Movement is governed by rotational population dynamics in spinal motor networks

Abstract Although the nervous system is elegantly orchestrating movements, the underlying neural principles remain unclear. Since flexor- and extensor-muscles alternate during movements like walking, it is often assumed that the responsible neural circuitry is similarly alternating in opposition. Here, we present ensemble recordings of neurons in the lumbar spinal cord that indicate that, rather than alternation, the population is performing a "rotation" in neural space, i.e. the neural activity is cycling through all phases continuously during the rhythmic behavior. The radius of rotation correlates with the intended muscle force. Since existing models of spinal motor control offer an inadequate explanation of rotation, we propose a new theory of neural generation of movement from which this and other unresolved issues, such as speed regulation, force control, and multi-functionalism, are conveniently explained.

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Movement is governed by rotational population dynamics in spinal motor networks

10.1101/2021.08.31.458405 ◽

2021 ◽

Author(s):

Henrik Lindén ◽

P. C. Petersen ◽

M. Vestergaard ◽

Rune W. Berg

Keyword(s):

Neural Activity ◽

Force Control ◽

Muscle Force ◽

Neural Circuitry ◽

Lumbar Spinal Cord ◽

Speed Regulation ◽

Spinal Motor ◽

Extensor Muscles ◽

Rhythmic Behavior ◽

Lumbar Spinal

ABSTRACTAlthough the nervous system is elegantly orchestrating movements, the underlying neural principles remain unclear. Since flexor- and extensor-muscles alternate during movements like walking, it is often assumed that the responsible neural circuitry is similarly alternating in opposition. Here, we present ensemble-recordings of neurons in the lumbar spinal cord that indicate that, rather than alternation, the population is performing a “rotation” in neural space, i.e. the neural activity is cycling through all phases continuously during the rhythmic behavior. The radius of rotation correlates with the intended muscle force. Since existing models of spinal motor control offer an inadequate explanation of rotation, we propose a new theory of neural generation of movement from which this and other unresolved issues, such as speed regulation, force control, and multi-functionalism, are conveniently explained.

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Modularity of Endpoint Force Patterns Evoked Using Intraspinal Microstimulation in Treadmill Trained and/or Neurotrophin-Treated Chronic Spinal Cats

Journal of Neurophysiology ◽

10.1152/jn.00034.2008 ◽

2009 ◽

Vol 101 (3) ◽

pp. 1309-1320 ◽

Cited By ~ 11

Author(s):

Vanessa S. Boyce ◽

Michel A. Lemay

Keyword(s):

Muscle Activity ◽

Vastus Lateralis ◽

Biceps Femoris ◽

Motor Output ◽

Medial Gastrocnemius ◽

Lumbar Spinal Cord ◽

Intraspinal Microstimulation ◽

Hindlimb Muscles ◽

Spinal Motor ◽

Lumbar Spinal

Chronic spinal cats with neurotrophin-secreting fibroblasts (NTF) transplants recover locomotor function. To ascertain possible mechanisms, intraspinal microstimulation was used to examine the lumbar spinal cord motor output of four groups of chronic spinal cats: untrained cats with unmodified-fibroblasts graft (Op-control) or NTF graft and locomotor-trained cats with unmodified-fibroblasts graft (Trained) or NTF graft (Combination). Forces generated via intraspinal microstimulation at different hindlimb positions were recorded and interpolated, generating representations of force patterns at the paw. Electromyographs (EMGs) of hindlimb muscles, medial gastrocnemius, tibialis anterior, vastus lateralis, and biceps femoris posterior, were also collected to examine relationships between activated muscles and force pattern types. The same four force pattern types obtained in spinal-intact cats were found in chronic spinal cats. Proportions of force patterns in spinal cats differed significantly from those in intact cats, but no significant differences in proportions were observed among individual spinal groups (Op-control, NTF, Trained, and Combination). However, the proportions of force patterns differed significantly between trained (Trained and Combination) and untrained groups (Op-control and NTF). Thus the frequency of expression of some response types was modified by injury and to a lesser extent by training. Force pattern laminar distribution differed in spinal cats compared with intact, with more responses obtained dorsally (0–1,000 μm) and fewer ventrally (3,200–5,200 μm). EMG analysis demonstrated that muscle activity highly predicted some force pattern types and was independent of hindlimb position. We conclude that spinal motor output modularity is preserved after injury.

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Identification of 17 highly expressed genes within mouse lumbar spinal cord anterior horn region from an in-situ hybridization atlas of 3430 genes: implications for motor neuron disease

Neurology International ◽

10.4081/ni.2014.5367 ◽

2014 ◽

Vol 6 (2) ◽

Cited By ~ 8

Author(s):

Michael A. Meyer

Keyword(s):

Spinal Cord ◽

Motor Neuron ◽

Motor Neuron Disease ◽

Motor Neurons ◽

Ventral Horn ◽

Janus Kinase ◽

Anterior Horn ◽

Lumbar Spinal Cord ◽

Spinal Motor ◽

Lumbar Spinal

In an effort to find possible new gene candidates involved in the causation of amyotrophic lateral sclerosis (ALS), a prior version of the on-line brain gene expression atlas GENSAT was extensively searched for selectively intense expression within spinal motor neurons. Using autoradiographic data of in-situ hybridization from 3430 genes, a search for selectively intense activity was made for the anterior horn region of murine lumbar spinal cord sectioned in the axial plane. Of 3430 genes, a group of 17 genes was found to be highly expressed within the anterior horn suggesting localization to its primary cellular constituent, the alpha spinal motor neuron. For some genes, an inter-relationship to ALS was already known, such as for heavy, medium, and light neurofilaments, and peripherin. Other genes identified include: Gamma Synuclein, GDNF, SEMA3A, Extended Synaptotagmin-like protein 1, LYNX1, HSPA12a, Cadherin 22, PRKACA, TPPP3 as well as Choline Acetyltransferase, Janus Kinase 1, and the Motor Neuron and Pancreas Homeobox 1. Based on this study, Fibroblast Growth Factor 1 was found to have a particularly selective and intense localization pattern to the ventral horn and may be a good target for development of motor neuron disease therapies; further research is needed.

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Lipomeningocele associated with diplomyelia in a dog

Tierärztliche Praxis Ausgabe K Kleintiere / Heimtiere ◽

10.15654/tpk-170751 ◽

2018 ◽

Vol 46 (05) ◽

pp. 323-329 ◽

Cited By ~ 2

Author(s):

Nele Ondreka ◽

Sara Malberg ◽

Emma Laws ◽

Martin Schmidt ◽

Sabine Schulze

Keyword(s):

Spinal Cord ◽

Neurological Status ◽

Split Cord Malformation ◽

Lumbar Spinal Cord ◽

Histopathological Diagnosis ◽

Type I ◽

Thoracic Spinal Cord ◽

Thoracic Spinal ◽

Subcutaneous Mass ◽

Lumbar Spinal

SummaryA 2-year-old male neutered mixed breed dog with a body weight of 30 kg was presented for evaluation of a soft subcutaneous mass on the dorsal midline at the level of the caudal thoracic spine. A further clinical sign was intermittent pain on palpation of the area of the subcutaneous mass. The owner also described a prolonged phase of urination with repeated interruption and re-initiation of voiding. The findings of the neurological examination were consistent with a lesion localization between the 3rd thoracic and 3rd lumbar spinal cord segments. Magnetic resonance imaging revealed a spina bifida with a lipomeningocele and diplomyelia (split cord malformation type I) at the level of thoracic vertebra 11 and 12 and secondary syringomyelia above the aforementioned defects in the caudal thoracic spinal cord. Surgical resection of the lipomeningocele via a hemilaminectomy was performed. After initial deterioration of the neurological status postsurgery with paraplegia and absent deep pain sensation the dog improved within 2 weeks to non-ambulatory paraparesis with voluntary urination. Six weeks postoperatively the dog was ambulatory, according to the owner. Two years after surgery the owner recorded that the dog showed a normal gait, a normal urination and no pain. Histopathological diagnosis of the biopsied material revealed a lipomeningocele which confirmed the radiological diagnosis.

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Faculty Opinions recommendation of Functional organization of locomotor interneurons in the ventral lumbar spinal cord of the newborn rat.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.13601956.14995056 ◽

2012 ◽

Author(s):

Serge Rossignol

Keyword(s):

Spinal Cord ◽

Functional Organization ◽

Lumbar Spinal Cord ◽

Newborn Rat ◽

Lumbar Spinal

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Faculty Opinions recommendation of Neurologic improvement after thoracic, thoracolumbar, and lumbar spinal cord (conus medullaris) injuries.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.8263956.8692054 ◽

2011 ◽

Author(s):

Carlos Bagley

Keyword(s):

Spinal Cord ◽

Conus Medullaris ◽

Lumbar Spinal Cord ◽

Lumbar Spinal

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Aging process of the human lumbar spinal cord: A morphometric analysis

Neuropathology ◽

10.1111/j.1440-1789.1996.tb00164.x ◽

1996 ◽

Vol 16 (2) ◽

pp. 106-111 ◽

Cited By ~ 5

Author(s):

Ming Zhou ◽

Noboru Goto ◽

Chen Zhang ◽

Wei Tang

Keyword(s):

Spinal Cord ◽

Morphometric Analysis ◽

Aging Process ◽

Lumbar Spinal Cord ◽

Lumbar Spinal

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Multi-pronged neuromodulation intervention engages the residual motor circuitry to facilitate walking in a rat model of spinal cord injury

Nature Communications ◽

10.1038/s41467-021-22137-9 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Marco Bonizzato ◽

Nicholas D. James ◽

Galyna Pidpruzhnykova ◽

Natalia Pavlova ◽

Polina Shkorbatova ◽

...

Keyword(s):

Spinal Cord ◽

Spinal Cord Injury ◽

Rat Model ◽

Stress Responses ◽

Learning Algorithm ◽

Lumbar Spinal Cord ◽

Cord Injury ◽

Potential Synergy ◽

Lumbar Spinal ◽

Deep Brain

AbstractA spinal cord injury usually spares some components of the locomotor circuitry. Deep brain stimulation (DBS) of the midbrain locomotor region and epidural electrical stimulation of the lumbar spinal cord (EES) are being used to tap into this spared circuitry to enable locomotion in humans with spinal cord injury. While appealing, the potential synergy between DBS and EES remains unknown. Here, we report the synergistic facilitation of locomotion when DBS is combined with EES in a rat model of severe contusion spinal cord injury leading to leg paralysis. However, this synergy requires high amplitudes of DBS, which triggers forced locomotion associated with stress responses. To suppress these undesired responses, we link DBS to the intention to walk, decoded from cortical activity using a robust, rapidly calibrated unsupervised learning algorithm. This contingency amplifies the supraspinal descending command while empowering the rats into volitional walking. However, the resulting improvements may not outweigh the complex technological framework necessary to establish viable therapeutic conditions.

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