1
|
Veshchitskii A, Merkulyeva N. Calcium-binding protein parvalbumin in the spinal cord and dorsal root ganglia. Neurochem Int 2023; 171:105634. [PMID: 37967669 DOI: 10.1016/j.neuint.2023.105634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2023] [Revised: 09/20/2023] [Accepted: 10/26/2023] [Indexed: 11/17/2023]
Abstract
Parvalbumin is one of the calcium-binding proteins. In the spinal cord, it is mainly expressed in inhibitory neurons; in the dorsal root ganglia, it is expressed in proprioceptive neurons. In contrast to in the brain, weak systematization of parvalbumin-expressing neurons occurs in the spinal cord. The aim of this paper is to provide a systematic review of parvalbumin-expressing neuronal populations throughout the spinal cord and the dorsal root ganglia of mammals, regarding their mapping, co-expression with some functional markers. The data reviewed are mostly concerning rodentia species because they are predominantly presented in literature.
Collapse
Affiliation(s)
- Aleksandr Veshchitskii
- Neuromorphology Lab, Pavlov Institute of Physiology Russian Academy of Sciences, Saint Petersburg, Russia
| | - Natalia Merkulyeva
- Neuromorphology Lab, Pavlov Institute of Physiology Russian Academy of Sciences, Saint Petersburg, Russia.
| |
Collapse
|
2
|
Chacon C, Nwachukwu CV, Shahsavani N, Cowley KC, Chopek JW. Lumbar V3 interneurons provide direct excitatory synaptic input onto thoracic sympathetic preganglionic neurons, linking locomotor, and autonomic spinal systems. Front Neural Circuits 2023; 17:1235181. [PMID: 37701071 PMCID: PMC10493276 DOI: 10.3389/fncir.2023.1235181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Accepted: 08/10/2023] [Indexed: 09/14/2023] Open
Abstract
Although sympathetic autonomic systems are activated in parallel with locomotion, the neural mechanisms mediating this coordination are incompletely understood. Sympathetic preganglionic neurons (SPNs), primarily located in the intermediate laminae of thoracic and upper lumbar segments (T1-L2), increase activation of tissues and organs that provide homeostatic and metabolic support during movement and exercise. Recent evidence suggests integration between locomotor and autonomic nuclei occurs within the brainstem, initiating both descending locomotor and sympathetic activation commands. However, both locomotor and sympathetic autonomic spinal systems can be activated independent of supraspinal input, in part due to a distributed network involving propriospinal neurons. Whether an intraspinal mechanism exists to coordinate activation of these systems is unknown. We hypothesized that ascending spinal neurons located in the lumbar region provide synaptic input to thoracic SPNs. Here, we demonstrate that synaptic contacts from locomotor-related V3 interneurons (INs) are present in all thoracic laminae. Injection of an anterograde tracer into lumbar segments demonstrated that 8-20% of glutamatergic input onto SPNs originated from lumbar V3 INs and displayed a somatotopographical organization of synaptic input. Whole cell patch clamp recording in SPNs demonstrated prolonged depolarizations or action potentials in response to optical activation of either lumbar V3 INs in spinal cord preparations or in response to optical activation of V3 terminals in thoracic slice preparations. This work demonstrates a direct intraspinal connection between lumbar locomotor and thoracic sympathetic networks and suggests communication between motor and autonomic systems may be a general function of the spinal cord.
Collapse
|
3
|
Dukkipati SS, Walker SJ, Trevarrow MP, Busboom M, Baker SE, Kurz MJ. Reduced wrist flexor H-reflex excitability is linked with increased wrist proprioceptive error in adults with cerebral palsy. Front Neurol 2022; 13:930303. [PMID: 36016542 PMCID: PMC9396222 DOI: 10.3389/fneur.2022.930303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Accepted: 07/18/2022] [Indexed: 12/03/2022] Open
Abstract
Although most neurophysiological studies of persons with cerebral palsy (CP) have been focused on supraspinal networks, recent evidence points toward the spinal cord as a central contributor to their motor impairments. However, it is unclear if alterations in the spinal pathways are also linked to deficits in the sensory processing observed clinically. This investigation aimed to begin to address this knowledge gap by evaluating the flexor carpi radialis (FCR) H-reflex in adults with CP and neurotypical (NT) controls while at rest and during an isometric wrist flexion task. The maximal H-wave (Hmax) and M-wave (Mmax) at rest were calculated and utilized to compute Hmax/Mmax ratios (H:M ratios). Secondarily, the facilitation of the H-wave was measured while producing an isometric, voluntary wrist flexion contraction (i.e., active condition). Finally, a wrist position sense test was used to quantify the level of joint position sense. These results revealed that the adults with CP had a lower H:M ratio compared with the NT controls while at rest. The adults with CP were also unable to facilitate their H-reflexes with voluntary contraction and had greater position sense errors compared with the controls. Further, these results showed that the adults with CP that had greater wrist position sense errors tended to have a lower H:M ratio at rest. Overall, these findings highlight that aberration in the spinal cord pathways of adults with CP might play a role in the sensory processing deficiencies observed in adults with CP.
Collapse
Affiliation(s)
- S. Shekar Dukkipati
- Boys Town National Research Hospital, Omaha, NE, United States
- College of Medicine, University of Nebraska Medical Center, Omaha, NE, United States
| | - Sarah J. Walker
- Boys Town National Research Hospital, Omaha, NE, United States
| | | | - Morgan Busboom
- Boys Town National Research Hospital, Omaha, NE, United States
| | - Sarah E. Baker
- Boys Town National Research Hospital, Omaha, NE, United States
| | - Max J. Kurz
- Boys Town National Research Hospital, Omaha, NE, United States
- School of Medicine, Creighton University, Omaha, NE, United States
- *Correspondence: Max J. Kurz
| |
Collapse
|
4
|
Al’joboori YD, Edgerton VR, Ichiyama RM. Effects of Rehabilitation on Perineural Nets and Synaptic Plasticity Following Spinal Cord Transection. Brain Sci 2020; 10:brainsci10110824. [PMID: 33172143 PMCID: PMC7694754 DOI: 10.3390/brainsci10110824] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 10/27/2020] [Accepted: 11/03/2020] [Indexed: 01/08/2023] Open
Abstract
Epidural electrical stimulation (ES) of the lumbar spinal cord combined with daily locomotor training has been demonstrated to enhance stepping ability after complete spinal transection in rodents and clinically complete spinal injuries in humans. Although functional gain is observed, plasticity mechanisms associated with such recovery remain mostly unclear. Here, we investigated how ES and locomotor training affected expression of chondroitin sulfate proteoglycans (CSPG), perineuronal nets (PNN), and synaptic plasticity on spinal motoneurons. To test this, adult rats received a complete spinal transection (T9-T10) followed by daily locomotor training performed under ES with administration of quipazine (a serotonin (5-HT) agonist) starting 7 days post-injury (dpi). Excitatory and inhibitory synaptic changes were examined at 7, 21, and 67 dpi in addition to PNN and CSPG expression. The total amount of CSPG expression significantly increased with time after injury, with no effect of training. An interesting finding was that γ-motoneurons did not express PNNs, whereas α-motoneurons demonstrated well-defined PNNs. This remarkable difference is reflected in the greater extent of synaptic changes observed in γ-motoneurons compared to α-motoneurons. A medium negative correlation between CSPG expression and changes in putative synapses around α-motoneurons was found, but no correlation was identified for γ-motoneurons. These results suggest that modulation of γ-motoneuron activity is an important mechanism associated with functional recovery induced by locomotor training under ES after a complete spinal transection.
Collapse
Affiliation(s)
- Yazi D. Al’joboori
- Faculty of Biological Sciences, School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK;
| | - V. Reggie Edgerton
- Physiological Science, Neurobiology and Brain Research Institute, University of California, Los Angeles, CA 90095, USA;
| | - Ronaldo M. Ichiyama
- Faculty of Biological Sciences, School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK;
- Correspondence: ; Tel.: +44-113-343-4291
| |
Collapse
|
5
|
Loy K, Fourneau J, Meng N, Denecke C, Locatelli G, Bareyre FM. Semaphorin 7A restricts serotonergic innervation and ensures recovery after spinal cord injury. Cell Mol Life Sci 2020; 78:2911-2927. [PMID: 33128105 PMCID: PMC8004489 DOI: 10.1007/s00018-020-03682-w] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 09/15/2020] [Accepted: 10/09/2020] [Indexed: 11/25/2022]
Abstract
Descending serotonergic (5-HT) projections originating from the raphe nuclei form an important input to the spinal cord that control basic locomotion. The molecular signals that control this projection pattern are currently unknown. Here, we identify Semaphorin7A (Sema7A) as a critical cue that restricts serotonergic innervation in the spinal cord. Sema7A deficient mice show a marked increase in serotonergic fiber density in all layers of the spinal cord while the density of neurons expressing the corresponding 5-HTR2α receptor remains unchanged. These alterations appear to be successfully compensated as no obvious changes in rhythmic locomotion and skilled stepping are observed in adult mice. When the system is challenged with a spinal lesion, serotonergic innervation patterns in both Sema7A-deficient and -competent mice evolve over time with excessive innervation becoming most pronounced in the dorsal horn of Sema7A-deficient mice. These altered serotonergic innervation patterns correlate with diminished functional recovery that predominantly affects rhythmic locomotion. Our findings identify Sema7A as a critical regulator of serotonergic circuit formation in the injured spinal cord.
Collapse
Affiliation(s)
- Kristina Loy
- Institute of Clinical Neuroimmunology, University Hospital, LMU Munich, 81377, Munich, Germany.,Faculty of Medicine, Biomedical Center Munich (BMC), LMU Munich, 82152, Planegg-Martinsried, Germany.,Graduate School of Systemic Neurosciences, LMU Munich, 82152, Planegg-Martinsried, Germany
| | - Julie Fourneau
- Institute of Clinical Neuroimmunology, University Hospital, LMU Munich, 81377, Munich, Germany.,Faculty of Medicine, Biomedical Center Munich (BMC), LMU Munich, 82152, Planegg-Martinsried, Germany
| | - Ning Meng
- Institute of Clinical Neuroimmunology, University Hospital, LMU Munich, 81377, Munich, Germany.,Faculty of Medicine, Biomedical Center Munich (BMC), LMU Munich, 82152, Planegg-Martinsried, Germany
| | - Carmen Denecke
- Institute of Clinical Neuroimmunology, University Hospital, LMU Munich, 81377, Munich, Germany.,Faculty of Medicine, Biomedical Center Munich (BMC), LMU Munich, 82152, Planegg-Martinsried, Germany.,Graduate School of Systemic Neurosciences, LMU Munich, 82152, Planegg-Martinsried, Germany
| | - Giuseppe Locatelli
- Institute of Clinical Neuroimmunology, University Hospital, LMU Munich, 81377, Munich, Germany.,Faculty of Medicine, Biomedical Center Munich (BMC), LMU Munich, 82152, Planegg-Martinsried, Germany
| | - Florence M Bareyre
- Institute of Clinical Neuroimmunology, University Hospital, LMU Munich, 81377, Munich, Germany. .,Faculty of Medicine, Biomedical Center Munich (BMC), LMU Munich, 82152, Planegg-Martinsried, Germany. .,Munich Cluster of Systems Neurology (SyNergy), 81377, Munich, Germany.
| |
Collapse
|
6
|
Smith CC, Brownstone RM. Spinal motoneuron firing properties mature from rostral to caudal during postnatal development of the mouse. J Physiol 2020; 598:5467-5485. [PMID: 32851667 PMCID: PMC8436765 DOI: 10.1113/jp280274] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 08/24/2020] [Indexed: 12/16/2022] Open
Abstract
Key points Many mammals are born with immature motor systems that develop through a critical period of postnatal development. In rodents, postnatal maturation of movement occurs from rostral to caudal, correlating with maturation of descending supraspinal and local spinal circuits. We asked whether development of fundamental electrophysiological properties of spinal motoneurons follows the same rostro‐caudal sequence. We show that in both regions, repetitive firing parameters increase and excitability decreases with development; however, these characteristics mature earlier in cervical motoneurons. We suggest that in addition to autonomous mechanisms, motoneuron development depends on activity resulting from their circuit milieu.
Abstract Altricial mammals are born with immature nervous systems comprised of circuits that do not yet have the neuronal properties and connectivity required to produce future behaviours. During the critical period of postnatal development, neuronal properties are tuned to participate in functional circuits. In rodents, cervical motoneurons are born prior to lumbar motoneurons, and spinal cord development follows a sequential rostro‐caudal pattern. Here we asked whether birth order is reflected in the postnatal development of electrophysiological properties. We show that motoneurons of both regions have similar properties at birth and follow the same developmental profile, with maximal firing increasing and excitability decreasing into the third postnatal week. However, these maturative processes occur in cervical motoneurons prior to lumbar motoneurons, correlating with the maturation of premotor descending and local spinal systems. These results suggest that motoneuron properties do not mature by cell autonomous mechanisms alone, but also depend on developing premotor circuits. Many mammals are born with immature motor systems that develop through a critical period of postnatal development. In rodents, postnatal maturation of movement occurs from rostral to caudal, correlating with maturation of descending supraspinal and local spinal circuits. We asked whether development of fundamental electrophysiological properties of spinal motoneurons follows the same rostro‐caudal sequence. We show that in both regions, repetitive firing parameters increase and excitability decreases with development; however, these characteristics mature earlier in cervical motoneurons. We suggest that in addition to autonomous mechanisms, motoneuron development depends on activity resulting from their circuit milieu.
Collapse
Affiliation(s)
- Calvin C Smith
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London, London, UK
| | - Robert M Brownstone
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London, London, UK
| |
Collapse
|
7
|
Neuronal activity and microglial activation support corticospinal tract and proprioceptive afferent sprouting in spinal circuits after a corticospinal system lesion. Exp Neurol 2019; 321:113015. [PMID: 31326353 DOI: 10.1016/j.expneurol.2019.113015] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2019] [Revised: 05/12/2019] [Accepted: 07/17/2019] [Indexed: 12/17/2022]
Abstract
Spared corticospinal tract (CST) and proprioceptive afferent (PA) axons sprout after injury and contribute to rewiring spinal circuits, affecting motor recovery. Loss of CST connections post-injury results in corticospinal signal loss and associated reduction in spinal activity. We investigated the role of activity loss and injury on CST and PA sprouting. To understand activity-dependence after injury, we compared CST and PA sprouting after motor cortex (MCX) inactivation, produced by chronic MCX muscimol microinfusion, with sprouting after a CST lesion produced by pyramidal tract section (PTx). Activity suppression, which does not produce a lesion, is sufficient to trigger CST axon outgrowth from the active side to cross the midline and to enter the inactivated side of the spinal cord, to the same extent as PTx. Activity loss was insufficient to drive significant CST gray matter axon elongation, an effect of PTx. Activity suppression triggered presynaptic site formation, but less than PTx. Activity loss triggered PA sprouting, as PTx. To understand injury-dependent sprouting further, we blocked microglial activation and associated inflammation after PTX by chronic minocycline administration after PTx. Minocycline inhibited myelin debris phagocytosis contralateral to PTx and abolished CST axon elongation, formation of presynaptic sites, and PA sprouting, but not CST axon outgrowth from the active side to cross the midline. Our findings suggest sprouting after injury has a strong activity dependence and that microglial activation after injury supports axonal elongation and presynaptic site formation. Combining spinal activity support and inflammation control is potentially more effective in promoting functional restoration than either alone.
Collapse
|
8
|
Synowiec S, Lu J, Yu L, Goussakov I, Lieber R, Drobyshevsky A. Spinal Hyper-Excitability and Altered Muscle Structure Contribute to Muscle Hypertonia in Newborns After Antenatal Hypoxia-Ischemia in a Rabbit Cerebral Palsy Model. Front Neurol 2019; 9:1183. [PMID: 30705663 PMCID: PMC6344443 DOI: 10.3389/fneur.2018.01183] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Accepted: 12/21/2018] [Indexed: 12/17/2022] Open
Abstract
Rabbit kits after global antenatal hypoxic-ischemic injury exhibit motor deficits similar to humans with cerebral palsy. We tested several mechanisms previously implicated in spinal hyper-excitability after perinatal brain injury that may explain muscle hypertonia in newborns. Stiffness of hind limb muscles during passive stretch, electromyogram, and spinal excitability by Hoffman reflex, were assessed in rabbit kits with muscle hypertonia after global hypoxic-ischemic brain injury and naïve controls. Affected muscle architecture, motoneuron morphology, primary afferents density, gliosis, and KCC2 expression transporter in the spinal cord were also examined. Decrease knee stiffness after anesthetic administration was larger, but residual stiffness was higher in hypertonic kits compared to controls. Hypertonic kits exhibited muscle shortening and atrophy, in both agonists and antagonists. Sarcomere length was longer in tibialis anterior in hypertonic kits than in controls. Hypertonic kits had decreased rate dependent depression and increased Hmax/Mmax in H-reflex. Motor neuron soma sizes, primary afferent density were not different between controls and hypertonic kits. Length of dendritic tree and ramification index were lower in hypertonic group. Gene expression of KCC2 was lower in hypertonic kits, but protein content was not different between the groups. In conclusion, while we found evidence of decreased supraspinal inhibitory control and increased excitability by H-reflex that may contribute to neuronal component in hypertonia, increased joint resistance to stretch was explained predominantly by changes in passive properties of muscles and joints. We did not find structural evidence of increased sensory afferent input or morphological changes in motoneurons that might explain increased excitability. Gliosis, observed in spinal gray matter, may contribute to muscle hypertonia.
Collapse
Affiliation(s)
- Sylvia Synowiec
- Department of Pediatrics, NorthShore University HealthSystem Research Institute, Evanston, IL, United States
| | - Jing Lu
- Department of Pediatrics, University of Chicago, Chicago, IL, United States
| | - Lei Yu
- Department of Pediatrics, NorthShore University HealthSystem Research Institute, Evanston, IL, United States
| | - Ivan Goussakov
- Department of Pediatrics, NorthShore University HealthSystem Research Institute, Evanston, IL, United States
| | - Richard Lieber
- Department of Physical Medicine and Rehabilitation, Northwestern University and the Shirley Ryan Ability Lab, Chicago, IL, United States
| | - Alexander Drobyshevsky
- Department of Pediatrics, NorthShore University HealthSystem Research Institute, Evanston, IL, United States
| |
Collapse
|
9
|
Hilt PM, Delis I, Pozzo T, Berret B. Space-by-Time Modular Decomposition Effectively Describes Whole-Body Muscle Activity During Upright Reaching in Various Directions. Front Comput Neurosci 2018; 12:20. [PMID: 29666576 PMCID: PMC5891645 DOI: 10.3389/fncom.2018.00020] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 03/12/2018] [Indexed: 11/13/2022] Open
Abstract
The modular control hypothesis suggests that motor commands are built from precoded modules whose specific combined recruitment can allow the performance of virtually any motor task. Despite considerable experimental support, this hypothesis remains tentative as classical findings of reduced dimensionality in muscle activity may also result from other constraints (biomechanical couplings, data averaging or low dimensionality of motor tasks). Here we assessed the effectiveness of modularity in describing muscle activity in a comprehensive experiment comprising 72 distinct point-to-point whole-body movements during which the activity of 30 muscles was recorded. To identify invariant modules of a temporal and spatial nature, we used a space-by-time decomposition of muscle activity that has been shown to encompass classical modularity models. To examine the decompositions, we focused not only on the amount of variance they explained but also on whether the task performed on each trial could be decoded from the single-trial activations of modules. For the sake of comparison, we confronted these scores to the scores obtained from alternative non-modular descriptions of the muscle data. We found that the space-by-time decomposition was effective in terms of data approximation and task discrimination at comparable reduction of dimensionality. These findings show that few spatial and temporal modules give a compact yet approximate representation of muscle patterns carrying nearly all task-relevant information for a variety of whole-body reaching movements.
Collapse
Affiliation(s)
- Pauline M Hilt
- Institut National de la Santé et de la Recherche Médicale, U1093, Cognition Action Plasticité Sensorimotrice, Dijon, France.,Italian Institute of Technology CTNSC@UniFe (Center of Translational Neurophysiology for Speech and Communication), Ferrara, Italy
| | - Ioannis Delis
- Department of Biomedical Engineering, Columbia University, New York, NY, United States
| | - Thierry Pozzo
- Institut National de la Santé et de la Recherche Médicale, U1093, Cognition Action Plasticité Sensorimotrice, Dijon, France.,Italian Institute of Technology CTNSC@UniFe (Center of Translational Neurophysiology for Speech and Communication), Ferrara, Italy
| | - Bastien Berret
- CIAMS, Université Paris-Sud, Université Paris-Saclay, Orsay, France.,CIAMS, Université d'Orléans, Orléans, France.,Institut Universitaire de France, Paris, France
| |
Collapse
|
10
|
Williams PTJA, Jiang YQ, Martin JH. Motor system plasticity after unilateral injury in the developing brain. Dev Med Child Neurol 2017; 59:1224-1229. [PMID: 28972274 PMCID: PMC5773112 DOI: 10.1111/dmcn.13581] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 08/10/2017] [Indexed: 11/30/2022]
Abstract
UNLABELLED In maturity, motor skills depend on the corticospinal tract (CST) and brainstem pathways that together synapse on interneurons and motoneurons in the spinal cord. Descending signals to spinal neurons that mediate voluntary control can be distinguished from peripheral sensory signals, primarily for feedback control. These motor system circuits depend initially on developmental genetic mechanisms to establish their connections and neural activity- and use-dependent synaptic refinement during the early postnatal period to enable motor skills to develop. In this review we consider four key activity-dependent developmental mechanisms that provide insights into how the motor systems establish the proper connections for skilled movement control and how the same mechanisms also inform the mechanisms of motor impairments and developmental plasticity after corticospinal system injury: (1) synaptic competition between the CSTs from each hemisphere; (2) interactions between the CST and spinal cord neurons; (3) synaptic competition between the CST and proprioceptive sensory fibres; and (4) interactions between the developing corticospinal motor system and the rubrospinal tract. Our findings suggest that the corticospinal motor system effectively 'oversees' development of its subcortical targets through synaptic competition and trophic-like interactions and this has important implications for motor impairments after perinatal cortical stroke. WHAT THIS PAPER ADDS Neural activity-dependent processes inform the brain and spinal cord response to injury. The corticospinal motor system may 'oversee' development of its downstream subcortical targets through activity, trophic-like interactions, and synaptic competition.
Collapse
Affiliation(s)
- Preston TJA Williams
- Department of Physiology, Pharmacology and Neuroscience, City University of New York School of Medicine at City College, New York, NY, USA
| | - Yu-Qiu Jiang
- Department of Physiology, Pharmacology and Neuroscience, City University of New York School of Medicine at City College, New York, NY, USA
| | - John H Martin
- Department of Physiology, Pharmacology and Neuroscience, City University of New York School of Medicine at City College, New York, NY, USA,City University of New York Graduate Center, New York, NY, USA
| |
Collapse
|
11
|
Jean-Xavier C, Sharples SA, Mayr KA, Lognon AP, Whelan PJ. Retracing your footsteps: developmental insights to spinal network plasticity following injury. J Neurophysiol 2017; 119:521-536. [PMID: 29070632 DOI: 10.1152/jn.00575.2017] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
During development of the spinal cord, a precise interaction occurs between descending projections and sensory afferents, with spinal networks that lead to expression of coordinated motor output. In the rodent, during the last embryonic week, motor output first occurs as regular bursts of spontaneous activity, progressing to stochastic patterns of episodes that express bouts of coordinated rhythmic activity perinatally. Locomotor activity becomes functionally mature in the 2nd postnatal wk and is heralded by the onset of weight-bearing locomotion on the 8th and 9th postnatal day. Concomitantly, there is a maturation of intrinsic properties and key conductances mediating plateau potentials. In this review, we discuss spinal neuronal excitability, descending modulation, and afferent modulation in the developing rodent spinal cord. In the adult, plastic mechanisms are much more constrained but become more permissive following neurotrauma, such as spinal cord injury. We discuss parallel mechanisms that contribute to maturation of network function during development to mechanisms of pathological plasticity that contribute to aberrant motor patterns, such as spasticity and clonus, which emerge following central injury.
Collapse
Affiliation(s)
- C Jean-Xavier
- Hotchkiss Brain Institute, University of Calgary , Calgary, Alberta , Canada.,Department of Comparative Biology and Experimental Medicine, University of Calgary , Calgary, Alberta , Canada
| | - S A Sharples
- Hotchkiss Brain Institute, University of Calgary , Calgary, Alberta , Canada.,Department of Neuroscience, University of Calgary , Calgary, Alberta , Canada
| | - K A Mayr
- Hotchkiss Brain Institute, University of Calgary , Calgary, Alberta , Canada.,Department of Neuroscience, University of Calgary , Calgary, Alberta , Canada
| | - A P Lognon
- Department of Comparative Biology and Experimental Medicine, University of Calgary , Calgary, Alberta , Canada
| | - P J Whelan
- Hotchkiss Brain Institute, University of Calgary , Calgary, Alberta , Canada.,Department of Comparative Biology and Experimental Medicine, University of Calgary , Calgary, Alberta , Canada
| |
Collapse
|
12
|
Descending Systems Direct Development of Key Spinal Motor Circuits. J Neurosci 2017; 37:6372-6387. [PMID: 28576940 DOI: 10.1523/jneurosci.0149-17.2017] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Revised: 05/10/2017] [Accepted: 05/24/2017] [Indexed: 12/17/2022] Open
Abstract
The formation of mature spinal motor circuits is dependent on both activity-dependent and independent mechanisms during postnatal development. During this time, reorganization and refinement of spinal sensorimotor circuits occurs as supraspinal projections are integrated. However, specific features of postnatal spinal circuit development remain poorly understood. This study provides the first detailed characterization of rat spinal sensorimotor circuit development in the presence and absence of descending systems. We show that the development of proprioceptive afferent input to motoneurons (MNs) and Renshaw cells (RCs) is disrupted by thoracic spinal cord transection at postnatal day 5 (P5TX). P5TX also led to malformation of GABApre neuron axo-axonic contacts on Ia afferents and of the recurrent inhibitory circuit between MNs and RCs. Using a novel in situ perfused preparation for studying motor control, we show that malformation of these spinal circuits leads to hyperexcitability of the monosynaptic reflex. Our results demonstrate that removing descending input severely disrupts the development of spinal circuits and identifies key mechanisms contributing to motor dysfunction in conditions such as cerebral palsy and spinal cord injury.SIGNIFICANCE STATEMENT Acquisition of mature behavior during postnatal development correlates with the arrival and maturation of supraspinal projections to the spinal cord. However, we know little about the role that descending systems play in the maturation of spinal circuits. Here, we characterize postnatal development of key spinal microcircuits in the presence and absence of descending systems. We show that formation of these circuits is abnormal after early (postnatal day 5) removal of descending systems, inducing hyperexcitability of the monosynaptic reflex. The study is a detailed characterization of spinal circuit development elucidating how these mechanisms contribute to motor dysfunction in conditions such as cerebral palsy and spinal cord injury. Understanding these circuits is crucial to developing new therapeutics and improving existing ones in such conditions.
Collapse
|
13
|
Chen K, Marsh BC, Cowan M, Al'Joboori YD, Gigout S, Smith CC, Messenger N, Gamper N, Schwab ME, Ichiyama RM. Sequential therapy of anti-Nogo-A antibody treatment and treadmill training leads to cumulative improvements after spinal cord injury in rats. Exp Neurol 2017; 292:135-144. [DOI: 10.1016/j.expneurol.2017.03.012] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Revised: 03/15/2017] [Accepted: 03/21/2017] [Indexed: 11/16/2022]
|
14
|
Abstract
The corticospinal and rubrospinal systems function in skilled movement control. A key question is how do these systems develop the capacity to coordinate their motor functions and, in turn, if the red nucleus/rubrospinal tract (RN/RST) compensates for developmental corticospinal injury? We used the cat to investigate whether the developing rubrospinal system is shaped by activity-dependent interactions with the developing corticospinal system. We unilaterally inactivated M1 by muscimol microinfusion between postnatal weeks 5 and 7 to examine activity-dependent interactions and whether the RN/RST compensates for corticospinal tract (CST) developmental motor impairments and CST misprojections after M1 inactivation. We examined the RN motor map and RST cervical projections at 7 weeks of age, while the corticospinal system was inactivated, and at 14 weeks, after activity returned. During M1 inactivation, the RN on the same side showed normal RST projections and reduced motor thresholds, suggestive of precocious development. By contrast, the RN on the untreated/active M1 side showed sparse RST projections and an immature motor map. After M1 activity returned later in adolescent cat development, RN on the active M1/CST side continued to show a substantial loss of spinal terminations and an impaired motor map. RN/RST on the inactivated side regressed to a smaller map and fewer axons. Our findings suggest that the developing rubrospinal system is under activity-dependent regulation by the corticospinal system for establishing mature RST connections and RN motor map. The lack of RS compensation on the non-inactivated side can be explained by development of ipsilateral misprojections from the active M1 that outcompete the RST. Significance statement: Skilled movements reflect the activity of multiple descending motor systems and their interactions with spinal motor circuits. Currently, there is little insight into whether motor systems interact during development to coordinate their emerging functions and, if so, the mechanisms underlying this process. This study examined activity-dependent interactions between the developing corticospinal and rubrospinal systems, two key systems for skilled limb movements. We show that the developing rubrospinal system competes with the corticospinal system in establishing the red nucleus motor map and rubrospinal tract connections. This is the first demonstration of one motor system steering development, and ultimately function, of another. Knowledge of activity-dependent competition between these two systems helps predict the response of the rubrospinal system following corticospinal system developmental injury.
Collapse
|
15
|
Drobyshevsky A, Takada SH, Luo K, Derrick M, Yu L, Quinlan KA, Vasquez-Vivar J, Nogueira MI, Tan S. Elevated spinal monoamine neurotransmitters after antenatal hypoxia-ischemia in rabbit cerebral palsy model. J Neurochem 2015; 132:394-402. [PMID: 25421613 PMCID: PMC4329027 DOI: 10.1111/jnc.12997] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Revised: 11/10/2014] [Accepted: 11/12/2014] [Indexed: 12/14/2022]
Abstract
We hypothesized that a deficiency in the descending serotonergic input to spinal cord may underlie postnatal muscle hypertonia after global antenatal hypoxic-ischemic injury in a rabbit model of cerebral palsy. Neurotransmitter content was determined by HPLC in the spinal cord of newborns with and without muscle hypertonia after fetal global hypoxic-ischemic brain injury and naïve controls. Contrary to our hypothesis, serotonin levels in both cervical and lumbar expansions and norepinephrine in cervical expansion were increased in hypertonic kits relative to non-hypertonic kits and controls, with unchanged number of serotonergic cells in caudal raphe by stereological count. Serotonergic fiber length per unit of volume was also increased in hypertonic kits' cervical and lumbar spinal cord, both in dorsal and ventral horns. Gene expression of serotonin transporter was increased and 5-HTR2 receptors were decreased in hypertonic kits relative to controls in cervical and lumbar cord. Intrathecal administration of non-selective serotonin receptor inhibitor methysergide decreased muscle tone in hypertonic kits only. Conversely, intrathecal administration of serotonin solution increased muscle tone only in non-hypertonic kits. We speculate that maturation of serotonergic system in spinal cord may be directly affected by decreased corticospinal connectivity after antenatal hypoxic-ischemic brain injury. Following prenatal hypoxia-ischemia, newborn rabbits exhibit elevated levels of serotonin in the spinal cord that were linked to muscle hypertonia. Serotonergic terminal density was also increased in hypertonic newborns' spinal cord. Intrathecal administration of the non-selective serotonin receptor inhibitor methysergide decreased muscle tone in hypertonic newborns only. Elevated spinal serotonin thus suggests a novel pathophysiological mechanism of hypertonia in cerebral palsy.
Collapse
Affiliation(s)
- Alexander Drobyshevsky
- Department of Pediatrics NorthShore University HealthSystem, Evanston, and University of Chicago, Chicago, IL
| | - Silvia Honda Takada
- Department of Anatomy and Physiology, Institute of Biomedical Sciences, Universidade de São Paulo, Brazil
| | - Kehuan Luo
- Department of Pediatrics NorthShore University HealthSystem, Evanston, and University of Chicago, Chicago, IL
| | - Matthew Derrick
- Department of Pediatrics NorthShore University HealthSystem, Evanston, and University of Chicago, Chicago, IL
| | - Lei Yu
- Department of Pediatrics NorthShore University HealthSystem, Evanston, and University of Chicago, Chicago, IL
| | - Katharina A. Quinlan
- Departments of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL
| | | | - Maria Inês Nogueira
- Department of Anatomy and Physiology, Institute of Biomedical Sciences, Universidade de São Paulo, Brazil
| | - Sidhartha Tan
- Department of Pediatrics NorthShore University HealthSystem, Evanston, and University of Chicago, Chicago, IL
| |
Collapse
|
16
|
Clowry GJ, Basuodan R, Chan F. What are the Best Animal Models for Testing Early Intervention in Cerebral Palsy? Front Neurol 2014; 5:258. [PMID: 25538677 PMCID: PMC4255621 DOI: 10.3389/fneur.2014.00258] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Accepted: 11/21/2014] [Indexed: 11/13/2022] Open
Abstract
Interventions to treat cerebral palsy should be initiated as soon as possible in order to restore the nervous system to the correct developmental trajectory. One drawback to this approach is that interventions have to undergo exceptionally rigorous assessment for both safety and efficacy prior to use in infants. Part of this process should involve research using animals but how good are our animal models? Part of the problem is that cerebral palsy is an umbrella term that covers a number of conditions. There are also many causal pathways to cerebral palsy, such as periventricular white matter injury in premature babies, perinatal infarcts of the middle cerebral artery, or generalized anoxia at the time of birth, indeed multiple causes, including intra-uterine infection or a genetic predisposition to infarction, may need to interact to produce a clinically significant injury. In this review, we consider which animal models best reproduce certain aspects of the condition, and the extent to which the multifactorial nature of cerebral palsy has been modeled. The degree to which the corticospinal system of various animal models human corticospinal system function and development is also explored. Where attempts have already been made to test early intervention in animal models, the outcomes are evaluated in light of the suitability of the model.
Collapse
Affiliation(s)
- Gavin John Clowry
- Institute of Neuroscience, Newcastle University , Newcastle upon Tyne , UK
| | - Reem Basuodan
- Institute of Neuroscience, Newcastle University , Newcastle upon Tyne , UK
| | - Felix Chan
- Institute of Neuroscience, Newcastle University , Newcastle upon Tyne , UK
| |
Collapse
|
17
|
Jiang YQ, Williams PTJA, Martin JH. Rapid and persistent impairments of the forelimb motor representations following cervical deafferentation in rats. Eur J Neurosci 2013; 38:3702-11. [PMID: 24329730 DOI: 10.1111/ejn.12372] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2013] [Revised: 08/29/2013] [Accepted: 09/02/2013] [Indexed: 11/28/2022]
Abstract
Skilled motor control is regulated by the convergence of somatic sensory and motor signals in brain and spinal motor circuits. Cervical deafferentation is known to diminish forelimb somatic sensory representations rapidly and to impair forelimb movements. Our focus was to determine what effect deafferentation has on the motor representations in motor cortex, knowledge of which could provide new insights into the locus of impairment following somatic sensory loss, such as after spinal cord injury or stroke. We hypothesized that somatic sensory information is important for cortical motor map topography. To investigate this we unilaterally transected the dorsal rootlets in adult rats from C4 to C8 and mapped the forelimb motor representations using intracortical microstimulation, immediately after rhizotomy and following a 2-week recovery period. Immediately after deafferentation we found that the size of the distal representation was reduced. However, despite this loss of input there were no changes in motor threshold. Two weeks after deafferentation, animals showed a further distal representation reduction, an expansion of the elbow representation, and a small elevation in distal movement threshold. These changes were specific to the forelimb map in the hemisphere contralateral to deafferentation; there were no changes in the hindlimb or intact-side forelimb representations. Degradation of the contralateral distal forelimb representation probably contributes to the motor control deficits after deafferentation. We propose that somatic sensory inputs are essential for the maintenance of the forelimb motor map in motor cortex and should be considered when rehabilitating patients with peripheral or spinal cord injuries or after stroke.
Collapse
Affiliation(s)
- Yu-Qiu Jiang
- Department of Physiology, Pharmacology and Neuroscience, City College of the City University of New York, 160 Convent Avenue, New York, NY, 10031, USA
| | | | | |
Collapse
|
18
|
Asante CO, Martin JH. Differential joint-specific corticospinal tract projections within the cervical enlargement. PLoS One 2013; 8:e74454. [PMID: 24058570 PMCID: PMC3776849 DOI: 10.1371/journal.pone.0074454] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Accepted: 07/31/2013] [Indexed: 12/20/2022] Open
Abstract
The motor cortex represents muscle and joint control and projects to spinal cord interneurons and-in many primates, including humans-motoneurons, via the corticospinal tract (CST). To examine these spinal CST anatomical mechanisms, we determined if motor cortex sites controlling individual forelimb joints project differentially to distinct cervical spinal cord territories, defined regionally and by the locations of putative last-order interneurons that were transneuronally labeled by intramuscular injection of pseudorabies virus. Motor cortex joint-specific sites were identified using intracortical-microstimulation. CST segmental termination fields from joint-specific sites, determined using anterograde tracers, comprised a high density core of terminations that was consistent between animals and a surrounding lower density projection that was more variable. Core terminations from shoulder, elbow, and wrist control sites overlapped in the medial dorsal horn and intermediate zone at C5/C6 but were separated at C7/C8. Shoulder sites preferentially terminated dorsally, in the dorsal horn; wrist/digit sites, more ventrally in the intermediate zone; and elbow sites, medially in the dorsal horn and intermediate zone. Pseudorabies virus injected in shoulder, elbow, or wrist muscles labeled overlapping populations of predominantly muscle-specific putative premotor interneurons, at a survival time for disynaptic transfer from muscle. At C5/C6, CST core projections from all joint zones were located medial to regions of densely labeled last-order interneurons, irrespective of injected muscle. At C7/C8 wrist CST core projections overlapped the densest interneuron territory, which was located in the lateral intermediate zone. In contrast, elbow CST core projections were located medial to the densest interneuron territories, and shoulder CST core projections were located dorsally and only partially overlapped the densest interneuron territory. Our findings show a surprising fractionation of CST terminations in the caudal cervical enlargement that may be organized to engage different spinal premotor circuits for distal and proximal joint control.
Collapse
Affiliation(s)
- Curtis O. Asante
- Department of Physiology, Pharmacology, and Neuroscience, City College of the City University of New York, New York, New York, United States of America
| | - John H. Martin
- Department of Physiology, Pharmacology, and Neuroscience, City College of the City University of New York, New York, New York, United States of America
- Department of Neuroscience, Columbia University, New York, New York, United States of America
- * E-mail:
| |
Collapse
|
19
|
Selective corticospinal tract injury in the rat induces primary afferent fiber sprouting in the spinal cord and hyperreflexia. J Neurosci 2012; 32:12896-908. [PMID: 22973013 DOI: 10.1523/jneurosci.6451-11.2012] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The corticospinal tract (CST) has dense contralateral and sparse ipsilateral spinal cord projections that converge with proprioceptive afferents on common spinal targets. Previous studies in adult rats indicate that the loss of dense contralateral spinal CST connections after unilateral pyramidal tract section (PTx), which models CST loss after stroke or spinal cord injury, leads to outgrowth from the spared side into the affected, ipsilateral, spinal cord. The reaction of proprioceptive afferents after this CST injury, however, is not known. Knowledge of proprioceptive afferent responses after loss of the CST could inform mechanisms of maladaptive plasticity in spinal sensorimotor circuits after injury. Here, we hypothesize that the loss of the contralateral CST results in a reactive increase in muscle afferents from the impaired limb and enhancement of their physiological actions within the cervical spinal cord. We found that 10 d after PTx, proprioceptive afferents sprout into cervical gray matter regions denervated by the loss of CST terminations. Furthermore, VGlut1-positive boutons, indicative of group 1A afferent terminals, increased on motoneurons. PTx also produced an increase in microglial density within the gray matter regions where CST terminations were lost. These anatomical changes were paralleled by reduction in frequency-dependent depression of the H-reflex, suggesting hyperreflexia. Our data demonstrate for the first time that selective CST injury induces maladaptive afferent fiber plasticity remote from the lesion. Our findings suggest a novel structural reaction of proprioceptive afferents to the loss of CST terminations and provide insight into mechanisms underlying spasticity.
Collapse
|
20
|
Abstract
AbstractThe young human brain is highly plastic and thus early brain lesions can lead to aberrant development of connectivity and mapping of functions. This is why initially in cerebral palsy only subtle changes in spontaneous movements are seen after the time of lesion, followed by a progressive evolution of a movement disorder over many months and years. Thus we propose that interventions to treat cerebral palsy should be initiated as soon as possible in order to restore the nervous system to the correct developmental trajectory. One such treatment might be autologous stem cell transplantation either intracerebrally or intravenously. All babies come with an accessible supply of stem cells, the umbilical cord, which can supply cells that could theoretically replace missing neural cell types, or act indirectly by supplying trophic support or modulating inflammatory responses to hypoxia/ischaemia. However, for such radical treatment to be proposed, it is necessary to be able to detect and accurately predict the outcomes of brain injury from a very early age. This article reviews our current understanding of perinatal injuries that lead to cerebral palsy, how well modern imaging might predict outcomes, what stem cells are yielded from umbilical cord blood and experimental models of brain repair using stem cells.
Collapse
|