scholarly journals Broadly Tuned Spinal Neurons for Each Form of Fictive Scratching in Spinal Turtles

2001 ◽  
Vol 86 (2) ◽  
pp. 1017-1025 ◽  
Author(s):  
Ari Berkowitz
Keyword(s):  
Spinal Cord ◽  
Gray Matter ◽  
Body Surface ◽  
The Body ◽  
Spinal Neurons ◽  
Behavioral Choice ◽  
Spinal Cord Segment ◽  
Single Animal ◽  
Large Populations ◽  
Propriospinal Neurons

Behavioral choice can be mediated either by a small number of sharply tuned neurons or by large populations of broadly tuned neurons. This issue can be conveniently examined in the turtle spinal cord, which generates each of three forms of scratching—rostral, pocket, and caudal—in response to mechanical stimulation in each of three adjacent regions of the body surface. Previous research showed that many propriospinal neurons are broadly tuned to either the rostral scratch region or the pocket scratch region, but responses to caudal scratch stimulation could not be examined in that reduced preparation. In the current study, individual spinal neurons were recorded extracellularly from the gray matter of the turtle spinal cord hindlimb enlargement, while sites in the rostral, pocket, and caudal scratch regions were mechanically stimulated. Many neurons were broadly tuned to the caudal scratch region; other neurons were broadly tuned to either the pocket scratch or rostral scratch region. All three types were typically found within a single animal. These data are consistent with the hypothesis that the turtle spinal cord relies on large populations of broadly tuned neurons to select each of the three forms of scratching. In addition, neurons that were broadly tuned to each of the scratch regions were typically found in each spinal cord segment and within the same range of mediolateral and dorsoventral locations. Providing that these neurons are related to the selection and generation of the three forms of scratching, this would indicate that cells of this type are not segregated into distinct regions of the spinal cord gray matter.

Rhythmicity of Spinal Neurons Activated During Each Form of Fictive Scratching in Spinal Turtles

2001 ◽  
Vol 86 (2) ◽  
pp. 1026-1036 ◽  
Author(s):  
Ari Berkowitz
Keyword(s):  
Gray Matter ◽  
Body Surface ◽  
Activity Cycle ◽  
The Body ◽  
Circular Statistics ◽  
Spinal Neurons ◽  
Active Neuron ◽  
Spinal Interneurons ◽  
Hip Flexor ◽  
Phase Preference

Are behaviors that rely on common muscles and motoneurons generated by separate or overlapping groups of pattern-generating neurons? This question was investigated for the three forms of scratching in immobilized, spinal turtles. Individual neurons were recorded extracellularly from the gray matter through most of the spinal cord hindlimb enlargement gray matter, but were avoided in the region of motoneuron cell bodies. Each form of fictive scratching was elicited by mechanical stimulation of the body surface. The rhythmic modulation of spinal neurons was assessed using phase histograms and circular statistics. The degree of rhythmic modulation and the phase preference of each rhythmically active neuron were measured with respect to the activity cycle of the ipsilateral hip flexor nerve. The action potentials of rhythmic neurons tended to be concentrated in a particular phase of the ipsilateral hip flexor activity cycle no matter which form of fictive scratching was elicited. This consistent phase preference suggests that some of these neurons may contribute to generation of the hip rhythm for all three forms of scratching, strengthening the case that vertebrate pattern-generating circuitry for distinct behaviors can be overlapping. The degree of rhythmic modulation of each unit during fictive scratching was consistently correlated with the dorsoventral location of the recording, but not with the mediolateral or rostrocaudal location; neurons located more ventrally tended to be more rhythmic. The phase preferences of units were related to the region of the body surface to which each neuron responded maximally (i.e., the region to which each unit was broadly tuned). Units tuned to the rostral scratch or pocket scratch region tended to have a phase preference during ipsilateral hip flexor activity, whereas units tuned to the caudal scratch region did not. This suggests the hypothesis that the hip flexes further during rostral and pocket scratching, and extends further during caudal scratching, due to the net effects of a population of spinal interneurons that are both broadly tuned and rhythmically active.

scholarly journals EA Improves the Motor Function in Rats with Spinal Cord Injury by Inhibiting Signal Transduction of Semaphorin3A and Upregulating of the Peripheral Nerve Networks

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Rong Hu ◽  
Haipeng Xu ◽  
Yaheng Jiang ◽  
Yi Chen ◽  
Kelin He ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Peripheral Nerve ◽  
Motor Function ◽  
Gray Matter ◽  
Ventral Horn ◽  
Damage Site ◽  
Central Tube ◽  
Spinal Cord Segment ◽  
Cord Injury

Peripheral nerve networks (PNNs) play a vital role in the neural recovery after spinal cord injury (SCI). Electroacupuncture (EA), as an alternative medicine, has been widely used in SCI and was proven to be effective on neural functional recovery. In this study, the interaction between PNNs and semaphrin3A (Sema3A) in the recovery of the motor function after SCI was observed, and the effect of EA on them was evaluated. After the establishment of the SCI animal model, we found that motor neurons in the ventral horn of the injured spinal cord segment decreased, Nissl bodies were blurry, and PNNs and Sema3A as well as its receptor neuropilin1 (NRP1) aggregated around the central tube of the gray matter of the spinal cord. When we knocked down the expression of Sema3A at the damage site, NRP1 also downregulated, importantly, PNNs concentration decreased, and tenascin-R (TN-R) and aggrecan were also reduced, while the Basso-Beattie-Bresnahan (BBB) motor function score dramatically increased. In addition, when conducting EA stimulation on Jiaji (EX-B2) acupoints, the highly upregulated Sema3A and NRP1 were reversed post-SCI, which can lessen the accumulation of PNNs around the central tube of the spinal cord gray matter, and simultaneously promote the recovery of motor function in rats. These results suggest that EA may further affect the plasticity of PNNs by regulating the Sema3A signal and promoting the recovery of the motor function post-SCI.

scholarly journals Proximal and distal spinal neurons innervating multiple synergist and antagonist motor pools

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Remi Ronzano ◽  
Camille Lancelin ◽  
Gardave Singh Bhumbra ◽  
Robert M Brownstone ◽  
Marco Beato
Keyword(s):  
Spinal Cord ◽  
Ankle Joint ◽  
Rabies Virus ◽  
Cervical Cord ◽  
Spinal Neurons ◽  
Antagonist Muscles ◽  
Premotor Neurons ◽  
Virus Tracing ◽  
Propriospinal Neurons ◽  
Descending Propriospinal Neurons

Motoneurons control muscle contractions, and their recruitment by premotor circuits is tuned to produce accurate motor behaviours. To understand how these circuits coordinate movement across and between joints, it is necessary to understand whether spinal neurons pre-synaptic to motor pools have divergent projections to more than one motoneuron population. Here, we used modified rabies virus tracing in mice to investigate premotor INs projecting to synergist flexor or extensor motoneurons, as well as those projecting to antagonist pairs of muscles controlling the ankle joint. We show that similar proportions of premotor neurons diverge to synergist and antagonist motor pools. Divergent premotor neurons were seen throughout the spinal cord, with decreasing numbers but increasing proportion with distance from the hindlimb enlargement. In the cervical cord, divergent long descending propriospinal neurons were found in contralateral lamina VIII, had large somata, were neither glycinergic, nor cholinergic, and projected to both lumbar and cervical motoneurons. We conclude that distributed spinal premotor neurons coordinate activity across multiple motor pools and that there are spinal neurons mediating co-contraction of antagonist muscles.

Visceral and somatic afferent convergence onto neurons near the central canal in the sacral spinal cord of the cat

1985 ◽  
Vol 53 (4) ◽  
pp. 1059-1078 ◽  
Author(s):  
C. N. Honda
Keyword(s):  
Spinal Cord ◽  
Gray Matter ◽  
Receptive Fields ◽  
Central Canal ◽  
The Body ◽  
Wide Range ◽  
Pelvic Viscera ◽  
Somatic Receptive Fields ◽  
Sacral Spinal Cord ◽  
Stimulation Of

One hundred and sixty extracellularly and intracellularly recorded unitary discharges from the sacral or caudal spinal segments of 30 anemically decerebrated cats were studied to examine the effects of somatic and visceral afferent stimulation on neurons near the central canal (CC). The recorded unitary activity was histologically verified (by dye marks or horseradish peroxidase, HRP) as having come from the gray matter surrounding the CC that approximates Rexed's lamina X. In the absence of intentional stimulation or apparent injury by the recording electrode, 62% of the units exhibited ongoing discharges. Each unit was tested for responses to the stimulation of somatic (cutaneous and subcutaneous) and visceral (bladder and colon) structures. Seventy-six (48%) of the units responded exclusively to the stimulation of somatic receptive fields, and 10 (6%) of the units were selectively responsive to stimulation of the pelvic viscera. The activity of the remaining 74 (46%) was influenced by activity in both somatic and visceral afferent fibers. Eighteen of the 160 neurons were intracellularly marked with HRP. Based on perikaryal size and dendritic extent, it was possible to divide these cells into two partially overlapping groups. One group consisted of seven neurons with small to medium-sized perikarya, dendritic arbors largely restricted to the gray matter surrounding the CC, and small, singular somatic receptive fields. The second group comprised 11 cells with medium to large-sized soma and dendrites extending out of lamina X. These larger neurons usually possessed multiple, widely distributed somatic receptive fields. The principal finding of the present study is that in the sacral spinal cord many cells near the CC receive primary afferent inputs converging from a wide range of receptor types in somatic and visceral structures. Such neurons are capable of integrating afferent information from somatic structures on both sides of the body with information originating in pelvic viscera and midline regions such as the genitals.

scholarly journals FETAL ANATOMY OF THE HUMAN SPINAL CORD

2020 ◽  
Vol 19 (3) ◽  
pp. 5-12
Author(s):  
V. Shkolnikov
Keyword(s):  
Spinal Cord ◽  
White Matter ◽  
Glial Cells ◽  
Motor Neurons ◽  
Gray Matter ◽  
The Body ◽  
Diagnostic Methods ◽  
Large Area ◽  
Intrauterine Development ◽  
Human Spinal Cord

Due to the development and improvement of medical technologies and diagnostic methods, in recent years, the interest of neuromorphologists, neuropathologists, neurosurgeons and reproductive specialists in the histogenesis of the structures of the central nervous system, in particular, the spinal cord, has increased. In the process of macro- and microscopic examination of the spinal cord of human fetuses of 20-21 weeks of intrauterine development, the topography of the thickenings in relation to the parts of the spinal column was established according to our own method, the morphometric parameters of the structures of the spinal cord segments and the regularities of cytoarchitectonics were determined. In 20-21 week old fetuses, the ratio of the length of the spine to the parietococcygeal length of the fetus is 65.0%, and the ratio of the length of the spinal cord to the parietococcygeal length of the fetus is 54.0 %. The border between the cervical and thoracic spine is projected onto a conditional line that connects the spine of the scapula. The border between the thoracic and lumbar regions of the spine is the line between the upper three quarters and the lower one quarter of the body length. The border between the lumbar and sacral parts runs along a conventionally drawn line that connects the posterior lower iliac spines, and the border of the transition of the sacral to the coccygeal is the level of the lower third of the gluteal region. The structure of the gray matter of the spinal cord segments in this age period corresponds to that in people of mature age – the presence of anterior, lateral and posterior horns. A large area of gray matter is observed in the cervical and lumbar segments, a smaller area in the thoracic and sacral segments. The structuredness of the white matter of the spinal cord segments in this age period corresponds to that in adults – the presence of anterior, lateral and posterior cords. The cervical and lumbar segments have a large area of white matter, and in magnitude they are the same. The nuclei of radial glial cells are relatively equal in size in all segments. The thickness of the matrix layer varies throughout the entire spinal cord, but reaches its greatest size in the ventral parts. The sizes of the nuclei of neuroblasts also fluctuate: the nuclei of motor neurons have large sizes, and the smaller ones are inserted and vegetative. The nuclei of glial cells have relatively identical sizes of different segments of the spinal cord, but 2-3 times less than the nuclei of neuroblasts.

Changes in responses of medial pontomedullary reticular neurons during repetitive cutaneous, vestibular, cortical, and tectal stimulation

1976 ◽  
Vol 39 (3) ◽  
pp. 564-581 ◽  
Author(s):  
B. W. Peterson ◽  
J. I. Franck ◽  
N. G. Daunton
Keyword(s):  
Spinal Cord ◽  
Superior Colliculus ◽  
Body Surface ◽  
Repetitive Stimulation ◽  
The Body ◽  
Response Decrement ◽  
Afferent Pathways ◽  
Stimulus Rate ◽  
Reticular Neurons ◽  
Stimulation Of

1. In cats anesthetized with chloralose, responses of medial pontomedullary reticular neurons to stimulation of the body surface, vestibular nerves, superior colliculi, pericruciate cortices, cerebral peduncles, and spinal cord were studied at different stimulus rates. Raising the rate from 1/10 s to between 1/4 s and 2/s caused a significant decrement or increment in the response of most neurons tested. Response decrement typically began near the beginning of the higher frequency stimulus sequence and increased throughout the sequence. Response increment usually began somewhat later, rose to a peak, and then declined. Recovery from response decrement or increment usually occurred within 30-60 s at a 1/10 s stimulus rate.2. Measurements of response latency and of changes occurring in the initial and longer latency portions of responses indicated that all components of a response typically decreased or increased in parallel. Background spontaneous activity did not change during response decrements, but sometimes increased during response increment.3. Where changes could be detected, response decrement usually developed more rapidly when a sequence of repetitive stimulation was repeated.4. Response decrement was most pronounced at the highest stimulation rates and lowest stimulus intensities. Response increment was usually maximal at a stimulus rate of 1/s: at lower rates less increment occurred; at higher rates responses began to exhibit decrement.5. Response changes varied with the type of stimulus applied. Response decrements predominated when the body surface, vestibular nerves, or ipsilateral superior colliculus were stimulated. Approximately equal amounts of response increment and decrement were produced by repetitive stimulation of the cerebral peduncles and contralateral superior colliculus. Stimulation of the surface of the pericruciate cortex or of the spinal cord usually produced a long-lasting response increment.6. Generalization of response decrement and increment was observed in cases where trains of stimuli at a rate of 2/s applied to one point produced changes in the response to stimulation of another point which was tested once per 10 s and where single-shock stimulation of the first point was without effect on the test response. Generalization of response decrement occurred most often when two nearby points were stimulated. Generalization of response increment appeared to spread widely between distant cutaneous points and stimuli of different kinds.7. The response decrement and increment observed in medial pontomedullary reticular neurons displayed most of the parametric features of behavioral habituation and sensitization (8, 33) and therefore appear to represent neural analogs of these latter phenomena. The properties of response decrement suggest that it may occur to a large extent within afferent pathways leading to medial reticular neurons...

Multiple axon collaterals of single corticospinal axons in the cat spinal cord

1986 ◽  
Vol 55 (3) ◽  
pp. 425-448 ◽  
Author(s):  
Y. Shinoda ◽  
T. Yamaguchi ◽  
T. Futami
Keyword(s):  
Spinal Cord ◽  
Motor Cortex ◽  
Gray Matter ◽  
Cervical Spinal Cord ◽  
Cervical Cord ◽  
Antidromic Activation ◽  
Axon Collaterals ◽  
Thoracic Cord ◽  
Propriospinal Neurons ◽  
Caudal Level

To investigate intraspinal branching patterns of single corticospinal neurons (CSNs), we recorded extracellular spike activities from cell bodies of 408 CSNs in the motor cortex in anesthetized cats and mapped the distribution of effective stimulating sites for antidromic activation of their terminal branches in the spinal gray matter. To search for all spinal axon branches belonging to single CSNs in the "forelimb area" of the motor cortex, we microstimulated the gray matter from the dorsal to the ventral border at 100-micron intervals at an intensity of 150-250 microA and systematically mapped effective stimulating penetrations at 1-mm intervals rostrocaudally from C3 to the most caudal level of their axons. From the depth-threshold curves, the comparison of the antidromic latencies of spikes evoked from the gray matter and the lateral funiculus, and the calculated conduction times of the collaterals, we could ascertain that axon collaterals were stimulated in the gray matter rather than stem axons in the corticospinal tract due to current spread. Virtually all CSNs examined in the forelimb area of the motor cortex had three to seven branches at widely separated segments of the cervical and the higher thoracic cord. In addition to terminating at the brachial segments, they had one to three collaterals to the upper cervical cord (C3-C4), where the propriospinal neurons projecting to forelimb motoneurons are located. About three quarters of these CSNs had two to four collaterals in C6-T1. This finding held true for both fast and slow CSNs. About one third of the CSNs in the forelimb area of the motor cortex projected to the thoracic cord below T3. These CSNs also sent axon collaterals to the cervical spinal cord. CSNs in the "hindlimb area" of the motor cortex had three to five axon branches in the lumbosacral cord. These branches were mainly observed at L4 and the lower lumbosacral cord. None of these CSNs had axon collaterals in the cervical cord. CSNs terminating at different segments of the cervical and the thoracic cord were distributed in a wide area of the motor cortex and were intermingled. To determine the detailed trajectory of single axon branches, microstimulation was made at a matrix of points of 100 or 200 micron at the maximum intensity of 30 microA, and their axonal trajectory was reconstructed on the basis of the location of low-threshold foci and the latency of antidromic spikes.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Neuroscan of Normal and Abnormal Vertebrae and Spinal Cord

2008 ◽  
Vol 2 (3) ◽  
pp. 9-18
Author(s):  
Ritsuko K Pooh
Keyword(s):  
Spinal Cord ◽  
Vertebral Body ◽  
Vertebral Column ◽  
Spinous Process ◽  
The Body ◽  
Spinal Nerves ◽  
Spinal Cord Segment ◽  
Relationship Of ◽  
The Relationship ◽  
Vertebral Arch

Abstract The vertebral body, neural arch and its processes develop from the sclerotome of the primitive mesodermal segments. After chondrification, separate ossification centres appear for the body and one for each of the neural arches. Vertebrae are composed of a body and a vertebral arch. The vertebral foramina, which consist of the vertebral arch and back of vertebral body, form the vertebral canal including and protecting the spinal cord. The vertebral arches are formed by two pedicles and two laminae which unite as a spinous process. Relation between the vertebrae and spinal cord during pregnancy is interesting. In embryonal period, the CNS develops earlier than other part of embryonal structures and occupies approximately one third of the whole embryonal body. At the 3rd month of development the length of the spinal cord equals that of the vertebral column. The spinal nerves and the relationship of the spinal nerves to the vertebra are established. Therefore the spinal cord segment is at the same level as the corresponding vertebral level. In subsequent fetal period, however, fetal body structure including vertebral column develops faster than the neural tube. As the consequence of this different development of the column and nerves, caudal end of the spinal cord within the vertebral column relatively moves upward with advancing gestation and reaches to the level of the third lumber vertebra at birth.

The terminations of single, physiologically identified, somatosensory, corticospinal tract axons in the lumbar spinal cord of the cat

1991 ◽  
Vol 66 (5) ◽  
pp. 1738-1749 ◽  
Author(s):  
E. J. Casale ◽  
A. R. Light
Keyword(s):  
Spinal Cord ◽  
Gray Matter ◽  
Corticospinal Tract ◽  
Lumbar Spinal Cord ◽  
Spinal Cord Segment ◽  
Apparent Correlation ◽  
Dorsolateral Funiculus ◽  
The Mean ◽  
Lumbar Spinal ◽  
Area 3B

1. Two hundred and twelve corticospinal axons were identified by stimulation in the hindlimb representation in area 3b of the somatosensory cortex and were recorded in the left dorsolateral funiculus of the spinal cord of the cat. The mean conduction velocity was 38 m/s, range 9-113 m/s. 2. Electrical stimulation of the receptive field evoked discharge in corticospinal axons with a mean latency of 36 ms (range 9-100 ms). 3. One hundred nine of the 212 recorded axons were successfully intra-axonally labeled by iontophoretic injection of horseradish peroxidase, with the mean length of labeled axon being 4.8 mm. Seventy-three of the labeled axons issued no collaterals, and 36 issued at least one labeled collateral into the spinal gray matter along the labeled portion of the parent axon. 4. Most labeled axons issued only one labeled collateral per spinal cord segment. Fourteen collaterals from 10 units were labeled well enough to permit reconstruction of their terminal arborizations. 5. Most terminal collaterals were oriented rostrocaudally and terminated in laminae V, VI, and VII. Most collaterals terminated within large mediolateral extents of the gray matter with no apparent topographic organization. 6. No collaterals terminated in laminae I or II or within the motoneuron pools, and no apparent correlation was found between their anatomic and physiological characteristics.

scholarly journals Etiology and Pathophysiology of the Spina Bifida

2021 ◽  
Author(s):  
René Opšenák ◽  
Romana Richterová ◽  
Branislav Kolarovszki
Keyword(s):  
Congenital Anomaly ◽  
Spinal Cord ◽  
Environmental Factors ◽  
Spina Bifida ◽  
Body Surface ◽  
Lifetime Cost ◽  
Spinal Dysraphism ◽  
The Body ◽  
Neurological Effects ◽  
Open Spina Bifida

The spina bifida is a congenital anomaly that results in an abnormal formation of the spine and the spinal cord. The two dominant types of spinal dysraphism are based on appearance - open spina bifida if the lesion is visible and closed spina bifida if the lesion is not visible on the body surface. These conditions lead to a different spectrum of neurological effects according to the degree of neurulation disruption. The prevalence of neural tube defects has different rates among different ethnicity, geography, gender, and countries. Genetic, nutritional and environmental factors play a role in the etiology and pathogenesis of the spina bifida. Congenital anomalies in the vast majority concern children living in the early neonatal period who have important medical, social or educational needs. The lifetime cost of a child born with the spina bifida is estimated at over €500,000.

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