Modular organization of motor behavior in the frog's spinal cord

1995 ◽  
Vol 18 (10) ◽  
pp. 442-446 ◽  
Author(s):  
Emilio Bizzi ◽  
Simon F. Giszter ◽  
Eric Loeb ◽  
Fernando A. Mussa-Ivaldi ◽  
Philippe Saltiel
Keyword(s):  
Spinal Cord ◽  
Motor Behavior ◽  
Modular Organization

Modular Organization of Motor Behavior

1998 ◽  
Vol 53 (7-8) ◽  
pp. 510-517 ◽  
Author(s):  
E. Bizzi ◽  
P. Saltiei ◽  
M. Tresch
Keyword(s):  
Spinal Cord ◽  
Equilibrium Point ◽  
Motor Behavior ◽  
Arm Movements ◽  
Modular Organization ◽  
Muscle Forces ◽  
Simple Manner ◽  
Motor Behaviors ◽  
Motor Outputs

Abstract The issue of translating the planning of arm movements into muscle forces is discussed in relation to the recent discovery of structures in the spinal cord. These structures contain circuitry that, when activated, produce precisely balanced contractions in groups of muscles. These synergistic contractions generate forces that direct the limb toward an equilibrium point in space. Remarkably, the force outputs, produced by activating different spinal-cord structures, sum vectorially. This vectorial combination of motor outputs might be a mecha­nism for producing a vast repertoire of motor behaviors in a simple manner.

scholarly journals Mouse Corticospinal System Comprises Different Functional Neuronal Ensembles Depending On Their Hodology

2019 ◽  
Author(s):  
Rafael Olivares-Moreno ◽  
Mónica López-Hidalgo ◽  
Alain Altamirano-Espinoza ◽  
Adriana González-Gallardo ◽  
Anaid Antaramian ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Pyramidal Neurons ◽  
Functional Organization ◽  
Modular Organization ◽  
Subcortical Structures ◽  
Neuronal Ensembles ◽  
Synaptic Interactions ◽  
Spinal Cord Segment ◽  
Different Populations ◽  
Cortex Slices

Abstract Background: Movement performance depends on the synaptic interactions generated by coherent parallel sensorimotor cortical outputs to different downstream targets. The major outputs of the neocortex to subcortical structures are driven by pyramidal tract neurons (PTNs) located in layer 5B. One of the main targets of PTNs is the spinal cord through the corticospinal (CS) system, which is formed by a complex collection of distinct CS circuits. However, little is known about intracortical synaptic interactions that originate CS commands and how different populations of CS neurons are functionally organized. To further understand the functional organization of the CS system, we analyzed the activity of unambiguously identified CS neurons projecting to different zones of the same spinal cord segment using two-photon calcium imaging and retrograde neuronal tracers. Results: Sensorimotor cortex slices obtained from transgenic mice expressing GCaMP6 funder the Thy1 promoter were used to analyze the spontaneous calcium transients in layer 5 pyramidal neurons. Distinct subgroups of CS neurons projecting to dorsal horn and ventral areas of the same segment show more synchronous activity between them than with other subgroups. Conclusions: The results indicate that CS neurons projecting to different spinal cord zones segregated into functional ensembles depending on their hodology, suggesting that a modular organization of CS outputs controls sensorimotor behaviors in a coordinated manner.

The control of rostrocaudal pattern in the developing spinal cord: specification of motor neuron subtype identity is initiated by signals from paraxial mesoderm

Development ◽  
1998 ◽  
Vol 125 (6) ◽  
pp. 969-982 ◽  
Author(s):  
M. Ensini ◽  
T.N. Tsuchida ◽  
H.G. Belting ◽  
T.M. Jessell
Keyword(s):  
Spinal Cord ◽  
Motor Neuron ◽  
Motor Neurons ◽  
Neural Tube ◽  
Motor Behavior ◽  
Neural Tube Closure ◽  
Paraxial Mesoderm ◽  
Homeodomain Protein ◽  
Mesodermal Cell ◽  
Developing Spinal Cord

The generation of distinct classes of motor neurons is an early step in the control of vertebrate motor behavior. To study the interactions that control the generation of motor neuron subclasses in the developing avian spinal cord we performed in vivo grafting studies in which either the neural tube or flanking mesoderm were displaced between thoracic and brachial levels. The positional identity of neural tube cells and motor neuron subtype identity was assessed by Hox and LIM homeodomain protein expression. Our results show that the rostrocaudal identity of neural cells is plastic at the time of neural tube closure and is sensitive to positionally restricted signals from the paraxial mesoderm. Such paraxial mesodermal signals appear to control the rostrocaudal identity of neural tube cells and the columnar subtype identity of motor neurons. These results suggest that the generation of motor neuron subtypes in the developing spinal cord involves the integration of distinct rostrocaudal and dorsoventral patterning signals that derive, respectively, from paraxial and axial mesodermal cell groups.

scholarly journals Spinal Cord Modular Organization and Rhythm Generation: An NMDA Iontophoretic Study in the Frog

1998 ◽  
Vol 80 (5) ◽  
pp. 2323-2339 ◽  
Author(s):  
Philippe Saltiel ◽  
Matthew C. Tresch ◽  
Emilio Bizzi
Keyword(s):  
Spinal Cord ◽  
Isometric Force ◽  
Pattern Generation ◽  
The Body ◽  
Lumbar Spinal Cord ◽  
Modular Organization ◽  
Rhythmic Pattern ◽  
Rhythm Generation ◽  
Force Output ◽  
Electrical Microstimulation

Saltiel, Philippe, Matthew C. Tresch, and Emilio Bizzi. Spinal cord modular organization and rhythm generation: a NMDA iontophoretic study in the frog. J. Neurophysiol. 80: 2323–2339, 1998. Previous work using electrical microstimulation has suggested the existence of modules subserving limb posture in the spinal cord. In this study, the question of modular organization was reinvestigated with the more selective method of chemical microstimulation. N-methyl-d-aspartate (NMDA) iontophoresis was applied to 229 sites of the lumbar spinal cord gray while monitoring the isometric force output of the ipsilateral hindlimb at the ankle. A force response was elicited from 69 sites. At 18 of these sites, tonic forces were generated and rhythmic forces at 44. In the case of tonic forces, their directions clustered along four orientations: lateral extension, rostral flexion, adduction, and caudal extension. For the entire set of forces (tonic and rhythmic), the same clusters of orientations were found with the addition of a cluster directed as a flexion toward the body. This distribution of force orientations was quite comparable to that obtained with electrical stimulation at the same sites. The map of tonic responses revealed a topographic organization; each type of force orientation was elicited from sites that grouped together in zones at distinct rostrocaudal and depth locations. In the case of rhythmic sequences of force orientations, some were distinctly more common, whereas others were rarely elicited by NMDA. Mapping of the most common rhythms showed that each was elicited from two or three regions of the cord. These regions were close in location to the tonic regions that produced those forces that represented components specific to that rhythm. There was an additional caudal region from which the different rhythms also could be elicited. Taken together, these results support the concept of a modular organization of the motor system in the frog's spinal cord and delineate the topography of these modules. They also suggest that these modules are used by the circuitry underlying rhythmic pattern generation by the spinal cord.

scholarly journals Different phase delays of peripheral input to primate motor cortex and spinal cord promote cancellation at physiological tremor frequencies

2014 ◽  
Vol 111 (10) ◽  
pp. 2001-2016 ◽  
Author(s):  
Saša Koželj ◽  
Stuart N. Baker
Keyword(s):  
Spinal Cord ◽  
Motor Cortex ◽  
Motor Behavior ◽  
Cervical Spinal Cord ◽  
Late Response ◽  
Physiological Tremor ◽  
Phase Cancellation ◽  
Overall Stability ◽  
Response Onset ◽  
Frequency Relationship

Neurons in the spinal cord and motor cortex (M1) are partially phase-locked to cycles of physiological tremor, but with opposite phases. Convergence of spinal and cortical activity onto motoneurons may thus produce phase cancellation and a reduction in tremor amplitude. The mechanisms underlying this phase difference are unknown. We investigated coherence between spinal and M1 activity with sensory input. In two anesthetized monkeys, we electrically stimulated the medial, ulnar, deep radial, and superficial radial nerves; stimuli were timed as independent Poisson processes (rate 10 Hz). Single units were recorded from M1 (147 cells) or cervical spinal cord (61 cells). Ninety M1 cells were antidromically identified as pyramidal tract neurons (PTNs); M1 neurons were additionally classified according to M1 subdivision (rostral/caudal, M1r/c). Spike-stimulus coherence analysis revealed significant coupling over a broad range of frequencies, with the strongest coherence at <50 Hz. Delays implied by the slope of the coherence phase-frequency relationship were greater than the response onset latency, reflecting the importance of late response components for the transmission of oscillatory inputs. The spike-stimulus coherence phase over the 6–13 Hz physiological tremor band differed significantly between M1 and spinal cells (phase differences relative to the cord of 2.72 ± 0.29 and 1.72 ± 0.37 radians for PTNs from M1c and M1r, respectively). We conclude that different phases of the response to peripheral input could partially underlie antiphase M1 and spinal cord activity during motor behavior. The coordinated action of spinal and cortical feedback will act to reduce tremulous oscillations, possibly improving the overall stability and precision of motor control.

Absence of Local Sign Withdrawal in Chronic Human Spinal Cord Injury

2003 ◽  
Vol 90 (5) ◽  
pp. 3232-3241 ◽  
Author(s):  
Brian D. Schmit ◽  
T. George Hornby ◽  
Vicki M. Tysseling-Mattiace ◽  
Ela N. Benz
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Stimulus Location ◽  
Joint Torque ◽  
Test Sequence ◽  
Modular Organization ◽  
Human Spinal Cord ◽  
Local Sign ◽  
Cord Injury ◽  
Hip Flexion

Local sign withdrawal, a reflex to direct the limb away from noxious cutaneous stimuli, is thought to be indicative of a modular organization of the spinal cord. To assess the integrity of such an organization of the spinal cord in chronic human spinal cord injury (SCI), we tested the electromyogram (EMG) and joint torque responses to cutaneous stimuli applied to 6 locations of the leg in 10 SCI volunteers and 3 spinal-intact controls. The 6 locations included the medial arch of the foot, the second metatarsal, the dorsum, the region over the sural nerve at the lateral malleolus, and the anterior and posterior aspects of the lower leg. Although spinal-intact subjects demonstrated local sign withdrawal, the data from SCI subjects indicated that an invariant flexion response pattern was produced regardless of stimulus location. Ankle dorsiflexion and hip flexion were produced in all subjects at all locations and no difference in the ratio of hip:ankle torques could be detected for the 6 test locations. A windup-crossover test, employing a sequence of 6 stimuli at 1-s intervals was used to assess whether common neuronal pathways were responsible for the loss of modular organization. An additional 10 SCI volunteers were tested using stimuli in which the stimulus location was switched between the 2nd and 3rd stimulus of the test sequence. The response to the crossover stimulus more closely resembled the response to the 3rd stimulus of a windup sequence than a response without conditioning stimuli. These results indicate that increased excitability produced by windup at one stimulus site is maintained at the 2nd site. This observation suggests that deep dorsal horn neurons, typically associated with musculotopic mapping, may be reorganized in chronic spinal cord injury.

ISDN2014_0143: A hybrid electrical and chemical circuit in the spinal cord generates a novel transient embryonic motor behavior

2015 ◽  
Vol 47 (Part_A) ◽  
pp. 41-42
Author(s):  
Laura D. Knogler ◽  
Joel Ryan ◽  
Louis Saint‐Amant ◽  
Pierre Drapeau
Keyword(s):  
Spinal Cord ◽  
Motor Behavior

scholarly journals Multifactorial motor behavior assessment for real-time evaluation of emerging therapeutics to treat neurologic impairments

2019 ◽  
Author(s):  
Riazul Islam ◽  
Carlos Cuellar ◽  
Ben Felmlee ◽  
Tori Riccelli ◽  
Jodi Silvernail ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Body Weight ◽  
Motor Activity ◽  
Real Time ◽  
Open Field ◽  
Hind Limb ◽  
Motor Behavior ◽  
Motor Evoked Potentials ◽  
Network Activity ◽  
Novel Approach

AbstractIntegrating multiple assessment parameters of motor behavior is critical for understanding neural activity dynamics during motor control in both intact and dysfunctional nervous systems. Here, we described a novel approach (termed Multifactorial Behavioral Assessment (MfBA)) to integrate, in real-time, electrophysiological and biomechanical properties of rodent spinal sensorimotor network activity with behavioral aspects of motor task performance. Specifically, the MfBA simultaneously records limb kinematics, multi-directional forces and electrophysiological metrics, such as high-fidelity chronic intramuscular electromyography synchronized in time to spinal stimulation in order to characterize spinal cord functional motor evoked potentials (fMEPs). Additionally, we designed the MfBA to incorporate a body weight support system to allow bipedal and quadrupedal stepping on a treadmill and in an open field environment to assess function in rodent models of neurologic disorders that impact motor activity This novel approach was validated using, a neurologically intact cohort, a cohort with unilateral Parkinsonian motor deficits due to midbrain lesioning, and a cohort with complete hind limb paralysis due to T8 spinal cord transection. In the SCI cohort, lumbosacral epidural electrical stimulation (EES) was applied, with and without administration of the serotonergic agonist Quipazine, to enable hind limb motor functions following paralysis. The results presented herein demonstrate the MfBA is capable of integrating multiple metrics of motor activity in order to characterize relationships between EES inputs that modulate mono- and polysynaptic outputs from spinal circuitry which in turn, can be used to elucidate underlying electrophysiologic mechanisms of motor behavior by synchronizing these datasets to metrics of movement and behavior. These results also demonstrate that proposed MfBA is an effective tool to integrate biomechanical and electrophysiology metrics, synchronized to therapeutic inputs such as EES or pharmacology, during body weight supported treadmill or open field motor activities, to target a high range of variations in motor behavior as a result of neurological deficit at the different levels of CNS.

scholarly journals Multifactorial motor behavior assessment for real-time evaluation of emerging therapeutics to treat neurologic impairments

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Riazul Islam ◽  
Carlos A. Cuellar ◽  
Ben Felmlee ◽  
Tori Riccelli ◽  
Jodi Silvernail ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Body Weight ◽  
Motor Activity ◽  
Real Time ◽  
Open Field ◽  
Hind Limb ◽  
Motor Behavior ◽  
Motor Evoked Potentials ◽  
Network Activity ◽  
Novel Approach

Abstract Integrating multiple assessment parameters of motor behavior is critical for understanding neural activity dynamics during motor control in both intact and dysfunctional nervous systems. Here, we described a novel approach (termed Multifactorial Behavioral Assessment (MfBA)) to integrate, in real-time, electrophysiological and biomechanical properties of rodent spinal sensorimotor network activity with behavioral aspects of motor task performance. Specifically, the MfBA simultaneously records limb kinematics, multi-directional forces and electrophysiological metrics, such as high-fidelity chronic intramuscular electromyography synchronized in time to spinal stimulation in order to characterize spinal cord functional motor evoked potentials (fMEPs). Additionally, we designed the MfBA to incorporate a body weight support system to allow bipedal and quadrupedal stepping on a treadmill and in an open field environment to assess function in rodent models of neurologic disorders that impact motor activity. This novel approach was validated using, a neurologically intact cohort, a cohort with unilateral Parkinsonian motor deficits due to midbrain lesioning, and a cohort with complete hind limb paralysis due to T8 spinal cord transection. In the SCI cohort, lumbosacral epidural electrical stimulation (EES) was applied, with and without administration of the serotonergic agonist Quipazine, to enable hind limb motor functions following paralysis. The results presented herein demonstrate the MfBA is capable of integrating multiple metrics of motor activity in order to characterize relationships between EES inputs that modulate mono- and polysynaptic outputs from spinal circuitry which in turn, can be used to elucidate underlying electrophysiologic mechanisms of motor behavior. These results also demonstrate that proposed MfBA is an effective tool to integrate biomechanical and electrophysiology metrics, synchronized to therapeutic inputs such as EES or pharmacology, during body weight supported treadmill or open field motor activities, to target a high range of variations in motor behavior as a result of neurological deficit at the different levels of CNS.

Sign in / Sign up

Export Citation Format

Share Document