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 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.

Effects of reversible blockade of basal ganglia on a voluntary arm movement

1992 ◽  
Vol 68 (5) ◽  
pp. 1516-1534 ◽  
Author(s):  
M. Kato ◽  
M. Kimura
Keyword(s):  
Basal Ganglia ◽  
Elbow Joint ◽  
Dynamic Control ◽  
Arm Movement ◽  
Gamma Aminobutyric Acid ◽  
Tonic Activity ◽  
Visually Guided ◽  
Holding Period ◽  
Antagonist Muscles ◽  
Agonist And Antagonist

1. The effects of a reversible blockade of basal ganglia were examined in two monkeys trained to perform a visually guided, step-tracking arm movement around the elbow joint. To block glutamatergic excitation, kynurenate (a glutamate antagonist) was locally injected into the putamen and the external segment (GPe) and the internal segment (GPi) of the globus pallidus contralateral to the arm tested. Muscimol [a gamma-aminobutyric acid (GABA) agonist] was also used to suppress neuronal activity in these structures. The drugs were injected in the arm area of the putamen, which was identified by microstimulation or by recording neural activity. For the GPe and GPi, injections were made into the area medioventral to the arm area of the putamen. 2. The blockade of the putamen caused abnormal braking of the arm movements. The first step of the movement became hypometric, and multiple steps were necessary to reach the target. The electromyographic (EMG) analysis revealed an increase of burst activity in the antagonist muscles and a decrease of that in the agonist muscles at the fast movements. The tonic activity increased in the extensor muscles during a holding period. 3. The blockade of the GPi caused dysmetric movements. Amplitude and peak velocity of the first step of movement largely fluctuated among trials. It became difficult for the animal to brake and adjust its arm onto the target. 4. The blockade of the GPe caused a flexion posture at the elbow joint of the contralateral arm. The tonic activity of the flexor muscles increased. Cocontraction of the agonist and antagonist muscles was also observed. 5. These results suggest that the putaminopallidal system of the basal ganglia contributes to both of two motor functions: 1) static control to maintain the posture with tonic muscle activity, and 2) dynamic control to enable fast movements.

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.

Neck Muscle Responses to Stimulation of Monkey Superior Colliculus. II. Gaze Shift Initiation and Volitional Head Movements

2002 ◽  
Vol 88 (4) ◽  
pp. 2000-2018 ◽  
Author(s):  
Brian D. Corneil ◽  
Etienne Olivier ◽  
Douglas P. Munoz
Keyword(s):  
Superior Colliculus ◽  
Neck Muscles ◽  
Head Movements ◽  
Emg Activity ◽  
Neck Muscle ◽  
Gaze Shift ◽  
Antagonist Muscles ◽  
Agonist And Antagonist ◽  
Agonist And Antagonist Muscles ◽  
Stimulation Of

We report neck muscle activity and head movements evoked by electrical stimulation of the superior colliculus (SC) in head-unrestrained monkeys. Recording neck electromyography (EMG) circumvents complications arising from the head's inertia and the kinetics of muscle force generation and allows precise assessment of the neuromuscular drive to the head plant. This study served two main purposes. First, we sought to test the predictions made in the companion paper of a parallel drive from the SC onto neck muscles. Low-current, long-duration stimulation evoked both neck EMG responses and head movements either without or prior to gaze shifts, testifying to a SC drive to neck muscles that is independent of gaze-shift initiation. However, gaze-shift initiation was linked to a transient additional EMG response and head acceleration, confirming the presence of a SC drive to neck muscles that is dependent on gaze-shift initiation. We forward a conceptual neural architecture and suggest that this parallel drive provides the oculomotor system with the flexibility to orient the eyes and head independently or together, depending on the behavioral context. Second, we compared the EMG responses evoked by SC stimulation to those that accompanied volitional head movements. We found characteristic features in the underlying pattern of evoked neck EMG that were not observed during volitional head movements in spite of the seemingly natural kinematics of evoked head movements. These features included reciprocal patterning of EMG activity on the agonist and antagonist muscles during stimulation, a poststimulation increase in the activity of antagonist muscles, and synchronously evoked responses on agonist and antagonist muscles regardless of initial horizontal head position. These results demonstrate that the electrically evoked SC drive to the head cannot be considered as a neural replicate of the SC drive during volitional head movements and place important new constraints on the interpretation of electrically evoked head movements.

Selective Neurotomy of the Tibial Nerve for Treatment of the Spastic Foot

Neurosurgery ◽  
1988 ◽  
Vol 23 (6) ◽  
pp. 738-744 ◽  
Author(s):  
Marc Sindou ◽  
Patrick Mertens
Keyword(s):  
Tibial Nerve ◽  
Complete Suppression ◽  
Nerve Branch ◽  
Beneficial Effects ◽  
Antagonist Muscles ◽  
Abnormal Posture ◽  
Total Pain ◽  
Agonist And Antagonist ◽  
Selective Neurotomy

Abstract One of the most frequent neurological sequelae seen by the specialist in rehabilitation is the spastic foot. Spasticity in the foot may be responsible for abnormal posture and painful or trophic disturbances impairing standing and walking. This disability can be corrected by a simple neurosurgical procedure, the selective tibial neurotomy. In this procedure, one sections the tibial nerve branches to the muscles sustaining spasticity, i.e, the soleus and/or the gastrocnemius nerves for equinus and ankle clonus or the posterior tibialis branch for varus and the flexor fascicles for tonic flexion of the toes. After microsurgical dissection of each tibial nerve branch at the lower part of the popliteal region and their identification with bipolar electrostimulation, the selected branches are partially sectioned under the operating microscope. The present series consists of 62 operations performed in 53 patients, 9 bilaterally and 44 unilaterally. Operation obtained complete suppression of the disabling spasticity that had been present for 2 to 17 years (4 on average), total pain relief, and consequently improvement of the residual voluntary movements (by achieving a better balance between agonist and antagonist muscles) in 51 of the 62 spastic feet (i.e., 82% of the cases). For all of these patients, the beneficial effects were long-lasting over the 1- to 10-year follow-up (3 years on average). Selective neurotomy of the tibial nerve should be considered only after failure of intensive prolonged kinestherapy and of all available medical treatment. It must take place, however, before the onset of irreversible articular disturbances and musculotendinous retractions, which require complementary orthopedic corrections.

Effect of the phase of force production on corticomuscular coherence with agonist and antagonist muscles

2018 ◽  
Vol 48 (10) ◽  
pp. 3288-3298 ◽  
Author(s):  
Gauthier Desmyttere ◽  
Emilie Mathieu ◽  
Mickael Begon ◽  
Emilie Simoneau‐Buessinger ◽  
Sylvain Cremoux
Keyword(s):  
Force Production ◽  
Corticomuscular Coherence ◽  
Antagonist Muscles ◽  
Agonist And Antagonist ◽  
Agonist And Antagonist Muscles

Tonic drive to sympathetic premotor neurons of rostral ventrolateral medulla from caudal pressor area neurons

1999 ◽  
Vol 276 (4) ◽  
pp. R1209-R1213 ◽  
Author(s):  
R. R. Campos ◽  
R. M. McAllen
Keyword(s):  
Blood Pressure ◽  
Significant Proportion ◽  
Rostral Ventrolateral Medulla ◽  
Ventrolateral Medulla ◽  
Cervical Cord ◽  
Neuron Activity ◽  
Tonic Activity ◽  
Premotor Neurons ◽  
Sympathetic Premotor Neurons ◽  
Caudal Pressor

The responses of sympathetic premotor neurons in the rostral ventrolateral medulla (RVLM) to activation or inactivation of neurons in the caudal pressor area (CPA) were studied in urethan-anesthetized rats. Extracellular recordings were made from 32 barosensitive single units in the RVLM, of which 26 were antidromically activated from the cervical cord. Unilateral microinjections ofl-glutamate (0.5–5 nmol) into the CPA increased firing in 13 of 14 premotor neurons by 90 ± 30% while raising blood pressure. Both ipsilateral and contralateral injections were effective. Unilateral or bilateral inhibition of CPA neuron activity by microinjecting glycine (5–200 nmol/side) lowered blood pressure, while it reduced firing in 9 of 10 and 16 of 17 premotor neurons, respectively, by 45 ± 9 and 39 ± 6%. A significant proportion of tonic activity in RVLM sympathetic premotor neurons is thus driven, directly or indirectly, by neurons in the CPA.

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