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Bonagiri A, Biswas D, Chakravarthy S. Coupled Memristor Oscillators for Neuromorphic Locomotion Control: Modeling and Analysis. IEEE TRANSACTIONS ON NEURAL NETWORKS AND LEARNING SYSTEMS 2024; 35:8638-8652. [PMID: 37018567 DOI: 10.1109/tnnls.2022.3231298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
The recent surge of interest in brain-inspired architectures along with the development of nonlinear dynamical electronic devices and circuits has enabled energy-efficient hardware realizations of several important neurobiological systems and features. Central pattern generator (CPG) is one such neural system underlying the control of various rhythmic motor behaviors in animals. A CPG can produce spontaneous coordinated rhythmic output signals without any feedback mechanism, ideally realizable by a system of coupled oscillators. Bio-inspired robotics aims to use this approach to control the limb movement for synchronized locomotion. Hence, devising a compact and energy-efficient hardware platform to implement neuromorphic CPGs would be of great benefit for bio-inspired robotics. In this work, we demonstrate that four capacitively coupled vanadium dioxide (VO2) memristor-based oscillators can produce spatiotemporal patterns corresponding to the primary quadruped gaits. The phase relationships underlying the gait patterns are governed by four tunable bias voltages (or four coupling strengths) making the network programmable, reducing the complex problem of gait selection and dynamic interleg coordination to the choice of four control parameters. To this end, we first introduce a dynamical model for the VO2 memristive nanodevice, then perform analytical and bifurcation analysis of a single oscillator, and finally demonstrate the dynamics of coupled oscillators through extensive numerical simulations. We also show that adopting the presented model for a VO2 memristor reveals a striking resemblance between VO2 memristor oscillators and conductance-based biological neuron models such as the Morris-Lecar (ML) model. This can inspire and guide further research on implementation of neuromorphic memristor circuits that emulate neurobiological phenomena.
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2
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Wyart C, Carbo-Tano M, Cantaut-Belarif Y, Orts-Del'Immagine A, Böhm UL. Cerebrospinal fluid-contacting neurons: multimodal cells with diverse roles in the CNS. Nat Rev Neurosci 2023; 24:540-556. [PMID: 37558908 DOI: 10.1038/s41583-023-00723-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/26/2023] [Indexed: 08/11/2023]
Abstract
The cerebrospinal fluid (CSF) is a complex solution that circulates around the CNS, and whose composition changes as a function of an animal's physiological state. Ciliated neurons that are bathed in the CSF - and thus referred to as CSF-contacting neurons (CSF-cNs) - are unusual polymodal interoceptive neurons. As chemoreceptors, CSF-cNs respond to variations in pH and osmolarity and to bacterial metabolites in the CSF. Their activation during infections of the CNS results in secretion of compounds to enhance host survival. As mechanosensory neurons, CSF-cNs operate together with an extracellular proteinaceous polymer known as the Reissner fibre to detect compression during spinal curvature. Once activated, CSF-cNs inhibit motor neurons, premotor excitatory neurons and command neurons to enhance movement speed and stabilize posture. At longer timescales, CSF-cNs instruct morphogenesis throughout life via the release of neuropeptides that act over long distances on skeletal muscle. Finally, recent evidence suggests that mouse CSF-cNs may act as neural stem cells in the spinal cord, inspiring new paths of investigation for repair after injury.
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Affiliation(s)
- Claire Wyart
- Institut du Cerveau (ICM), INSERM U1127, UMR CNRS 7225 Paris, Sorbonne Université, Paris, France.
| | - Martin Carbo-Tano
- Institut du Cerveau (ICM), INSERM U1127, UMR CNRS 7225 Paris, Sorbonne Université, Paris, France
| | - Yasmine Cantaut-Belarif
- Institut du Cerveau (ICM), INSERM U1127, UMR CNRS 7225 Paris, Sorbonne Université, Paris, France
| | | | - Urs L Böhm
- NeuroCure Cluster of Excellence, Charité Universitätsmedizin Berlin, Berlin, Germany
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3
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Erazo-Toscano R, Osan R. Synaptic propagation in neuronal networks with finite-support space-dependent coupling. Phys Rev E 2023; 107:034403. [PMID: 37073055 DOI: 10.1103/physreve.107.034403] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Accepted: 12/16/2022] [Indexed: 04/20/2023]
Abstract
Traveling waves of electrical activity are ubiquitous in biological neuronal networks. Traveling waves in the brain are associated with sensory processing, phase coding, and sleep. The neuron and network parameters that determine traveling waves' evolution are the synaptic space constant, synaptic conductance, membrane time constant, and synaptic decay time constant. We used an abstract neuron model in a one-dimensional network to investigate the propagation characteristics of traveling wave activity. We formulate a set of evolution equations based on the network connectivity parameters. Using a combination of numerical and analytical approaches, we show that these traveling waves are stable to a series of perturbations with biological relevance.
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Affiliation(s)
- Ricardo Erazo-Toscano
- Neuroscience Institute, College of Arts and Sciences, Georgia State University, Atlanta, Georgia 30303, USA
| | - Remus Osan
- Neuroscience Institute, College of Arts and Sciences, Georgia State University, Atlanta, Georgia 30303, USA
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4
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Stochastic spinal neuromodulation tunes the intrinsic logic of spinal neural networks. Exp Neurol 2022; 355:114138. [DOI: 10.1016/j.expneurol.2022.114138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 05/30/2022] [Accepted: 06/01/2022] [Indexed: 11/22/2022]
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5
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Taccola G, Culaclii S, Zhong H, Gad P, Liu W, Edgerton VR. An epidural stimulating interface unveils the intrinsic modulation of electrically motor evoked potentials in behaving rats. J Neurophysiol 2021; 126:1635-1641. [PMID: 34644129 PMCID: PMC8782665 DOI: 10.1152/jn.00278.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 08/25/2021] [Accepted: 10/07/2021] [Indexed: 01/26/2023] Open
Abstract
In intact and spinal-injured anesthetized animals, stimulation levels that did not induce any visible muscle twitches were used to elicit motor evoked potentials (MEPs) of varying amplitude, reflecting the temporal and amplitude dynamics of the background excitability of spinal networks. To characterize the physiological excitability states of neuronal networks driving movement, we designed five experiments in awake rats chronically implanted with an epidural stimulating interface, with and without a spinal cord injury (SCI). First, an uninjured rat at rest underwent a series of single electrical pulses at sub-motor threshold intensity, which generated responses that were continuously recorded from flexor and extensor hindlimb muscles, showing an intrinsic patterned modulation of MEPs. Responses were recruited by increasing strengths of stimulation, and the amplitudes were moderately correlated between flexors and extensors. Next, after SCI, four awake rats at rest showed electrically induced MEPs, varying largely in amplitude, of both flexors and extensors that were mainly synchronously modulated. After full anesthesia, MEP amplitudes were largely reduced, although stimulation still generated random baseline changes, unveiling an intrinsic stochastic modulation. The present five cases demonstrate a methodology that can be feasibly replicated in a broader group of awake and behaving rats to further define experimental treatments involving neuroplasticity. Besides validating a new technology for a neural stimulating interface, the present data support the broader message that there is intrinsic patterned and stochastic modulation of baseline excitability reflecting the dynamics of physiological states of spinal networks.NEW & NOTEWORTHY Chronic implants of a new epidural stimulating interface trace dynamics of spinal excitability in awake rats, before and after injury. Motor evoked potentials induced by trains of pulses at sub-motor threshold intensity were continuously modulated in amplitude. Oscillatory patterns of amplitude modulation reduced with increasing strengths of stimulation and were replaced by an intrinsic stochastic tone under anesthesia. Variability of baseline excitability is a fundamental feature of spinal networks, affecting their responses to external input.
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Affiliation(s)
- Giuliano Taccola
- Department of Integrative Biology and Physiology, University of California, Los Angeles, California
- Neuroscience Department, International School for Advanced Studies (SISSA), Trieste, Italy
| | - Stanislav Culaclii
- Department of Bioengineering, University of California, Los Angeles, California
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California
| | - Hui Zhong
- Department of Integrative Biology and Physiology, University of California, Los Angeles, California
| | - Parag Gad
- Department of Neurobiology, University of California, Los Angeles, California
| | - Wentai Liu
- Department of Bioengineering, University of California, Los Angeles, California
- Brain Research Institute, University of California, Los Angeles, California
- UCLA California NanoSystems Institute, Los Angeles, California
| | - V Reggie Edgerton
- Department of Neurobiology, University of California, Los Angeles, California
- Brain Research Institute, University of California, Los Angeles, California
- Department of Neurosurgery, University of California, Los Angeles, California
- Institut Guttmann, Hospital de Neurorehabilitació, Institut Universitari adscrit a la Universitat Autònoma de Barcelona, Badalona, Barcelona, Spain
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6
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Yang K, Joshua Yang J, Huang R, Yang Y. Nonlinearity in Memristors for Neuromorphic Dynamic Systems. SMALL SCIENCE 2021. [DOI: 10.1002/smsc.202100049] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Affiliation(s)
- Ke Yang
- Department of Micro/nanoelectronics Peking University Beijing 100871 China
| | - J. Joshua Yang
- Electrical and Computer Engineering Department University of Southern California Los Angeles CA 90089 USA
| | - Ru Huang
- Department of Micro/nanoelectronics Peking University Beijing 100871 China
- Center for Brain Inspired Chips Institute for Artificial Intelligence Peking University Beijing 100871 China
- Center for Brain Inspired Intelligence Chinese Institute for Brain Research (CIBR) Beijing 102206 China
| | - Yuchao Yang
- Department of Micro/nanoelectronics Peking University Beijing 100871 China
- Center for Brain Inspired Chips Institute for Artificial Intelligence Peking University Beijing 100871 China
- Center for Brain Inspired Intelligence Chinese Institute for Brain Research (CIBR) Beijing 102206 China
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7
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Lindén H, Berg RW. Why Firing Rate Distributions Are Important for Understanding Spinal Central Pattern Generators. Front Hum Neurosci 2021; 15:719388. [PMID: 34539363 PMCID: PMC8446347 DOI: 10.3389/fnhum.2021.719388] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 06/02/2021] [Indexed: 01/16/2023] Open
Abstract
Networks in the spinal cord, which are responsible for the generation of rhythmic movements, commonly known as central pattern generators (CPGs), have remained elusive for decades. Although it is well-known that many spinal neurons are rhythmically active, little attention has been given to the distribution of firing rates across the population. Here, we argue that firing rate distributions can provide an important clue to the organization of the CPGs. The data that can be gleaned from the sparse literature indicate a firing rate distribution, which is skewed toward zero with a long tail, akin to a normal distribution on a log-scale, i.e., a “log-normal” distribution. Importantly, such a shape is difficult to unite with the widespread assumption of modules composed of recurrently connected excitatory neurons. Spinal modules with recurrent excitation has the propensity to quickly escalate their firing rate and reach the maximum, hence equalizing the spiking activity across the population. The population distribution of firing rates hence would consist of a narrow peak near the maximum. This is incompatible with experiments, that show wide distributions and a peak close to zero. A way to resolve this puzzle is to include recurrent inhibition internally in each CPG modules. Hence, we investigate the impact of recurrent inhibition in a model and find that the firing rate distributions are closer to the experimentally observed. We therefore propose that recurrent inhibition is a crucial element in motor circuits, and suggest that future models of motor circuits should include recurrent inhibition as a mandatory element.
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Affiliation(s)
- Henrik Lindén
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Rune W Berg
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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Wu Q, Dang B, Lu C, Xu G, Yang G, Wang J, Chuai X, Lu N, Geng D, Wang H, Li L. Spike Encoding with Optic Sensory Neurons Enable a Pulse Coupled Neural Network for Ultraviolet Image Segmentation. NANO LETTERS 2020; 20:8015-8023. [PMID: 33063511 DOI: 10.1021/acs.nanolett.0c02892] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Drawing inspiration from biology, neuromorphic systems are of great interest in direct interaction and efficient processing of analogue signals in the real world and could be promising for the development of smart sensors. Here, we demonstrate an artificial sensory neuron consisting of an InGaZnO4 (IGZO4)-based optical sensor and NbOx-based oscillation neuron in series, which can simultaneously sense the optical information even beyond the visible light region and encode them into electrical impulses. Such artificial vision sensory neurons can convey visual information in a parallel manner analogous to biological vision systems, and the output spikes can be effectively processed by a pulse coupled neural network, demonstrating the capability of image segmentation out of a complex background. This study could facilitate the construction of artificial visual systems and pave the way for the development of light-driven neurorobotics, bioinspired optoelectronics, and neuromorphic computing.
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Affiliation(s)
- Quantan Wu
- Key Laboratory of Microelectronic Devices & Integrated Technology, Institute of Microelectronics of Chinese Academy of Sciences, Beijing 100029, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Bingjie Dang
- Key Laboratory of Wide Band Gap Semiconductor Technology, School of Microelectronics, Xidian University, Xi'an 710071, China
- Key Laboratory of Microelectronic Devices and Circuits (MOE), Institute of Microelectronics, Peking University, Beijing 100871, China
| | - Congyan Lu
- Key Laboratory of Microelectronic Devices & Integrated Technology, Institute of Microelectronics of Chinese Academy of Sciences, Beijing 100029, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Guangwei Xu
- Key Laboratory of Microelectronic Devices & Integrated Technology, Institute of Microelectronics of Chinese Academy of Sciences, Beijing 100029, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Guanhua Yang
- Key Laboratory of Microelectronic Devices & Integrated Technology, Institute of Microelectronics of Chinese Academy of Sciences, Beijing 100029, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jiawei Wang
- Key Laboratory of Microelectronic Devices & Integrated Technology, Institute of Microelectronics of Chinese Academy of Sciences, Beijing 100029, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xichen Chuai
- Key Laboratory of Microelectronic Devices & Integrated Technology, Institute of Microelectronics of Chinese Academy of Sciences, Beijing 100029, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Nianduan Lu
- Key Laboratory of Microelectronic Devices & Integrated Technology, Institute of Microelectronics of Chinese Academy of Sciences, Beijing 100029, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Di Geng
- Key Laboratory of Microelectronic Devices & Integrated Technology, Institute of Microelectronics of Chinese Academy of Sciences, Beijing 100029, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Hong Wang
- Key Laboratory of Wide Band Gap Semiconductor Technology, School of Microelectronics, Xidian University, Xi'an 710071, China
| | - Ling Li
- Key Laboratory of Microelectronic Devices & Integrated Technology, Institute of Microelectronics of Chinese Academy of Sciences, Beijing 100029, China
- University of Chinese Academy of Sciences, Beijing 100049, China
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9
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Taccola G, Salazar BH, Apicella R, Hogan MK, Horner PJ, Sayenko D. Selective Antagonism of A1 Adenosinergic Receptors Strengthens the Neuromodulation of the Sensorimotor Network During Epidural Spinal Stimulation. Front Syst Neurosci 2020; 14:44. [PMID: 32760254 PMCID: PMC7372902 DOI: 10.3389/fnsys.2020.00044] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Accepted: 06/16/2020] [Indexed: 01/02/2023] Open
Abstract
Although epidural spinal stimulation (ESS) results in promising therapeutic effects in individuals with spinal cord injury (SCI), its potential to generate functional motor recovery varies between individuals and remains largely unclear. However, both preclinical and clinical studies indicate the capacity of electrical and pharmacological interventions to synergistically increase the engagement of spinal sensorimotor networks and regain motor function after SCI. This study explored whether selective pharmacological antagonism of the adenosine A1 receptor subtype synergizes with ESS, thereby increasing motor response. We hypothesized that selective pharmacological antagonism of A1 receptors during ESS would produce facilitatory effects in spinal sensorimotor networks detected as an increased amplitude of spinally-evoked motor potentials and sustained duration of ESS induced activity. Terminal experiments were performed in adult rats using trains of stereotyped pulses at 40 Hz delivered at L5 with the local administration to the cord of 8-cyclopentyl-1,3-dipropylxanthine (DPCPX). We demonstrated that ESS combined with the blockage of A1 receptors increased the magnitude of the endogenous modulation and postponed the decay of responses that occur during ESS alone. Although DPCPX significantly increased the yield of repetitive stimulation in intact spinal cords, the effects of A1 antagonism on motor evoked responses after an acute spinal transection was not detected. These studies support the future investigation of the optimal dosage, methods of delivery, and systemic effects of the synergistic application of A1 antagonists and spinal stimulation in the intact and injured spinal cord.
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Affiliation(s)
- Giuliano Taccola
- Department of Neuroscience, International School for Advanced Studies (SISSA), Trieste, Italy
- Department of Neurosurgery, Center for Neuroregeneration, Houston Methodist Research Institute, Houston, TX, United States
| | - Betsy Habeth Salazar
- Department of Neurosurgery, Center for Neuroregeneration, Houston Methodist Research Institute, Houston, TX, United States
| | - Rosamaria Apicella
- Department of Neuroscience, International School for Advanced Studies (SISSA), Trieste, Italy
| | - Matthew Kevin Hogan
- Department of Neurosurgery, Center for Neuroregeneration, Houston Methodist Research Institute, Houston, TX, United States
| | - Philip John Horner
- Department of Neurosurgery, Center for Neuroregeneration, Houston Methodist Research Institute, Houston, TX, United States
| | - Dimitry Sayenko
- Department of Neurosurgery, Center for Neuroregeneration, Houston Methodist Research Institute, Houston, TX, United States
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10
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Moreno-Castillo M, Meza R, Romero-Vaca J, Huidobro N, Méndez-Fernández A, Martínez-Castillo J, Mabil P, Flores A, Manjarrez E. The Hemodynamic Mass Action of a Central Pattern Generator. Front Neurosci 2020; 14:38. [PMID: 32076397 PMCID: PMC7006454 DOI: 10.3389/fnins.2020.00038] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Accepted: 01/13/2020] [Indexed: 12/12/2022] Open
Abstract
The hemodynamic response is a neurovascular and metabolic process in which there is rapid delivery of blood flow to a neuronal tissue in response to neuronal activation. The functional magnetic resonance imaging (fMRI) and the functional near-infrared spectroscopy (fNIRS), for instance, are based on the physiological principles of such hemodynamic responses. Both techniques allow the mapping of active neuronal regions in which the neurovascular and metabolic events are occurring. However, although both techniques have revolutionized the neurosciences, they are mostly employed for neuroimaging of the human brain but not for the spinal cord during functional tasks. Moreover, little is known about other techniques measuring the hemodynamic response in the spinal cord. The purpose of the present study was to show for the first time that a simple optical system termed direct current photoplethysmography (DC-PPG) can be employed to detect hemodynamic responses of the spinal cord and the brainstem during the functional activation of the spinal central pattern generator (CPG). In particular, we positioned two DC-PPG systems directly on the brainstem and spinal cord during fictive scratching in the cat. The optical DC-PPG systems allowed the trial-by-trial recording of massive hemodynamic signals. We found that the “strength” of the flexor-plus-extensor motoneuron activities during motor episodes of fictive scratching was significantly correlated to the “strengths” of the brainstem and spinal DC-PPG signals. Because the DC-PPG was robustly detected in real-time, we claim that such a functional signal reflects the hemodynamic mass action of the brainstem and spinal cord associated with the CPG motor action. Our findings shed light on an unexplored hemodynamic observable of the spinal CPGs, providing a proof of concept that the DC-PPG can be used for the assessment of the integrity of the human CPGs.
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Affiliation(s)
| | - Roberto Meza
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
| | - Jesús Romero-Vaca
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
| | - Nayeli Huidobro
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
| | | | - Jaime Martínez-Castillo
- Centro de Investigación en Micro y Nanotecnología, Universidad Veracruzana, Veracruz, Mexico
| | - Pedro Mabil
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
| | - Amira Flores
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
| | - Elias Manjarrez
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
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11
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Dutta S, Parihar A, Khanna A, Gomez J, Chakraborty W, Jerry M, Grisafe B, Raychowdhury A, Datta S. Programmable coupled oscillators for synchronized locomotion. Nat Commun 2019; 10:3299. [PMID: 31341167 PMCID: PMC6656780 DOI: 10.1038/s41467-019-11198-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Accepted: 06/21/2019] [Indexed: 01/25/2023] Open
Abstract
The striking similarity between biological locomotion gaits and the evolution of phase patterns in coupled oscillatory network can be traced to the role of central pattern generator located in the spinal cord. Bio-inspired robotics aim at harnessing this control approach for generation of rhythmic patterns for synchronized limb movement. Here, we utilize the phenomenon of synchronization and emergent spatiotemporal pattern from the interaction among coupled oscillators to generate a range of locomotion gait patterns. We experimentally demonstrate a central pattern generator network using capacitively coupled Vanadium Dioxide nano-oscillators. The coupled oscillators exhibit stable limit-cycle oscillations and tunable natural frequencies for real-time programmability of phase-pattern. The ultra-compact 1 Transistor-1 Resistor implementation of oscillator and bidirectional capacitive coupling allow small footprint area and low operating power. Compared to biomimetic CMOS based neuron and synapse models, our design simplifies on-chip implementation and real-time tunability by reducing the number of control parameters. Designing alternative paradigms for bio-inspired analog computing that harnesses collective dynamics remains a challenge. Here, the authors exploit the synchronization dynamics of coupled vanadium dioxide-based insulator-to-metal phase-transition nano-oscillators for adaptive locomotion control.
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Affiliation(s)
- Sourav Dutta
- Department of Electrical Engineering, University of Notre Dame, Notre Dame, IN, 46556, USA.
| | - Abhinav Parihar
- School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Abhishek Khanna
- Department of Electrical Engineering, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - Jorge Gomez
- Department of Electrical Engineering, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - Wriddhi Chakraborty
- Department of Electrical Engineering, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - Matthew Jerry
- Department of Electrical Engineering, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - Benjamin Grisafe
- Department of Electrical Engineering, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - Arijit Raychowdhury
- School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Suman Datta
- Department of Electrical Engineering, University of Notre Dame, Notre Dame, IN, 46556, USA
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12
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Dewolf AH, Ivanenko YP, Zelik KE, Lacquaniti F, Willems PA. Differential activation of lumbar and sacral motor pools during walking at different speeds and slopes. J Neurophysiol 2019; 122:872-887. [PMID: 31291150 DOI: 10.1152/jn.00167.2019] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Organization of spinal motor output has become of interest for investigating differential activation of lumbar and sacral motor pools during locomotor tasks. Motor pools are associated with functional grouping of motoneurons of the lower limb muscles. Here we examined how the spatiotemporal organization of lumbar and sacral motor pool activity during walking is orchestrated with slope of terrain and speed of progression. Ten subjects walked on an instrumented treadmill at different slopes and imposed speeds. Kinetics, kinematics, and electromyography of 16 lower limb muscles were recorded. The spinal locomotor output was assessed by decomposing the coordinated muscle activation profiles into a small set of common factors and by mapping them onto the rostrocaudal location of the motoneuron pools. Our results show that lumbar and sacral motor pool activity depend on slope and speed. Compared with level walking, sacral motor pools decrease their activity at negative slopes and increase at positive slopes, whereas lumbar motor pools increase their engagement when both positive and negative slope increase. These findings are consistent with a differential involvement of the lumbar and the sacral motor pools in relation to changes in positive and negative center of body mass mechanical power production due to slope and speed.NEW & NOTEWORTHY In this study, the spatiotemporal maps of motoneuron activity in the spinal cord were assessed during walking at different slopes and speeds. We found differential involvement of lumbar and sacral motor pools in relation to changes in positive and negative center of body mass power production due to slope and speed. The results are consistent with recent findings about the specialization of neuronal networks located at different segments of the spinal cord for performing specific locomotor tasks.
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Affiliation(s)
- A H Dewolf
- Laboratory of Biomechanics and Physiology of Locomotion, Institute of NeuroScience, Université catholique de Louvain, Louvain-la-Neuve, Belgium
| | - Y P Ivanenko
- Laboratory of Neuromotor Physiology, IRCCS Santa Lucia Foundation, Rome, Italy
| | - K E Zelik
- Laboratory of Neuromotor Physiology, IRCCS Santa Lucia Foundation, Rome, Italy.,Department of Mechanical Engineering, Vanderbilt University, Nashville, Tennessee.,Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee.,Department of Physical Medicine and Rehabilitation, Vanderbilt University, Nashville, Tennessee
| | - F Lacquaniti
- Laboratory of Neuromotor Physiology, IRCCS Santa Lucia Foundation, Rome, Italy.,Department of Systems Medicine and Center of Space Biomedicine, University of Rome Tor Vergata, Rome, Italy
| | - P A Willems
- Laboratory of Biomechanics and Physiology of Locomotion, Institute of NeuroScience, Université catholique de Louvain, Louvain-la-Neuve, Belgium
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Resetting the Respiratory Rhythm with a Spinal Central Pattern Generator. eNeuro 2019; 6:ENEURO.0116-19.2019. [PMID: 31043462 PMCID: PMC6497907 DOI: 10.1523/eneuro.0116-19.2019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Accepted: 03/26/2019] [Indexed: 01/10/2023] Open
Abstract
There is evidence that a variety of central and afferent stimuli, including swallowing, can produce phase resetting in the respiratory rhythmicity. Also, there are reports about the intrinsic linkage between locomotion and respiration. However, little is known about the interaction between the central pattern generators (CPGs) for scratching and respiration. The present study aims to examine whether the activation of scratching CPG produces phase resetting of the respiratory rhythm. We employed decerebrate cats to apply brief tactile stimuli to the pinna during the inspiratory-expiratory transition. We observed that those stimuli to the pinna not eliciting fictive scratching did not reset the respiratory rhythm. However, when the pinna stimuli elicited fictive scratching, then the respiratory rhythm exhibited a significant phase resetting. We also found interneurons in the medulla oblongata exhibiting phase resetting related to scratching-CPG episodes. This second finding suggests that this type of resetting involves brainstem components of the respiratory CPG. These results shed new light on the resetting action from a spinal CPG on the respiratory rhythm.
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Cuellar CA, De La Torre Valdovinos B, Huidobro N, Delgado-Lezama R, Ornelas-Kobayashi R, Manjarrez E. The Spinal Neurons Exhibit an ON-OFF and OFF-ON Firing Activity Around the Onset of Fictive Scratching Episodes in the Cat. Front Cell Neurosci 2018; 12:68. [PMID: 29593502 PMCID: PMC5859142 DOI: 10.3389/fncel.2018.00068] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Accepted: 02/27/2018] [Indexed: 01/21/2023] Open
Abstract
In a previous report, we found neurons with ON-OFF and OFF-ON firing activity in the obex reticular formation during scratching. The aim of the present study was to examine whether the spinal neurons also exhibit this type of activity in relation to the “postural stage” of fictive scratching in the cat. We found that the extensor and intermediate scratching neurons exhibit an ON-OFF firing rate; conversely, the flexor neurons show an OFF-ON activity, relative to every scratching episode. These patterns of spiking activity are similar to those found in neurons from the obex reticular formation during scratching. Our findings provide support to the following hypotheses. First, there is a possible functional link between supraspinal and spinal, ON-OFF and OFF-ON neuronal groups. Second, the fictive goal-directed motor action to maintain the fictive “postural stage” of the hindlimb during fictive scratching is associated with the neuronal tonic activity of the OFF-ON spinal neurons, whereas the ON-OFF spinal neurons are associated with an extensor tone that occurred prior the postural stage.
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Affiliation(s)
- Carlos A Cuellar
- Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, United States
| | | | - Nayeli Huidobro
- Instituto de Fisiología, Benemerita Universidad Autonoma de Puebla, Puebla, Mexico
| | - Rodolfo Delgado-Lezama
- Departamento de Fisiologia, Biofisica y Neurociencias, CINVESTAV IPN, Mexico City, Mexico
| | | | - Elias Manjarrez
- Instituto de Fisiología, Benemerita Universidad Autonoma de Puebla, Puebla, Mexico
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15
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Saltiel P, d’Avella A, Tresch MC, Wyler K, Bizzi E. Critical Points and Traveling Wave in Locomotion: Experimental Evidence and Some Theoretical Considerations. Front Neural Circuits 2017; 11:98. [PMID: 29276476 PMCID: PMC5727018 DOI: 10.3389/fncir.2017.00098] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Accepted: 11/20/2017] [Indexed: 11/13/2022] Open
Abstract
The central pattern generator (CPG) architecture for rhythm generation remains partly elusive. We compare cat and frog locomotion results, where the component unrelated to pattern formation appears as a temporal grid, and traveling wave respectively. Frog spinal cord microstimulation with N-methyl-D-Aspartate (NMDA), a CPG activator, produced a limited set of force directions, sometimes tonic, but more often alternating between directions similar to the tonic forces. The tonic forces were topographically organized, and sites evoking rhythms with different force subsets were located close to the constituent tonic force regions. Thus CPGs consist of topographically organized modules. Modularity was also identified as a limited set of muscle synergies whose combinations reconstructed the EMGs. The cat CPG was investigated using proprioceptive inputs during fictive locomotion. Critical points identified both as abrupt transitions in the effect of phasic perturbations, and burst shape transitions, had biomechanical correlates in intact locomotion. During tonic proprioceptive perturbations, discrete shifts between these critical points explained the burst durations changes, and amplitude changes occurred at one of these points. Besides confirming CPG modularity, these results suggest a fixed temporal grid of anchoring points, to shift modules onsets and offsets. Frog locomotion, reconstructed with the NMDA synergies, showed a partially overlapping synergy activation sequence. Using the early synergy output evoked by NMDA at different spinal sites, revealed a rostrocaudal topographic organization, where each synergy is preferentially evoked from a few, albeit overlapping, cord regions. Comparing the locomotor synergy sequence with this topography suggests that a rostrocaudal traveling wave would activate the synergies in the proper sequence for locomotion. This output was reproduced in a two-layer model using this topography and a traveling wave. Together our results suggest two CPG components: modules, i.e., synergies; and temporal patterning, seen as a temporal grid in the cat, and a traveling wave in the frog. Animal and limb navigation have similarities. Research relating grid cells to the theta rhythm and on segmentation during navigation may relate to our temporal grid and traveling wave results. Winfree's mathematical work, combining critical phases and a traveling wave, also appears important. We conclude suggesting tracing, and imaging experiments to investigate our CPG model.
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Affiliation(s)
- Philippe Saltiel
- Department of Brain and Cognitive Sciences and McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA, United States
- Département de Neurosciences, Faculté de Médecine, Université de Montréal, Montréal, QC, Canada
| | - Andrea d’Avella
- Department of Biomedical and Dental Sciences and Morphofunctional Imaging, University of Messina, Messina, Italy
- Laboratory of Neuromotor Physiology, Santa Lucia Foundation, Rome, Italy
| | - Matthew C. Tresch
- Departments of Biomedical Engineering, Physical Medicine and Rehabilitation, and Physiology, Northwestern University, Chicago, IL, United States
| | - Kuno Wyler
- Department of Brain and Cognitive Sciences and McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Emilio Bizzi
- Department of Brain and Cognitive Sciences and McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA, United States
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16
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Yokoyama H, Hagio K, Ogawa T, Nakazawa K. Motor module activation sequence and topography in the spinal cord during air-stepping in human: Insights into the traveling wave in spinal locomotor circuits. Physiol Rep 2017; 5:5/22/e13504. [PMID: 29180480 PMCID: PMC5704080 DOI: 10.14814/phy2.13504] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Revised: 10/24/2017] [Accepted: 10/25/2017] [Indexed: 01/06/2023] Open
Abstract
Coordinated locomotor muscle activity is generated by the spinal central pattern generators (CPGs), which are modulated by peripheral and supraspinal inputs. The CPGs would consist of multiple motor modules generating basic muscle activity, which are distributed rostrocaudally along the spinal cord. To activate the motor modules in proper sequence, rostrocaudally traveling waves of activation in the spinal cord are important mechanisms in the CPGs. The traveling waves of activation have been observed in nonhuman vertebrates. However, they have not yet been confirmed during human locomotion. Although, rostrocaudal wave‐like activations in the spinal cord were observed during walking in humans in a previous study, the propagation shifted rostrally toward the upper lumbar segments at foot contact. Here, using an air stepping task to remove the foot‐contact interactions, we examined whether the traveling wave mechanism exists in the human spinal circuits based on the activation sequence of motor modules and their topography. We measured electromyographic activity of lower leg muscles during the air‐stepping task. Then, we extracted motor modules (i.e., basic patterns of sets of muscle activations: muscle synergies) from the measured muscle activities using nonnegative matrix factorization method. Next, we reconstructed motoneuron (MN) activity from each module activity based on myotomal charts. We identified four types of motor modules from muscle activities during the air‐stepping task. Each motor module represented different sets of synergistic muscle activations. MN clusters innervating each motor module were sequentially activated from the rostral to caudal region in the spinal cord, from the initial flexion to the last extension phase during air‐stepping. The rostrocaudally sequential activation of MN clusters suggests the possibility that rostrocaudally traveling waves exist in human locomotor spinal circuits. The present results advance the understanding of human locomotor control mechanisms, and provide important insights into the evolution of locomotor networks in vertebrates.
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Affiliation(s)
- Hikaru Yokoyama
- Laboratory of Sports Sciences, Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan.,Japan Society for the Promotion of Science, Chiyoda-ku, Tokyo, Japan
| | - Kohtaroh Hagio
- Laboratory of Sports Sciences, Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan
| | - Tetsuya Ogawa
- Laboratory of Sports Sciences, Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan
| | - Kimitaka Nakazawa
- Laboratory of Sports Sciences, Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan
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17
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Taccola G, Sayenko D, Gad P, Gerasimenko Y, Edgerton VR. And yet it moves: Recovery of volitional control after spinal cord injury. Prog Neurobiol 2017; 160:64-81. [PMID: 29102670 PMCID: PMC5773077 DOI: 10.1016/j.pneurobio.2017.10.004] [Citation(s) in RCA: 114] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 10/09/2017] [Accepted: 10/21/2017] [Indexed: 12/12/2022]
Abstract
Preclinical and clinical neurophysiological and neurorehabilitation research has generated rather surprising levels of recovery of volitional sensory-motor function in persons with chronic motor paralysis following a spinal cord injury. The key factor in this recovery is largely activity-dependent plasticity of spinal and supraspinal networks. This key factor can be triggered by neuromodulation of these networks with electrical and pharmacological interventions. This review addresses some of the systems-level physiological mechanisms that might explain the effects of electrical modulation and how repetitive training facilitates the recovery of volitional motor control. In particular, we substantiate the hypotheses that: (1) in the majority of spinal lesions, a critical number and type of neurons in the region of the injury survive, but cannot conduct action potentials, and thus are electrically non-responsive; (2) these neuronal networks within the lesioned area can be neuromodulated to a transformed state of electrical competency; (3) these two factors enable the potential for extensive activity-dependent reorganization of neuronal networks in the spinal cord and brain, and (4) propriospinal networks play a critical role in driving this activity-dependent reorganization after injury. Real-time proprioceptive input to spinal networks provides the template for reorganization of spinal networks that play a leading role in the level of coordination of motor pools required to perform a given functional task. Repetitive exposure of multi-segmental sensory-motor networks to the dynamics of task-specific sensory input as occurs with repetitive training can functionally reshape spinal and supraspinal connectivity thus re-enabling one to perform complex motor tasks, even years post injury.
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Affiliation(s)
- G Taccola
- Department of Integrative Biology and Physiology, University of California, Los Angeles, CA 90095 USA; Neuroscience Department, International School for Advanced Studies (SISSA), Bonomea 265, Trieste, Italy
| | - D Sayenko
- Department of Integrative Biology and Physiology, University of California, Los Angeles, CA 90095 USA
| | - P Gad
- Department of Integrative Biology and Physiology, University of California, Los Angeles, CA 90095 USA
| | - Y Gerasimenko
- Department of Integrative Biology and Physiology, University of California, Los Angeles, CA 90095 USA; Pavlov Institute of Physiology, St. Petersburg 199034, Russia
| | - V R Edgerton
- Department of Integrative Biology and Physiology, University of California, Los Angeles, CA 90095 USA; Department of Neurobiology, University of California, Los Angeles, CA 90095 USA; Department of Neurosurgery, University of California, Los Angeles, CA 90095 USA; Brain Research Institute, University of California, Los Angeles, CA 90095 USA; The Centre for Neuroscience and Regenerative Medicine, Faculty of Science, University of Technology Sydney, Ultimo, 2007 NSW, Australia; Institut Guttmann, Hospital de Neurorehabilitació, Institut Universitari adscrit a la Universitat Autònoma de Barcelona, Barcelona, 08916 Badalona, Spain.
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18
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Johnson MD, Thompson CK, Tysseling VM, Powers RK, Heckman CJ. The potential for understanding the synaptic organization of human motor commands via the firing patterns of motoneurons. J Neurophysiol 2017; 118:520-531. [PMID: 28356467 DOI: 10.1152/jn.00018.2017] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Revised: 03/07/2017] [Accepted: 03/21/2017] [Indexed: 12/19/2022] Open
Abstract
Motoneurons are unique in being the only neurons in the CNS whose firing patterns can be easily recorded in human subjects. This is because of the one-to-one relationship between the motoneuron and muscle cell behavior. It has long been appreciated that the connection of motoneurons to their muscle fibers allows their action potentials to be amplified and recorded, but only recently has it become possible to simultaneously record the firing pattern of many motoneurons via array electrodes placed on the skin. These firing patterns contain detailed information about the synaptic organization of motor commands to the motoneurons. This review focuses on parameters in these firing patterns that are directly linked to specific features of this organization. It is now well established that motor commands consist of three components, excitation, inhibition, and neuromodulation; the importance of the third component has become increasingly evident. Firing parameters linked to each of the three components are discussed, along with consideration of potential limitations in their utility for understanding the underlying organization of motor commands. Future work based on realistic computer simulations of motoneurons may allow quantitative "reverse engineering" of human motoneuron firing patterns to provide good estimates of the relative amplitudes and temporal patterns of all three components of motor commands.
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Affiliation(s)
- Michael D Johnson
- Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois;
| | | | - Vicki M Tysseling
- Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois.,Department of Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, Illinois
| | - Randall K Powers
- Department of Physiology and Biophysics, University of Washington, Seattle, Washington
| | - Charles J Heckman
- Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois.,Department of Physical Medicine and Rehabilitation, Feinberg School of Medicine, Northwestern University, Chicago, Illinois.,Department of Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, Illinois
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19
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Shah PK, Lavrov I. Spinal Epidural Stimulation Strategies: Clinical Implications of Locomotor Studies in Spinal Rats. Neuroscientist 2017; 23:664-680. [PMID: 28345483 DOI: 10.1177/1073858417699554] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Significant advancements in spinal epidural stimulation (ES) strategies to enable volitional motor control in persons with a complete spinal cord injury (SCI) have generated much excitement in the field of neurorehabilitation. Still, an obvious gap lies in the ability of ES to effectively generate a robust locomotor stepping response after a complete SCI in rodents, but not in humans. In order to reveal potential discrepancies between rodent and human studies that account for this void, in this review, we summarize the findings of studies that have utilized ES strategies to enable successful hindlimb stepping in spinal rats. Recent clinical and preclinical evidence indicates that motor training with ES plays a crucial role in tuning spinal neural circuitry to generate meaningful motor output. Concurrently administered pharmacology can also facilitate the circuitry to provide near optimal motor performance in SCI rats. However, as of today, the evidence for pharmacological agents to enhance motor function in persons with complete SCI is insignificant. These and other recent findings discussed in this review provide insight into addressing the translational gap, guide the design of relevant preclinical experiments, and facilitate development of new approaches for motor recovery in patients with complete SCIs.
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Affiliation(s)
- Prithvi K Shah
- 1 Division of Rehabilitation Sciences, School of Health Technology and Management, Stony Brook University, Stony Brook, NY, USA.,2 Department of Neurobiology, Stony Brook University, Stony Brook, NY, USA
| | - Igor Lavrov
- 3 Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, USA.,4 Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN, USA.,5 Institute of Fundamental Medicine and Biology, Kazan Federal University, Kazan, Russia
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20
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Tolstenkov OO, Prokofiev VV, Pleskacheva MV, Gustafsson MKS, Zhukovskaya MI. Age and serotonin effects on locomotion in marine trematode cercariae. J EVOL BIOCHEM PHYS+ 2017. [DOI: 10.1134/s1234567817020069] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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21
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Neural Stem Cell Tumorigenicity and Biodistribution Assessment for Phase I Clinical Trial in Parkinson's Disease. Sci Rep 2016; 6:34478. [PMID: 27686862 PMCID: PMC5055076 DOI: 10.1038/srep34478] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 09/14/2016] [Indexed: 12/14/2022] Open
Abstract
Human pluripotent stem cells (PSC) have the potential to revolutionize regenerative medicine. However undifferentiated PSC can form tumors and strict quality control measures and safety studies must be conducted before clinical translation. Here we describe preclinical tumorigenicity and biodistribution safety studies that were required by the US Food and Drug Administration (FDA) and Australian Therapeutic Goods Administration (TGA) prior to conducting a Phase I clinical trial evaluating the safety and tolerability of human parthenogenetic stem cell derived neural stem cells ISC-hpNSC for treating Parkinson's disease (ClinicalTrials.gov Identifier NCT02452723). To mitigate the risk of having residual PSC in the final ISC-hpNSC population, we conducted sensitive in vitro assays using flow cytometry and qRT-PCR analyses and in vivo assays to determine acute toxicity, tumorigenicity and biodistribution. The results from these safety studies show the lack of residual undifferentiated PSC, negligible tumorigenic potential by ISC-hpNSC and provide additional assurance to their clinical application.
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22
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Stienen PJ, Venzi M, Poppendieck W, Hoffmann KP, Åberg E. Precaution for volume conduction in rodent cortical electroencephalography using high-density polyimide-based microelectrode arrays on the skull. J Neurophysiol 2016; 115:1970-7. [PMID: 26864767 DOI: 10.1152/jn.00932.2015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Accepted: 02/09/2016] [Indexed: 12/20/2022] Open
Abstract
In humans, significant progress has been made to link spatial changes in electroencephalographic (EEG) spectral density, connectivity strength, and phase-amplitude modulation to neurological, physiological, and psychological correlates. In contrast, standard rodent EEG techniques employ only few electrodes, which results in poor spatial resolution. Recently, a technique was developed to overcome this limitation in mice. This technique was based on a polyimide-based microelectrode (PBM) array applied on the mouse skull, maintaining a significant number of electrodes with consistent contact, electrode impedance, and mechanical stability. The present study built on this technique by extending it to rats. Therefore, a similar PBM array, but adapted to rats, was designed and fabricated. In addition, this array was connected to a wireless EEG headstage, allowing recording in untethered, freely moving rats. The advantage of a high-density array relies on the assumption that the signal recorded from the different electrodes is generated from distinct sources, i.e., not volume-conducted. Therefore, the utility and validity of the array were evaluated by determining the level of synchrony between channels due to true synchrony or volume conduction during basal vigilance states and following a subanesthetic dose of ketamine. Although the PBM array allowed recording with high signal quality, under both drug and drug-free conditions, high synchronization existed due to volume conduction between the electrodes even in the higher spectral frequency range. Discrimination existed only between frontally and centrally/distally grouped electrode pairs. Therefore, caution should be used in interpreting spatial data obtained from high-density PBM arrays in rodents.
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Affiliation(s)
- P J Stienen
- AstraZeneca Research and Development, Innovative Medicines and Early Development, Personalized Healthcare and Biomarkers, AstraZeneca Translational Science Centre at Science for Life Laboratory, Solna, Sweden; Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden; and
| | - M Venzi
- AstraZeneca Research and Development, Innovative Medicines and Early Development, Personalized Healthcare and Biomarkers, AstraZeneca Translational Science Centre at Science for Life Laboratory, Solna, Sweden; Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden; and
| | - W Poppendieck
- Department of Medical Engineering and Neuroprosthetics, Fraunhofer Institute for Biomedical Engineering, St. Ingbert, Germany
| | - K P Hoffmann
- Department of Medical Engineering and Neuroprosthetics, Fraunhofer Institute for Biomedical Engineering, St. Ingbert, Germany
| | - E Åberg
- AstraZeneca Research and Development, Innovative Medicines and Early Development, Personalized Healthcare and Biomarkers, AstraZeneca Translational Science Centre at Science for Life Laboratory, Solna, Sweden; Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden; and
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23
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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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24
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Trejo A, Tapia JA, De la Torre Valdovinos B, Huidobro N, Flores G, Flores-Hernandez J, Flores A, Manjarrez E. Transition of pattern generation: the phenomenon of post-scratching locomotion. Neuroscience 2014; 288:156-66. [PMID: 25556832 DOI: 10.1016/j.neuroscience.2014.12.038] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Revised: 12/17/2014] [Accepted: 12/20/2014] [Indexed: 11/29/2022]
Abstract
A fundamental problem in neurophysiology is the understanding of neuronal mechanisms by which the central nervous system produces a sequence of voluntary or involuntary motor acts from a diverse repertory of movements. These kinds of transitions between motor acts are extremely complex; however, they could be analyzed in a more simple form in decerebrate animals in the context of spinal central pattern generation. Here, we present for the first time a physiological phenomenon of post-scratching locomotion in which decerebrate cats exhibit a compulsory locomotor activity after an episode of scratching. We found flexor, extensor and intermediate single interneurons rhythmically firing in the same phase during both scratching and the subsequent post-scratching locomotion. Because no changes in phase of these neurons from scratching to post-scratching locomotion were found, we suggest that in the lumbar spinal cord there are neurons associated with both motor tasks. Moreover, because of its high reproducibility we suggest that the study of post-scratching fictive locomotion, together with the unitary recording of neurons, could become a useful tool to study neuronal mechanisms underlying transitions from one rhythmic motor task to another, and to study in more detail the central pattern generator circuitry in the spinal cord.
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Affiliation(s)
- A Trejo
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, 14 Sur 6301, Col. San Manuel, Puebla, Puebla CP 72570, Mexico
| | - J A Tapia
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, 14 Sur 6301, Col. San Manuel, Puebla, Puebla CP 72570, Mexico
| | - B De la Torre Valdovinos
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, 14 Sur 6301, Col. San Manuel, Puebla, Puebla CP 72570, Mexico
| | - N Huidobro
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, 14 Sur 6301, Col. San Manuel, Puebla, Puebla CP 72570, Mexico
| | - G Flores
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, 14 Sur 6301, Col. San Manuel, Puebla, Puebla CP 72570, Mexico
| | - J Flores-Hernandez
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, 14 Sur 6301, Col. San Manuel, Puebla, Puebla CP 72570, Mexico
| | - A Flores
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, 14 Sur 6301, Col. San Manuel, Puebla, Puebla CP 72570, Mexico
| | - E Manjarrez
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, 14 Sur 6301, Col. San Manuel, Puebla, Puebla CP 72570, Mexico.
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25
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Ryczko D, Knüsel J, Crespi A, Lamarque S, Mathou A, Ijspeert AJ, Cabelguen JM. Flexibility of the axial central pattern generator network for locomotion in the salamander. J Neurophysiol 2014; 113:1921-40. [PMID: 25540227 DOI: 10.1152/jn.00894.2014] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
In tetrapods, limb and axial movements are coordinated during locomotion. It is well established that inter- and intralimb coordination show considerable variations during ongoing locomotion. Much less is known about the flexibility of the axial musculoskeletal system during locomotion and the neural mechanisms involved. Here we examined this issue in the salamander Pleurodeles waltlii, which is capable of locomotion in both aquatic and terrestrial environments. Kinematics of the trunk and electromyograms from the mid-trunk epaxial myotomes were recorded during four locomotor behaviors in freely moving animals. A similar approach was used during rhythmic struggling movements since this would give some insight into the flexibility of the axial motor system. Our results show that each of the forms of locomotion and the struggling behavior is characterized by a distinct combination of mid-trunk motor patterns and cycle durations. Using in vitro electrophysiological recordings in isolated spinal cords, we observed that the spinal networks activated with bath-applied N-methyl-d-aspartate could generate these axial motor patterns. In these isolated spinal cord preparations, the limb motor nerve activities were coordinated with each mid-trunk motor pattern. Furthermore, isolated mid-trunk spinal cords and hemicords could generate the mid-trunk motor patterns. This indicates that each side of the cord comprises a network able to generate coordinated axial motor activity. The roles of descending and sensory inputs in the behavior-related changes in axial motor coordination are discussed.
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Affiliation(s)
- D Ryczko
- Institut National de la Santé et de la Recherche Médicale (INSERM) U 862-Neurocentre Magendie, Université de Bordeaux, Bordeaux Cedex, France; and
| | - J Knüsel
- Biorobotics Laboratory (BIOROB), Institute of Bioengineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - A Crespi
- Biorobotics Laboratory (BIOROB), Institute of Bioengineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - S Lamarque
- Institut National de la Santé et de la Recherche Médicale (INSERM) U 862-Neurocentre Magendie, Université de Bordeaux, Bordeaux Cedex, France; and
| | - A Mathou
- Institut National de la Santé et de la Recherche Médicale (INSERM) U 862-Neurocentre Magendie, Université de Bordeaux, Bordeaux Cedex, France; and
| | - A J Ijspeert
- Biorobotics Laboratory (BIOROB), Institute of Bioengineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - J M Cabelguen
- Institut National de la Santé et de la Recherche Médicale (INSERM) U 862-Neurocentre Magendie, Université de Bordeaux, Bordeaux Cedex, France; and
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Romero-Pimentel AL, Vázquez-Roque RA, Camacho-Abrego I, Hoffman KL, Linares P, Flores G, Manjarrez E. Histological correlates of N40 auditory evoked potentials in adult rats after neonatal ventral hippocampal lesion: animal model of schizophrenia. Schizophr Res 2014; 159:450-7. [PMID: 25261883 DOI: 10.1016/j.schres.2014.09.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Revised: 08/28/2014] [Accepted: 09/04/2014] [Indexed: 11/26/2022]
Abstract
The neonatal ventral hippocampal lesion (NVHL) is an established neurodevelopmental rat model of schizophrenia. Rats with NVHL exhibit several behavioral, molecular and physiological abnormalities that are similar to those found in schizophrenics. Schizophrenia is a severe psychiatric illness characterized by profound disturbances of mental functions including neurophysiological deficits in brain information processing. These deficits can be assessed by auditory evoked potentials (AEPs), where schizophrenics exhibit abnormalities in amplitude, duration and latency of such AEPs. The aim of the present study was to compare the density of cells in the temporal cerebral cortex and the N40-AEP of adult NVHL rats versus adult sham rats. We found that rats with NVHL exhibit significant lower amplitude of the N40-AEP and a significant lower number of cells in bilateral regions of the temporal cerebral cortex compared to sham rats. Because the AEP recordings were obtained from anesthetized rats, we suggest that NVHL leads to inappropriate innervation in thalamic-cortical pathways in the adult rat, leading to altered function of cortical networks involved in processing of primary auditory information.
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Affiliation(s)
- A L Romero-Pimentel
- Centro de Investigación en Reproducción Animal (CIRA), Universidad Autónoma de Tlaxcala-CINVESTAV, Tlaxcala, CP 90070, México; Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, 14 Sur 6301, Col. San Manuel, Puebla, Puebla, CP 72570, México
| | - R A Vázquez-Roque
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, 14 Sur 6301, Col. San Manuel, Puebla, Puebla, CP 72570, México
| | - I Camacho-Abrego
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, 14 Sur 6301, Col. San Manuel, Puebla, Puebla, CP 72570, México
| | - K L Hoffman
- Centro de Investigación en Reproducción Animal (CIRA), Universidad Autónoma de Tlaxcala-CINVESTAV, Tlaxcala, CP 90070, México
| | - P Linares
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, 14 Sur 6301, Col. San Manuel, Puebla, Puebla, CP 72570, México
| | - G Flores
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, 14 Sur 6301, Col. San Manuel, Puebla, Puebla, CP 72570, México.
| | - E Manjarrez
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, 14 Sur 6301, Col. San Manuel, Puebla, Puebla, CP 72570, México.
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Martínez-Silva L, Manjarrez E, Gutiérrez-Ospina G, Quevedo JN. Electrophysiological representation of scratching CpG activity in the cerebellum. PLoS One 2014; 9:e109936. [PMID: 25350378 PMCID: PMC4211676 DOI: 10.1371/journal.pone.0109936] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Accepted: 09/14/2014] [Indexed: 11/19/2022] Open
Abstract
We analyzed the electrical activity of neuronal populations in the cerebellum and the lumbar spinal cord during fictive scratching in adult decerebrate cats before and after selective sections of the Spino-Reticulo Cerebellar Pathway (SRCP) and the Ventral-Spino Cerebellar Tract (VSCT). During fictive scratching, we found a conspicuous sinusoidal electrical activity, called Sinusoidal Cerebellar Potentials (SCPs), in the cerebellar vermis, which exhibited smaller amplitude in the paravermal and hemisphere cortices. There was also a significant spino-cerebellar coherence between these SCPs and the lumbar sinusoidal cord dorsum potentials (SCDPs). However, during spontaneous activity such spino-cerebellar coherence between spontaneous potentials recorded in the same regions decreased. We found that the section of the SRCP and the VSCT did not abolish the amplitude of the SCPs, suggesting that there are additional pathways conveying information from the spinal CPG to the cerebellum. This is the first evidence that the sinusoidal activity associated to the spinal CPG circuitry for scratching has a broad representation in the cerebellum beyond the sensory representation from hindlimbs previously described. Furthermore, the SCPs represent the global electrical activity of the spinal CPG for scratching in the cerebellar cortex.
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Affiliation(s)
| | - Elias Manjarrez
- Instituto de Fisiología, BUAP, Puebla, México
- * E-mail: (JNQ); (EM)
| | | | - Jorge N. Quevedo
- Departamento de Fisiología, Biofísica y Neurociencias CINVESTAV, México City, México
- * E-mail: (JNQ); (EM)
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Cuellar C, Trejo A, Linares P, Delgado-Lezama R, Jiménez-Estrada I, Abyazova L, Baltina T, Manjarrez E. Spinal neurons bursting in phase with fictive scratching are not related to spontaneous cord dorsum potentials. Neuroscience 2014; 266:66-79. [DOI: 10.1016/j.neuroscience.2014.02.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2013] [Revised: 01/17/2014] [Accepted: 02/03/2014] [Indexed: 01/14/2023]
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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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30
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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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31
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Lacquaniti F, Ivanenko YP, Zago M. Development of human locomotion. Curr Opin Neurobiol 2012; 22:822-8. [PMID: 22498713 DOI: 10.1016/j.conb.2012.03.012] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2012] [Revised: 03/18/2012] [Accepted: 03/22/2012] [Indexed: 01/28/2023]
Abstract
Neural control of locomotion in human adults involves the generation of a small set of basic patterned commands directed to the leg muscles. The commands are generated sequentially in time during each step by neural networks located in the spinal cord, called Central Pattern Generators. This review outlines recent advances in understanding how motor commands are expressed at different stages of human development. Similar commands are found in several other vertebrates, indicating that locomotion development follows common principles of organization of the control networks. Movements show a high degree of flexibility at all stages of development, which is instrumental for learning and exploration of variable interactions with the environment.
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Affiliation(s)
- Francesco Lacquaniti
- Department of Systems Medicine, Neuroscience Section, University of Rome Tor Vergata, Via Montpellier 1, 00133 Rome, Italy.
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32
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Chávez D, Rodríguez E, Jiménez I, Rudomin P. Changes in correlation between spontaneous activity of dorsal horn neurones lead to differential recruitment of inhibitory pathways in the cat spinal cord. J Physiol 2012; 590:1563-84. [PMID: 22271870 DOI: 10.1113/jphysiol.2011.223271] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Simultaneous recordings of cord dorsum potentials along the lumbo-sacral spinal cord of the anaesthetized cat revealed the occurrence of spontaneous synchronous negative (n) and negative-positive (np) cord dorsum potentials (CDPs). The npCDPs, unlike the nCDPs, appeared preferentially associated with spontaneous negative dorsal root potentials (DRPs) resulting from primary afferent depolarization. Spontaneous npCDPs recorded in preparations with intact neuroaxis or after spinalization often showed a higher correlation than the nCDPs recorded from the same pair of segments. The acute section of the sural and superficial peroneal nerves further increased the correlation between paired sets of npCDPs and reduced the correlation between the nCDPs recorded from the same pair of segments. It is concluded that the spontaneous nCDPs and npCDPs are produced by the activation of interconnected sets of dorsal horn neurones located in Rexed's laminae III–IV and bilaterally distributed along the lumbo-sacral spinal cord. Under conditions of low synchronization in the activity of this network of neurones there would be a preferential activation of the intermediate nucleus interneurones mediating Ib non-reciprocal postsynaptic inhibition. Increased synchronization in the spontaneous activity of this ensemble of dorsal horn neurones would recruit the interneurones mediating primary afferent depolarization and presynaptic inhibition and, at the same time, reduce the activation of pathways mediating Ib postsynaptic inhibition. Central control of the synchronization in the spontaneous activity of dorsal horn neurones and its modulation by cutaneous inputs is envisaged as an effective mechanism for the selection of alternative inhibitory pathways during the execution of specific motor or sensory tasks.
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Affiliation(s)
- D Chávez
- Department of Physiology, Biophysics and Neurosciences, Centre for Research and Advanced Studies, National Polytechnic Institute, México DF, México
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33
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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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34
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Taccola G. The locomotor central pattern generator of the rat spinal cord in vitro is optimally activated by noisy dorsal root waveforms. J Neurophysiol 2011; 106:872-84. [DOI: 10.1152/jn.00170.2011] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The spinal cord contains an intrinsic locomotor program driven by a central pattern generator that rhythmically activates flexor and extensor limb motor pools. Although long-lasting locomotor activity can be generated pharmacologically, trains of afferent stimuli trigger only few locomotor cycles. The present study investigated whether a new electrical stimulation protocol (termed FL istim) could elicit long-lasting fictive locomotion (FL) in the rat spinal cord in vitro. Thus, after first inducing FL by bath application of N-methyl-d-aspartate and serotonin, the recorded waveform obtained from a lumbar ventral root was digitized and then applied to either a lumbar dorsal root or the cauda equina following washout of pharmacological agents. Two FL istim cycles were the threshold input to evoke an episode of FL from ventral roots. Longer cycles (up to 1 min) induced sustained FL (up to 1 min) with stereotyped periodicity (2.2 ± 0.5 s), despite changing frequency (2–4 s) or cycle amplitude of FL istim. Gradual filtering out of the noise from FL istim trace concomitantly decreased the efficiency of FL so that stimulation with equivalent pure sinusoids produced asynchronous, irregular discharges only that could not be converted to FL by adding spontaneous basal activity. This study is the first demonstration that epochs of rhythmic locomotor-like oscillations applied to a dorsal root represent an efficient stimulus to evoke FL as long as they contain the electrophysiological noise produced within FL cycles. These observations suggest novel strategies to improve the efficiency of electrical stimulation delivered by clinical devices for neurorehabilitation after spinal injury.
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Affiliation(s)
- Giuliano Taccola
- Neurobiology Sector, International School for Advanced Studies, Trieste; and
- Spinal Person Injury Neurorehabilitation Applied Laboratory, Istituto di Medicina Fisica e Riabilitazione, Udine, Italy
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35
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Rossignol S, Frigon A. Recovery of Locomotion After Spinal Cord Injury: Some Facts and Mechanisms. Annu Rev Neurosci 2011; 34:413-40. [PMID: 21469957 DOI: 10.1146/annurev-neuro-061010-113746] [Citation(s) in RCA: 215] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Serge Rossignol
- Groupe de Recherche sur le Système Nerveux Central (FRSQ), Department of Physiology, and Multidisciplinary Team in Locomotor Rehabilitation of the Canadian Institutes for Health Research, Université de Montréal, Montreal H3C 3J7, Canada;
| | - Alain Frigon
- Groupe de Recherche sur le Système Nerveux Central (FRSQ), Department of Physiology, and Multidisciplinary Team in Locomotor Rehabilitation of the Canadian Institutes for Health Research, Université de Montréal, Montreal H3C 3J7, Canada;
- Department of Physiology and Biophysics, Université de Sherbrooke, Sherbrooke JIH 5N4, Canada
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36
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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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37
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Dessem D. Physiological, morphological and neurochemical characterization of neurons modulated by movement. J Vis Exp 2011:2650. [PMID: 21540820 DOI: 10.3791/2650] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
The role of individual neurons and their function in neuronal circuits is fundamental to understanding the neuronal mechanisms of sensory and motor functions. Most investigations of sensorimotor mechanisms rely on either examination of neurons while an animal is static or record extracellular neuronal activity during a movement. While these studies have provided the fundamental background for sensorimotor function, they either do not evaluate functional information which occurs during a movement or are limited in their ability to fully characterize the anatomy, physiology and neurochemical phenotype of the neuron. A technique is shown here which allows extensive characterization of individual neurons during an in vivo movement. This technique can be used not only to study primary afferent neurons but also to characterize motoneurons and sensorimotor interneurons. Initially the response of a single neuron is recorded using electrophysiological methods during various movements of the mandible followed by determination of the receptive field for the neuron. A neuronal tracer is then intracellularly injected into the neuron and the brain is processed so that the neuron can be visualized with light, electron or confocal microscopy (Fig. 1). The detailed morphology of the characterized neuron is then reconstructed so that neuronal morphology can be correlated with the physiological response of the neuron (Figs. 2,3). In this communication important key details and tips for successful implementation of this technique are provided. Valuable additional information can be determined for the neuron under study by combining this method with other techniques. Retrograde neuronal labeling can be used to determine neurons with which the labeled neuron synapses; thus allowing detailed determination of neuronal circuitry. Immunocytochemistry can be combined with this method to examine neurotransmitters within the labeled neuron and to determine the chemical phenotypes of neurons with which the labeled neuron synapses. The labeled neuron can also be processed for electron microscopy to determine the ultrastructural features and microcircuitry of the labeled neuron. Overall this technique is a powerful method to thoroughly characterize neurons during in vivo movement thus allowing substantial insight into the role of the neuron in sensorimotor function.
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Affiliation(s)
- Dean Dessem
- Department of Neural and Pain Sciences, University of Maryland, USA.
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38
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Cabelguen JM, Ijspeert A, Lamarque S, Ryczko D. Axial dynamics during locomotion in vertebrates lesson from the salamander. PROGRESS IN BRAIN RESEARCH 2011; 187:149-62. [PMID: 21111206 DOI: 10.1016/b978-0-444-53613-6.00010-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/14/2023]
Abstract
Much of what we know about the flexibility of the locomotor networks in vertebrates is derived from studies examining the adaptation of limb movements during stepping in various conditions. However, the body movements play important roles during locomotion: they produce the thrust during undulatory locomotion and they help to increase the stride length during legged locomotion. In this chapter, we review our current knowledge about the flexibility in the neuronal circuits controlling the body musculature during locomotion. We focus especially on salamander because, as an amphibian, this animal is able to display a rich repertoire of aquatic and terrestrial locomotor modes.
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Affiliation(s)
- Jean-Marie Cabelguen
- Neurocentre Magendie, INSERM U 862, Université de Bordeaux, Bordeaux Cedex, France
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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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40
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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: 46] [Impact Index Per Article: 3.3] [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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41
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Ryczko D, Dubuc R, Cabelguen JM. Rhythmogenesis in axial locomotor networks: an interspecies comparison. PROGRESS IN BRAIN RESEARCH 2010; 187:189-211. [PMID: 21111209 DOI: 10.1016/b978-0-444-53613-6.00013-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
During locomotion, specialized neural networks referred to as "central pattern generators" ensure precise temporal relations between the axial segments, both in limbed and limbless vertebrates. These neural networks are intrinsically capable of generating coordinated patterns of rhythmic activity in the absence of sensory feedback or descending command from higher brain centers. Rhythmogenesis in these neural circuits lies on several mechanisms, both at the cellular and the network levels. In this chapter, we compare the anatomical organization of the axial networks, the role of identified spinal neurons, and their interactions in rhythmogenesis in four species: lamprey, zebrafish, Xenopus tadpole, and salamander. The comparison suggests that several principles in axial network design are phylogenetically conserved among vertebrates.
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Affiliation(s)
- Dimitri Ryczko
- Groupe de Recherche sur le Système Nerveux Central, Département de Physiologie, Université de Montréal, Montréal, Québec, Canada
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42
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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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Abstract
Hb9 interneurons (Hb9 INs) are putative components of the mouse spinal locomotor central pattern generator (CPG) and candidates for the rhythm-generating kernel. Studies in slices and hemisected spinal cords showed that Hb9 INs display TTX-resistant membrane potential oscillations, suggesting a role in rhythm generation. To further investigate the roles of Hb9 INs in the locomotor CPG, we used two-photon calcium imaging in the in vitro isolated whole neonatal mouse spinal cord preparation to record the activity of Hb9 INs, which were subsequently stained for unambiguous genetic identification. We elicited fictive locomotion by transmitter application or by electrically stimulating the caudal tip of the spinal cord. Although most Hb9 INs were rhythmically active during fictive locomotion, their activity was sparse and they failed to fire with each cycle of the episode. If Hb9 INs are the principal pacemakers of the CPG in the hemisegment in which they are located, they should direct the firing of motor neurons, with their activity preceding that of their ipsilateral segmental ventral roots. Instead, during each locomotor cycle, onset of Hb9 IN activity lagged behind the onset of the ipsilateral ventral root burst by a mean phase of 0.21 during electrical stimulation and 0.28 during transmitter application. Whole-cell recordings in intact and hemisected spinal cords confirmed the imaging results. Our data suggest that Hb9 INs participate in fictive locomotion, but the delayed onset of activity relative to ipsilateral motoneurons suggests that Hb9 INs are unlikely to be the sole intrasegmental rhythm-generating kernel of the CPG.
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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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Selionov VA, Ivanenko YP, Solopova IA, Gurfinkel VS. Tonic Central and Sensory Stimuli Facilitate Involuntary Air-Stepping in Humans. J Neurophysiol 2009; 101:2847-58. [DOI: 10.1152/jn.90895.2008] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Air-stepping can be used as a model for investigating rhythmogenesis and its interaction with sensory input. Here we show that it is possible to entrain involuntary rhythmic movement patterns in healthy humans by using different kinds of stimulation techniques. The subjects lay on their sides with one or both legs suspended, allowing low-friction horizontal rotation of the limb joints. To evoke involuntary stepping of the suspended leg, either we used continuous muscle vibration, electrical stimulation of the superficial peroneal or sural nerves, the Jendrassik maneuver, or we exploited the postcontraction state of neuronal networks (Kohnstamm phenomenon). The common feature across all stimulations was that they were tonic. Air-stepping could be elicited by most techniques in about 50% of subjects and involved prominent movements at the hip and the knee joint (∼40–70°). Typically, however, the ankle joint was not involved. Minimal loading forces (4–25 N) applied constantly to the sole (using a long elastic cord) induced noticeable (∼5–20°) ankle-joint-angle movements. The aftereffect of a voluntary long-lasting (30-s) contraction in the leg muscles featured alternating rhythmic leg movements that lasted for about 20–40 s, corresponding roughly to a typical duration of the postcontraction activity in static conditions. The Jendrassik maneuver per se did not evoke air-stepping. Nevertheless, it significantly prolonged rhythmic leg movements initiated manually by an experimenter or by a short (5-s) period of muscle vibration. Air-stepping of one leg could be evoked in both forward and backward directions with frequent spontaneous transitions, whereas involuntary alternating two-legged movements were more stable (no transitions). The hypothetical role of tonic influences, contact forces, and bilateral coordination in rhythmogenesis is discussed. The results overall demonstrated that nonspecific tonic drive may cause air-stepping and the characteristics and stability of the evoked pattern depended on the sensory input.
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