuron 2015; 87:111-23. [PMID: 26094608 DOI: 10.1016/j.neuron.2015.05.045] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Revised: 04/23/2015] [Accepted: 05/26/2015] [Indexed: 12/19/2022]
Abstract
The construction of spinal sensory-motor circuits involves the selection of appropriate synaptic partners and the allocation of precise synaptic input densities. Many aspects of spinal sensory-motor selectivity appear to be preserved when peripheral sensory activation is blocked, which has led to a view that sensory-motor circuits are assembled in an activity-independent manner. Yet it remains unclear whether activity-dependent refinement has a role in the establishment of connections between sensory afferents and those motor pools that have synergistic biomechanical functions. We show here that genetically abolishing central sensory-motor neurotransmission leads to a selective enhancement in the number and density of such "heteronymous" connections, whereas other aspects of sensory-motor connectivity are preserved. Spike-timing-dependent synaptic refinement represents one possible mechanism for the changes in connectivity observed after activity blockade. Our findings therefore reveal that sensory activity does have a limited and selective role in the establishment of patterned monosynaptic sensory-motor connections.
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Affiliation(s)
- Alana I Mendelsohn
- Howard Hughes Medical Institute, Kavli Institute for Brain Science, Zuckerman Mind Brain Behavior Institute, Departments of Neuroscience and Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Christian M Simon
- Center for Motor Neuron Biology and Disease, Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA
| | - L F Abbott
- Center for Theoretical Neuroscience, Departments of Physiology and Neuroscience, Columbia University, New York, NY 10032, USA
| | - George Z Mentis
- Center for Motor Neuron Biology and Disease, Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA
| | - Thomas M Jessell
- Howard Hughes Medical Institute, Kavli Institute for Brain Science, Zuckerman Mind Brain Behavior Institute, Departments of Neuroscience and Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA.
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60
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Coscia M, Monaco V, Martelloni C, Rossi B, Chisari C, Micera S. Muscle synergies and spinal maps are sensitive to the asymmetry induced by a unilateral stroke. J Neuroeng Rehabil 2015; 12:39. [PMID: 25928264 PMCID: PMC4411739 DOI: 10.1186/s12984-015-0031-7] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Accepted: 04/10/2015] [Indexed: 01/20/2023] Open
Abstract
Background Previous studies have shown that a cerebrovascular accident disrupts the coordinated control of leg muscles during locomotion inducing asymmetric gait patterns. However, the ability of muscle synergies and spinal maps to reflect the redistribution of the workload between legs after the trauma has not been investigated so far. Methods To investigate this issue, twelve post-stroke and ten healthy participants were asked to walk on a treadmill at controlled speeds (0.5, 0.7, 0.9, 1.1 km/h), while the EMG activity of twelve leg muscles was recorded on both legs. The synergies underlying muscle activation and the estimated motoneuronal activity in the lumbosacral enlargement (L2-S2) were computed and compared between groups. Results Results showed that muscle synergies in the unaffected limb were significantly more comparable to those of the healthy control group than the ones in the affected side. Spinal maps were dissimilar between the affected and unaffected sides highlighting a significant shift of the foci of the activity toward the upper levels of the spinal cord in the unaffected leg. Conclusions Muscle synergies and spinal maps reflect the asymmetry as a motor deficit after stroke. However, further investigations are required to support or reject the hypothesis that the altered muscular organization highlighted by muscle synergies and spinal maps may be due to the concomitant contribution of the altered information coming from the upper part of the CNS, as resulting from the stroke, and to the abnormal sensory feedback due to the neuromuscular adaptation of the patients.
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Affiliation(s)
- Martina Coscia
- Translational Neural Engineering Laboratory, Center for Neuroprosthetics and School of Engineering, École Polytechnique Fédérale de Lausanne, BM 3210, Station 17, 1015, Lausanne, Switzerland. .,Neural Engineering Area, The BioRobotics Institute, Scuola Superiore Sant'Anna, Pisa, Italy.
| | - Vito Monaco
- Neural Engineering Area, The BioRobotics Institute, Scuola Superiore Sant'Anna, Pisa, Italy.
| | - Chiara Martelloni
- Neural Engineering Area, The BioRobotics Institute, Scuola Superiore Sant'Anna, Pisa, Italy.
| | - Bruno Rossi
- Neurorehabilitation Unit, Ospedale Cisanello, Pisa, Italy.
| | | | - Silvestro Micera
- Translational Neural Engineering Laboratory, Center for Neuroprosthetics and School of Engineering, École Polytechnique Fédérale de Lausanne, BM 3210, Station 17, 1015, Lausanne, Switzerland. .,Neural Engineering Area, The BioRobotics Institute, Scuola Superiore Sant'Anna, Pisa, Italy. .,Bertarelli Foundation Chair in Translational Neuroengineering, Center for Neuroprosthetics and Institute of Bioengineering, School of Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.
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61
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Sylos-Labini F, La Scaleia V, d'Avella A, Pisotta I, Tamburella F, Scivoletto G, Molinari M, Wang S, Wang L, van Asseldonk E, van der Kooij H, Hoellinger T, Cheron G, Thorsteinsson F, Ilzkovitz M, Gancet J, Hauffe R, Zanov F, Lacquaniti F, Ivanenko YP. EMG patterns during assisted walking in the exoskeleton. Front Hum Neurosci 2014; 8:423. [PMID: 24982628 PMCID: PMC4058900 DOI: 10.3389/fnhum.2014.00423] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Accepted: 05/27/2014] [Indexed: 12/30/2022] Open
Abstract
Neuroprosthetic technology and robotic exoskeletons are being developed to facilitate stepping, reduce muscle efforts, and promote motor recovery. Nevertheless, the guidance forces of an exoskeleton may influence the sensory inputs, sensorimotor interactions and resulting muscle activity patterns during stepping. The aim of this study was to report the muscle activation patterns in a sample of intact and injured subjects while walking with a robotic exoskeleton and, in particular, to quantify the level of muscle activity during assisted gait. We recorded electromyographic (EMG) activity of different leg and arm muscles during overground walking in an exoskeleton in six healthy individuals and four spinal cord injury (SCI) participants. In SCI patients, EMG activity of the upper limb muscles was augmented while activation of leg muscles was typically small. Contrary to our expectations, however, in neurologically intact subjects, EMG activity of leg muscles was similar or even larger during exoskeleton-assisted walking compared to normal overground walking. In addition, significant variations in the EMG waveforms were found across different walking conditions. The most variable pattern was observed in the hamstring muscles. Overall, the results are consistent with a non-linear reorganization of the locomotor output when using the robotic stepping devices. The findings may contribute to our understanding of human-machine interactions and adaptation of locomotor activity patterns.
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Affiliation(s)
- Francesca Sylos-Labini
- Laboratory of Neuromotor Physiology, Santa Lucia Foundation Rome, Italy ; Centre of Space Bio-medicine, University of Rome Tor Vergata Rome, Italy
| | - Valentina La Scaleia
- Laboratory of Neuromotor Physiology, Santa Lucia Foundation Rome, Italy ; Centre of Space Bio-medicine, University of Rome Tor Vergata Rome, Italy
| | - Andrea d'Avella
- Laboratory of Neuromotor Physiology, Santa Lucia Foundation Rome, Italy
| | - Iolanda Pisotta
- Spinal Cord Rehab Unit and CaRMA Lab, Santa Lucia Foundation Rome, Italy
| | | | - Giorgio Scivoletto
- Spinal Cord Rehab Unit and CaRMA Lab, Santa Lucia Foundation Rome, Italy
| | - Marco Molinari
- Spinal Cord Rehab Unit and CaRMA Lab, Santa Lucia Foundation Rome, Italy
| | - Shiqian Wang
- Biomechanical Engineering, Delft University of Technology Delft, Netherlands
| | - Letian Wang
- Biomechanical Engineering, University of Twente Enschede, Netherlands
| | | | - Herman van der Kooij
- Biomechanical Engineering, Delft University of Technology Delft, Netherlands ; Biomechanical Engineering, University of Twente Enschede, Netherlands
| | - Thomas Hoellinger
- Laboratory of Neurophysiology and Movement Biomechanics, Université Libre de Bruxelles Brussels, Belgium
| | - Guy Cheron
- Laboratory of Neurophysiology and Movement Biomechanics, Université Libre de Bruxelles Brussels, Belgium
| | | | | | - Jeremi Gancet
- Space Applications Services N.V./S.A. Zaventem, Belgium
| | | | | | - Francesco Lacquaniti
- Laboratory of Neuromotor Physiology, Santa Lucia Foundation Rome, Italy ; Centre of Space Bio-medicine, University of Rome Tor Vergata Rome, Italy ; Department of Systems Medicine, University of Rome Tor Vergata Rome, Italy
| | - Yuri P Ivanenko
- Laboratory of Neuromotor Physiology, Santa Lucia Foundation Rome, Italy
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La Scaleia V, Ivanenko YP, Zelik KE, Lacquaniti F. Spinal motor outputs during step-to-step transitions of diverse human gaits. Front Hum Neurosci 2014; 8:305. [PMID: 24860484 PMCID: PMC4030139 DOI: 10.3389/fnhum.2014.00305] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Accepted: 04/25/2014] [Indexed: 12/22/2022] Open
Abstract
Aspects of human motor control can be inferred from the coordination of muscles during movement. For instance, by combining multimuscle electromyographic (EMG) recordings with human neuroanatomy, it is possible to estimate alpha-motoneuron (MN) pool activations along the spinal cord. It has previously been shown that the spinal motor output fluctuates with the body's center-of-mass motion, with bursts of activity around foot-strike and foot lift-off during walking. However, it is not known whether these MN bursts are generalizable to other ambulation tasks, nor is it clear if the spatial locus of the activity (along the rostrocaudal axis of the spinal cord) is fixed or variable. Here we sought to address these questions by investigating the spatiotemporal characteristics of the spinal motor output during various tasks: walking forward, backward, tiptoe and uphill. We reconstructed spinal maps from 26 leg muscle EMGs, including some intrinsic foot muscles. We discovered that the various walking tasks shared qualitative similarities in their temporal spinal activation profiles, exhibiting peaks around foot-strike and foot-lift. However, we also observed differences in the segmental level and intensity of spinal activations, particularly following foot-strike. For example, forward level-ground walking exhibited a mean motor output roughly 2 times lower than the other gaits. Finally, we found that the reconstruction of the spinal motor output from multimuscle EMG recordings was relatively insensitive to the subset of muscles analyzed. In summary, our results suggested temporal similarities, but spatial differences in the segmental spinal motor outputs during the step-to-step transitions of disparate walking behaviors.
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Affiliation(s)
- Valentina La Scaleia
- Department of Systems Medicine, University of Rome Tor Vergata Rome, Italy ; Centre of Space Bio-medicine, University of Rome Tor Vergata Rome, Italy ; Laboratory of Neuromotor Physiology, Santa Lucia Foundation Rome, Italy
| | - Yuri P Ivanenko
- Laboratory of Neuromotor Physiology, Santa Lucia Foundation Rome, Italy
| | - Karl E Zelik
- Laboratory of Neuromotor Physiology, Santa Lucia Foundation Rome, Italy
| | - Francesco Lacquaniti
- Department of Systems Medicine, University of Rome Tor Vergata Rome, Italy ; Centre of Space Bio-medicine, University of Rome Tor Vergata Rome, Italy ; Laboratory of Neuromotor Physiology, Santa Lucia Foundation Rome, Italy
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63
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Kato H, Cuellar CA, Delgado-Lezama R, Rudomin P, Jimenez-Estrada I, Manjarrez E, Mirasso CR. Modeling zero-lag synchronization of dorsal horn neurons during the traveling of electrical waves in the cat spinal cord. Physiol Rep 2013; 1:e00021. [PMID: 24303110 PMCID: PMC3831917 DOI: 10.1002/phy2.21] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Accepted: 06/04/2013] [Indexed: 11/18/2022] Open
Abstract
The first electrophysiological evidence of the phenomenon of traveling electrical waves produced by populations of interneurons within the spinal cord was reported by our interdisciplinary research group. Two interesting observations derive from this study: first, the negative spontaneous cord dorsum potentials (CDPs) that are superimposed on the propagating sinusoidal electrical waves are not correlated with any scratching phase; second, these CDPs do not propagate along the lumbosacral spinal segments, but they appear almost simultaneously at different spinal segments. The aim of this study was to provide experimental data and a mathematical model to explain the simultaneous occurrence of traveling waves and the zero-lag synchronization of some CDPs.
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Affiliation(s)
- Hideyuki Kato
- Instituto de Física Interdisciplinar y Sistemas Complejos (IFISC, UIB-CSIC), Campus Universitat de les Illes Balears E-07122, Palma de Mallorca, Spain
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64
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Holinski BJ, Everaert DG, Mushahwar VK, Stein RB. Real-time control of walking using recordings from dorsal root ganglia. J Neural Eng 2013; 10:056008. [PMID: 23928579 DOI: 10.1088/1741-2560/10/5/056008] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE The goal of this study was to decode sensory information from the dorsal root ganglia (DRG) in real time, and to use this information to adapt the control of unilateral stepping with a state-based control algorithm consisting of both feed-forward and feedback components. APPROACH In five anesthetized cats, hind limb stepping on a walkway or treadmill was produced by patterned electrical stimulation of the spinal cord through implanted microwire arrays, while neuronal activity was recorded from the DRG. Different parameters, including distance and tilt of the vector between hip and limb endpoint, integrated gyroscope and ground reaction force were modelled from recorded neural firing rates. These models were then used for closed-loop feedback. MAIN RESULTS Overall, firing-rate-based predictions of kinematic sensors (limb endpoint, integrated gyroscope) were the most accurate with variance accounted for >60% on average. Force prediction had the lowest prediction accuracy (48 ± 13%) but produced the greatest percentage of successful rule activations (96.3%) for stepping under closed-loop feedback control. The prediction of all sensor modalities degraded over time, with the exception of tilt. SIGNIFICANCE Sensory feedback from moving limbs would be a desirable component of any neuroprosthetic device designed to restore walking in people after a spinal cord injury. This study provides a proof-of-principle that real-time feedback from the DRG is possible and could form part of a fully implantable neuroprosthetic device with further development.
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Affiliation(s)
- B J Holinski
- Department of Biomedical Engineering, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
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65
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Changes in the spinal segmental motor output for stepping during development from infant to adult. J Neurosci 2013; 33:3025-36a. [PMID: 23407959 DOI: 10.1523/jneurosci.2722-12.2013] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Human stepping movements emerge in utero and show several milestones during development to independent walking. Recently, imaging has become an essential tool for investigating the development and function of pattern generation networks in the spinal cord. Here we examine the development of the spinal segmental output by mapping the distribution of motoneuron activity in the lumbosacral spinal cord during stepping in newborns, toddlers, preschoolers, and adults. Newborn stepping is characterized by an alternating bilateral motor output with only two major components that are active at all lumbosacral levels of the spinal cord. This feature was similar across different cycle durations of neonate stepping. The alternating spinal motor output is consistent with a simpler organization of neuronal networks in neonates. Furthermore, a remarkable feature of newborn stepping is a higher overall activation of lumbar versus sacral segments, consistent with a rostrocaudal excitability gradient. In toddlers, the stance-related motor pool activity migrates to the sacral cord segments, while the lumbar motoneurons are separately activated at touchdown. In the adult, the lumbar and sacral patterns become more dissociated with shorter activation times. We conclude that the development of human locomotion from the neonate to the adult starts from a rostrocaudal excitability gradient and involves a gradual functional reorganization of the pattern generation circuitry.
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66
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Arle JE, Shils JL, Malik WQ. Localized stimulation and recording in the spinal cord with microelectrode arrays. 2012 ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY 2012; 2012:1851-4. [PMID: 23366273 DOI: 10.1109/embc.2012.6346312] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Jeffrey E Arle
- Lahey Clinic, Tufts University School of Medicine, Burlington, MA, USA.
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67
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Spatial organization of cortical and spinal neurons controlling motor behavior. Curr Opin Neurobiol 2012; 22:812-21. [PMID: 22841417 DOI: 10.1016/j.conb.2012.07.002] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Revised: 07/04/2012] [Accepted: 07/06/2012] [Indexed: 11/21/2022]
Abstract
A major task of the central nervous system (CNS) is to control behavioral actions, which necessitates a precise regulation of muscle activity. The final components of the circuitry controlling muscles are the motorneurons, which settle into pools in the ventral horn of the spinal cord in positions that mirror the musculature organization within the body. This 'musculotopic' motor-map then becomes the internal CNS reference for the neuronal circuits that control motor commands. This review describes recent progress in defining the neuroanatomical organization of the higher-order motor circuits in the cortex and spinal cord, and our current understanding of the integrative features that contribute to complex motor behaviors. We highlight emerging evidence that cortical and spinal motor command centers are loosely organized with respect to the musculotopic spatial-map, but these centers also incorporate organizational features that associate with the function of different muscle groups during commonly enacted behaviors.
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68
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Coscia M, Monaco V, Capogrosso M, Chisari C, Micera S. Computational aspects of MN activity estimation: a case study with post-stroke subjects. IEEE Int Conf Rehabil Robot 2012; 2011:5975405. [PMID: 22275608 DOI: 10.1109/icorr.2011.5975405] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Spinal circuits play an important role in the generation of rhythmic motor activity, intermediating between descending signals and peripheral sensory information. The study of these circuits can provide a better understanding of the control mechanisms during the execution of cyclic motor tasks in healthy subjects or in patients with motor deficits due to a neurological disease. This work shows preliminary results regarding the estimation of spinal cord activity of post-stroke subjects obtained from the EMG signals by improving the computational model. This new model allows a better quantitative evaluation of motor performance in clinical contexts.
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Affiliation(s)
- Martina Coscia
- The BioRobotics Institute, Scuola Superiore Sant’Anna, Pisa, Italy.
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69
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Neurophysiological characterization of the New Anatomy and motor control that results from neurological injury or disease. Clin Neurol Neurosurg 2012; 114:447-54. [DOI: 10.1016/j.clineuro.2012.01.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2011] [Revised: 01/10/2012] [Accepted: 01/11/2012] [Indexed: 12/14/2022]
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70
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Sousa ASP, Santos R, Oliveira FPM, Carvalho P, Tavares JMRS. Analysis of ground reaction force and electromyographic activity of the gastrocnemius muscle during double support. Proc Inst Mech Eng H 2012; 226:397-405. [DOI: 10.1177/0954411912439671] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Mechanisms associated with energy expenditure during gait have been extensively researched and studied. According to the double-inverted pendulum model energy expenditure is higher during double support, as lower limbs need to work to redirect the centre of mass velocity. This study looks into how the ground reaction force of one limb affects the muscle activity required by the medial gastrocnemius of the contralateral limb during step-to-step transition. Thirty-five subjects were monitored as to the medial gastrocnemius electromyographic activity of one limb and the ground reaction force of the contralateral limb during double support. After determination of the Pearson correlation coefficient (r), a moderate correlation was observed between the medial gastrocnemius electromyographic activity of the dominant leg and the vertical (Fz) and anteroposterior (Fy) components of ground reaction force of the non-dominant leg (r = 0.797, p < 0.0001; r = –0.807, p < 0.0001). A weak and moderate correlation was observed between the medial gastrocnemius electromyographic activity of the non-dominant leg and the Fz and Fy of the dominant leg, respectively (r = 0.442, p = 0.018; r = –0.684 p < 0.0001). The results obtained suggest that during double support, ground reaction force is associated with the electromyographic activity of the contralateral medial gastrocnemius and that there is an increased dependence between the ground reaction force of the non-dominant leg and the electromyographic activity of the dominant medial gastrocnemius.
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Affiliation(s)
- Andreia SP Sousa
- Área Científica de Fisioterapia, Centro de Estudos de Movimento e Actividade Humana, Escola Superior de Tecnologia da Saúde do Porto, Instituto de Engenharia Mecânica e Gestão Industrial, Faculdade de Engenharia, Universidade do Porto, Portugal
| | - Rubim Santos
- Departamento de Física, Centro de Estudos de Movimento e Actividade Humana, Escola Superior de Tecnologia da Saúde do Porto, Portugal
| | - Francisco PM Oliveira
- Instituto de Engenharia Mecânica e Gestão Industrial, Faculdade de Engenharia, Universidade do Porto, Portugal
| | - Paulo Carvalho
- Departamento de Fisioterapia, Centro de Estudos de Movimento e Actividade Humana, Escola Superior de Tecnologia da Saúde do Porto, Portugal
| | - João Manuel RS Tavares
- Instituto de Engenharia Mecânica e Gestão Industrial, Faculdade de Engenharia, Universidade do Porto, Portugal
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71
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A perimotor framework reveals functional segmentation in the motoneuronal network controlling locomotion in Caenorhabditis elegans. J Neurosci 2011; 31:14611-23. [PMID: 21994377 DOI: 10.1523/jneurosci.2186-11.2011] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The neuronal connectivity dataset of the nematode Caenorhabditis elegans attracts wide attention from computational neuroscientists and experimentalists. However, the dataset is incomplete. The ventral and dorsal nerve cords of a single nematode were reconstructed halfway along the body and the posterior data are missing, leaving 21 of 75 motoneurons of the locomotor network with partial or no connectivity data. Using a new framework for network analysis, the perimotor space, we identified rules of connectivity that allowed us to approximate the missing data by extrapolation. Motoneurons were mapped into perimotor space in which each motoneuron is located according to the muscle cells it innervates. In this framework, a pattern of iterative connections emerges which includes most (0.90) of the connections. We identified a repeating unit consisting of 12 motoneurons and 12 muscle cells. The cell bodies of the motoneurons of such a unit are not necessarily anatomical neighbors and there is no obvious anatomical segmentation. A connectivity model, composed of six repeating units, is a description of the network that is both simplified (modular and without noniterative connections) and more complete (includes the posterior part) than the original dataset. The perimotor framework of observed connectivity and the segmented connectivity model give insights and advance the study of the neuronal infrastructure underlying locomotion in C. elegans. Furthermore, we suggest that the tools used herein may be useful to interpret, simplify, and represent connectivity data of other motor systems.
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72
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Dominici N, Ivanenko YP, Cappellini G, d'Avella A, Mondì V, Cicchese M, Fabiano A, Silei T, Di Paolo A, Giannini C, Poppele RE, Lacquaniti F. Locomotor Primitives in Newborn Babies and Their Development. Science 2011; 334:997-9. [PMID: 22096202 DOI: 10.1126/science.1210617] [Citation(s) in RCA: 415] [Impact Index Per Article: 31.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- Nadia Dominici
- Laboratory of Neuromotor Physiology, IRCCS Santa Lucia Foundation, Rome, Italy
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73
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Tripodi M, Stepien AE, Arber S. Motor antagonism exposed by spatial segregation and timing of neurogenesis. Nature 2011; 479:61-6. [DOI: 10.1038/nature10538] [Citation(s) in RCA: 177] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Accepted: 09/02/2011] [Indexed: 11/09/2022]
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74
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Maclellan MJ, Ivanenko YP, Cappellini G, Sylos Labini F, Lacquaniti F. Features of hand-foot crawling behavior in human adults. J Neurophysiol 2011; 107:114-25. [PMID: 21975454 DOI: 10.1152/jn.00693.2011] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Interlimb coordination of crawling kinematics in humans shares features with other primates and nonprimate quadrupeds, and it has been suggested that this is due to a similar organization of the locomotor pattern generators (CPGs). To extend the previous findings and to further explore the neural control of bipedal vs. quadrupedal locomotion, we used a crawling paradigm in which healthy adults crawled on their hands and feet at different speeds and at different surface inclinations (13°, 27°, and 35°). Ground reaction forces, limb kinematics, and electromyographic (EMG) activity from 26 upper and lower limb muscles on the right side of the body were collected. The EMG activity was mapped onto the spinal cord in approximate rostrocaudal locations of the motoneuron pools to characterize the general features of cervical and lumbosacral spinal cord activation. The spatiotemporal pattern of spinal cord activity significantly differed between quadrupedal and bipedal gaits. In addition, participants exhibited a large range of kinematic coordination styles (diagonal vs. lateral patterns), which is in contrast to the stereotypical kinematics of upright bipedal walking, suggesting flexible coupling of cervical and lumbosacral pattern generators. Results showed strikingly dissimilar directional horizontal forces for the arms and legs, considerably retracted average leg orientation, and substantially smaller sacral vs. lumbar motoneuron activity compared with quadrupedal gait in animals. A gradual transition to a more vertical body orientation (increasing the inclination of the treadmill) led to the appearance of more prominent sacral activity (related to activation of ankle plantar flexors), typical of bipedal walking. The findings highlight the reorganization and adaptation of CPG networks involved in the control of quadrupedal human locomotion and a high specialization of the musculoskeletal apparatus to specific gaits.
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Affiliation(s)
- M J Maclellan
- Laboratory of Neuromotor Physiology, IRCCS Fondazione Santa Lucia, 306 via Ardeatina, 00179 Rome, Italy.
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75
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Auyong N, Ollivier-Lanvin K, Lemay MA. Population spatiotemporal dynamics of spinal intermediate zone interneurons during air-stepping in adult spinal cats. J Neurophysiol 2011; 106:1943-53. [PMID: 21775722 DOI: 10.1152/jn.00258.2011] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The lumbar spinal cord circuitry can autonomously generate locomotion, but it remains to be determined which types of neurons constitute the locomotor generator and how their population activity is organized spatially in the mammalian spinal cord. In this study, we investigated the spatiotemporal dynamics of the spinal interneuronal population activity in the intermediate zone of the adult mammalian cord. Segmental interneuronal population activity was examined via multiunit activity (MUA) during air-stepping initiated by perineal stimulation in subchronic spinal cats. In contrast to single-unit activity, MUA provides a continuous measure of neuronal activity within a ∼100-μm volume around the recording electrode. MUA was recorded during air-stepping, along with hindlimb muscle activity, from segments L3 to L7 with two multichannel electrode arrays placed into the left and right hemicord intermediate zones (lamina V-VII). The phasic modulation and spatial organization of MUA dynamics were examined in relation to the locomotor cycle. Our results show that segmental population activity is modulated with respect to the ipsilateral step cycle during air-stepping, with maximal activity occurring near the ipsilateral swing to stance transition period. The phase difference between the population activity within the left and right hemicords was also found to correlate to the left-right alternation of the step cycle. Furthermore, examination of MUA throughout the rostrocaudal extent showed no differences in population dynamics between segmental levels, suggesting that the spinal interneurons targeted in this study may operate as part of a distributed "clock" mechanism rather than a rostrocaudal oscillation as seen with motoneuronal activity.
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Affiliation(s)
- Nicholas Auyong
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania, USA
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76
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English AW, Wilhelm JC, Sabatier MJ. Enhancing recovery from peripheral nerve injury using treadmill training. Ann Anat 2011; 193:354-61. [PMID: 21498059 PMCID: PMC3137663 DOI: 10.1016/j.aanat.2011.02.013] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2010] [Revised: 02/03/2011] [Accepted: 02/22/2011] [Indexed: 12/25/2022]
Abstract
Full functional recovery after traumatic peripheral nerve injury is rare. We postulate three reasons for the poor functional outcome measures observed. Axon regeneration is slow and not all axons participate. Significant misdirection of regenerating axons to reinnervate inappropriate targets occurs. Seemingly permanent changes in neural circuitry in the central nervous system are found to accompany axotomy of peripheral axons. Exercise in the form of modest daily treadmill training impacts all three of these areas. Compared to untrained controls, regenerating axons elongate considerably farther in treadmill trained animals and do so via an autocrine/paracrine neurotrophin signaling pathway. This enhancement of axon regeneration takes place without an increase in the amount of misdirection of regenerating axons found without training. The enhancement also occurs in a sex-dependent manner. Slow continuous training is effective only in males, while more intense interval training is effective only in females. In treadmill trained, but not untrained mice the extent of coverage of axotomized motoneurons is maintained, thus preserving important elements of the spinal circuitry.
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Affiliation(s)
- Arthur W English
- Department of Cell Biology, Emory University School of Medicine, 615 Michael Street, Atlanta, GA 30322, USA.
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Sabatier MJ, To BN, Nicolini J, English AW. Effect of slope and sciatic nerve injury on ankle muscle recruitment and hindlimb kinematics during walking in the rat. ACTA ACUST UNITED AC 2011; 214:1007-16. [PMID: 21346129 DOI: 10.1242/jeb.051508] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Slope-related differences in hindlimb movements and activation of the soleus and tibialis anterior muscles were studied during treadmill locomotion in intact rats and in rats 4 and 10 weeks following transection and surgical repair of the sciatic nerve. In intact rats, the tibialis anterior and soleus muscles were activated reciprocally at all slopes, and the overall intensity of activity in tibialis anterior and the mid-step activity in soleus increased with increasing slope. Based on the results of principal components analysis, the pattern of activation of soleus, but not of tibialis anterior, changed significantly with slope. Slope-related differences in hindlimb kinematics were found in intact rats, and these correlated well with the demands of walking up or down slopes. Following recovery from sciatic nerve injury, the soleus and tibialis anterior were co-activated throughout much of the step cycle and there was no difference in intensity or pattern of activation with slope for either muscle. Unlike intact rats, these animals walked with their feet flat on the treadmill belt through most of the stance phase. Even so, during downslope walking limb length and limb orientation throughout the step cycle were not significantly changed from values found in intact rats. This conservation of hindlimb kinematics was not observed during level or upslope walking. These findings are interpreted as evidence that the recovering animals adopt a novel locomotor strategy that involves stiffening of the ankle joint by antagonist co-activation and compensation at more proximal joints. Their movements are most suitable to the requirements of downslope walking but the recovering rats lack the ability to adapt to the demands of level or upslope walking.
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Affiliation(s)
- Manning J Sabatier
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA.
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78
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Bouyer LJ. Chapter 8--challenging the adaptive capacity of rhythmic movement control: from denervation to force field adaptation. PROGRESS IN BRAIN RESEARCH 2011; 188:119-34. [PMID: 21333806 DOI: 10.1016/b978-0-444-53825-3.00013-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The neural control of walking involves voluntary descending drive, automatic rhythm and pattern-generating circuits, and sensory feedback to produce appropriate motor output. This control system has to be both robust and adaptable to remain appropriately calibrated to the changes in body size and in environmental demands that occur throughout life. In this chapter, current experimental models that are used to study the adaptive capacity of rhythmic movement control will be presented. Overall, while walking is a complex movement requiring extremely well-timed muscle activation sequences, and considering the presence of automatic rhythm generating circuits, its neural control nevertheless shows a large potential for adaptive modification. Regardless if the need for motor output modification is of internal (e.g., denervations) or external (e.g., changes in environment dynamics) origin, the system copes with the challenge rapidly and efficiently. Neural structures involved in adaptation are distributed, and even reduced preparations such as low spinal cats show extensive adaptive capacity. The degree of adaptive capacity is not unlimited, however. Functional flexors cannot be turned into extensors, and vice versa. In addition, recent evidence suggest that adaptive capacity may be dependent on the timing in the movement where adaptation is required (phase dependency), some phases being more amendable to change than others. Clearly, while important progress has been achieved using denervations and motor adaptation protocols, many questions remain to be answered regarding the mechanisms underlying adaptation and retention of adapted motor output, as well as regarding how sensory inputs are used to trigger adaptation. Recent advances in robotics, together with the design of simple, yet clever protocols such as catch trials are very promising tools to provide more answers.
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Affiliation(s)
- Laurent J Bouyer
- Center for Interdisciplinary Research in Rehabilitation and Social Integration (CIRRIS), Department of Rehabilitation, Université Laval, Quebec, Canada
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79
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AuYong N, Ollivier-Lanvin K, Lemay MA. Preferred locomotor phase of activity of lumbar interneurons during air-stepping in subchronic spinal cats. J Neurophysiol 2010; 105:1011-22. [PMID: 21084683 DOI: 10.1152/jn.00523.2010] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Spinal locomotor circuits are intrinsically capable of driving a variety of behaviors such as stepping, scratching, and swimming. Based on an observed rostrocaudal wave of activity in the motoneuronal firing during locomotor tasks, the traveling-wave hypothesis proposes that spinal interneuronal firing follows a similar rostrocaudal pattern of activation, suggesting the presence of spatially organized interneuronal modules within the spinal motor system. In this study, we examined if the spatial organization of the lumbar interneuronal activity patterns during locomotor activity in the adult mammalian spinal cord was consistent with a traveling-wave organizational scheme. The activity of spinal interneurons within the lumbar intermediate zone was examined during air-stepping in subchronic spinal cats. The preferred phase of interneuronal activity during a step cycle was determined using circular statistics. We found that the preferred phases of lumbar interneurons from both sides of the cord were evenly distributed over the entire step cycle with no indication of functional groupings. However, when units were subcategorized according to spinal hemicords, the preferred phases of units on each side largely fell around the period of extensor muscle activity on each side. In addition, there was no correlation between the preferred phases of units and their rostrocaudal locations along the spinal cord with preferred phases corresponding to both flexion and extension phases of the step cycle found at every rostrocaudal level of the cord. These results are consistent with the hypothesis that interneurons operate as part of a longitudinally distributed network rather than a rostrocaudally organized traveling-wave network.
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Affiliation(s)
- Nicholas AuYong
- Drexel University College of Medicine, Department of Neurobiology and Anatomy, 2900 W. Queen Lane, Philadelphia, PA 19129, USA
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80
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Cappellini G, Ivanenko YP, Dominici N, Poppele RE, Lacquaniti F. Migration of motor pool activity in the spinal cord reflects body mechanics in human locomotion. J Neurophysiol 2010; 104:3064-73. [PMID: 20881204 DOI: 10.1152/jn.00318.2010] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
During the evolution of bipedal modes of locomotion, a sequential rostrocaudal activation of trunk muscles due to the undulatory body movements was replaced by more complex and discrete bursts of activity. Nevertheless, the capacity for segmental rhythmogenesis and the rostrocaudal propagation of spinal cord activity has been conserved. In humans, motoneurons of different muscles are arranged in columns, with a specific grouping of muscles at any given segmental level. The muscle patterns of locomotor activity and the biomechanics of the body center of mass have been studied extensively, but their interrelationship remains poorly understood. Here we mapped the electromyographic activity recorded from 30 bilateral leg muscles onto the spinal cord in approximate rostrocaudal locations of the motoneuron pools during walking and running in humans. We found that the rostrocaudal displacements of the center of bilateral motoneuron activity mirrored the changes in the energy due to the center-of-body mass motion. The results suggest that biomechanical mechanisms of locomotion, such as the inverted pendulum in walking and the pogo-stick bouncing in running, may be tightly correlated with specific modes of progression of motor pool activity rostrocaudally in the spinal cord.
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Affiliation(s)
- Germana Cappellini
- Laboratory of Neuromotor Physiology, IRCCS Fondazione Santa Lucia, 306 via Ardeatina, 00179 Rome, Italy
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81
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Monaco V, Ghionzoli A, Micera S. Age-related modifications of muscle synergies and spinal cord activity during locomotion. J Neurophysiol 2010; 104:2092-102. [PMID: 20685924 DOI: 10.1152/jn.00525.2009] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Recent findings have shown that neural circuits located in the spinal cord drive muscular activations during locomotion while intermediating between descending signals and peripheral sensory information. This relationship could be modified by the natural aging process. To address this issue, the activity of 12 ipsilateral leg muscles was analyzed in young and elderly people (7 subjects per group) while walking at six different cadences (40-140 steps/min). These signals were used to extract synergies underlying muscle activation and to map the motoneuronal activity of the pools belonging to the lumbosacral enlargement (L(2)-S(2)). The comparison between the two groups showed that neither temporal patterning of motor primitives nor muscles loading synergies seemed to be significantly affected by aging. Conversely, as the cadence increased, spinal maps differ significantly between the groups, showing higher and scattered activity during the whole gait cycle in elders and well-defined bursts in young subjects. The results suggested that motor primitives lead the synchronization of muscle activation mainly depending on the biomechanical demand of the locomotion; hence they are not significantly affected by aging. Nevertheless, at the spinal cord level, biomechanical requirements, peripheral afference, and descending inputs are differently integrated between the two groups, probably reflecting age-related changes of both nervous system and motor control strategies during locomotion.
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Affiliation(s)
- Vito Monaco
- Advanced Robotics Technology and System Laboratory, Scuola Superiore Sant'Anna, Pisa, Italy
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82
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Cappellini G, Ivanenko YP, Dominici N, Poppele RE, Lacquaniti F. Motor patterns during walking on a slippery walkway. J Neurophysiol 2009; 103:746-60. [PMID: 19955283 DOI: 10.1152/jn.00499.2009] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Friction and gravity represent two basic physical constraints of terrestrial locomotion that affect both motor patterns and the biomechanics of bipedal gait. To provide insights into the spatiotemporal organization of the motor output in connection with ground contact forces, we studied adaptation of human gait to steady low-friction conditions. Subjects walked along a slippery walkway (7 m long; friction coefficient approximately 0.06) or a normal, nonslippery floor at a natural speed. We recorded gait kinematics, ground reaction forces, and bilateral electromyographic (EMG) activity of 16 leg and trunk muscles and we mapped the recorded EMG patterns onto the spinal cord in approximate rostrocaudal locations of the motoneuron (MN) pools to characterize the spatiotemporal organization of the motor output. The results revealed several idiosyncratic features of walking on the slippery surface. The step length, cycle duration, and horizontal shear forces were significantly smaller, the head orientation tended to be stabilized in space, whereas arm movements, trunk rotations, and lateral trunk inclinations considerably increased and foot motion and gait kinematics resembled those of a nonplantigrade gait. Furthermore, walking on the slippery surface required stabilization of the hip and of the center-of-body mass in the frontal plane, which significantly improved with practice. Motor patterns were characterized by an enhanced (roughly twofold) level of MN activity, substantial decoupling of anatomical synergists, and the absence of systematic displacements of the center of MN activity in the lumbosacral enlargement. Overall, the results show that when subjects are confronted with unsteady surface conditions, like the slippery floor, they adopt a gait mode that tends to keep the COM centered over the supporting limbs and to increase limb stiffness. We suggest that this behavior may represent a distinct gait mode that is particularly suited to uncertain surface conditions in general.
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Affiliation(s)
- Germana Cappellini
- Laboratory of Neuromotor Physiology, Scientific Institute Foundation Santa Lucia, 00179 Rome, Italy.
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83
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Musienko P, van den Brand R, Maerzendorfer O, Larmagnac A, Courtine G. Combinatory Electrical and Pharmacological Neuroprosthetic Interfaces to Regain Motor Function After Spinal Cord Injury. IEEE Trans Biomed Eng 2009; 56:2707-11. [PMID: 19635690 DOI: 10.1109/tbme.2009.2027226] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Pavel Musienko
- Experimental Neurorehabilitation Laboratory, Department of Neurology, University of Zurich, CH-8006 Zurich, Switzerland.
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84
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Pérez T, Tapia JA, Mirasso CR, García-Ojalvo J, Quevedo J, Cuellar CA, Manjarrez E. An intersegmental neuronal architecture for spinal wave propagation under deletions. J Neurosci 2009; 29:10254-63. [PMID: 19692599 PMCID: PMC6665792 DOI: 10.1523/jneurosci.1737-09.2009] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2009] [Revised: 07/09/2009] [Accepted: 07/13/2009] [Indexed: 11/21/2022] Open
Abstract
Recent studies have established and characterized the propagation of traveling electrical waves along the cat spinal cord during scratching, but the neuronal architecture that allows for the persistence of such waves even during periods of absence of bursts of motoneuron activity (deletions) is still unclear. Here we address this problem both theoretically and experimentally. Specifically, we monitored during long lasting periods of time the global electrical activity of spinal neurons during scratching. We found clear deletions of unaltered cycle in extensor activity without associated deletions of the traveling spinal wave. Furthermore, we also found deletions with a perturbed cycle associated with a concomitant absence of the traveling spinal wave. Numerical simulations of an asymmetric two-layer model of a central-pattern generator distributed longitudinally along the spinal cord qualitatively reproduce the sinusoidal traveling waves, and are able to replicate both classes of deletions. We believe these findings shed light into the longitudinal organization of the central-pattern generator networks in the spinal cord.
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Affiliation(s)
- Toni Pérez
- Instituto de Física Interdisciplinar y Sistemas Complejos, Consejo Superior de Investigaciones Científicas-Universidad de las Islas Baleares, Campus Universitat de les Illes Balears, E-07122 Palma de Mallorca, Spain
| | - Jesus A. Tapia
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, CP 72570 Puebla, Mexico
| | - Claudio R. Mirasso
- Instituto de Física Interdisciplinar y Sistemas Complejos, Consejo Superior de Investigaciones Científicas-Universidad de las Islas Baleares, Campus Universitat de les Illes Balears, E-07122 Palma de Mallorca, Spain
| | - Jordi García-Ojalvo
- Departament de Física i Enginyeria Nuclear, Universitat Politècnica de Catalunya, E-08222 Terrassa, Spain
| | - Jorge Quevedo
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados, CP 07360 Distrito Federal, Mexico, and
| | - Carlos A. Cuellar
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, CP 72570 Puebla, Mexico
| | - Elias Manjarrez
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, CP 72570 Puebla, Mexico
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85
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Kim H, Major LA, Jones KE. Derivation of cable parameters for a reduced model that retains asymmetric voltage attenuation of reconstructed spinal motor neuron dendrites. J Comput Neurosci 2009; 27:321-36. [PMID: 19387812 DOI: 10.1007/s10827-009-0145-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2008] [Revised: 02/18/2009] [Accepted: 02/25/2009] [Indexed: 02/04/2023]
Abstract
Spinal motor neurons have voltage gated ion channels localized in their dendrites that generate plateau potentials. The physical separation of ion channels for spiking from plateau generating channels can result in nonlinear bistable firing patterns. The physical separation and geometry of the dendrites results in asymmetric coupling between dendrites and soma that has not been addressed in reduced models of nonlinear phenomena in motor neurons. We measured voltage attenuation properties of six anatomically reconstructed and type-identified cat spinal motor neurons to characterize asymmetric coupling between the dendrites and soma. We showed that the voltage attenuation at any distance from the soma was direction-dependent and could be described as a function of the input resistance at the soma. An analytical solution for the lumped cable parameters in a two-compartment model was derived based on this finding. This is the first two-compartment modeling approach that directly derived lumped cable parameters from the geometrical and passive electrical properties of anatomically reconstructed neurons.
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Affiliation(s)
- Hojeong Kim
- Department of Biomedical Engineering, University of Alberta, Edmonton, AB T6G 2V2, Canada
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86
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Propagation of sinusoidal electrical waves along the spinal cord during a fictive motor task. J Neurosci 2009; 29:798-810. [PMID: 19158305 DOI: 10.1523/jneurosci.3408-08.2009] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We present for the first time direct electrophysiological evidence of the phenomenon of traveling electrical waves produced by populations of interneurons within the spinal cord. We show that, during a fictive rhythmic motor task, scratching, an electrical field potential of spinal interneurons takes the shape of a sinuous wave, "sweeping" the lumbosacral spinal cord rostrocaudally with a mean speed of approximately 0.3 m/s. We observed that traveling waves and scratching have the same cycle duration and that duration of the flexor phase, but not of the extensor phase, is highly correlated with the cycle duration of the traveling waves. Furthermore, we found that the interneurons from the deep dorsal horn and the intermediate nucleus can generate the spinal traveling waves, even in the absence of motoneuronal activity. These findings show that the sinusoidal field potentials generated during fictive scratching could be a powerful tool to disclose the organization of central pattern generator networks.
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87
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Ivanenko YP, Cappellini G, Poppele RE, Lacquaniti F. Spatiotemporal organization of alpha-motoneuron activity in the human spinal cord during different gaits and gait transitions. Eur J Neurosci 2008; 27:3351-68. [PMID: 18598271 DOI: 10.1111/j.1460-9568.2008.06289.x] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Here we studied the spatiotemporal organization of motoneuron (MN) activity during different human gaits. We recorded the electromyographic (EMG) activity patterns in 32 ipsilateral limb and trunk muscles from normal subjects while running and walking on a treadmill (3-12 km/h). In addition, we recorded backward walking and skipping, a distinct human gait that comprises the features of both walking and running. We mapped the recorded EMG activity patterns onto the spinal cord in approximate rostrocaudal locations of the MN pools. The activation of MNs tends to occur in bursts and be segregated by spinal segment in a gait-specific manner. In particular, sacral and cervical activation timings were clearly gait-dependent. Swing-related activity constituted an appreciable fraction (> 30%) of the total MN activity of leg muscles. Locomoting at non-preferred speeds (running and walking at 5 and 9 km/h, respectively) showed clear differences relative to preferred speeds. Running at low speeds was characterized by wider sacral activation. Walking at high non-preferred speeds was accompanied by an 'atypical' locus of activation in the upper lumbar spinal cord during late stance and by a drastically increased activation of lumbosacral segments. The latter findings suggest that the optimal speed of gait transitions may be related to an optimal intensity of the total MN activity, in addition to other factors previously described. The results overall support the idea of flexibility and adaptability of spatiotemporal activity in the spinal circuitry with constraints on the temporal functional connectivity of hypothetical pulsatile burst generators.
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Affiliation(s)
- Y P Ivanenko
- Department of Neuromotor Physiology, Scientific Institute Foundation Santa Lucia, 306 via Ardeatina, 00179 Rome, Italy.
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88
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O'Donovan MJ, Bonnot A, Mentis GZ, Arai Y, Chub N, Shneider NA, Wenner P. Imaging the spatiotemporal organization of neural activity in the developing spinal cord. Dev Neurobiol 2008; 68:788-803. [PMID: 18383543 DOI: 10.1002/dneu.20620] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
In this review, we discuss the use of imaging to visualize the spatiotemporal organization of network activity in the developing spinal cord of the chick embryo and the neonatal mouse. We describe several different methods for loading ion- and voltage-sensitive dyes into spinal neurons and consider the advantages and limitations of each one. We review work in the chick embryo, suggesting that motoneurons play a critical role in the initiation of each cycle of spontaneous network activity and describe how imaging has been used to identify a class of spinal interneuron that appears to be the avian homolog of mammalian Renshaw cells or 1a-inhibitory interneurons. Imaging of locomotor-like activity in the neonatal mouse revealed a wave-like activation of motoneurons during each cycle of discharge. We discuss the significance of this finding and its implications for understanding how locomotor-like activity is coordinated across different segments of the cord. In the last part of the review, we discuss some of the exciting new prospects for the future.
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Affiliation(s)
- Michael J O'Donovan
- National Institute of Neurological Disorder and Stroke, NIH, Bethesda, Maryland 20892, USA.
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89
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De Marco Garcia NV, Jessell TM. Early motor neuron pool identity and muscle nerve trajectory defined by postmitotic restrictions in Nkx6.1 activity. Neuron 2008; 57:217-31. [PMID: 18215620 DOI: 10.1016/j.neuron.2007.11.033] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2007] [Revised: 10/11/2007] [Accepted: 11/26/2007] [Indexed: 12/29/2022]
Abstract
The fidelity with which spinal motor neurons innervate their limb target muscles helps to coordinate motor behavior, but the mechanisms that determine precise patterns of nerve-muscle connectivity remain obscure. We show that Nkx6 proteins, a set of Hox-regulated homeodomain transcription factors, are expressed by motor pools soon after motor neurons leave the cell cycle, before the formation of muscle nerve side branches in the limb. Using mouse genetics, we show that the status of Nkx6.1 expression in certain motor neuron pools regulates muscle nerve formation, and the pattern of innervation of individual muscles. Our findings provide genetic evidence that neurons within motor pools possess an early transcriptional identity that controls target muscle specificity.
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90
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Frigon A, Rossignol S. Short-Latency Crossed Inhibitory Responses in Extensor Muscles During Locomotion in the Cat. J Neurophysiol 2008; 99:989-98. [DOI: 10.1152/jn.01274.2007] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
During locomotion, contacting an obstacle generates a coordinated response involving flexion of the stimulated leg and activation of extensors contralaterally to ensure adequate support and forward progression. Activation of motoneurons innervating contralateral muscles (i.e., crossed extensor reflex) has always been described as an excitation, but the present paper shows that excitatory responses during locomotion are almost always preceded by a short period of inhibition. Data from seven cats chronically implanted with bipolar electrodes to record electromyography (EMG) of several hindlimb muscles bilaterally were used. A stimulating cuff electrode placed around the left tibial and left superficial peroneal nerves at the level of the ankle in five and two cats, respectively, evoked cutaneous reflexes during locomotion. During locomotion, short-latency (∼13 ms) inhibitory responses were frequently observed in extensors of the right leg (i.e., contralateral to the stimulation), such as gluteus medius and triceps surae muscles, which were followed by excitatory responses (∼25 ms). Burst durations of the left sartorius (Srt), a hip flexor, and ankle extensors of the right leg increased concomitantly in the mid- to late-flexion phases of locomotion with nerve stimulation. Moreover, the onset and offset of Srt and ankle extensor bursts bilaterally were altered in specific phases of the step cycle. Short-latency crossed inhibition in ankle extensors appears to be an integral component of cutaneous reflex pathways in intact cats during locomotion, which could be important in synchronizing EMG bursts in muscles of both legs.
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91
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Pearson KG. Role of sensory feedback in the control of stance duration in walking cats. ACTA ACUST UNITED AC 2007; 57:222-7. [PMID: 17761295 DOI: 10.1016/j.brainresrev.2007.06.014] [Citation(s) in RCA: 121] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2007] [Accepted: 06/17/2007] [Indexed: 11/21/2022]
Abstract
The rate of stepping in the hind legs of chronic spinal and decerebrate cats adapts to the speed of the treadmill on which the animals walk. This adaptive behavior depends on sensory signals generated near the end of stance phase controlling the transition from stance to swing. Two sensory signals have been identified to have this role: one from afferents activated by hip extension, most likely arising from muscle spindles in hip flexor muscles, and the other from group Ib afferents from Golgi tendon organs in the ankle extensor muscles. The relative importance of these two signals in controlling the stance to swing transition differs in chronic spinal cats and in decerebrate cats. Activation of hip afferents is necessary for controlling the transition in chronic spinal cats but not in decerebrate cats, while reduction in activity in group Ib afferents from GTOs is the primary factor controlling the transition in decerebrate cats. Possible mechanisms for this difference are discussed. The extent to which these two sensory signals control the stance to swing transition in normal walking cats is unknown, but it is likely that both could play an important role when animals are walking in a variable environment.
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Affiliation(s)
- K G Pearson
- Department of Physiology, University of Alberta, Edmonton, Canada T6G 2H7.
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92
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Scivoletto G, Ivanenko Y, Morganti B, Grasso R, Zago M, Lacquaniti F, Ditunno J, Molinari M. Review Article: Plasticity of Spinal Centers in Spinal Cord Injury Patients: New Concepts for Gait Evaluation and Training. Neurorehabil Neural Repair 2007; 21:358-65. [PMID: 17353461 DOI: 10.1177/1545968306295561] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Recent data on spinal cord plasticity after spinal cord injury (SCI) were reviewed to analyze the influence of training on the neurophysiological organization of locomotor spinal circuits in SCI patients. In particular, the authors studied the relationship between central pattern generators (CPGs) and motor neuron pool activation during gait. An analysis of the relations between locomotor recovery and compensatory mechanisms focuses on the hierarchical organization of gait parameters and allows characterizing kinematic parameters that are highly stable during different gait conditions and in recovered gait after SCI. The importance of training characteristics and the use of robotic/automated devices in gait recovery is analyzed and discussed. The role of CPG in defining kinematic gait parameters is summarized, and spatio-temporal maps of EMG activity during gait are used to clarify the role of CPG plasticity in sustaining gait recovery.
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93
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Manjarrez E, Vázquez M, Flores A. Computing the center of mass for traveling alpha waves in the human brain. Brain Res 2007; 1145:239-47. [PMID: 17320825 DOI: 10.1016/j.brainres.2007.01.114] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2006] [Revised: 01/25/2007] [Accepted: 01/26/2007] [Indexed: 11/28/2022]
Abstract
The phenomenon of traveling waves of the brain is an intriguing area of research, and its mechanisms and neurobiological bases have been unknown since the 1950s. The present study offers a new method to compute traveling alpha waves using the center of mass algorithm. Electroencephalographic alpha waves are oscillations with a characteristic frequency range and reactivity to closed eyes. Several lines of evidence derived from qualitative observations suggest that the alpha waves represent a spreading wave process with specific trajectories in the human brain. We found that during a certain alpha wave peak recorded with 30 electrodes the trajectory starts and ends in distinct regions of the brain, mostly frontal-occipital, frontal-frontal, or occipital-frontal, but the position of the trajectory at the time in which the maximal positivity of the alpha wave occurs has a definite position near the central regions. Thus we observed that the trajectory always crossed around the central zones, traveling from one region to another region of the brain. A similar trajectory pattern was observed for different alpha wave peaks in one alpha burst, and in different subjects, with a mean velocity of 2.1+/-0.29 m/s. We found that all our results were clear and reproducible in all of the subjects. To our knowledge, the present method documents the first explicit description of a spreading wave process with a singular pattern in the human brain in terms of the center of mass algorithm.
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Affiliation(s)
- Elías Manjarrez
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, 14 Sur 6301, Col. San Manuel, Apartado Postal 406, Puebla, Pue. CP 72570, Mexico.
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94
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Guevremont L, Norton JA, Mushahwar VK. Physiologically based controller for generating overground locomotion using functional electrical stimulation. J Neurophysiol 2007; 97:2499-510. [PMID: 17229823 DOI: 10.1152/jn.01177.2006] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The physiological control of stepping is governed both by signals descending from supraspinal systems and by circuitry residing within the lumbosacral spinal cord. The goal of this study was to evaluate the capacity of physiologically based controllers to restore functional overground locomotion after neurological damage, such as spinal cord injury when used in conjunction with functional electrical stimulation. For this purpose we implemented and tested two controllers: 1) an intrinsically timed system that generated a predetermined rhythmic output and 2) a sensory-based system that used feedback signals to make appropriate transitions between the unloaded (flexion) and loaded (extension) phases of the gait cycle. A third controller, a combination of the intrinsically timed and sensory-driven controllers, was implemented and two sessions were conducted to demonstrate the functional advantages of this approach. The controllers were tested in anesthetized cats, implanted with intramuscular electrodes in six major extensor and flexor muscles of the hindlimbs. The cats were partially supported on a sliding trolley that was propelled by the hindlimbs along a 2.5-m instrumented walkway. Ground reaction forces and limb positions were measured by force plates in the walkway and by accelerometers secured to the legs of the cat, respectively. The controllers were used to generate patterns of stimulation that would elicit alternating flexor (swing) and extensor (stance) movements in the hindlimbs. Using either the intrinsically timed or sensory-driven controllers, the cats were able to travel a distance of 2.5 m, taking five to 12 steps. Functional stepping sequences were more easily achieved using the intrinsically timed controller as the result of a lower sensitivity to the selection of initial stimulation parameters. However, unlike the sensory-driven controller, the intrinsically timed controller was unable to adjust to overcome walkway resistance and muscle fatigue. Neither system was consistently able to ensure load-bearing stepping. Therefore we propose the use of a "combined controller" that relies heavily on intrinsic timing but that can be reset based on sensory signals. A combined controller such as this one may provide the best solution for restoring robust overground locomotion after spinal cord injury.
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Affiliation(s)
- Lisa Guevremont
- Department of Biomedical Engineering and Centre for Neuroscience, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
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95
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Frigon A, Rossignol S. Experiments and models of sensorimotor interactions during locomotion. BIOLOGICAL CYBERNETICS 2006; 95:607-27. [PMID: 17115216 DOI: 10.1007/s00422-006-0129-x] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2006] [Accepted: 10/23/2006] [Indexed: 05/12/2023]
Abstract
During locomotion sensory information from cutaneous and muscle receptors is continuously integrated with the locomotor central pattern generator (CPG) to generate an appropriate motor output to meet the demands of the environment. Sensory signals from peripheral receptors can strongly impact the timing and amplitude of locomotor activity. This sensory information is gated centrally depending on the state of the system (i.e., rest vs. locomotion) but is also modulated according to the phase of a given task. Consequently, if one is to devise biologically relevant walking models it is imperative that these sensorimotor interactions at the spinal level be incorporated into the control system.
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Affiliation(s)
- Alain Frigon
- Center and Group for Neurological Sciences, Department of Physiology, CIHR group in Neurological Sciences, CIHR Regenerative Medicine and Nanomedicine Team, Université de Montréal, Quebec, Canada
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96
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Abstract
The question of how the central nervous system coordinates muscle activity is central to an understanding of motor control. The authors argue that motor programs may be considered as a characteristic timing of muscle activations linked to specific kinematic events. In particular, muscle activity occurring during human locomotion can be accounted for by five basic temporal components in a variety of locomotion conditions. Spatiotemporal maps of spinal cord motoneuron activation also show discrete periods of activity. Furthermore, the coordination of locomotion with voluntary tasks is accomplished through a superposition of motor programs or activation timings that are separately associated with each task. As a consequence, the selection of muscle synergies appears to be downstream from the processes that generate activation timings.
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Affiliation(s)
- Yuri P Ivanenko
- Department of Neuromotor Physiology, IRCCS Fondazione Santa Lucia, Rome, Italy.
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97
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Krouchev N, Kalaska JF, Drew T. Sequential activation of muscle synergies during locomotion in the intact cat as revealed by cluster analysis and direct decomposition. J Neurophysiol 2006; 96:1991-2010. [PMID: 16823029 DOI: 10.1152/jn.00241.2006] [Citation(s) in RCA: 120] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
During goal-directed locomotion, descending signals from supraspinal structures act through spinal interneuron pathways to effect modifications of muscle activity that are appropriate to the task requirements. Recent studies using decomposition methods suggest that this control might be facilitated by activating synergies organized at the level of the spinal cord. However, it is difficult to directly relate these mathematically defined synergies to the patterns of electromyographic activity observed in the original recordings. To address this issue, we have used a novel cluster analysis to make a detailed study of the organization of the synergistic patterns of muscle activity observed in the fore- and hindlimb during treadmill locomotion. The results show that the activity of a large number of forelimb muscles (26 bursts of activity from 18 muscles) can be grouped into 11 clusters on the basis of synchronous co-activation. Nine (9/11) of these clusters defined muscle activity during the swing phase of locomotion; these clusters were distributed in a sequential manner and were related to discrete behavioral events. A comparison with the synergies identified by linear decomposition methods showed some striking similarities between the synergies identified by the different methods. In the hindlimb, a simpler organization was observed, and a sequential activation of muscles similar to that observed in the forelimb during swing was less clear. We suggest that this organization of synergistic muscles provides a means by which descending signals could provide the detailed control of different muscle groups that is necessary for the flexible control of multi-articular movements.
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Affiliation(s)
- Nedialko Krouchev
- Département de physiologie, Université de Montréal, Centre-ville, Montreal, Quebec, H3C 3J7 Canada
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98
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Ivanenko YP, Poppele RE, Lacquaniti F. Spinal Cord Maps of Spatiotemporal Alpha-Motoneuron Activation in Humans Walking at Different Speeds. J Neurophysiol 2006; 95:602-18. [PMID: 16282202 DOI: 10.1152/jn.00767.2005] [Citation(s) in RCA: 135] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Functional MRI (fMRI) imaging of motoneuron activity in the human spinal cord is still in its infancy, and it will remain difficult to apply to walking. Here we present a viable alternative for documenting the spatiotemporal maps of α-motorneuron (MN) activity in the human spinal cord during walking, similar to the method recently reported for the cat. We recorded EMG activity from 16 to 32 ipsilateral limb and trunk muscles in 13 healthy subjects walking on a treadmill at different speeds (1–7 km/h) and mapped the recorded patterns onto the spinal cord in approximate rostrocaudal locations of the motoneuron pools. This approach can provide information about pattern generator output during locomotion in terms of segmental control rather than in terms of individual muscle control. A striking feature we found is that nearly every spinal segment undergoes at least two cycles of activation in the step cycle, thus supporting the idea of half-center oscillators controlling MN activation at any segmental level. The resulting spatiotemporal map patterns seem highly stereotyped over the range of walking speeds studied, although there were also some systematic redistributions of MN activity with speed. Bursts of MN activity were either temporally aligned across several spinal segments or switched between different segments. For example, the center of mass of MN activity in the lumbosacral levels generally shifted from rostral to caudal positions in two cycles for each step, revealing four major activation foci: two in the upper lumbar segments and two in the sacral segments. The results are consistent with the presence of at least two and possibly more pattern generators controlling the activation of lumbosacral MNs.
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Affiliation(s)
- Y P Ivanenko
- Department of Neuromotor Physiology, Scientific Institute Foundation Santa Lucia, Rome, Italy.
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99
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Collazos-Castro JE, López-Dolado E, Nieto-Sampedro M. Locomotor Deficits and Adaptive Mechanisms after Thoracic Spinal Cord Contusion in the Adult Rat. J Neurotrauma 2006; 23:1-17. [PMID: 16430369 DOI: 10.1089/neu.2006.23.1] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The rat is widely used for modeling human spinal cord injury (SCI) and paraplegia. However, quadruped animals adapt trunk, forelimb and hindlimb movements to compensate for deficits, improving their behavioral scores and complicating the interpretation of spontaneous and treatment-induced function recovery. The kinematics of locomotion was studied in rats, both normal and after SCI (T9 contusion), and variables indicative of hindlimb function were related to brain-spinal cord connections (BSCC) spared during lesioning. Normal animals showed forward velocities characteristic of fast walking. The hind paw was placed approximately three centimeters in front of the hip at the initial contact. Hip height decreased during the first third of hindlimb stance and increased later. Mild and moderate spinal cord contusions destroyed the gray matter and adjacent axons but spared the ventrolateral tracts to various degrees. Injured animals placed the hindpaw in a more caudal position than normal and showed reduced forward velocity and hip height. Knee extension was also impaired, and both hindlimb and forelimb steps were adapted to compensate for the deficits. BSCC was estimated by averaging the transverse area of white matter at the lesion epicenter and the percentage of brain neurons labeled after peroxidase injection into L2 and L3. Recovery of hindlimb motor function was proportional to the amount of BSCC. On average, injured animals retained 18% of BSSC and recovered 23% of hindlimb function. These findings show that kinematic analysis is a reliable tool for assessing locomotor deficits and compensations and suggest limited spontaneous motor plasticity after SCI.
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100
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Tachibana A, McVea DA, Donelan JM, Pearson KG. Recruitment of gastrocnemius muscles during the swing phase of stepping following partial denervation of knee flexor muscles in the cat. Exp Brain Res 2005; 169:449-60. [PMID: 16261338 DOI: 10.1007/s00221-005-0160-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2005] [Accepted: 06/24/2005] [Indexed: 10/25/2022]
Abstract
In walking cats, the biarticular medial and lateral gastrocnemius (MG-LG) muscles act to produce extension and flexion torques at the ankle and knee, respectively, and they usually display only one burst of activity beginning just before ground contact and ending near the end of the stance phase. Currently, the MG-LG muscles are considered to function primarily to control extension movements around the ankle joint during the stance phase. However, their flexion action at the knee means that they have the capacity to regulate rotations at the knee, but this role has not yet been clearly defined. Following partial denervation of the other muscles that normally act to flex the knee during swing, we observed that the MG-LG muscles, but not the Soleus muscle (a pure ankle extensor), often generated strong bursts of activity during early swing. These bursts were enhanced following mechanical stimulation of the paw, and they were especially prominent when the leg trailed over an object. They were absent when the leg led over an object. During treadmill walking the swing-related bursts in MG and LG had little influence on ankle flexion at the beginning of swing, but they were associated with slowing of ankle flexion when the leg trailed over an object. We hypothesized that the recruitment of these bursts functions to partially compensate for the reduction in knee torque resulting from the denervation of other knee flexors. Consistent with this hypothesis was our finding that the magnitude of the swing-related activity in the MG-LG muscles was linearly correlated to the extent of the knee flexion and to the peak angular velocity of knee flexion, and that the timing of the bursts was similar to that in the denervated muscles prior to denervation. Our findings suggest that an excitatory pathway exists from the flexor half-center of the central pattern-generating network to MG-LG motoneurons, and that this pathway is strongly regulated by central and/or peripheral signals.
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Affiliation(s)
- A Tachibana
- Department of Physiology, University of Alberta, Edmonton, AB, T6G 2H7, Canada
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