scholarly journals Distinct Spinal V2a and V0d Microcircuits Distribute Locomotor Control in Larval Zebrafish

2019 ◽  
Author(s):  
Evdokia Menelaou ◽  
Sandeep Kishore ◽  
David L. McLean
Keyword(s):  
Spinal Cord ◽  
Conceptual Framework ◽  
Distributed Control ◽  
Motor Neurons ◽  
Type I ◽  
Type Ii ◽  
Spinal Interneurons ◽  
Larval Zebrafish ◽  
Locomotor Control ◽  
Pattern Control

SUMMARYSpinal interneurons coordinate adjustments in the rhythm and pattern of locomotor movements. Two prevailing models predict that interneurons either share or hierarchically distribute control of these key parameters. Here, we have tested each model in the coordination of swimming in larval zebrafish by circumferential excitatory V2a and commissural inhibitory V0d interneurons. We define two types of V2a neuron based on morphology, electrophysiology and connectivity. Type I V2as primarily propagate and amplify rhythmic signals biased to interneurons, while type II V2as primarily segregate and expedite patterning signals biased to motor neurons. Distributed control arises by differences in the likelihood of connections within types and the relative weights of connections between them, but not by a strict anatomical hierarchy. Heterogeneity among V0d neurons supports a similar functional distinction. Our findings provide a hybrid conceptual framework to better understand the origins of rhythm and pattern control in the spinal cord.

scholarly journals Hierarchical control of locomotion by distinct types of spinal V2a interneurons in zebrafish

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Evdokia Menelaou ◽  
David L. McLean
Keyword(s):  
Spinal Cord ◽  
Motor Neurons ◽  
Hierarchical Control ◽  
Higher Order ◽  
Type I ◽  
Type Ii ◽  
Timing Control ◽  
Amplitude Control ◽  
Spinal Interneurons ◽  
Larval Zebrafish

Abstract In all vertebrates, excitatory spinal interneurons execute dynamic adjustments in the timing and amplitude of locomotor movements. Currently, it is unclear whether interneurons responsible for timing control are distinct from those involved in amplitude control. Here, we show that in larval zebrafish, molecularly, morphologically and electrophysiologically distinct types of V2a neurons exhibit complementary patterns of connectivity. Stronger higher-order connections from type I neurons to other excitatory V2a and inhibitory V0d interneurons provide timing control, while stronger last-order connections from type II neurons to motor neurons provide amplitude control. Thus, timing and amplitude are coordinated by distinct interneurons distinguished not by their occupation of hierarchically-arranged anatomical layers, but rather by differences in the reliability and probability of higher-order and last-order connections that ultimately form a single anatomical layer. These findings contribute to our understanding of the origins of timing and amplitude control in the spinal cord.

Cellular studies of peripheral neurons in siphon skin of Aplysia californica

1979 ◽  
Vol 42 (2) ◽  
pp. 530-557 ◽  
Author(s):  
C. H. Bailey ◽  
V. F. Castellucci ◽  
J. Koester ◽  
E. R. Kandel
Keyword(s):  
Motor Neurons ◽  
Synaptic Input ◽  
Firing Pattern ◽  
White Cell ◽  
Type I ◽  
Type Ii ◽  
Peripheral Neurons ◽  
Peripheral Neuron ◽  
Type I Neuron ◽  
Kinetics Of

1. To account for the similarity in the kinetics of habituation between the central and peripheral components of siphon withdrawal, we have tested the idea (52) that each centrally located mechanoreceptor sensory neuron sends two branches to siphon motor neurons; one to centrally located siphon motor neurons and a collateral branch that remains in the periphery and innervates the peripheral siphon motor neurons. 2. We have found a group of peripheral siphon motor neurons and tested the connection onto these cells by central mechanoreceptors. In addition, we have defined by various electrophysiological and morphological criteria two general classes of peripheral neurons that lie along the course of the siphon nerve. 3. One class (type I) consists of only a single cell in each animal. This peripheral neuron typically has the largest cell body found lying along the siphon nerve and is the only peripheral nerve cell that appears white when viewed under epi-illumination. The type I neuron often has a highly regular firing pattern, which occurs in the absence of spontaneous synaptic input. The three-dimensional morphology of this neuron suggests a paucity of fine processes, most of which do not arborize and may terminate in the connective tissue sheath. Fine structural observations of the peripheral white cell have revealed the presence of large densecore granules. The peripheral type I neuron is similar in most of its electrophysiological and morphological properties to central neurons postulated to be neurosecretory. The peripheral white cell is, at present, the only peripheral neuron we can identify with certainty as a unique individual. 4. The second class (type II) of peripheral neurons are siphon motor neurons for the peripheral component of the siphon-withdrawal reflex. In contrast to the type I neurons, members of the second class of peripheral neurons possess smaller, more spherical cell bodies that have varying amounts of orange pigmentation and which give rise to a relatively well-developed and arborized dendritic tree. Type II neurons feature an irregular spontaneous firing pattern that is occasionally modulated by a rich spontaneous synaptic input. Peripheral siphon motor neurons have restricted motor fields that produce contraction of the mantle floor and the base of the siphon. Most of the type II neurons were found to be electrically coupled to one another. 5. The peripheral siphon motor neurons resemble the central siphon motor neurons in that they receive a collateral synapse from centrally located mechanoreceptor sensory neurons. This peripheral sensory-to-motor synapse exhibits the same kinetics of decrement as its central counterpart, both of which parallel behavioral habituation. 6. The rich mechanoreceptor input onto the relatively isolated dendritic trees of the peripheral siphon motor neurons provide a uniquely restricted neuropil to study the sensory-to-motor synapse. The peripheral motor neurons may, therefore, be a useful simple preparation for the cellular study of behavioral plasticity.

Split spinal cord malformations in children

1998 ◽  
Vol 88 (1) ◽  
pp. 57-65 ◽  
Author(s):  
Yusuf Ersşahin ◽  
Saffet Mutluer ◽  
Sevgül Kocaman ◽  
Eren Demirtasş
Keyword(s):  
Spinal Cord ◽  
Neurological Deficits ◽  
Single Type ◽  
Type I ◽  
Type Ii ◽  
Content Type ◽  
Spinal Lesion ◽  
The Mean ◽  
Fine Print

Object. The authors reviewed and analyzed information on 74 patients with split spinal cord malformations (SSCMs) treated between January 1, 1980 and December 31, 1996 at their institution with the aim of defining and classifying the malformations according to the method of Pang, et al. Methods. Computerized tomography myelography was superior to other radiological tools in defining the type of SSCM. There were 46 girls (62%) and 28 boys (38%) ranging in age from less than 1 day to 12 years (mean 33.08 months). The mean age (43.2 months) of the patients who exhibited neurological deficits and orthopedic deformities was significantly older than those (8.2 months) without deficits (p = 0.003). Fifty-two patients had a single Type I and 18 patients a single Type II SSCM; four patients had composite SSCMs. Sixty-two patients had at least one associated spinal lesion that could lead to spinal cord tethering. After surgery, the majority of the patients remained stable and clinical improvement was observed in 18 patients. Conclusions. The classification of SSCMs proposed by Pang, et al., will eliminate the current chaos in terminology. In all SSCMs, either a rigid or a fibrous septum was found to transfix the spinal cord. There was at least one unrelated lesion that caused tethering of the spinal cord in 85% of the patients. The risk of neurological deficits resulting from SSCMs increases with the age of the patient; therefore, all patients should be surgically treated when diagnosed, especially before the development of orthopedic and neurological manifestations.

scholarly journals Catecholaminergic Fiber Innervation of the Vocal Motor System Is Intrasexually Dimorphic in a Teleost with Alternative Reproductive Tactics

2015 ◽  
Vol 86 (2) ◽  
pp. 131-144 ◽  
Author(s):  
Zachary N. Ghahramani ◽  
Miky Timothy ◽  
Gurpreet Kaur ◽  
Michelle Gorbonosov ◽  
Alena Chernenko ◽  
...  
Keyword(s):  
Motor Neurons ◽  
Motor System ◽  
Advertisement Call ◽  
Motor Nucleus ◽  
Type I ◽  
Type Ii ◽  
Fiber Density ◽  
Reproductive Tactics ◽  
Long Duration ◽  
Behavioral Divergence

Catecholamines, which include the neurotransmitters dopamine and noradrenaline, are known modulators of sensorimotor function, reproduction, and sexually motivated behaviors across vertebrates, including vocal-acoustic communication. Recently, we demonstrated robust catecholaminergic (CA) innervation throughout the vocal motor system in the plainfin midshipman fish Porichthys notatus, a seasonal breeding marine teleost that produces vocal signals for social communication. There are 2 distinct male reproductive morphs in this species: type I males establish nests and court females with a long-duration advertisement call, while type II males sneak spawn to steal fertilizations from type I males. Like females, type II males can only produce brief, agonistic, grunt type vocalizations. Here, we tested the hypothesis that intrasexual differences in the number of CA neurons and their fiber innervation patterns throughout the vocal motor pathway may provide neural substrates underlying divergence in reproductive behavior between morphs. We employed immunofluorescence (-ir) histochemistry to measure tyrosine hydroxylase (TH; a rate-limiting enzyme in catecholamine synthesis) neuron numbers in several forebrain and hindbrain nuclei as well as TH-ir fiber innervation throughout the vocal pathway in type I and type II males collected from nests during the summer reproductive season. After controlling for differences in body size, only one group of CA neurons displayed an unequivocal difference between male morphs: the extraventricular vagal-associated TH-ir neurons, located just lateral to the dimorphic vocal motor nucleus (VMN), were significantly greater in number in type II males. In addition, type II males exhibited greater TH-ir fiber density within the VMN and greater numbers of TH-ir varicosities with putative contacts on vocal motor neurons. This strong inverse relationship between the predominant vocal morphotype and the CA innervation of vocal motor neurons suggests that catecholamines may function to inhibit vocal output in midshipman. These findings support catecholamines as direct modulators of vocal behavior, and differential CA input appears reflective of social and reproductive behavioral divergence between male midshipman morphs.

Ketamine, an N -methyl-d-aspartate Receptor Antagonist, Inhibits the Spinal Neuronal Responses to Distension of the Rat Urinary Bladder

2002 ◽  
Vol 96 (6) ◽  
pp. 1410-1419 ◽  
Author(s):  
Pablo J. Castroman ◽  
Timothy J. Ness
Keyword(s):  
Spinal Cord ◽  
Urinary Bladder ◽  
Spinal Dorsal Horn ◽  
Type I ◽  
Type Ii ◽  
Neuronal Responses ◽  
Spinal Dorsal ◽  
Aspartate Receptor ◽  
Dose Dependent ◽  
Intravenous Ketamine

Background The effect of ketamine as a treatment of visceral pain is not known. The current study investigated the effect of ketamine on spinal dorsal horn neurons excited by urinary bladder distension (UBD). The effect of other clinically available N-methyl-D-aspartate receptor antagonists on these responses was also studied. Methods Extracellular recordings of neurons located in the L6-S2 spinal dorsal horn of cervical spinal cord-transected, decerebrate female rats were obtained. Cutaneous receptive fields of neuronal units excited by UBD were characterized for responses to segmental noxious and nonnoxious stimuli. Nonsegmental noxious stimuli were also applied, and neurons were classified as type I (inhibited) and type II (noninhibited) by the stimulus. The effect of intravenous ketamine (1, 3, and 10 mg/kg), dextromethorphan (5 mg/kg), and memantine (16 mg/kg) on neuronal responses of these units was measured. Results Spontaneous and evoked neuronal activity to UBD was reduced in a dose-dependent fashion by ketamine. Responses to nonnoxious cutaneous stimuli were also significantly reduced after treatment. Dextromethorphan inhibited neuronal activity evoked by UBD in type I neurons. A similar selective effect of treatment on type I versus type II neurons was observed after intravenous ketamine and memantine. Conclusions Intravenous ketamine produces dose-dependent inhibition of the spinal cord neuronal responses evoked by UBD. All three N-methyl-D-aspartate receptor antagonists showed selective effects on spinal cord neurons subject to counterirritation. This neurophysiologic evidence supports a spinally mediated analgesic effect of ketamine in this model of urinary bladder nociception, an effect likely caused by N-methyl-D-aspartate receptor antagonism.

Decompression Sickness Damaging the Spinal Cord in a Scuba Diver: Case Report

1987 ◽  
Vol 3 (2) ◽  
pp. 41-45
Author(s):  
B.G. Mathew
Keyword(s):  
Spinal Cord ◽  
Decompression Sickness ◽  
The United States ◽  
Neurological Involvement ◽  
Detailed Knowledge ◽  
Type I ◽  
Type Ii ◽  
Pulmonary Barotrauma ◽  
Emergency Personnel ◽  
Diving Accidents

Scuba diving has become a popular sport resulting in an increased incidence of diving accidents. A survey done by the United States Navy from 1955 to 1960 revealed that decompression sickness (D.C.S.) is the most common serious complication experienced by scuba divers and the third most likely cause of death. The major cause is drowning and the second is arterial gas embolism from pulmonary barotrauma.D.C.S. has been classified into two groups. Type I includes the less severe forms with bubbles in the skin (“itches”), joints and other tissues. Type II includes the serious conditions with neurological involvement “staggers.” A detailed knowledge of D.C.S., commonly known as “the bends,” is essential to both divers and emergency personnel in order to minimize the morbidity and mortality associated with this condition.A case of Type II bends with spinal cord damage is presented and the condition discussed.

scholarly journals Antioxidant Gene Expression in Vocal Hindbrain of a Teleost Fish

2018 ◽  
Author(s):  
Clara Liao ◽  
Ni Y. Feng ◽  
Andrew H. Bass
Keyword(s):  
Oxidative Stress ◽  
Breeding Season ◽  
Motor Neurons ◽  
Sound Production ◽  
Cellular Respiration ◽  
Type I ◽  
Type Ii ◽  
Antioxidant Genes ◽  
Long Duration ◽  
Significant Difference

ABSTRACTPlainfin midshipman fish (Porichthys notatus) have a remarkable capacity to generate long duration advertisement calls known as hums, each of which may last for close to two hours and be repeated throughout a night of courtship activity during the breeding season. The midshipman’s striking sound production capabilities provide a unique opportunity to investigate the mechanisms that motor neurons require for withstanding high-endurance activity. The temporal properties of midshipman vocal behaviors are largely controlled by a hindbrain central pattern generator that includes vocal motor neurons (VMN) that directly determine the activity pattern of target sonic muscles and, in turn, a sound’s pulse repetition rate, duration and pattern of amplitude modulation. Of the two adult midshipman male reproductive phenotypes -- types I and II-- only type I males acoustically court females with hums from nests that they build and guard, while type II males do not produce courtship hums but instead sneak or satellite spawn to steal fertilizations from type I males. A prior study using next generation RNA sequencing showed increased expression of a number of cellular respiration and antioxidant genes in the VMN of type I males during the breeding season, suggesting they help to combat potentially high levels of oxidative stress linked to this extreme behavior. This led to the question of whether the expression of these genes in the VMN would vary between actively humming versus non-humming states as well as between male morphs. Here, we tested the hypothesis that to combat oxidative stress, the VMN of reproductively active type I males would exhibit higher mRNA transcript levels for two superoxide dismutases (sod1,sod2) compared to the VMN of type II males and females that do not hum and in general both of which have a more limited vocal repertoire than type I males. The results showed no significant difference insod1transcript expression across reproductive morphs in the VMN and the surrounding hindbrain, and no difference ofsod2across the two male morphs and females in the SH. However, we observed a surprising, significantly lower expression ofsod2transcripts in the VMN of type I males as compared to type II males. We also found no significant difference insod1andsod2expression between actively humming and non-humming type I males in both the VMN and surrounding hindbrain. These findings overall lead us to conclude that increased transcription ofsod1andsod2is not necessary for combatting oxidative stress from the demands of the midshipman high-endurance vocalizations, but warrant future studies to assess protein levels, enzyme activity levels, as well as the expression of other antioxidant genes. These results also eliminate one of the proposed mechanisms that male midshipman use to combat potentially high levels of oxidative stress incurred by motor neurons driving long duration vocalization and provide more insight into how motor neurons are adapted to the performance of extreme behaviors.

Total Endovascular Repair With Parallel Stent-Grafts for Postdissection Thoracoabdominal Aneurysm After Prior Proximal Repair

2019 ◽  
Vol 26 (5) ◽  
pp. 668-675 ◽  
Author(s):  
Junjun Liu ◽  
Zhenjiang Li ◽  
Jiaxuan Feng ◽  
Jian Zhou ◽  
Zhiqing Zhao ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Endovascular Therapy ◽  
Endovascular Repair ◽  
Spinal Cord Ischemia ◽  
Thoracoabdominal Aortic Aneurysm ◽  
Type I ◽  
Type Ii ◽  
Technical Success ◽  
Stent Grafts

Purpose: To evaluate the safety and efficacy of total endovascular repair with parallel stent-grafts for postoperative residual dissection thoracoabdominal aortic aneurysm (TAAA). Materials and Methods: A retrospective study was undertaken of 21 patients (mean age 64.0±12.5 years; 17 men) undergoing total endovascular therapy with parallel stent-grafts for postdissection TAAA after prior proximal repair between 2014 and 2016. The preoperative minimum true lumen diameter was 12.3±4.8 mm and the mean extent of dissection was 248.1±48.2 mm. Pre-, intra-, and postoperative medical records were reviewed to assess technical success, spinal cord ischemia, patency of target branch arteries, endoleak, and short-term outcomes of this approach. Results: Technical success was achieved in 17 of 21 patients owing to 4 type I endoleaks at the end of the procedures. A total of 70 branch arteries were revascularized and 14 celiac trunks were covered intentionally without reconstruction. Of 7 intraoperative endoleaks, 2 were managed intraoperatively and 5 (4 type I and 1 type II) disappeared spontaneously within 1 month. No spinal cord or abdominal organ or limb ischemia was observed. Mean follow-up was 16.2±6.1 months. No death or type I or III endoleak occurred during the follow-up; 2 type II endoleaks were observed. Nineteen of the 21 false lumens thrombosed, and the total aortic diameter decreased (57.3±8.4 to 55.3±7.4 mm, p<0.01). Three (4.3%) of 70 target branch arteries occluded during follow-up. The cumulative patency of retrogradely and antegradely revascularized branch arteries was 97.3% vs 100% at 12 months and 91.2% vs 100% at 18 months. Conclusion: Total endovascular therapy with parallel stent-grafts could be an effective alternative in treating postdissection TAAA. Further studies with long-term follow-up and larger sample size are recommended to evaluate the technique.

Physiology of Neuronal Subtypes in the Respiratory–Vocal Integration Nucleus Retroamigualis of the Male Zebra Finch

2005 ◽  
Vol 94 (4) ◽  
pp. 2379-2390 ◽  
Author(s):  
M. F. Kubke ◽  
Y. Yazaki-Sugiyama ◽  
R. Mooney ◽  
J. M. Wild
Keyword(s):  
Motor Neurons ◽  
Zebra Finch ◽  
Synaptic Input ◽  
Cell Types ◽  
Inhibitory Input ◽  
Type I ◽  
Type Ii ◽  
Intracellular Recordings ◽  
Electrophysiological Properties ◽  
Premotor Neurons

Learned vocalizations, such as bird song, require intricate coordination of vocal and respiratory muscles. Although the neural basis for this coordination remains poorly understood, it likely includes direct synaptic interactions between respiratory premotor neurons and vocal motor neurons. In birds, as in mammals, the medullary nucleus retroambigualis (RAm) receives synaptic input from higher level respiratory and vocal control centers and projects to a variety of targets. In birds, these include vocal motor neurons in the tracheosyringeal part of the hypoglossal motor nucleus (XIIts), other respiratory premotor neurons, and expiratory motor neurons in the spinal cord. Although various cell types in RAm are distinct in their anatomical projections, their electrophysiological properties remain unknown. Furthermore, although prior studies have shown that RAm provides both excitatory and inhibitory input onto XIIts motor neurons, the identity of the cells in RAm providing either of these inputs remains to be established. To characterize the different RAm neuron types electrophysiologically, we used intracellular recordings in a zebra finch brain stem slice preparation. Based on numerous differences in intrinsic electrophysiological properties and a principal components analysis, we identified two distinct RAm neuron types (types I and II). Antidromic stimulation methods and intracellular staining revealed that type II neurons, but not type I neurons, provide bilateral synaptic input to XIIts. Paired intracellular recordings in RAm and XIIts further indicated that type II neurons with a hyperpolarization-dependent bursting phenotype are a potential source of inhibitory input to XIIts motor neurons. These results indicate that electrically distinct cell types exist in RAm, affording physiological heterogeneity that may play an important role in respiratory–vocal signaling.

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