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Brain Research Reviews Jan 2008Locomotor networks in the spinal cord are controlled by descending systems which in turn receive feedback signals from ascending systems about the state of the locomotor... (Review)
Review
Locomotor networks in the spinal cord are controlled by descending systems which in turn receive feedback signals from ascending systems about the state of the locomotor networks. In lamprey, the ascending system consists of spinobulbar neurons which convey spinal network signals to the two descending systems, the reticulospinal and vestibulospinal neurons. Previous studies showed that spinobulbar neurons consist of both ipsilaterally and contralaterally projecting cells distributed at all rostrocaudal levels of the spinal cord, though most numerous near the obex. The axons of spinobulbar neurons ascend in the ventrolateral spinal cord and brainstem to the caudal mesencephalon and within the dendritic arbors of reticulospinal and vestibulospinal neurons. Compared to mammals, the ascending system in lampreys is more direct, consisting of excitatory and inhibitory monosynaptic inputs from spinobulbar neurons to reticulospinal neurons. The spinobulbar neurons are rhythmically active during fictive locomotion, representing a wide range of timing relationships with nearby ventral root bursts including those in phase, out of phase, and active during burst transitions between opposite ventral roots. The spinobulbar neurons are not simply relay cells because they can have mutual synaptic interactions with their reticulospinal neuron targets and they can have synaptic outputs to other spinal neurons. Spinobulbar neurons not only receive locomotor inputs but also receive direct inputs from primary mechanosensory neurons. Due to the relative simplicity of the lamprey nervous system and motor control system, the spinobulbar neurons and their interactions with reticulospinal neurons may be advantageous for investigating the general organization of ascending systems in the vertebrate.
Topics: Animals; Electrophysiology; Lampreys; Locomotion; Neurons; Spinal Cord; Synapses
PubMed: 17716741
DOI: 10.1016/j.brainresrev.2007.07.010 -
Neuroscience Dec 19871. The existence of direct projections to spinal motoneurons and interneurons from the raphe pallidus and obscurus, the adjoining ventral medial reticular formation and... (Review)
Review
1. The existence of direct projections to spinal motoneurons and interneurons from the raphe pallidus and obscurus, the adjoining ventral medial reticular formation and the locus coeruleus and subcoeruleus is now well substantiated by various anatomical techniques. 2. The spinal projections from the raphe nuclei and the adjoining medial reticular formation contain serotonergic and non-serotonergic fibres. These projections also contain various peptides, several of which are contained within the serotonergic fibres. Whether still other transmitter substances (e.g. acetylcholine) are present in the various descending brainstem projections to motoneurons remains to be determined. 3. The spinal projections from the locus coeruleus and subcoeruleus are mainly noradrenergic, but there also exists a non-noradrenergic spinal projection. 4. Pharmacological, physiological and behavioural studies indicate an overall facilitatory action of noradrenaline and serotonin (including several peptides) on motoneurons. This may lead to an enhanced susceptibility for excitatory inputs from other sources. 5. The brainstem areas in question receive an important projection from several components of the limbic system. This suggests that the emotional brain can exert a powerful influence on all regions of the spinal cord and may thus control both its sensory input and motor output.
Topics: Animals; Brain Mapping; Brain Stem; Efferent Pathways; Horseradish Peroxidase; Motor Neurons; Neurotransmitter Agents; Spinal Cord
PubMed: 2893995
DOI: 10.1016/0306-4522(87)90160-6 -
The Neuroscientist : a Review Journal... Jun 2014Spontaneous activity is known to be essential for the proper formation of sensory networks in the developing CNS. This activity can be produced by a variety of... (Review)
Review
Spontaneous activity is known to be essential for the proper formation of sensory networks in the developing CNS. This activity can be produced by a variety of mechanisms including the presence of "pacemaker" neurons, which can be defined by their intrinsic ability to generate rhythmic bursts of action potential discharge. Recent work has identified pacemaker activity within lamina I of the neonatal rodent spinal cord that emerges from a complex interaction between voltage-dependent and voltage-independent ("leak") ionic conductances, including an important modulatory role for the inward-rectifying K(+) (Kir) channels. The available evidence suggests that lamina I pacemakers are glutamatergic and project extensively throughout the dorsal-ventral axis of the spinal cord, although the identity of their postsynaptic targets has yet to be elucidated. A better understanding of this connectivity could yield valuable insight into the role of the lamina I pacemaker population in the maturation of spinal circuitry underlying nociceptive processing and/or sensorimotor integration.
Topics: Animals; Biological Clocks; Neurons; Nociception; Spinal Cord; Spinal Cord Dorsal Horn
PubMed: 24510073
DOI: 10.1177/1073858414521499 -
Pediatric Radiology Dec 2010
Topics: Humans; Infant; Magnetic Resonance Imaging; Meningomyelocele; Radionuclide Imaging; Spinal Cord; Tomography, X-Ray Computed
PubMed: 20535458
DOI: 10.1007/s00247-010-1734-3 -
Biomedica : Revista Del Instituto... Jun 2018Introduction: Information about the neuroanatomical details of the ascendant transport of the rabies virus through the spinal cord is scarce. Objective: To identify the...
Introduction: Information about the neuroanatomical details of the ascendant transport of the rabies virus through the spinal cord is scarce. Objective: To identify the neuroanatomical route of dissemination of the rabies virus at each of the levels of the spinal cord of mice after being inoculated intramuscularly. Materials and methods: Mice were inoculated with the rabies virus in the hamstrings. After 24 hours post-inoculation, every eight hours, five animals were sacrificed by perfusion with paraformaldehyde. Then, the spinal cord was removed, and transverse cuts were made at the lumbosacral, thoracic, and cervical levels. These were processed by immunohistochemistry for the detection of viral antigens. Results: The first antigens of rabies were observed as aggregated particles in the lumbar spinal cord at 24 hours post-inoculation, within the ventral horn in the same side of the inoculated limb. At 32 hours post inoculation the first motoneurons immunoreactive to the virus became visible. At 40 hours postinoculation the first immunoreactive neurons were revealed in the thoracic level, located on lamina 8 and at 48 hours post-inoculation in the cervical cord, also on lamina 8. At 56 hours post-inoculation the virus had spread throughout the spinal cord, but the animals still did not show signs of the disease. Conclusion: In the mouse model we used, the rabies virus entered the spinal cord through the motoneurons and probably used the descending propriospinal pathway for its retrograde axonal transport to the encephalus.
Topics: Animals; Female; Mice; Rabies virus; Spinal Cord
PubMed: 30184349
DOI: 10.7705/biomedica.v38i0.3711 -
Journal of Morphology Dec 1986The spinal cord of two tetraodontiform fishes, the Japanese file fish (Navodon modestus) and the panther puffer (Takifugu pardalis), are unusual among vertebrates in... (Comparative Study)
Comparative Study
The spinal cord of two tetraodontiform fishes, the Japanese file fish (Navodon modestus) and the panther puffer (Takifugu pardalis), are unusual among vertebrates in having a markedly abbreviated spinal cord with a long and flattened filum terminale. Only the rostral short part of the cord of both species is cylindrical; the greater part of the cord is markedly flat. The majority of the spinal nerve roots leave the short cylindrical part. The flattened part of the cord contains the central canal, myelinated nerve fibers, and a few motoneurons surrounding the cauda equina, and it is histologically similar to the filum terminale of amphibians and mammals. The spinal cords of other teleosts, the sun-fish and angler, also are abbreviated and possess a filum terminale and cauda equina. These orders possess an enormous head and short trunk. However, the correlation between this body form and an abbreviated cord is not causal, since the tetraodontiform species described here show ordinary body proportions. The spinal cord may be abbreviated in tetraodontiform fishes in general.
Topics: Animals; Fishes; Motor Neurons; Species Specificity; Spinal Cord
PubMed: 3806684
DOI: 10.1002/jmor.1051900309 -
Journal of Nippon Medical School =... Apr 2001
Review
Topics: Evoked Potentials, Somatosensory; Humans; Ischemia; Regional Blood Flow; Spinal Cord
PubMed: 11301358
DOI: 10.1272/jnms.68.139 -
Anesthesiology Jan 1973
Topics: Spinal Cord
PubMed: 4681944
DOI: 10.1097/00000542-197301000-00001 -
Annals of the New York Academy of... Nov 1998We studied the GABAergic control of the spinal locomotor network using an isolated brain stem/spinal cord from newborn rats, in which locomotor-like activity was... (Review)
Review
We studied the GABAergic control of the spinal locomotor network using an isolated brain stem/spinal cord from newborn rats, in which locomotor-like activity was recorded. We demonstrate that endogenously released GABA controls the locomotor network, by decreasing or completely abolishing all locomotor-like activity. At first, we investigated the role played by GABA in the control of the locomotor period. By separately superfusing various compartments of the lumbar cord, we identified the targets of GABA. When bath-applied on the upper lumbar segments (L1/L2), GABA or its agonists (muscimol, baclofen) modulated the locomotor period, whereas it had no effects when bath-applied on the caudal lumbar cord (L3/L6). In the second step we studied how GABA may presynaptically control the locomotor drive arising from the locomotor network located in L1/L2. By use of the partitioned spinal cord, intracellular recordings from the caudal pool motoneurons (L4/L5) were performed, while initiating locomotor-like activity in L1/L2. We found that GABA or its agonists decreased the monosynaptic locomotor drive that the motoneurons received from the L1/L2 network, and we found a presynaptic effect exerted through the activation of GABAB receptors. In conclusion, this study emphasizes the role played by GABA at various levels in the control of the locomotor network in mammals.
Topics: Animals; Animals, Newborn; Locomotion; Motor Neurons; Neural Pathways; Rats; Spinal Cord; gamma-Aminobutyric Acid
PubMed: 9928310
DOI: 10.1111/j.1749-6632.1998.tb09047.x -
Neuroradiology 1988The antero-posterior movement of the spinal cord with flexion and extension of the neck was analyzed in order to clarify the mechanism of spinal cord compression in...
The antero-posterior movement of the spinal cord with flexion and extension of the neck was analyzed in order to clarify the mechanism of spinal cord compression in cases with postoperative spinal deformity, and to contribute to the improvement of the surgical methods of conventional laminectomy. The control subjects were 47 cases without cervico-thoracic neurological symptoms, who underwent CT myelography in flexion and extension of the neck; the cervical spinal cord was examined in 27 of these cases and the thoracic cord in the other 20. CT myelography was also carried out in 16 patients with cervical myelopathy and in 5 patients after posterior decompression surgery (suspension laminotomy). CT sections in flexion and extension of the neck were analyzed for 1) change of configuration of the dura mater and the spinal cord, and 2) antero-posterior shift of the spinal cord in the subarachnoid space. In the control subjects, the configuration of the dura mater was slightly flattened at C5/6, C6 and C6/7 in extension of the neck. The cervical spinal cord shifted anteriorly in flexion and posteriorly in extension of the neck, and was flattened at the midcervical level in flexion in the control subjects. There was a statistically significant correlation between the location of the spinal cord and the adjacent intervertebral angles at the levels of C4, C5 and C6. These results were compared with the results from the 16 patients with cervical myelopathy and 5 patients after suspension laminotomy.(ABSTRACT TRUNCATED AT 250 WORDS)
Topics: Adult; Aged; Female; Humans; Laminectomy; Male; Middle Aged; Movement; Spinal Cord; Spinal Cord Diseases; Spine; Tomography, X-Ray Computed
PubMed: 3226542
DOI: 10.1007/BF00339697