scholarly journals Spinal Cord Modular Organization and Rhythm Generation: An NMDA Iontophoretic Study in the Frog

1998 ◽  
Vol 80 (5) ◽  
pp. 2323-2339 ◽  
Author(s):  
Philippe Saltiel ◽  
Matthew C. Tresch ◽  
Emilio Bizzi
Keyword(s):  
Spinal Cord ◽  
Isometric Force ◽  
Pattern Generation ◽  
The Body ◽  
Lumbar Spinal Cord ◽  
Modular Organization ◽  
Rhythmic Pattern ◽  
Rhythm Generation ◽  
Force Output ◽  
Electrical Microstimulation

Saltiel, Philippe, Matthew C. Tresch, and Emilio Bizzi. Spinal cord modular organization and rhythm generation: a NMDA iontophoretic study in the frog. J. Neurophysiol. 80: 2323–2339, 1998. Previous work using electrical microstimulation has suggested the existence of modules subserving limb posture in the spinal cord. In this study, the question of modular organization was reinvestigated with the more selective method of chemical microstimulation. N-methyl-d-aspartate (NMDA) iontophoresis was applied to 229 sites of the lumbar spinal cord gray while monitoring the isometric force output of the ipsilateral hindlimb at the ankle. A force response was elicited from 69 sites. At 18 of these sites, tonic forces were generated and rhythmic forces at 44. In the case of tonic forces, their directions clustered along four orientations: lateral extension, rostral flexion, adduction, and caudal extension. For the entire set of forces (tonic and rhythmic), the same clusters of orientations were found with the addition of a cluster directed as a flexion toward the body. This distribution of force orientations was quite comparable to that obtained with electrical stimulation at the same sites. The map of tonic responses revealed a topographic organization; each type of force orientation was elicited from sites that grouped together in zones at distinct rostrocaudal and depth locations. In the case of rhythmic sequences of force orientations, some were distinctly more common, whereas others were rarely elicited by NMDA. Mapping of the most common rhythms showed that each was elicited from two or three regions of the cord. These regions were close in location to the tonic regions that produced those forces that represented components specific to that rhythm. There was an additional caudal region from which the different rhythms also could be elicited. Taken together, these results support the concept of a modular organization of the motor system in the frog's spinal cord and delineate the topography of these modules. They also suggest that these modules are used by the circuitry underlying rhythmic pattern generation by the spinal cord.

An intracortical neuroprosthesis immediately alleviates walking deficits and improves recovery of leg control after spinal cord injury

2021 ◽  
Vol 13 (586) ◽  
pp. eabb4422
Author(s):  
Marco Bonizzato ◽  
Marina Martinez
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Pattern Generation ◽  
Rhythmic Pattern ◽  
Cortical Control ◽  
Motor Mapping ◽  
Cortical Motor ◽  
Locomotor Control ◽  
Cord Injury

Most rehabilitation interventions after spinal cord injury (SCI) only target the sublesional spinal networks, peripheral nerves, and muscles. However, mammalian locomotion is not a mere act of rhythmic pattern generation. Recovery of cortical control is essential for voluntary movement and modulation of gait. We developed an intracortical neuroprosthetic intervention to SCI, with the goal to condition cortical locomotor control. Neurostimulation delivered in phase coherence with ongoing locomotion immediately alleviated primary SCI deficits, such as leg dragging, in rats with incomplete SCI. Cortical neurostimulation achieved high fidelity and markedly proportional online control of leg trajectories in both healthy and SCI rats. Long-term neuroprosthetic training lastingly improved cortical control of locomotion, whereas short training held transient improvements. We performed longitudinal awake cortical motor mapping, unveiling that recovery of cortico-spinal transmission tightly parallels return of locomotor function in rats. These results advocate directly targeting the motor cortex in clinical neuroprosthetic approaches.

scholarly journals Spatiotemporal contribution of neuromesodermal progenitor-derived neural cells in the elongation of developing mouse spinal cord

2020 ◽  
Author(s):  
Mohammed R Shaker ◽  
Ju-Hyun Lee ◽  
Kyung Hyun Kim ◽  
Veronica Jihyun Kim ◽  
Joo Yeon Kim ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Neural Tube ◽  
Dorsal Side ◽  
Lineage Tracing ◽  
The Body ◽  
Lumbar Spinal Cord ◽  
Genetic Lineage ◽  
Mouse Development ◽  
Axial Elongation

ABSTRACTDuring vertebrate development, the posterior end of the embryo progressively elongates in a head-to-tail direction to form the body plan. Recent lineage tracing experiments revealed that bi-potent progenitors, called neuromesodermal progenitors (NMPs), produce caudal neural and mesodermal tissues during axial elongation. However, their precise location and contribution to spinal cord development remain elusive. Here we used NMP-specific markers (Sox2 and BraT) and a genetic lineage tracing system to localize NMP progeny in vivo. NMPs were initially located at the tail tip, but were later found in the caudal neural tube, which is a unique feature of mouse development. In the neural tube, they produced neural stem cells (NSCs) and contributed to the spinal cord gradually along the AP axis during axial elongation. Interestingly, NMP-derived NSCs preferentially contributed to the ventral side first and later to the dorsal side at the lumbar spinal cord level, which may be associated with atypical junctional neurulation in mice. Our current observations detail the contribution of NMP progeny to spinal cord elongation and provide insights into how different species uniquely execute caudal morphogenesis.

scholarly journals Forelimb force direction and magnitude independently controlled by spinal modules in the macaque

2020 ◽  
Vol 117 (44) ◽  
pp. 27655-27666
Author(s):  
Amit Yaron ◽  
David Kowalski ◽  
Hiroaki Yaguchi ◽  
Tomohiko Takei ◽  
Kazuhiko Seki
Keyword(s):  
Spinal Cord ◽  
Control System ◽  
Force Field ◽  
Cognitive Complexity ◽  
Motor System ◽  
Cervical Spinal Cord ◽  
Neural Mechanism ◽  
Lumbar Spinal Cord ◽  
Modular Organization ◽  
Spinal Motor

Modular organization of the spinal motor system is thought to reduce the cognitive complexity of simultaneously controlling the large number of muscles and joints in the human body. Although modular organization has been confirmed in the hindlimb control system of several animal species, it has yet to be established in the forelimb motor system or in primates. Expanding upon experiments originally performed in the frog lumbar spinal cord, we examined whether costimulation of two sites in the macaque monkey cervical spinal cord results in motor activity that is a simple linear sum of the responses evoked by stimulating each site individually. Similar to previous observations in the frog and rodent hindlimb, our analysis revealed that in most cases (77% of all pairs) the directions of the force fields elicited by costimulation were highly similar to those predicted by the simple linear sum of those elicited by stimulating each site individually. A comparable simple summation of electromyography (EMG) output, especially in the proximal muscles, suggested that this linear summation of force field direction was produced by a spinal neural mechanism whereby the forelimb motor output recruited by costimulation was also summed linearly. We further found that the force field magnitudes exhibited supralinear (amplified) summation, which was also observed in the EMG output of distal forelimb muscles, implying a novel feature of primate forelimb control. Overall, our observations support the idea that complex movements in the primate forelimb control system are made possible by flexibly combined spinal motor modules.

A few words about local anesthesia eikain B.

1901 ◽  
Vol 1 (1-2) ◽  
pp. 1-10
Author(s):  
N. A. Gerken
Keyword(s):  
Spinal Cord ◽  
Local Anesthesia ◽  
The Body ◽  
Lower Half ◽  
Lumbar Spinal Cord ◽  
Subdural Space ◽  
Lumbar Spinal

The question of various methods of anesthesia does not cease to interest surgeons until the last time. A new way of anesthesia of the lower half of the body, by injecting a solution of cocaine into the subdural space of the lumbar spinal cord, has arisen and is being developed in the most recent years.

Activities of identified interneurons, motoneurons, and muscle fibers during fictive swimming in the lamprey and effects of reticulospinal and dorsal cell stimulation

1982 ◽  
Vol 47 (5) ◽  
pp. 948-960 ◽  
Author(s):  
J. T. Buchanan ◽  
A. H. Cohen
Keyword(s):  
Spinal Cord ◽  
Muscle Fibers ◽  
Membrane Potentials ◽  
Pattern Generation ◽  
The Body ◽  
Swimming Activity ◽  
Burst Intensity ◽  
Intracellular Stimulation ◽  
Dorsal Cells ◽  
Stimulation Of

1. Application of D-glutamate to the isolated spinal cord of the lamprey produces phasic activity in ventral roots, which is similar to that of the muscles of the intact swimming animal (5,18). Therefore, the isolated spinal cord may be used as a convenient model for the investigation of the generation of locomotor rhythms in a vertebrate. 2. Almost all slow muscle fibers exhibited excitatory junctional potentials (EJPs) during swimming activity. The number of EJPs per cycle increased with the intensity of ventral root (VR) bursting. Few twitch fibers were active, and these fired action potentials only during high intensities of VR bursts. 3. As was found by Russell and Wallen (25), myotomal motoneurons had oscillating membrane potentials during fictive swimming which, on the average, reached a peak depolarization in the middle of the VR burst (phi = 0.21 +/- 0.05; phi = 0 is defined as the onset of the VR burst, and the duration of the cycle is set equal to 1). Membrane potential oscillations in fin motoneurons were antiphasic to those of nearby myotomal motoneurons (peak depolarization phi = 0.68 +/- 0.05). 4. Lateral interneurons had oscillating membrane potentials in synchrony with those of myotomal motoneurons (peak depolarization phi = 0.21 +/- 0.10). Interneurons with axons projecting contralaterally and caudally (CC interneurons) had oscillating membrane potentials that peaked significantly earlier in the cycle (peak depolarization phi = 0.06 +/- 0.12). 5. Edge cells were only weakly modulated during fictive swimming. Their peak depolarizations occurred near the end of the VR burst (phi = 0.33 +/- 0.10). Most giant interneurons were not phasically modulated during fictive swimming. 6. Repetitive intracellular stimulation of Muller cells during fictive swimming generally evoked an increased burst intensity in ipsilateral VRs and a decreased burst intensity in contralateral VRs. The cells M3, B1, and B2 also produced increases or decreases in the frequency of VR bursts. Repetitive intracellular stimulation of sensory dorsal cells could also change the intensities and timing of VR bursts. 7. This study is an initial survey of lamprey spinal interneurons that participate in swimming activity. Lateral interneurons and CC interneurons are active during fictive swimming and probably help coordinate the undulations of the body, but their roles in pattern generation are not known. The central pattern generator is subject to modification by descending and sensory inputs.

scholarly journals Asymmetric Operation of the Locomotor Central Pattern Generator in the Neonatal Mouse Spinal Cord

2008 ◽  
Vol 100 (6) ◽  
pp. 3043-3054 ◽  
Author(s):  
Toshiaki Endo ◽  
Ole Kiehn
Keyword(s):  
Spinal Cord ◽  
Central Pattern Generator ◽  
Motor Neurons ◽  
Decomposition Methods ◽  
Pattern Generator ◽  
Lumbar Spinal Cord ◽  
Modular Organization ◽  
Phase Tuning ◽  
Conductance Changes ◽  
Synaptic Conductances

The rhythmic voltage oscillations in motor neurons (MNs) during locomotor movements reflect the operation of the pre-MN central pattern generator (CPG) network. Recordings from MNs can thus be used as a method to deduct the organization of CPGs. Here, we use continuous conductance measurements and decomposition methods to quantitatively assess the weighting and phase tuning of synaptic inputs to different flexor and extensor MNs during locomotor-like activity in the isolated neonatal mice lumbar spinal cord preparation. Whole cell recordings were obtained from 22 flexor and 18 extensor MNs in rostral and caudal lumbar segments. In all flexor and the large majority of extensor MNs the extracted excitatory and inhibitory synaptic conductances alternate but with a predominance of inhibitory conductances, most pronounced in extensors. These conductance changes are consistent with a “push–pull” operation of locomotor CPG. The extracted excitatory and inhibitory synaptic conductances varied between 2 and 56% of the mean total conductance. Analysis of the phase tuning of the extracted synaptic conductances in flexor and extensor MNs in the rostral lumbar cord showed that the flexor-phase–related synaptic conductance changes have sharper locomotor-phase tuning than the extensor-phase–related conductances, suggesting a modular organization of premotor CPG networks consisting of reciprocally coupled, but differently composed, flexor and extensor CPG networks. There was a clear difference between phase tuning in rostral and caudal MNs, suggesting a distinct operation of CPG networks in different lumbar segments. The highly asymmetric features were preserved throughout all ranges of locomotor frequencies investigated and with different combinations of locomotor-inducing drugs. The asymmetric nature of CPG operation and phase tuning of the conductance profiles provide important clues to the organization of the rodent locomotor CPG and are compatible with a multilayered and distributed structure of the network.

Strong interactions between spinal cord networks for locomotion and scratching

2011 ◽  
Vol 106 (4) ◽  
pp. 1766-1781 ◽  
Author(s):  
Zhao-Zhe Hao ◽  
Lucy E. Spardy ◽  
Edward B. L. Nguyen ◽  
Jonathan E. Rubin ◽  
Ari Berkowitz
Keyword(s):  
Spinal Cord ◽  
Motor Pattern ◽  
Pattern Generation ◽  
Strong Interactions ◽  
Generation Model ◽  
Network Architectures ◽  
Rhythm Generation ◽  
Motor Patterns ◽  
Simultaneous Activation ◽  
Rhythmic Behaviors

Distinct rhythmic behaviors involving a common set of motoneurons and muscles can be generated by separate central nervous system (CNS) networks, a single network, or partly overlapping networks in invertebrates. Less is known for vertebrates. Simultaneous activation of two networks can reveal overlap or interactions between them. The turtle spinal cord contains networks that generate locomotion and three forms of scratching (rostral, pocket, and caudal), having different knee-hip synergies. Here, we report that in immobilized spinal turtles, simultaneous delivery of types of stimulation, which individually evoked forward swimming and one form of scratching, could 1) increase the rhythm frequency; 2) evoke switches, hybrids, and intermediate motor patterns; 3) recruit a swim motor pattern even when the swim stimulation was reduced to subthreshold intensity; and 4) disrupt rhythm generation entirely. The strength of swim stimulation could influence the result. Thus even pocket scratching and caudal scratching, which do not share a knee-hip synergy with forward swimming, can interact with swim stimulation to alter both rhythm and pattern generation. Model simulations were used to explore the compatibility of our experimental results with hypothetical network architectures for rhythm generation. Models could reproduce experimental observations only if they included interactions between neurons involved in swim and scratch rhythm generation, with maximal consistency between simulations and experiments attained using a model architecture in which certain neurons participated actively in both swim and scratch rhythmogenesis. Collectively, these findings suggest that the spinal cord networks that generate locomotion and scratching have important shared components or strong interactions between them.

scholarly journals Estimating total maximum isometric force output of trunk and hip muscles after spinal cord injury

2020 ◽  
Vol 58 (4) ◽  
pp. 739-751
Author(s):  
Akhil Bheemreddy ◽  
Aidan Friederich ◽  
Lisa Lombardo ◽  
Ronald J. Triolo ◽  
Musa L. Audu
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Isometric Force ◽  
Force Output ◽  
Cord Injury ◽  
Maximum Isometric Force ◽  
Hip Muscles ◽  
Total Maximum

Lipomeningocele associated with diplomyelia in a dog

2018 ◽  
Vol 46 (05) ◽  
pp. 323-329 ◽  
Author(s):  
Nele Ondreka ◽  
Sara Malberg ◽  
Emma Laws ◽  
Martin Schmidt ◽  
Sabine Schulze
Keyword(s):  
Spinal Cord ◽  
Neurological Status ◽  
Split Cord Malformation ◽  
Lumbar Spinal Cord ◽  
Histopathological Diagnosis ◽  
Type I ◽  
Thoracic Spinal Cord ◽  
Thoracic Spinal ◽  
Subcutaneous Mass ◽  
Lumbar Spinal

SummaryA 2-year-old male neutered mixed breed dog with a body weight of 30 kg was presented for evaluation of a soft subcutaneous mass on the dorsal midline at the level of the caudal thoracic spine. A further clinical sign was intermittent pain on palpation of the area of the subcutaneous mass. The owner also described a prolonged phase of urination with repeated interruption and re-initiation of voiding. The findings of the neurological examination were consistent with a lesion localization between the 3rd thoracic and 3rd lumbar spinal cord segments. Magnetic resonance imaging revealed a spina bifida with a lipomeningocele and diplomyelia (split cord malformation type I) at the level of thoracic vertebra 11 and 12 and secondary syringomyelia above the aforementioned defects in the caudal thoracic spinal cord. Surgical resection of the lipomeningocele via a hemilaminectomy was performed. After initial deterioration of the neurological status postsurgery with paraplegia and absent deep pain sensation the dog improved within 2 weeks to non-ambulatory paraparesis with voluntary urination. Six weeks postoperatively the dog was ambulatory, according to the owner. Two years after surgery the owner recorded that the dog showed a normal gait, a normal urination and no pain. Histopathological diagnosis of the biopsied material revealed a lipomeningocele which confirmed the radiological diagnosis.

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