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Vieillard J, Franck MCM, Hartung S, Jakobsson JET, Ceder MM, Welsh RE, Lagerström MC, Kullander K. Adult spinal Dmrt3 neurons receive direct somatosensory inputs from ipsi- and contralateral primary afferents and from brainstem motor nuclei. J Comp Neurol 2023; 531:5-24. [PMID: 36214727 PMCID: PMC9828095 DOI: 10.1002/cne.25405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 08/15/2022] [Accepted: 08/22/2022] [Indexed: 01/12/2023]
Abstract
In the spinal cord, sensory-motor circuits controlling motor activity are situated in the dorso-ventral interface. The neurons identified by the expression of the transcription factor Doublesex and mab-3 related transcription factor 3 (Dmrt3) have previously been associated with the coordination of locomotion in horses (Equus caballus, Linnaeus, 1758), mice (Mus musculus, Linnaeus, 1758), and zebrafish (Danio rerio, F. Hamilton, 1822). Based on earlier studies, we hypothesized that, in mice, these neurons may be positioned to receive sensory and central inputs to relay processed commands to motor neurons. Thus, we investigated the presynaptic inputs to spinal Dmrt3 neurons using monosynaptic retrograde replication-deficient rabies tracing. The analysis showed that lumbar Dmrt3 neurons receive inputs from intrasegmental neurons, and intersegmental neurons from the cervical, thoracic, and sacral segments. Some of these neurons belong to the excitatory V2a interneurons and to plausible Renshaw cells, defined by the expression of Chx10 and calbindin, respectively. We also found that proprioceptive primary sensory neurons of type Ia2, Ia3, and Ib, defined by the expression of calbindin, calretinin, and Brn3c, respectively, provide presynaptic inputs to spinal Dmrt3 neurons. In addition, we demonstrated that Dmrt3 neurons receive inputs from brain areas involved in motor regulation, including the red nucleus, primary sensory-motor cortex, and pontine nuclei. In conclusion, adult spinal Dmrt3 neurons receive inputs from motor-related brain areas as well as proprioceptive primary sensory neurons and have been shown to connect directly to motor neurons. Dmrt3 neurons are thus positioned to provide sensory-motor control and their connectivity is suggestive of the classical reflex pathways present in the spinal cord.
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Affiliation(s)
- Jennifer Vieillard
- Department of Immunology, Genetics and PathologyUppsala UniversityUppsalaSweden
| | - Marina C. M. Franck
- Department of Immunology, Genetics and PathologyUppsala UniversityUppsalaSweden,Present address: Department of Medical Biochemistry and BiophysicsKarolinska InstitutetStockholmSweden
| | - Sunniva Hartung
- Department of Immunology, Genetics and PathologyUppsala UniversityUppsalaSweden
| | - Jon E. T. Jakobsson
- Department of Immunology, Genetics and PathologyUppsala UniversityUppsalaSweden
| | - Mikaela M. Ceder
- Department of Immunology, Genetics and PathologyUppsala UniversityUppsalaSweden
| | - Robert E. Welsh
- Department of Immunology, Genetics and PathologyUppsala UniversityUppsalaSweden
| | - Malin C. Lagerström
- Department of Immunology, Genetics and PathologyUppsala UniversityUppsalaSweden
| | - Klas Kullander
- Department of Immunology, Genetics and PathologyUppsala UniversityUppsalaSweden
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Spinal Cord Circuits: Models and Reality. NEUROPHYSIOLOGY+ 2022. [DOI: 10.1007/s11062-022-09927-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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Eisdorfer JT, Sobotka-Briner H, Schramfield S, Moukarzel G, Chen J, Campion TJ, Smit R, Rauscher BC, Lemay MA, Smith GM, Spence AJ. Chemogenetic modulation of sensory afferents induces locomotor changes and plasticity after spinal cord injury. Front Mol Neurosci 2022; 15:872634. [PMID: 36090254 PMCID: PMC9461563 DOI: 10.3389/fnmol.2022.872634] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 07/26/2022] [Indexed: 12/12/2022] Open
Abstract
Neuromodulatory therapies for spinal cord injury (SCI) such as electrical epidural stimulation (EES) are increasingly effective at improving patient outcomes. These improvements are thought to be due, at least in part, to plasticity in neuronal circuits. Precisely which circuits are influenced and which afferent classes are most effective in stimulating change remain important open questions. Genetic tools, such as Designer Receptors Exclusively Activated by Designer Drugs (DREADDs), support targeted and reversible neuromodulation as well as histological characterization of manipulated neurons. We therefore transduced and activated lumbar large diameter peripheral afferents with excitatory (hM3Dq) DREADDs, in a manner analogous to EES, in a rat hemisection model, to begin to trace plasticity and observe concomitant locomotor changes. Chronic DREADDs activation, coupled with thrice weekly treadmill training, was observed to increase afferent fluorescent labeling within motor pools and Clarke's column when compared to control animals. This plasticity may underlie kinematic differences that we observed across stages of recovery, including an increased and less variable hindquarters height in DREADDs animals, shorter step durations, a more flexed ankle joint early in recovery, a less variable ankle joint angle in swing phase, but a more variable hip joint angle. Withdrawal of DREADDs agonist, clozapine-N-oxide (CNO) left these kinematic differences largely unaffected; suggesting that DREADDs activation is not necessary for them later in recovery. However, we observed an intermittent “buckling” phenomenon in DREADDs animals without CNO activation, that did not occur with CNO re-administration. Future studies could use more refined genetic targeted of specific afferent classes, and utilize muscle recordings to find where afferent modulation is most influential in altering motor output.
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Affiliation(s)
- Jaclyn T. Eisdorfer
- Department of Bioengineering, College of Engineering, Temple University, Philadelphia, PA, United States
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ, United States
| | - Hannah Sobotka-Briner
- Department of Bioengineering, College of Engineering, Temple University, Philadelphia, PA, United States
| | - Susan Schramfield
- Department of Bioengineering, College of Engineering, Temple University, Philadelphia, PA, United States
| | - George Moukarzel
- Department of Bioengineering, College of Engineering, Temple University, Philadelphia, PA, United States
| | - Jie Chen
- Department of Neuroscience, Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
| | - Thomas J. Campion
- Department of Neuroscience, Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
| | - Rupert Smit
- Department of Neuroscience, Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
| | - Bradley C. Rauscher
- Department of Bioengineering, College of Engineering, Temple University, Philadelphia, PA, United States
| | - Michel A. Lemay
- Department of Bioengineering, College of Engineering, Temple University, Philadelphia, PA, United States
| | - George M. Smith
- Department of Neuroscience, Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
| | - Andrew J. Spence
- Department of Bioengineering, College of Engineering, Temple University, Philadelphia, PA, United States
- *Correspondence: Andrew J. Spence
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Eisdorfer JT, Smit RD, Keefe KM, Lemay MA, Smith GM, Spence AJ. Epidural Electrical Stimulation: A Review of Plasticity Mechanisms That Are Hypothesized to Underlie Enhanced Recovery From Spinal Cord Injury With Stimulation. Front Mol Neurosci 2020; 13:163. [PMID: 33013317 PMCID: PMC7497436 DOI: 10.3389/fnmol.2020.00163] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 08/07/2020] [Indexed: 12/17/2022] Open
Abstract
Spinal cord injury (SCI) often results in life-long sensorimotor impairment. Spontaneous recovery from SCI is limited, as supraspinal fibers cannot spontaneously regenerate to form functional networks below the level of injury. Despite this, animal models and humans exhibit many motor behaviors indicative of recovery when electrical stimulation is applied epidurally to the dorsal aspect of the lumbar spinal cord. In 1976, epidural stimulation was introduced to alleviate spasticity in Multiple Sclerosis. Since then, epidural electrical stimulation (EES) has been demonstrated to improve voluntary mobility across the knee and/or ankle in several SCI patients, highlighting its utility in enhancing motor activation. The mechanisms that EES induces to drive these improvements in sensorimotor function remain largely unknown. In this review, we discuss several sensorimotor plasticity mechanisms that we hypothesize may enable epidural stimulation to promote recovery, including changes in local lumbar circuitry, propriospinal interneurons, and the internal model. Finally, we discuss genetic tools for afferent modulation as an emerging method to facilitate the search for the mechanisms of action.
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Affiliation(s)
- Jaclyn T Eisdorfer
- Department of Bioengineering, College of Engineering, Temple University, Philadelphia, PA, United States
| | - Rupert D Smit
- Department of Neuroscience, Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
| | - Kathleen M Keefe
- Department of Bioengineering, College of Engineering, Temple University, Philadelphia, PA, United States
| | - Michel A Lemay
- Department of Bioengineering, College of Engineering, Temple University, Philadelphia, PA, United States
| | - George M Smith
- Department of Neuroscience, Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
| | - Andrew J Spence
- Department of Bioengineering, College of Engineering, Temple University, Philadelphia, PA, United States
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Niewiadomski C, Bianco RJ, Arnoux PJ, Evin M. Isometric osteopathic manipulation influences on cervical ranges of motion and correlation with osteopathic palpatory diagnosis: A randomized trial. Complement Ther Med 2020; 48:102278. [DOI: 10.1016/j.ctim.2019.102278] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 12/10/2019] [Accepted: 12/10/2019] [Indexed: 11/17/2022] Open
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Callister RJ, Brichta AM, Schaefer AT, Graham BA, Stuart DG. Pioneers in CNS inhibition: 2. Charles Sherrington and John Eccles on inhibition in spinal and supraspinal structures. Brain Res 2019; 1734:146540. [PMID: 31704081 DOI: 10.1016/j.brainres.2019.146540] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Revised: 10/29/2019] [Accepted: 11/01/2019] [Indexed: 12/27/2022]
Abstract
This article reviews the contributions of the English neurophysiologist, Charles Scott Sherrington [1857-1952], and his Australian PhD trainee and collaborator, John Carew Eccles [1903-1997], to the concept of central inhibition in the spinal cord and brain. Both were awarded Nobel Prizes; Sherrington in 1932 for "discoveries regarding the function of neurons," and Eccles in 1963 for "discoveries concerning the ionic mechanisms involved in excitation and inhibition in central portions of the nerve cell membrane." Both spoke about central inhibition at their Nobel Prize Award Ceremonies. The subsequent publications of their talks were entitled "Inhibition as a coordinative factor" and "The ionic mechanism of postsynaptic inhibition", respectively. Sherrington's work on central inhibition spanned 41 years (1893-1934), and for Eccles 49 years (1928-1977). Sherrington first studied central inhibition by observing hind limb muscle responses to electrical (peripheral nerve) and mechanical (muscle) stimulation. He used muscle length and force measurements until the early 1900s and electromyography in the late 1920s. Eccles used these techniques while working with Sherrington, but later employed extracellular microelectrode recording in the spinal cord followed in 1951 by intracellular recording from spinal motoneurons. This considerably advanced our understanding of central inhibition. Sherrington's health was poor during his retirement years but he nonetheless made a small number of largely humanities contributions up to 1951, one year before his death at the age of 94. In contrast, Eccles retained his health and vigor until 3 years before his death and published prolifically on many subjects during his 22 years of official retirement. His last neuroscience article appeared in 1994 when he was 91. Despite poor health he continued thinking about his life-long interest, the mind-brain problem, and was attempting to complete his autobiography in the last years of his life.
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Affiliation(s)
- Robert J Callister
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Newcastle, NSW 2308, Australia.
| | - Alan M Brichta
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Newcastle, NSW 2308, Australia.
| | - Andreas T Schaefer
- Neurophysiology of Behaviour Laboratory, The Francis Crick Institute, London, United Kingdom; Department of Neuroscience, Physiology & Pharmacology, University College, London, United Kingdom.
| | - Brett A Graham
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Newcastle, NSW 2308, Australia.
| | - Douglas G Stuart
- Department of Physiology, University of Arizona, PO Box 210093, Tucson, AZ 85721-0093, USA
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Pumprasart T, Pramodhyakul N, Piriyaprasarth P. The effect of the Bobath therapy programme on upper limb and hand function in chronic stroke individuals with moderate to severe deficits. INTERNATIONAL JOURNAL OF THERAPY AND REHABILITATION 2019. [DOI: 10.12968/ijtr.2018.0124] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Background/Aims The Bobath concept has long been used to improve postural control and limb function post-stroke, yet its effect in patients with deficits have not been clearly demonstrated. This study aimed to investigate the effect of the latest Bobath therapy programme on upper limb functions, muscle tone and sensation in chronic stroke individuals with moderate to severe deficits. Methods A pre–post test design was implemented. The participants were chronic stroke individuals (n=26). Home-based intervention based on the Bobath concept was administered 3 days per week for 6 weeks (20 repetitions × 3 sets per task each session). Outcome measures consisted of the Wolf Motor Function Test, Fugl-Meyer Assessment for the upper extremity, Modified Ashworth Scale, and the Revised Nottingham Sensory Assessment. Data were analysed using the Wilcoxon Signed rank test. Results Almost all items of the Wolf Motor Function Test and the Fugl-Meyer Assessment for the upper extremity demonstrated statistically significant differences post-intervention. Finger flexor muscle tone and stereognosis were also significantly improved. Conclusions The 6-week Bobath therapy programme could improve upper limb function and impairments in chronic stroke individuals with moderate to severe deficits. Its effects were also demonstrated in improving muscle tone and cortical sensation.
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Affiliation(s)
- Thanchanok Pumprasart
- MS Student, Department of Physical Therapy, Faculty of Allied Health Sciences, Thammasat University, Pathum Thani, Thailand
| | - Noppol Pramodhyakul
- Associate Professor, Faculty of Physical Therapy, Mahidol University, Phutthamonthon, Thailand
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Côté MP, Murray LM, Knikou M. Spinal Control of Locomotion: Individual Neurons, Their Circuits and Functions. Front Physiol 2018; 9:784. [PMID: 29988534 PMCID: PMC6026662 DOI: 10.3389/fphys.2018.00784] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 06/05/2018] [Indexed: 12/31/2022] Open
Abstract
Systematic research on the physiological and anatomical characteristics of spinal cord interneurons along with their functional output has evolved for more than one century. Despite significant progress in our understanding of these networks and their role in generating and modulating movement, it has remained a challenge to elucidate the properties of the locomotor rhythm across species. Neurophysiological experimental evidence indicates similarities in the function of interneurons mediating afferent information regarding muscle stretch and loading, being affected by motor axon collaterals and those mediating presynaptic inhibition in animals and humans when their function is assessed at rest. However, significantly different muscle activation profiles are observed during locomotion across species. This difference may potentially be driven by a modified distribution of muscle afferents at multiple segmental levels in humans, resulting in an altered interaction between different classes of spinal interneurons. Further, different classes of spinal interneurons are likely activated or silent to some extent simultaneously in all species. Regardless of these limitations, continuous efforts on the function of spinal interneuronal circuits during mammalian locomotion will assist in delineating the neural mechanisms underlying locomotor control, and help develop novel targeted rehabilitation strategies in cases of impaired bipedal gait in humans. These rehabilitation strategies will include activity-based therapies and targeted neuromodulation of spinal interneuronal circuits via repetitive stimulation delivered to the brain and/or spinal cord.
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Affiliation(s)
- Marie-Pascale Côté
- CÔTÉ Lab, Spinal Cord Research Center, Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, United States
| | - Lynda M. Murray
- Motor Control and NeuroRecovery Research Laboratory (Klab4Recovery), Department of Physical Therapy, College of Staten Island, City University of New York, New York, NY, United States
- Graduate Center, Ph.D. Program in Biology, City University of New York, New York, NY, United States
| | - Maria Knikou
- Motor Control and NeuroRecovery Research Laboratory (Klab4Recovery), Department of Physical Therapy, College of Staten Island, City University of New York, New York, NY, United States
- Graduate Center, Ph.D. Program in Biology, City University of New York, New York, NY, United States
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Plantier V, Brocard F. [Calpain as a new therapeutic target for treating spasticity after a spinal cord injury]. Med Sci (Paris) 2017; 33:629-636. [PMID: 28990565 DOI: 10.1051/medsci/20173306020] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
After a spinal cord injury (SCI), patients develop spasticity, a motor disorder characterized by hyperreflexia and stiffness of muscles. Spasticity results from alterations in motoneurons with an upregulation of their persistent sodium current (I NaP), simultaneously with a disinhibition caused by a reduction of expression of chloride (Cl-) co-transporters KCC2. Until recently the origin of alterations was unknown. After reviewing pathophysiology of spasticity, the manuscript relates our recent work showing a tight relationship between the calpain-dependent proteolysis of voltage-gated sodium channels, the upregulation of I NaP and spasticity following SCI. We also discuss KCC2 as a substrate of calpains which may contribute to the disinhibition of motoneurons below the lesion. This led us to consider the proteolytic cleavage of both sodium channels and KCC2 as the upstream mechanism contributing to the development of spasticity after SCI.
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Affiliation(s)
- Vanessa Plantier
- Équipe P3M, Institut de Neurosciences de la Timone, UMR7289, Aix Marseille Université et Centre National de la Recherche Scientifique (CNRS), Marseille, France
| | - Frédéric Brocard
- Équipe P3M, Institut de Neurosciences de la Timone, UMR7289, Aix Marseille Université et Centre National de la Recherche Scientifique (CNRS), Marseille, France
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Falgairolle M, Puhl JG, Pujala A, Liu W, O'Donovan MJ. Motoneurons regulate the central pattern generator during drug-induced locomotor-like activity in the neonatal mouse. eLife 2017; 6. [PMID: 28671548 PMCID: PMC5550280 DOI: 10.7554/elife.26622] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Accepted: 06/30/2017] [Indexed: 12/17/2022] Open
Abstract
Motoneurons are traditionally viewed as the output of the spinal cord that do not influence locomotor rhythmogenesis. We assessed the role of motoneuron firing during ongoing locomotor-like activity in neonatal mice expressing archaerhopsin-3 (Arch), halorhodopsin (eNpHR), or channelrhodopsin-2 (ChR2) in Choline acetyltransferase neurons (ChAT+) or Arch in LIM-homeodomain transcription factor Isl1+ neurons. Illumination of the lumbar cord in mice expressing eNpHR or Arch in ChAT+ or Isl1+ neurons, depressed motoneuron discharge, transiently decreased the frequency, and perturbed the phasing of the locomotor-like rhythm. When the light was turned off motoneuron firing and locomotor frequency both transiently increased. These effects were not due to cholinergic neurotransmission, persisted during partial blockade of gap junctions and were mediated, in part, by AMPAergic transmission. In spinal cords expressing ChR2, illumination increased motoneuron discharge and transiently accelerated the rhythm. We conclude that motoneurons provide feedback to the central pattern generator (CPG) during drug-induced locomotor-like activity. DOI:http://dx.doi.org/10.7554/eLife.26622.001
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Affiliation(s)
- Melanie Falgairolle
- Developmental Neurobiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
| | - Joshua G Puhl
- Department of Entomology, University of Minnesota, Saint Paul, United States
| | - Avinash Pujala
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Wenfang Liu
- Developmental Neurobiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
| | - Michael J O'Donovan
- Developmental Neurobiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
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Hofstoetter US, Danner SM, Freundl B, Binder H, Mayr W, Rattay F, Minassian K. Periodic modulation of repetitively elicited monosynaptic reflexes of the human lumbosacral spinal cord. J Neurophysiol 2015; 114:400-10. [PMID: 25904708 DOI: 10.1152/jn.00136.2015] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Accepted: 04/22/2015] [Indexed: 01/29/2023] Open
Abstract
In individuals with motor-complete spinal cord injury, epidural stimulation of the lumbosacral spinal cord at 2 Hz evokes unmodulated reflexes in the lower limbs, while stimulation at 22-60 Hz can generate rhythmic burstlike activity. Here we elaborated on an output pattern emerging at transitional stimulation frequencies with consecutively elicited reflexes alternating between large and small. We analyzed responses concomitantly elicited in thigh and leg muscle groups bilaterally by epidural stimulation in eight motor-complete spinal cord-injured individuals. Periodic amplitude modulation of at least 20 successive responses occurred in 31.4% of all available data sets with stimulation frequency set at 5-26 Hz, with highest prevalence at 16 Hz. It could be evoked in a single muscle group only but was more strongly expressed and consistent when occurring in pairs of antagonists or in the same muscle group bilaterally. Latencies and waveforms of the modulated reflexes corresponded to those of the unmodulated, monosynaptic responses to 2-Hz stimulation. We suggest that the cyclical changes of reflex excitability resulted from the interaction of facilitatory and inhibitory mechanisms emerging after specific delays and with distinct durations, including postactivation depression, recurrent inhibition and facilitation, as well as reafferent feedback activation. The emergence of large responses within the patterns at a rate of 5.5/s or 8/s may further suggest the entrainment of spinal mechanisms as involved in clonus. The study demonstrates that the human lumbosacral spinal cord can organize a simple form of rhythmicity through the repetitive activation of spinal reflex circuits.
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Affiliation(s)
- Ursula S Hofstoetter
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria;
| | - Simon M Danner
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria; Institute of Analysis and Scientific Computing, Vienna University of Technology, Vienna, Austria; and
| | - Brigitta Freundl
- Neurological Center, Maria Theresien Schloessel, Otto Wagner Hospital, Vienna, Austria
| | - Heinrich Binder
- Neurological Center, Maria Theresien Schloessel, Otto Wagner Hospital, Vienna, Austria
| | - Winfried Mayr
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Frank Rattay
- Institute of Analysis and Scientific Computing, Vienna University of Technology, Vienna, Austria; and
| | - Karen Minassian
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
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Deardorff AS, Romer SH, Sonner PM, Fyffe REW. Swimming against the tide: investigations of the C-bouton synapse. Front Neural Circuits 2014; 8:106. [PMID: 25278842 PMCID: PMC4167003 DOI: 10.3389/fncir.2014.00106] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Accepted: 08/17/2014] [Indexed: 11/19/2022] Open
Abstract
C-boutons are important cholinergic modulatory loci for state-dependent alterations in motoneuron firing rate. m2 receptors are concentrated postsynaptic to C-boutons, and m2 receptor activation increases motoneuron excitability by reducing the action potential afterhyperpolarization. Here, using an intensive review of the current literature as well as data from our laboratory, we illustrate that C-bouton postsynaptic sites comprise a unique structural/functional domain containing appropriate cellular machinery (a “signaling ensemble”) for cholinergic regulation of outward K+ currents. Moreover, synaptic reorganization at these critical sites has been observed in a variety of pathologic states. Yet despite recent advances, there are still great challenges for understanding the role of C-bouton regulation and dysregulation in human health and disease. The development of new therapeutic interventions for devastating neurological conditions will rely on a complete understanding of the molecular mechanisms that underlie these complex synapses. Therefore, to close this review, we propose a comprehensive hypothetical mechanism for the cholinergic modification of α-MN excitability at C-bouton synapses, based on findings in several well-characterized neuronal systems.
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Affiliation(s)
- Adam S Deardorff
- Boonshoft School of Medicine, Department of Neuroscience, Cell Biology and Physiology, Wright State University Dayton, OH, USA
| | - Shannon H Romer
- Boonshoft School of Medicine, Department of Neuroscience, Cell Biology and Physiology, Wright State University Dayton, OH, USA
| | - Patrick M Sonner
- Boonshoft School of Medicine, Department of Neuroscience, Cell Biology and Physiology, Wright State University Dayton, OH, USA
| | - Robert E W Fyffe
- Boonshoft School of Medicine, Department of Neuroscience, Cell Biology and Physiology, Wright State University Dayton, OH, USA
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Machacek DW, Hochman S. Noradrenaline unmasks novel self-reinforcing motor circuits within the mammalian spinal cord. J Neurosci 2006; 26:5920-8. [PMID: 16738234 PMCID: PMC2680501 DOI: 10.1523/jneurosci.4623-05.2006] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Spiking activity in motor axons represents the final central coding for muscle contraction. Recurrent collaterals in spinal cord from these same axons are known to offer a negative feedback control of motor output via a class of interposed inhibitory interneurons. Here we demonstrate that, during noradrenergic drive, a previously unknown recurrent excitatory pathway is unmasked and expressed. These excitatory projections are shown to have broad bilateral actions within and between hindlimb spinal segments and can alter ongoing pattern-generating motor behaviors. Thus, motor output strength is controlled via central positive and negative feedback loops, undoubtedly to provide a greater flexibility and dynamic range of control. That this novel function is regulated by a descending neuromodulatory transmitter indicates a conditional recruitment during certain behavioral states as part of the central noradrenergic arousal apparatus.
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Mattei B, Schmied A, Vedel JP. Recurrent inhibition of wrist extensor motoneurones: a single unit study on a deafferented patient. J Physiol 2003; 549:975-84. [PMID: 12702741 PMCID: PMC2342996 DOI: 10.1113/jphysiol.2003.039040] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
In order to document the effects of recurrent inhibition on the firing times of human alpha-motoneurones during natural motor behaviour, a case study was performed on a deafferented patient. The fact that this subject had completely lost the large-diameter sensory afferents provided us with a unique opportunity of selectively stimulating the motor axons in the nerves. The tonic activity of single motor units (n = 21) was recorded in the extensor carpi radialis muscles while applying randomly timed antidromic electrical stimuli to the radial nerve. The peristimulus time histogram analysis showed the presence of biphasic inhibitory effects, including an early, short-lasting component followed by a longer-lasting component occurring 20-40 ms later. The interspike interval (ISI) during which the stimulation occurred was generally lengthened as compared to the previous ISIs. The stimulation was most effective when delivered early (20-30 ms) after a spike. It was also effective, although less so, when delivered at the end of the ISI (70-100 ms after a spike). The lengthening effect sometimes extended over one or two of the subsequent ISIs. The lengthening effect of the motor axon stimulation was followed by an excitatory-like effect, which took the form of a shortening that affected up to five ISIs after the stimulation. The biphasic inhibitory effects and the subsequent facilitatory effects are discussed in terms of the dual nature of the synaptic processes involved in the recurrent inhibitory network, the postactivation facilitation/depression processes and the mutual inhibition occurring between Renshaw cells.
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Affiliation(s)
- Benjamin Mattei
- CNRS-INPC, 31 chemin Joseph Aiguier, 13402 Marseille CEDEX 20, France.
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Dragoi V, Sur M. Dynamic properties of recurrent inhibition in primary visual cortex: contrast and orientation dependence of contextual effects. J Neurophysiol 2000; 83:1019-30. [PMID: 10669513 DOI: 10.1152/jn.2000.83.2.1019] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
A fundamental feature of neural circuitry in the primary visual cortex (V1) is the existence of recurrent excitatory connections between spiny neurons, recurrent inhibitory connections between smooth neurons, and local connections between excitatory and inhibitory neurons. We modeled the dynamic behavior of intermixed excitatory and inhibitory populations of cells in V1 that receive input from the classical receptive field (the receptive field center) through feedforward thalamocortical afferents, as well as input from outside the classical receptive field (the receptive field surround) via long-range intracortical connections. A counterintuitive result is that the response of oriented cells can be facilitated beyond optimal levels when the surround stimulus is cross-oriented with respect to the center and suppressed when the surround stimulus is iso-oriented. This effect is primarily due to changes in recurrent inhibition within a local circuit. Cross-oriented surround stimulation leads to a reduction of presynaptic inhibition and a supraoptimal response, whereas iso-oriented surround stimulation has the opposite effect. This mechanism is used to explain the orientation and contrast dependence of contextual interactions in primary visual cortex: responses to a center stimulus can be both strongly suppressed and supraoptimally facilitated as a function of surround orientation, and these effects diminish as stimulus contrast decreases.
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Affiliation(s)
- V Dragoi
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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Turkin VV, Monroe KS, Hamm TM. Organization of recurrent inhibition and facilitation in motor nuclei innervating ankle muscles of the cat. J Neurophysiol 1998; 79:778-90. [PMID: 9463441 DOI: 10.1152/jn.1998.79.2.778] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The distribution of recurrent inhibition and facilitation to motor nuclei of muscles that act at the cat ankle joint was compared with the locomotor activity and mechanical action of those muscles described in published studies. Emphasis was placed on motor nuclei whose muscles have a principal action about the abduction-adduction axis and the pretibial flexors: tibialis posterior (TP), peroneus longus (PerL), peroneus brevis (PerB), the anterior part of tibialis anterior (TA) and extensor digitorum longus (EDL). Most intracellular recordings in spinalized, unanesthetized decerebrate cats showed only inhibitory or excitatory responses to antidromic stimulation of peripheral nerves, but mixed effects were also seen. Recurrent effects among motor nuclei of ankle abductors and adductors were not distributed uniformly. TP motoneurons received recurrent inhibition from most other nuclei active in stance and stimulation of the TP nerve inhibited these motor nuclei. Although PerB motoneurons are also active during stance, they received primarily facilitation from most motor nuclei. PerL received mixtures of inhibition and facilitation from all sources. Stimulation of the nerves to PerL, PerB, and peroneus tertius (PerT) produced weak recurrent inhibition and facilitation, even in homonymous motoneurons and motoneurons of Ia synergists. The ankle flexors TA and EDL displayed different patterns of recurrent inhibition and facilitation. TA motoneurons received prominent homonymous inhibition and inhibition from semitendinosus (St). EDL, whose activity profile differs from TA and which also acts at the digits, did not receive strong recurrent inhibition from either TA or St, nor did stimulation of the EDL nerve produce much inhibition. The distribution of recurrent inhibition and facilitation is correlated with the pattern of locomotor activity, but with exceptions that suggest an influence of mechanical action, particularly in the antagonistic interactions between TP and PerB. The extended pattern of recurrent inhibition, the reduction or absence of inhibition produced by motor nuclei with individualized functions or digit function and the prevalence of facilitation suggest that the recurrent Renshaw system is organized into inhibitory and disinhibitory projections that participate in the control of sets of motor nuclei engaged in rhythmic and stereotyped movements.
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Affiliation(s)
- V V Turkin
- Division of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona 85013, USA
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Tóth K, Freund TF, Miles R. Disinhibition of rat hippocampal pyramidal cells by GABAergic afferents from the septum. J Physiol 1997; 500 ( Pt 2):463-74. [PMID: 9147330 PMCID: PMC1159396 DOI: 10.1113/jphysiol.1997.sp022033] [Citation(s) in RCA: 320] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
1. Slices were prepared from rat forebrain to include both the septum and the hippocampus in order to examine the effects of septal stimulation on hippocampal inhibitory circuits. 2. Repetitive stimulation of septo-hippocampal fibres caused a maintained decrease in the frequency of spontaneous IPSPs recorded from CA3 pyramidal cells in the presence of antagonists of excitatory amino acid receptors and of muscarine receptors. 3. In records made from pyramidal cells with CsCl-filled electrodes, IPSPs were examined at potentials both more positive and more negative than their reversal potential. Single septal stimuli hyperpolarized pyramidal cells when IPSPs were depolarizing events and depolarized them when IPSPs were hyperpolarizing. The GABAA receptor antagonist picrotoxin abolished the effects of septal stimulation. 4. Activation of septal afferents initiated an IPSP in hippocampal inhibitory cells but not in pyramidal cells. Septal IPSPs had similar kinetics to those initiated by local hippocampal stimulation and could suppress inhibitory cell discharge. 5. In pyramidal cells recorded with potassium acetate-filled electrodes, septal stimuli initiated a depolarization that increased with the driving force for Cl- and that could cause firing. 6. Rhythmic stimulation of septo-hippocampal fibres at 5 Hz initiated, in the hippocampus, a maintained out-of-phase oscillation of pyramidal cell discharge and inhibitory cell firing, as detected by the occurrence of spontaneous IPSPs. 7. These results suggest that GABAergic septo-hippocampal afferents selectively inhibit hippocampal inhibitory cells and so disinhibit pyramidal cells. This disinhibition could contribute to the transmission of the theta rhythm from the septum to the hippocampus.
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Affiliation(s)
- K Tóth
- Laboratoire de Neurobiologie Cellulaire, Institut Pasteur, Paris, France
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Affiliation(s)
- E Jankowska
- Department of Physiology, University of Göteborg, Sweden
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Illert M, Wietelmann D. Distribution of recurrent inhibition in the cat forelimb. PROGRESS IN BRAIN RESEARCH 1989; 80:273-81; discussion 269-71. [PMID: 2699367 DOI: 10.1016/s0079-6123(08)62221-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
This chapter reviews experiments on the distribution of recurrent pathways from motor axon collaterals to alpha motoneurones in the brachial enlargement of the cat. In anaesthetized cats intracellular recording from identified forelimb motoneurones was used to reveal the pattern of recurrent inhibition or excitation following stimulation of muscle nerves. The recurrent connections of the motor nuclei acting on the elbow follow the tight mechanical agonism of the muscles involved. Extensive bidirectional recurrent inhibitory connections were found between motor nuclei innervating elbow and wrist muscles. It is suggested that one group of these connections supports the organization of limb extension, the other group organization of limb flexion. The supinator and the pronator teres motornuclei have identical recurrent connections. Co-convergence from elbow flexor and extensor motornuclei in one and the same motoneurone is frequent. It is suggested that this pattern may serve the stabilization of the radio-ulnar plane. Neither homonymous nor heteronymous recurrent actions were observed in the radial motornuclei acting on the digits, which suggests a lack of recurrent axon collaterals in these nuclei. These results draw attention to the fact that recurrent inhibition is not evenly distributed between all limb motor nuclei.
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Yuan CS, Sasaki S, Taylor A, Reinking RM, Stuart DG. Effects of chloralose-urethane anesthesia on single-axon reciprocal Ia IPSPs in the cat. Neurosci Lett 1988; 94:291-6. [PMID: 2974516 DOI: 10.1016/0304-3940(88)90033-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Reciprocal Ia inhibitory postsynaptic potentials (IPSPs) generated by single afferents have been recorded with signal averaging in unanesthetized ischemic-decapitate cats for comparison with measurements previously obtained from preparations anesthetized with a mixture of chloralose and urethane. The results are similar to those which we obtained recently for single-axon recurrent IPSPs. Together, the studies show that chloralose-urethane anesthesia has a depressant effect on two widely studied circuits in the mammalian spinal cord.
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Affiliation(s)
- C S Yuan
- Department of Physiology, University of Arizona, Tucson 85724
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Motoneuronal interaction in spinal cord isolated from infant rats. NEUROPHYSIOLOGY+ 1988. [DOI: 10.1007/bf02141336] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Hamm TM, Sasaki S, Stuart DG, Windhorst U, Yuan CS. The measurement of single motor-axon recurrent inhibitory post-synaptic potentials in the cat. J Physiol 1987; 388:631-51. [PMID: 3656201 PMCID: PMC1192569 DOI: 10.1113/jphysiol.1987.sp016635] [Citation(s) in RCA: 113] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
1. Signal averaging was used in forty experiments on low-spinal cats to measure and characterize the oligosynaptic responses of seventy-six motoneurons supplying the medial gastrocnemius muscle to the single impulses of antidromically stimulated single motor axons supplying the same muscle. 2. In thirteen experiments on chloralose-urethane anaesthetized preparations, twelve (43%) of the tested twenty-eight motoneurones exhibited a single-axon recurrent inhibitory post-synaptic potential (recurrent i.p.s.p.), as compared to sixty-four (62%) of the 103 motoneurones tested in twenty-seven animals in the absence of anaesthetic after ischaemic decapitation. 3. Single-axon recurrent i.p.s.p.s most often consisted of a single, long-lasting hyperpolarization. Ten of the recurrent i.p.s.p.s contained a second late peak of hyperpolarization. In another eight of the i.p.s.p.s, a small late depolarization was evident. 4. The distinct profiles of the recurrent i.p.s.p.s were readily distinguished from the relatively flat profiles with low noise levels in the averages of the fifty-five 'no-response' cells. The transmembrane and post-synaptic nature of the i.p.s.p.s was confirmed by extracellular control recordings taken immediately outside seven of the cells with positive responses. In addition, ten cells with positive responses were subjected to current passage during the averaging procedure. In all cases, depolarization increased and hyperpolarization reduced the amplitude of their single-axon recurrent i.p.s.p.s. 5. The mean amplitude of the responses was 12.0 microV in chloralose-urethane preparations as compared to a peak-to-peak noise level less than 6.0 microV in the no-response averages. Corresponding values in ischaemic-decapitate preparations were 46.2 microV and less than 7.5 microV, respectively. 6. Latency, rise-time and half-width (i.e. duration at half-amplitude) values of the i.p.s.p.s were similar for chloralose-urethane and ischaemic-decapitate preparations. The average values in both preparations were 2.5, 5.6 and 19.3 ms, respectively. The latency values indicated both disynaptic and, perhaps, longer components in the recurrent i.p.s.p.s. The rise-time and half-width values were relatively similar to those reported or measured from published records for analogous composite recurrent i.p.s.p.s (i.e. responses to antidromic stimulation of the whole muscle nerve rather than single motor axons). A weak, but significant, correlation between rise-time and half-width was observed for the sixty-six single-axon recurrent i.p.s.p.s with a single negative-going peak.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- T M Hamm
- Department of Physiology, University of Arizona, College of Medicine, Tucson 85724
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Schieppati M, Crenna P. Excitability of reciprocal and recurrent inhibitory pathways after voluntary muscle relaxation in man. Exp Brain Res 1985; 59:249-56. [PMID: 4029300 DOI: 10.1007/bf00230904] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
We studied the potential contribution of postsynaptic mechanisms to the depression of reflex excitability which occurs immediately after a voluntary release from tonic muscle contraction. The excitability of the Soleus (Sol) motor pool was tested at rest and after voluntary muscle relaxation. In both cases the Sol H-reflex was conditioned by a single shock to the peroneal nerve, in order to activate the Ia interneurones (INs) mediating the reciprocal inhibition via a peripheral input, or by a short-lasting voluntary contraction of the Tibialis Anterior (TA) muscle, to activate the Ia INs via a central command. Changes in excitability of Renshaw cells were also tested at rest and after release, to assess the role of recurrent inhibition in the release-induced inhibition of the Sol H-reflex. It was demonstrated that: the excitability of the INs mediating the reciprocal inhibition was only slightly enhanced in comparison with resting conditions; the H-reflex of the antagonist muscle (TA) evoked after Sol release was not consistently facilitated with respect to rest; the command to contract the TA muscle reduced the H-reflex of the Sol muscle during rest but not after Sol release; recurrent inhibition did not increase its effect in the post-release period. Such features suggest that recurrent and reciprocal post-synaptic inhibitions do not play a major role in reducing the reflex excitability of a relaxing muscle; rather, the command to release prevents the reciprocal inhibitory effect which accompanies the contraction of the antagonist muscle.(ABSTRACT TRUNCATED AT 250 WORDS)
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Appelberg B, Hulliger M, Johansson H, Sojka P. Recurrent actions on gamma-motoneurones mediated via large and small ventral root fibres in the cat. J Physiol 1983; 335:293-305. [PMID: 6875879 PMCID: PMC1197353 DOI: 10.1113/jphysiol.1983.sp014534] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Effects on single lumbar gamma-motoneurones, mediated via fibres running in the ventral roots, were studied by micro-electrode recording in cats anaesthetized with chloralose. Graded electrical stimulation of ventral roots or of peripheral nerves was used. The cells were identified as gamma-motoneurones by antidromic stimulation and by measurement of their axonal conduction velocity. Some of the cells were classified as static or dynamic. The findings confirm the previously demonstrated existence of low-threshold, presumed recurrent, inhibition of both static and dynamic gamma-motoneurones. Strong evidence for the occurrence of high-threshold recurrent inhibition of gamma-motoneurones is also presented. In addition, excitatory effects on gamma-cells, also mediated via fibres in the ventral roots, are described. The low-threshold effects from ventral root fibres are attributed to recurrent alpha-collateral activity and the high-threshold effects to gamma-collateral activity. The significance of recurrent inhibition of gamma-motoneurones is discussed in relation to the 'gain regulator' concept proposed by Hultborn, Lindström & Wigström (1979).
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Abstract
1. The external and internal intercostal nerves of a single intercostal space were stimulated in anaesthetized paralysed cats with dorsal roots cut in the corresponding spinal cord segment. 2. Extracellular recording in the ventral horn revealed single units which fired short high frequency bursts of spikes at short latency to stimulation of either or both of the two nerves at stimulus strengths appropriate to the activation of alpha motor axons. These units were deduced to be Renshaw cells. 3. Small (0.1-0.2 mV) hyperpolarizing potentials of duration up to 50 msec were recorded intracellularly in both inspiratory and expiratory motoneurones of the same segment. Latencies and thresholds were appropriate for disynaptic i.p.s.p.s evoked by collaterals of alpha motor axons. 4. The changes in probability of firing following the stimuli were examined for inspiratory alpha motoneurones by constructing post-stimulus histograms of efferent discharges recorded from filaments of the external intercostal nerve of the segment stimulated and from other segments. 5. A period of reduced probability of firing of up to 24 msec duration, corresponding in all respects to disynaptic inhibition from alpha motor axon collaterals, was seen in the segment stimulated and up to three segments distant, though declining in intensity with distance. Either nerve could evoke such inhibition although that evoked from the internal intercostal nerve was stronger, as were the intensities of the Renshaw cell discharges. 6. We conclude that recurrent inhibition, via Renshaw cells which have axons up to 30 mm in length, is present for intercostal motoneurones. Arguments are adduced to show that although the effects from stimulating any one segmental nerve may be relatively weak, the over-all effect resulting from the widely spread projections of the Renshaw cells concerned is an inhibition comparable intensity with that seen in many hind limb motor nuclei.
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Jankowska E, Odutola A. Crosses and uncrossed synaptic actions on motoneurones of back muscles in the cat. Brain Res 1980; 194:65-78. [PMID: 6445769 DOI: 10.1016/0006-8993(80)91319-0] [Citation(s) in RCA: 115] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Intracellular recording from motoneurones of back muscles was used to analyze their synaptic input. The sample included motoneurones located in Th13--L2 spinal segments, identified by their antidromic invasion following stimulation of medial, intermediate and lateral branches of the dorsal rami. The motoneurones were monosynaptically excited from lowest threshold ipsilateral afferents and from ipsilateral descending spinal tracts. Polysynaptic EPSPs and/or IPSPs were evoked in them from higher threshold ipsilateral and contralateral afferents and from descending spinal tracts, and recurrent inhibition was evoked from ipsilateral motor axon collaterals. There was no evidence of crossed disynaptic inhibition from group I afferents, or crossed recurrent inhibition of these neurones. Supplementary records from another group of neurones in Th13--L2 segments, unidentified but likely to innervate other back or abdominal muscles, showed monosynaptic and polysynaptic PSPs of the same origin, and in addition disynaptic IPSPs and disynaptic EPSPs from contralateral ventral roots. The crossed IPSPs had features of the crossed recurrent IPSPs, while the crossed EPSPs appeared to be more likely evoked by some afferents passing via the ventral roots. Generally, the input to the investigated neurones showed greatest similarities to the input to motoneurones of neck muscles and differed from that reported for tail motoneurones.
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Abstract
1. The reflex connexions from muscle afferents and ventral root fibres to the motoneurones of the muscles biventer-cervicis, complexus, sternocleidomastoid, trapezius and splenius, the principal muscles involved in head movement in the cat, were studied with the technique of intracellular recording. 2. Electrical stimulation of homonymous muscle afferents of biventer-cervicis and complexus, sternocleidomastoid and trapezius, at strengths below 1.6 times threshold of the dorsal root afferent volley, produced monosynaptic e.p.s.p.s in the corresponding motoneurones. Recruitment of higher threshold muscle afferents produced additional p.s.p.s with longer central delays. 3. Stimulation of low-threshold muscle afferents did not produce any p.s.p.s in the motoneurones of the ipsilateral antagonist. Stimulation of higher threshold afferents evoked i.p.s.p.s with central delays longer than 1.6 msec, or mixed e.p.s.p.-i.p.s.p.s in the ipsilateral antagonist. 4. Mixed e.p.s.p.-i.p.s.p.s or i.p.s.p.s with central delays longer than 1.5 msec were evoked in trapezius motoneurones upon stimulation of high threshold afferents from biventer-cervicis and complexus, while stimulation of low-threshold biventercervicis and complexus afferents evoked no p.s.p.s in trapezius motoneurones. 5. Stimulation of contralateral low-threshold biventer-cervicis and complexus afferents evoked a sequence of i.p.s.p. disinhibition in sternocleidomastoid motoneurones, and vice versa, with central delays longer than 1.7 msec. 6. Stimulation of the deafferented biventer-cervicis, complexus, splenius, sternocleidomastoid and trapezius muscle nerves frequently activated interneurones in the ventral horn at monosynaptic central delays. Activation of homoynmous ventral root fibres rarely evoked p.s.p.s in biventer-cervicis, complexius, splenius or sternocleidomastoid motoneurones, while it produced disynaptic i.p.s.p.s in 80% of trapezius motoneurones. 7. It is concluded that Ia reciprocal inhibition and recurrent inhibition, two reflex circuits which are so prominent in limb segments of the spinal cord, do not play a major role in the generation of head movement. Rather, head movement may be primarily controlled from supraspinal centres.
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Abstract
1. Intracellular recording was made from motoneurones in lower sacral (S2 and S3) segments of the spinal cord in cats, to analyse the neuronal organization of the inhibition evoked in these motoneurones from contralateral afferents. 2. It was confirmed that stimulation of the lowest threshold afferents of contralateral dorsal roots evokes i.p.s.p.s with latencies similar to those of disynaptic i.p.s.p.s. evoked from group Ia muscle spindle afferents in limb motoneurones. 3. The crossed disynaptic i.p.s.p.s in sacral motoneurones were found to be mediated by interneurones which are themselves inhibited by Renshaw cells, these interneurones and Renshaw cells being activated from the dorsal and ventral roots respectively, on the side of the body opposite to the location of the inhibited motoneurones. 4. In unanaesthetized decerebrate preparations crossed recurrent facilitation of sacral motoneurones was evoked with a time course similar to that of recurrent facilitation of lumbar motoneurones. It was taken to indicate a tonic inhibition of sacral motoneurones by interneurones responsible for their crossed disynaptic inhibition, and a disinhibition following stimulation of contralateral ventral roots. 5. In anaesthetized preparations crossed recurrent inhibition appeared, instead of the recurrent facilitation, in more than one half of the tested motoneurones. 6. A comparison of the input from ipsilateral and contralateral afferents to identified motoneurones of tail muscles with the input to pudendal motoneurones led to the conclusion that crossed disynaptic inhibition is evoked specifically in tail motoneurones. 7. Intracellular staining of sacral motoneurones with horseradish peroxidase revealed that the tail motoneurones and others with crossed disynaptic inhibition differ from the pudendal motoneurones in their location and in a number of morphological features; tail motoneurones are larger, they have differently directed dendrites and they show more extensively branched initial axon collaterals which appeared to ramify only within the ventral and lateral parts of the ipsilateral ventral horn. 8. One Renshaw cell which was stained with horseradish peroxidase was found to project contralaterally, after giving a number of axon collaterals ipsilaterally.
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Fu TC, Hultborn H, Larsson R, Lundberg A. Reciprocal inhibition during the tonic stretch reflex in the decerebrate cat. J Physiol 1978; 284:345-69. [PMID: 731548 PMCID: PMC1282825 DOI: 10.1113/jphysiol.1978.sp012544] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
1. The aim of this study was to investigate post-synaptic reciprocal Ia inhibition during the stretch reflex; particularly the extent to which an increased Ia excitation of the Ia inhibitory interneurones will be counteracted by recurrent inhibition from motor axon collaterals. For this purpose we investigated depression of monosynaptic test reflexes antagonist flexors (reciprocal inhibition) during static stretch of quadriceps or triceps surae in unanaesthetized decerebrate cats. 3. With increasing stretch of the extensor muscle there was first a linear augmentation of reciprocal inhibition, but along with the stretch reflex in the extensor a plateau appeared in the inhibition of the flexors, although the extensor stretch reflex (judged by the e.m.g.) increased with further stretching. Within the range of stretching of triceps surae which gave increased stretch reflexes the plateau in the reciprocal inhibition was usually maintained, while during stretching of quadriceps a second phase of augmenting reciprocal inhibition often appeared. Stretch beyond the level which increased the stretch reflex activity gave augmenting reciprocal inhibition both in case of quadriceps and triceps surae. 3. Excitability measurements from central terminals of Ia afferents revealed that the increasing reciprocal inhibition during increasing stretch reflex activity in quadriceps was associated with a primary afferent depolarization in knee flexor Ia afferents; there was no corresponding effect in ankle flexor Ia afferents during stretch reflexes in triceps surae. 4. The primary afferent depolarization evoked in knee flexor Ia afferents by electrical nerve stimulation was then compared with the presynaptic inhibition of knee flexor monosynaptic test reflexes produced by the same stimuli. The results suggest that the second phase of increasing reciprocal inhibition in knee flexors is due to presynaptic inhibition and accordingly that the depth of post-synaptic reciprocal inhibition remains constant at different degrees of stretch reflex activity in both knee and ankle extensors. 5. It is postulated that during increasing stretch reflex activity the increment in Ia excitation and recurrent inhibitio; on to the Ia inhibitory interneurones almost exactly balance each other. It is suggested that recurrent inhibition of Ia inhibitory interneurones may serve as a segmental autoregulatory mechanism to keep 'alpha-gamma-linked reciprocal inhibition' at a constant depth during different levels of agonist activity.
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Goldfarb J. Excitation of Renshaw cells via motor neuron collaterals in acute and chronic spinal cats. Brain Res 1976; 106:176-83. [PMID: 1063597 DOI: 10.1016/0006-8993(76)90084-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Homma S. Frequency characteristics of the impulse decoding ratio between the spinal afferents and efferents in the stretch reflex. PROGRESS IN BRAIN RESEARCH 1976; 44:15-30. [PMID: 188071 DOI: 10.1016/s0079-6123(08)60720-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Benecke R, Böttcher U, Henatsch HD, Meyer-Lohmann J, Schmidt J. Recurrent inhibition of individual Ia inhibitory interneurones and disinhibition of their target alpha-motoneurones during muscle stretches. Exp Brain Res 1975; 23:13-28. [PMID: 1149846 DOI: 10.1007/bf00238726] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The effects of ramp stretches applied to triceps surae muscle on the discharge patterns of single Ia inhibitory interneurones, monosynaptically invaded from various nerves, were studied in either decerebrate or anesthetized cats. Interneurones which received direct excitatory Ia input from the stretched muscle exhibited augmented activity both during the dynamic and static phase of stretch, which was, however, interrupted by a transient inhibitory influence during the dynamic phase of stretch. The influences on Ia inhibitory interneurones, monosynaptically invaded from hamstring or tibial nerve, were exclusively inhibitory. These stretch-induced inhibitions were better demonstrable in decerebrate than in anesthetized preparations. The timing of the discharge patterns of additionally recorded Renshaw cells during stretch, and the disappearance or reduction of the above described inhibitory effects after administration of DHE, strongly support the idea that these inhibitory actions are caused by Renshaw inhibition. In Ia inhibitory interneurones, monosynaptically activated from the antagonistic peroneal nerve, stretch induced also pronounced inhibitory effects, which were most probably caused by mutual inhibition between Ia inhibitory interneurones. The suppression of agonistic Ia inhibitory interneurone activity below the tonic resting activity corresponded to an enhancement of the monosynaptic reflex amplitude of the antagonistic motoneurone pool. The findings suggest that normal orthodromic activation of Renshaw cells, and consequently the recurrent inhibition of the Ia inhibitory interneurones, is predominantly linked with rapid phasic, rather than slow tonic, motoneuronal firing. The functional role of this mechanism for the performance of rapidly alternating movements and the damping of ballistic agonist contractions is discussed.
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Fedina L, Hultborn H, Illert M. Facilitation from contralateral primary afferents of interneuronal transmission in the Ia inhibitory pathway to motoneurones. ACTA PHYSIOLOGICA SCANDINAVICA 1975; 94:198-221. [PMID: 1155177 DOI: 10.1111/j.1748-1716.1975.tb05880.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The action of volleys in contralateral primary afferents on transmission in the Ia inhibitory pathways to motoneurones was investigated with intracellular recording from motoneurones. Ia IPSPs in flexor as well as most extensor motoneurones were regularly facilitated by volleys in contralateral high threshold muscle, cutaneous and joint afferents in spinal cats under chloralose anaesthesia. In decerebrate cats with a low pontine lesion transmission in Ia inhibitory pathways was not facilitated but rather depressed by volleys in these afferents. The recurrent effects from motor axon collaterals were investigated on inhibitory transmission from different contralateral afferents to motoneurones. Previous investigations have shown that the interneurones mediating the reciprocal Ia inhibition receive recurrent inhibition via motor axon collaterals and Renshaw cells. Now a strong positive correlation was revealed between recurrent depression of IPSPs evoked from different contralateral afferents and facilitation of Ia IPSPs by the same afferent volleys. These results suggest that the recurrent depression of IPSPs from different contralateral primary afferents depends on their excitatory convergence onto the Ia inhibitory interneurones, which then partly mediate the IPSP evoked in the motoneurone from these afferents.
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Jankowska E, Fu TC, Lundberg A. Reciprocal La inhibition during the late reflexes evoked from the flexor reflex afferents after DOPA. Brain Res 1975; 85:99-102. [PMID: 162846 DOI: 10.1016/0006-8993(75)91012-4] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Haase J, Cleveland S, Ross HG. Problems of postsynaptic autogenous and recurrent inhibition in the mammalian spinal cord. Rev Physiol Biochem Pharmacol 1975; 73:73-129. [PMID: 175429 DOI: 10.1007/bfb0034660] [Citation(s) in RCA: 40] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Bruggencate G. Functions of extrapyramidal systems in motor control II. Cortical and subcortical pathways. PHARMACOLOGY & THERAPEUTICS. PART B: GENERAL & SYSTEMATIC PHARMACOLOGY 1975; 1:611-72. [PMID: 772713 DOI: 10.1016/0306-039x(75)90022-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Gustafsson B, Lindström S. Recurrent control from motor axon collaterals of Ia inhibitory pathways to ventral spinocerebellar tract neurones. ACTA PHYSIOLOGICA SCANDINAVICA 1973; 89:457-81. [PMID: 4359504 DOI: 10.1111/j.1748-1716.1973.tb05541.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Piercey MF, Goldfarb J, Ryall RW. Effects of picrotoxin and bicuculline on the excitation and inhibition of Renshaw cells. Neuropharmacology 1973; 12:975-82. [PMID: 4750565 DOI: 10.1016/0028-3908(73)90029-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Lindström S, Schomburg ED. Recurrent inhibition from motor axon collaterals of ventral spinocerebellar tract neurones. ACTA PHYSIOLOGICA SCANDINAVICA 1973; 88:505-15. [PMID: 4765599 DOI: 10.1111/j.1748-1716.1973.tb05479.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Jankowska E, Smith DO. Antidromic activation of Renshaw cells and their axonal projections. ACTA PHYSIOLOGICA SCANDINAVICA 1973; 88:198-214. [PMID: 4764179 DOI: 10.1111/j.1748-1716.1973.tb05447.x] [Citation(s) in RCA: 98] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Jankowska E, Lindström S. Morphology of interneurones mediating Ia reciprocal inhibition of motoneurones in the spinal cord of the cat. J Physiol 1972; 226:805-23. [PMID: 4118049 PMCID: PMC1331178 DOI: 10.1113/jphysiol.1972.sp010011] [Citation(s) in RCA: 113] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
1. Interneurones identified by physiological criteria (Hultborn, Jankowska & Lindström, 1971b) to mediate Ia reciprocal inhibition of motoneurones in the spinal cord of the cat were stained by intracellular injection of a fluorescent dye (Procion Yellow).2. The somas of the stained cells were found in Rexed's lamina VII, just dorsal or dorsomedial to the motor nuclei. Their size was about 30 x 20 mum. The cells had four to five slender, weakly branching dendrites. The total extension of their dendritic trees was about 600 mum dorsoventrally, 400 mum mediolaterally and 300 mum rostrocaudally.3. The axons originated from a separate axon hillock or from the base of a dendrite. They were myelinated with external diameter of about 6-14 mum and projected to either the ipsilateral ventral or lateral funiculi. Early collaterals were found only exceptionally. Some axons bifurcated into an ascending and a descending branch within the funiculi.4. The possibility of identifying the Ia inhibitory interneurones on purely morphological grounds is discussed.
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Hultborn H. Convergence on interneurones in the reciprocal Ia inhibitory pathway to motoneurones. ACTA PHYSIOLOGICA SCANDINAVICA. SUPPLEMENTUM 1972; 375:1-42. [PMID: 4339925 DOI: 10.1111/j.1748-1716.1972.tb05298.x] [Citation(s) in RCA: 86] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Fedina L, Hultborn H. Facilitation from ipsilateral primary afferents of interneuronal transmission in the Ia inhibitory pathway to motoneurones. ACTA PHYSIOLOGICA SCANDINAVICA 1972; 86:59-81. [PMID: 4344469 DOI: 10.1111/j.1748-1716.1972.tb00225.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Hultborn H, Udo M. Recurrent depression from motor axon collaterals of supraspinal inhibition in motoneurones. ACTA PHYSIOLOGICA SCANDINAVICA 1972; 85:44-57. [PMID: 4340654 DOI: 10.1111/j.1748-1716.1972.tb05234.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Cleveland S, Haase J, Ross HG, Wand P. Antidromic conditioning of reciprocally inhibited monosynaptic extensor and flexor reflexes in decerebrate cats. Pflugers Arch 1972; 337:219-28. [PMID: 4677159 DOI: 10.1007/bf00586846] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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