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.

scholarly journals Spinal neurons innervating multiple local and distant motor pools

2021 ◽  
Author(s):  
Remi Ronzano ◽  
Camille Lancelin ◽  
Gardave Singh Bhumbra ◽  
Robert M Brownstone ◽  
Marco Beato
Keyword(s):  
Motor Neurons ◽  
Cervical Cord ◽  
Spinal Neurons ◽  
Neuron Population ◽  
Antagonist Muscles ◽  
Premotor Neurons ◽  
Agonist And Antagonist ◽  
Virus Tracing ◽  
Propriospinal Neurons ◽  
Descending Propriospinal Neurons

Motor neurons 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, project to more than one motor neuron population. Here, we used modified rabies virus tracing in mice to investigate premotor INs projecting to synergist flexor or extensor motor neurons, as well as those projecting to antagonist pairs of muscles controlling the ankle joint. We show that similar proportions of premotor neurons diverge to agonist 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 excitatory, projected to both lumbar and cervical motoneurons, and were at least in part of the V0 class. 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.

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.

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 Arrow-Shot Injury to Pediatric Spinal Cord

2021 ◽  
Author(s):  
Vijayveer Singh ◽  
Sharad Thanvi
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injuries ◽  
Pediatric Population ◽  
Cervical Region ◽  
Cervical Cord ◽  
Cord Injury ◽  
Dural Suturing ◽  
Stab Injuries ◽  
Early Surgical Intervention

AbstractPenetrating spinal cord injuries (PSCI) in cervical region are extremely rare in pediatric population. Most injuries in pediatric population are accidental due to gunshot or a stab injury with a sharp or pointed object. Gun shots may result into a severe wound which is usually fatal and may result in death, quadriplegia, or serious long-term disability. Stab injuries are less severe and may result in neurological sequalae. In this paper, an unusual case of pediatric arrow shot partial cervical cord injury is reported which was managed by aggressive neurosurgical management. The arrow lodged in the cervical cord was very near to the vertebral artery leading to parapariesis which recovered well without any complications. Diagnostic imaging at admission included radiographs, computed tomography (CT), and CT angiography of the cervical region. The patient underwent early surgical intervention with removal of foreign body from the cord and subsequent dural suturing.

Responses of interneurons in the cat cervical cord to vestibular tilt stimulation

1986 ◽  
Vol 56 (4) ◽  
pp. 1147-1156 ◽  
Author(s):  
R. H. Schor ◽  
I. Suzuki ◽  
S. J. Timerick ◽  
V. J. Wilson
Keyword(s):  
Cervical Spinal Cord ◽  
Semicircular Canals ◽  
Body Tilt ◽  
Whole Body ◽  
Cervical Cord ◽  
Otolith Organs ◽  
Phase Lag ◽  
Response Dynamics ◽  
Decerebrate Cat ◽  
Propriospinal Neurons

The responses of interneurons in the cervical spinal cord of the decerebrate cat to whole-body tilt were studied with a goal of identifying spinal elements in the production of forelimb vestibular postural reflexes. Interneurons both in the cervical enlargement and at higher levels, from which propriospinal neurons have been identified, were examined, both in animals with intact labyrinths and in animals with nonfunctional semicircular canals (canal plugged). Most cervical interneurons responding to tilt respond best to rotations in vertical planes aligned within 30 degrees of the roll plane. Two to three times as many neurons are excited by side-up roll tilt as are excited by side-down roll. In cats with intact labyrinths, most responses have dynamics proportional either to (and in phase with) the position of the animal or to a sum of position and tilt velocity. This is consistent with input from both otolith organs and semicircular canals. In animals without functioning canals, the "velocity" response is absent. In a few cells (8 out of 76), a more complex response, characterized by an increasing gain and progressive phase lag, was observed. These response dynamics characterize the forelimb reflex in canal-plugged cats and have been previously observed in vestibular neurons in such preparations.

Sign in / Sign up

Export Citation Format

Share Document