Spinal Source for the Synchronous Fluctuations of Bilateral Monosynaptic Reflexes in Cats

2005 ◽  
Vol 94 (5) ◽  
pp. 3199-3210 ◽  
Author(s):  
E. Manjarrez ◽  
Z. Hernández-Paxtián ◽  
A. F. Kohn
Keyword(s):  
Spinal Cord ◽  
Spinal Neurons ◽  
Constant Intensity ◽  
Variable Amplitude ◽  
Cross Covariance ◽  
Long Time ◽  
Spinal Segments ◽  
Left And Right ◽  
Ventral Roots ◽  
Lumbar Spinal

Successive stimuli of constant intensity applied to Ia afferents produce spinal monosynaptic reflexes (MSRs) of variable amplitude. We recorded simultaneous MSRs in the left and right L7 (or L6) ventral roots of anesthetized cats. We analyzed the cross-covariance (CCV) between the amplitudes of bilateral MSRs. Long-time series (5 to 8 h) of these bilateral MSRs exhibited transitory changes in their covariations (as measured by the zero-lag peak of their CCV), thus suggesting the existence of certain neural sources contributing to produce these changes. The aim of the present study was to show that spinal centers producing negative spontaneous cord dorsum potentials (nSCDPs) contribute to maintain correlations in the amplitude of bilateral MSRs. After spinal cord transection at the L1 segment, no significant changes were observed in the correlation between the amplitude of bilateral nSCDPs versus the amplitude of bilateral MSRs. However, this correlation, as well as the peak at zero lag in the CCV between bilateral MSRs and the CCV between bilateral nSCDPs, respectively, were abolished after a subsequent longitudinal bisection at the L1–S2 spinal segments. These results suggest that lumbar spinal neurons (bilaterally interconnected) contribute to maintain the synchronous fluctuations of bilateral MSRs.

scholarly journals Spinal V3 interneurons and left-right coordination in mammalian locomotion

2019 ◽  
Author(s):  
Simon M. Danner ◽  
Han Zhang ◽  
Natalia A. Shevtsova ◽  
Joanna Borowska ◽  
Ilya A. Rybak ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Rhythmic Activity ◽  
Contralateral Side ◽  
Lumbar Spinal Cord ◽  
Spinal Neurons ◽  
Ipsilateral Side ◽  
Current Experimental Data ◽  
Left And Right ◽  
Lumbar Spinal

AbstractCommissural interneurons (CINs) mediate interactions between rhythm-generating locomotor circuits located on each side of the spinal cord and are necessary for left-right limb coordination during locomotion. While glutamatergic V3 CINs have been implicated in left-right coordination, their functional connectivity remains elusive. Here, we addressed this issue by combining experimental and modeling approaches. We employed Sim1Cre/+; Ai32 mice, in which light-activated Channelrhodopsin-2 was selectively expressed in V3 interneurons. Fictive locomotor activity was evoked by NMDA and 5-HT in the isolated neonatal lumbar spinal cord. Flexor and extensor activities were recorded from left and right L2 and L5 ventral roots, respectively. Bilateral photoactivation of V3 interneurons increased the duration of extensor bursts resulting in a slowed down on-going rhythm. At high light intensities, extensor activity could become sustained. When light stimulation was shifted toward one side of the cord, the duration of extensor bursts still increased on both sides, but these changes were more pronounced on the contralateral side than on the ipsilateral side. Additional bursts appeared on the ipsilateral side not seen on the contralateral side. Further increase of the stimulation could suppress the contralateral oscillations by switching to a sustained extensor activity, while the ipsilateral rhythmic activity remained. To delineate the function of V3 interneurons and their connectivity, we developed a computational model of the spinal circuits consisting of two (left and right) rhythm generators (RGs) interacting via V0V, V0D and V3 CINs. Both types of V0 CINs provided mutual inhibition between the left and right flexor RG centers and promoted left-right alternation. V3 CINs mediated mutual excitation between the left and right extensor RG centers. These interactions allowed the model to reproduce our current experimental data, while being consistent with previous data concerning the role of V0V and V0D CINs in securing left-right alternation and the changes in left-right coordination following their selective removal. We suggest that V3 CINs provide mutual excitation between the spinal neurons involved in the control of left and right extensor activity, which may promote left-right synchronization during locomotion.

Changes in serotonin-induced potentials during spinal cord development

1993 ◽  
Vol 69 (4) ◽  
pp. 1338-1349 ◽  
Author(s):  
L. Ziskind-Conhaim ◽  
B. S. Seebach ◽  
B. X. Gao
Keyword(s):  
Spinal Cord ◽  
Direct Action ◽  
Membrane Resistance ◽  
Ventral Horn ◽  
Repetitive Firing ◽  
Lumbar Spinal Cord ◽  
Receptor Subtypes ◽  
Gamma Aminobutyric Acid ◽  
Spinal Neurons ◽  
Lumbar Spinal

1. Motoneuron responses to serotonin (5-hydroxytryptamine, 5-HT), and the growth pattern of 5-HT projections into the ventral horn were studied in the isolated spinal cord of embryonic and neonatal rats. 2. 5-HT projections first appeared in lumbar spinal cord at days 16-17 of gestation (E16-E17) and were localized in the lateral and ventral funiculi. By E18, the projections had grown into the ventral horn, and at 1-2 days after birth they were in close apposition to motoneuron somata. 3. At E16-E17, slow-rising depolarizing potentials of 1-4 mV were recorded intracellularly in lumbar motoneurons in response to bath application of 5-HT. These potentials were not apparent after E18; at that time 5-HT generated long-lasting depolarizations with an average amplitude of 6 mV, and an increase of 11% in membrane resistance. Starting at E18, 5-HT also induced high-frequency fast-rising potentials that were blocked by antagonists of glutamate, gamma-aminobutyric acid, and glycine. 4. Motoneuron responses to 5-HT increased significantly after birth, when 5-HT produced an average depolarization of 19 mV and repetitive firing of action potentials. 5. Tetrodotoxin and high Mg2+ did not reduce the amplitude of the long-lasting depolarizations, which suggested that they were produced by direct action of 5-HT on motoneuron membrane. 6. At all developmental ages, 5-HT reduced the amplitude of dorsal root-evoked potentials. The suppressed responses were neither due to 5-HT-induced depolarization nor the result of a decrease in motoneuron excitability. 7. The pharmacological profile of 5-HT-induced potentials was studied with the use of various agonists and antagonists of 5-HT. The findings indicated that the actions of 5-HT on spinal neurons were mediated via multiple 5-HT receptor subtypes. 8. Our results suggested that 5-HT excited spinal neurons before 5-HT projections grew into the ventral horn. The characteristics of 5-HT-induced potentials changed, however, at the time when the density of 5-HT projections increased in the motor nuclei.

Features of laminar and somatotopic organization of lumbar spinal cord units receiving cutaneous inputs from hindlimb receptive fields

1984 ◽  
Vol 52 (3) ◽  
pp. 449-458 ◽  
Author(s):  
A. R. Light ◽  
R. G. Durkovic
Keyword(s):  
Spinal Cord ◽  
Receptive Field ◽  
Receptive Fields ◽  
Lumbar Spinal Cord ◽  
Spinal Neurons ◽  
Spinal Cord Neurons ◽  
Somatotopic Organization ◽  
Single Unit Recordings ◽  
Lumbar Spinal ◽  
Rectangular Columns

Single-unit recordings from 312 units of lamina I-VII of the lumbar spinal cord of unanesthetized, decerebrate, T8 spinal cats were used to determine the somatotopic and laminar organization of spinal neurons responding to cutaneous stimulation of the hindlimb. Properties of cells confined to different Rexed laminae (I-VII) were shown to differ in several respects, including responses to variations in stimulus intensity, receptive-field areas, spontaneous frequencies, and central delays. Spinal cord neurons with similarly localized cutaneous receptive fields were found to be organized in sagittally oriented rectangular columns. These columns were 7 to at least 20 mm long (rostral-caudal axis), 0.5-1.0 mm wide, and could encompass laminae I-VII in depth. Touch, pressure, and pinch were effective excitatory inputs into each column subserving a given receptive-field location. A map of the somatotopic organization of units in the horizontal plane is presented, which in general confirms previous reports and in particular deals with the organization of units with receptive fields on the plantar cushion and individual toes.

Differential effects of left and right neuropathy on opioid gene expression in lumbar spinal cord

2018 ◽  
Vol 1695 ◽  
pp. 78-83 ◽  
Author(s):  
Olga Kononenko ◽  
Irina Mityakina ◽  
Vladimir Galatenko ◽  
Hiroyuki Watanabe ◽  
Igor Bazov ◽  
...  
Keyword(s):  
Gene Expression ◽  
Spinal Cord ◽  
Lumbar Spinal Cord ◽  
Differential Effects ◽  
Left And Right ◽  
Lumbar Spinal

Properties of Rhythmic Activity Generated by the Isolated Spinal Cord of the Neonatal Mouse

2000 ◽  
Vol 84 (6) ◽  
pp. 2821-2833 ◽  
Author(s):  
Patrick Whelan ◽  
Agnes Bonnot ◽  
Michael J. O'Donovan
Keyword(s):  
Spinal Cord ◽  
Ampa Receptors ◽  
Rhythmic Activity ◽  
Ventral Root ◽  
Neonatal Mouse ◽  
Drug Induced ◽  
Lumbosacral Spinal Cord ◽  
Hindlimb Muscle ◽  
Left And Right ◽  
Ventral Roots

We examined the ability of the isolated lumbosacral spinal cord of the neonatal mouse (P0–7) to generate rhythmic motor activity under several different conditions. In the absence of electrical or pharmacological stimulation, we recorded several patterns of spontaneous ventral root depolarization and discharge. Spontaneous, alternating discharge between contralateral ventral roots could occur two to three times over a 10-min interval. We also observed other patterns, including left-right synchrony and rhythmic activity restricted to one side of the cord. Trains of stimuli delivered to the lumbar/coccygeal dorsal roots or the sural nerve reliably evoked episodes of rhythmic activity. During these evoked episodes, rhythmic ventral root discharges could occur on one side of the cord or could alternate from side to side. Bath application of a combination of N-methyl-d,l-aspartate (NMA), serotonin, and dopamine produced rhythmic activity that could last for several hours. Under these conditions, the discharge recorded from the left and right L1–L3 ventral roots alternated. In the L4–L5segments, the discharge had two peaks in each cycle, coincident with discharge of the ipsilateral and contralateral L1–L3 roots. The L6 ventral root discharge alternated with that recorded from the ipsilateral L1–L3 roots. We established that the drug-induced rhythm was locomotor-like by recording an alternating pattern of discharge between ipsilateral flexor and extensor hindlimb muscle nerves. In addition, by recording simultaneously from ventral roots and muscle nerves, we established that ankle flexor discharge was in phase with ipsilateral L1/L2 ventral root discharge, while extensor discharge was in phase with ipsilateral L6 ventral root discharge. Rhythmic patterns of ventral root discharge were preserved following mid-sagittal section of the spinal cord, demonstrating that reciprocal inhibitory connections between the left and right sides of the cord are not essential for rhythmogenesis in the neonatal mouse cord. Blocking N-methyl-d-aspartate receptors, in both the intact and the hemisected preparation, revealed that these receptors contribute to but are not essential for rhythmogenesis. In contrast, the rhythm was abolished following blockade of kainate/AMPA receptors with 6-cyano-7-nitroquinoxalene-2,3-dione. These findings demonstrate that the isolated mouse spinal cord can produce a variety of coordinated activities, including locomotor-like activity. The ability to study these behaviors under a variety of different conditions offers promise for future studies of rhythmogenic mechanisms in this preparation.

scholarly journals Caudal-rostral progression of alpha motoneurone degeneration in the SOD1G93A mouse model of amyotrophic lateral sclerosis

2020 ◽  
Author(s):  
Alastair J Kirby ◽  
Thomas Palmer ◽  
Richard Mead ◽  
Ronaldo Ichiyama ◽  
Samit Chakrabarty
Keyword(s):  
Spinal Cord ◽  
Cervical Spinal Cord ◽  
Motor Impairment ◽  
Ventral Horn ◽  
Lumbar Spinal Cord ◽  
List Type ◽  
Spatial Trend ◽  
Transgenic Expression ◽  
Spinal Segments ◽  
Lumbar Spinal

AbstractMice with transgenic expression of human SOD1G93A are a widely used model of ALS, with a caudal-rostral progression of motor impairment. Previous studies have quantified the progression of motoneurone (MN) degeneration based on size, even though alpha (α-) and gamma (γ-) MNs overlap in size. Therefore, using molecular markers and synaptic inputs, we quantified the survival of α-MNs and γ-MNs at the lumbar and cervical spinal segments of 3- and 4-month SOD1G93A mice, to investigate whether there is a caudal-rostral progression of MN death. By 3-months, in the cervical and lumbar spinal cord, there was α-MN degeneration with complete γ-MN sparing. At 3-months the cervical spinal cord had more α-MNs per ventral horn than the lumbar spinal cord, in SOD1G93A mice. A similar spatial trend of degeneration was observed in the corticospinal tract, which remained intact in the cervical spinal cord at 3- and 4-months of age. These findings agree with the corticofugal synaptopathy model, that α-MN and CST of the lumbar spinal cord are more susceptible to degeneration in SOD1G93A mice. Hence, there is spatial and temporal caudal-rostral progression of α-MN and CST degeneration in SOD1G93A mice.HighlightsSOD1G93A mice display a caudal-rostral progression of motor impairment.Lumbar spinal cord of SOD1G93A mice has an enhanced susceptibility to degeneration.SOD1G93A mice exhibit a caudal-rostral progression of α-MN and CST degeneration

Evidence for a central component in the sensitization of spinal neurons with joint input during development of acute arthritis in cat's knee

1990 ◽  
Vol 64 (1) ◽  
pp. 299-311 ◽  
Author(s):  
V. Neugebauer ◽  
H. G. Schaible
Keyword(s):  
Spinal Cord ◽  
Knee Joint ◽  
Mechanical Stimulation ◽  
Receptive Fields ◽  
Lumbar Spinal Cord ◽  
Mechanical Stimuli ◽  
Spinal Neurons ◽  
Deep Tissue ◽  
Lumbar Spinal ◽  
Stimulation Of

1. In the spinalized cat, nociceptive spinal neurons with knee input show enhanced responses to mechanical stimulation of that joint once an inflammation has developed in the knee. Enhanced responses may result from increased afferent inflow as well as from modifications of the nociceptive processing within the spinal cord. To examine the significance of these components, we tested in 30 chloralose-anesthetized, spinalized cats whether, during development of arthritis, changes of responsiveness in spinal neurons are restricted to stimulation of the inflamed joint or whether responsiveness in these neurons is altered in general. While continuously recording from a neuron, we injected kaolin and carrageenan into one knee and tested the responses to mechanical stimuli applied to the joint and to regions adjacent to and remote from the knee during the developing arthritis. In addition, in six cats we monitored the neurons' responses to electrical stimulation of the sural nerves and the rostral lumbar spinal cord. 2. Of 32 neurons in laminae VI, VII, and VIII of the lumbar spinal cord, 15 ascending and eight nonascending cells were driven by mechanical stimulation of one or both knee joint(s). Nine of these were nociceptive specific (NS), responding exclusively or predominantly to noxious compression of the knee and other deep tissue, and 12 were wide-dynamic-range (WDR) cells with graded responses to gentle and noxious stimuli applied to the knee joint(s), deep tissue, and skin. Two neurons with high ongoing discharges had some excitatory joint input but showed marked inhibition by most stimuli used (INH neurons). The majority of the neurons had receptive fields on both legs. Nine of the 32 neurons had no input from the knee(s). 3. All 23 neurons with joint input became sensitive or more responsive to movements and gentle compression of the inflamed knee once the inflammation had developed. In general, these neurons also showed enhanced responses to compression of the adjacent muscles in thigh and lower leg. In 20 neurons, response properties were even altered for stimuli applied to regions remote from the inflamed joint, including the contralateral leg in 18 cases. We found expansion of initially restricted receptive fields (mainly in NS cells), enhancement of preexisting responses, and/or lowering of threshold to mechanical stimuli applied to these regions; few neurons developed inhibitory reactions.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals A point mutation in Ttc26 causes lumbar spinal cord fusion and synchronous hind-limb locomotion in hop mice

2020 ◽  
Author(s):  
Nadine Bernhardt ◽  
Fatima Memic ◽  
Anna Velica ◽  
Michelle A. Tran ◽  
Jennifer Vieillard ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Point Mutation ◽  
Central Pattern Generators ◽  
Lumbar Spinal Cord ◽  
Local Defect ◽  
Morphological Defects ◽  
Left And Right ◽  
Pattern Generators ◽  
Lumbar Spinal ◽  
Ventral Spinal Cord

AbstractIdentifying the spinal circuits controlling locomotion is critical for unravelling the mechanisms controlling the production of gaits. Development of the circuits governing left-right coordination relies on axon guidance molecules such as ephrins and netrins. To date, no other class of proteins have been shown to play a role during this process. Here we have analyzed hop mice, which walk with a characteristic hopping gait using their hind legs in synchrony. Fictive locomotion experiments suggest that a local defect in the ventral spinal cord contributes to the aberrant locomotor phenotype. Hop mutant spinal cords had severe morphological defects, including the absence of the ventral midline and a poorly defined border between white and grey matter. The hop mice represent the first model where the left and right central pattern generators (CPGs) are fused to form one central CPG, with a synchronous gait as a functional consequence. These defects were exclusively found in the lumbar domain and were associated with abnormal developmental processes, including a misplaced notochord and reduced induction of ventral progenitor domains. While the underlying mutation in hop mice has been suggested to lie within Ttc26, other genes in close vicinity have been associated with gait defects. By replicating the point mutation within Ttc26, employing CRISPR technology, we observed mice with an identical phenotype, thereby verifying the hop mutation. Thus, we show that the assembly of the lumbar CPG network is dependent on a fully functional TTC26 protein.

scholarly journals Episodic swimming in the larval zebrafish is generated by a spatially distributed spinal network with modular functional organization

2012 ◽  
Vol 108 (3) ◽  
pp. 925-934 ◽  
Author(s):  
Timothy D. Wiggin ◽  
Tatiana M. Anderson ◽  
John Eian ◽  
Jack H. Peck ◽  
Mark A. Masino
Keyword(s):  
Spinal Cord ◽  
Functional Organization ◽  
Body Wave ◽  
The Body ◽  
Body Segments ◽  
Larval Zebrafish ◽  
Spatially Distributed ◽  
Spinal Segments ◽  
Spinal Network ◽  
Left And Right

Despite the diverse methods vertebrates use for locomotion, there is evidence that components of the locomotor central pattern generator (CPG) are conserved across species. When zebrafish begin swimming early in development, they perform short episodes of activity separated by periods of inactivity. Within these episodes, the trunk flexes with side-to-side alternation and the traveling body wave progresses rostrocaudally. To characterize the distribution of the swimming CPG along the rostrocaudal axis, we performed transections of the larval zebrafish spinal cord and induced fictive swimming using N-methyl-d-aspartate (NMDA). In both intact and spinalized larvae, bursting is found throughout the rostrocaudal extent of the spinal cord, and the properties of fictive swimming observed were dependent on the concentration of NMDA. We isolated series of contiguous spinal segments by performing multiple spinal transections on the same larvae. Although series from all regions of the spinal cord have the capacity to produce bursts, the capacity to produce organized episodes of fictive swimming has a rostral bias: in the rostral spinal cord, only 12 contiguous body segments are necessary, whereas 23 contiguous body segments are necessary in the caudal spinal cord. Shorter series of segments were often active but produced either continuous rhythmic bursting or sporadic, nonrhythmic bursting. Both episodic and continuous bursting alternated between the left and right sides of the body and showed rostrocaudal progression, demonstrating the functional dissociation of the circuits responsible for episodic structure and fine burst timing. These findings parallel results in mammalian locomotion, and we propose a hierarchical model of the larval zebrafish swimming CPG.

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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