scholarly journals The Functional Connectivity between the Locust Leg Pattern Generating Networks and the Subesophageal Ganglion Higher Motor Center

2017 ◽  
Author(s):  
Daniel Knebel ◽  
Jan Rillich ◽  
Leonard Nadler ◽  
Hans-Joachim Pflueger ◽  
Amir Ayali
Keyword(s):  
Motor Neurons ◽  
Central Pattern Generators ◽  
Subesophageal Ganglion ◽  
Motor Center ◽  
Coupling Pattern ◽  
Descending Interneurons ◽  
Pattern Generators ◽  
Leg Movements

AbstractInteractions among different neuronal circuits are essential for adaptable coordinated behavior. Specifically, higher motor centers and central pattern generators (CPGs) induce rhythmic leg movements that act in concert in the control of locomotion. Here we explored the relations between the subesophageal ganglion (SEG) and thoracic leg CPGs in the desert locust. Backfill staining revealed about 300 SEG descending interneurons (DINs) and some overlap with the arborization of DINs and leg motor neurons. In accordance, in in-vitro preparations, electrical stimulation applied to the SEG excited these neurons, and in some cases also induced CPGs activity. Additionally, we found that the SEG regulates the coupling pattern among the CPGs: when the CPGs were activated pharmacologically, inputs from the SEG were able to synchronize contralateral CPGs. This motor output was correlated to the firing of SEG descending and local interneurons. Altogether, these findings point to a role of the SEG in both activating leg CPGs and in coordinating their oscillations, and suggest parallels between the SEG and the brainstem of vertebrates.

Sensory regulation of quadrupedal locomotion: a top-down or bottom-up control system?

2012 ◽  
Vol 108 (3) ◽  
pp. 709-711 ◽  
Author(s):  
Yann Thibaudier ◽  
Marie-France Hurteau
Keyword(s):  
Control System ◽  
Central Pattern Generators ◽  
Top Down ◽  
Bottom Up ◽  
Sensory Inputs ◽  
Sensory Regulation ◽  
Before And After ◽  
Pattern Generators

Propriospinal pathways are thought to be critical for quadrupedal coordination by coupling cervical and lumbar central pattern generators (CPGs). However, the mechanisms involved in relaying information between girdles remain largely unexplored. Using an in vitro spinal cord preparation in neonatal rats, Juvin and colleagues ( Juvin et al. 2012 ) have recently shown sensory inputs from the hindlimbs have greater influence on forelimb CPGs than forelimb sensory inputs on hindlimb CPGs, in other words, a bottom-up control system. However, results from decerebrate cats suggest a top-down control system. It may be that both bottom-up and top-down control systems exist and that the dominance of one over the other is task or context dependent. As such, the role of sensory inputs in controlling quadrupedal coordination before and after injury requires further investigation.

scholarly journals Excitatory Motor Neurons are Local Central Pattern Generators in an Anatomically Compressed Motor Circuit for Reverse Locomotion

2017 ◽  
Author(s):  
Shangbang Gao ◽  
Sihui Asuka Guan ◽  
Anthony D. Fouad ◽  
Jun Meng ◽  
Taizo Kawano ◽  
...  
Keyword(s):  
Motor Neurons ◽  
Calcium Imaging ◽  
Central Pattern Generators ◽  
Oscillatory Activity ◽  
Intrinsic Activity ◽  
C Elegans ◽  
Class A ◽  
Cell Ablation ◽  
Pattern Generators

AbstractCentral pattern generators are cell‐ or network-driven oscillators that underlie motor rhythmicity. The existence and identity of C. elegans CPGs remain unknown. Through cell ablation, electrophysiology, and calcium imaging, we identified oscillators for reverse locomotion. We show that the cholinergic and excitatory class A motor neurons exhibit intrinsic and oscillatory activity, and such an activity can drive reverse locomotion without premotor interneurons. Regulation of their oscillatory activity, either through effecting an endogenous constituent of oscillation, the P/Q/N high voltage-activated calcium channel UNC-2, or, via dual regulation – inhibition and activation ‐ by the descending premotor interneurons AVA, determines the propensity, velocity, and sustention of reverse locomotion. Thus, the reversal motor executors themselves serve as oscillators; regulation of their intrinsic activity controls the reversal motor state. These findings exemplify anatomic and functional compression: motor executors integrate the role of rhythm generation in a locomotor network that is constrained by small cell numbers.

scholarly journals Caenorhabditis elegans excitatory ventral cord motor neurons derive rhythm for body undulation

2018 ◽  
Vol 373 (1758) ◽  
pp. 20170370 ◽  
Author(s):  
Quan Wen ◽  
Shangbang Gao ◽  
Mei Zhen
Keyword(s):  
Caenorhabditis Elegans ◽  
Motor Neurons ◽  
Central Pattern Generators ◽  
Oscillatory Activity ◽  
C Elegans ◽  
Ventral Cord ◽  
Small Neuron ◽  
Motor Rhythm ◽  
Pattern Generators

The intrinsic oscillatory activity of central pattern generators underlies motor rhythm. We review and discuss recent findings that address the origin of Caenorhabditis elegans motor rhythm. These studies propose that the A- and mid-body B-class excitatory motor neurons at the ventral cord function as non-bursting intrinsic oscillators to underlie body undulation during reversal and forward movements, respectively. Proprioception entrains their intrinsic activities, allows phase-coupling between members of the same class motor neurons, and thereby facilitates directional propagation of undulations. Distinct pools of premotor interneurons project along the ventral nerve cord to innervate all members of the A- and B-class motor neurons, modulating their oscillations, as well as promoting their bi-directional coupling. The two motor sub-circuits, which consist of oscillators and descending inputs with distinct properties, form the structural base of dynamic rhythmicity and flexible partition of the forward and backward motor states. These results contribute to a continuous effort to establish a mechanistic and dynamic model of the C. elegans sensorimotor system. C. elegans exhibits rich sensorimotor functions despite a small neuron number. These findings implicate a circuit-level functional compression. By integrating the role of rhythm generation and proprioception into motor neurons, and the role of descending regulation of oscillators into premotor interneurons, this numerically simple nervous system can achieve a circuit infrastructure analogous to that of anatomically complex systems. C. elegans has manifested itself as a compact model to search for general principles of sensorimotor behaviours. This article is part of a discussion meeting issue ‘Connectome to behaviour: modelling C. elegans at cellular resolution’.

scholarly journals The functional connectivity between the locust leg pattern generators and the subesophageal ganglion higher motor center

2019 ◽  
Vol 692 ◽  
pp. 77-82 ◽  
Author(s):  
Daniel Knebel ◽  
Jan Rillich ◽  
Leonard Nadler ◽  
Hans-Joachim Pflüger ◽  
Amir Ayali
Keyword(s):  
Functional Connectivity ◽  
Subesophageal Ganglion ◽  
Motor Center ◽  
Pattern Generators

Intersegmental Coordination of Walking Movements in Stick Insects

2005 ◽  
Vol 93 (3) ◽  
pp. 1255-1265 ◽  
Author(s):  
Björn Ch. Ludwar ◽  
Marie L. Göritz ◽  
Joachim Schmidt
Keyword(s):  
Motor Pattern ◽  
Central Pattern Generators ◽  
Stick Insect ◽  
Neural Mechanisms ◽  
Chordotonal Organ ◽  
Adjacent Segment ◽  
Body Segments ◽  
Stick Insects ◽  
Pattern Generators ◽  
Leg Movements

Locomotion requires the coordination of movements across body segments, which in walking animals is expressed as gaits. We studied the underlying neural mechanisms of this coordination in a semi-intact walking preparation of the stick insect Carausius morosus. During walking of a single front leg on a treadmill, leg motoneuron (MN) activity tonically increased and became rhythmically modulated in the ipsilateral deafferented and deefferented mesothoracic (middle leg) ganglion. The pattern of modulation was correlated with the front leg cycle and specific for a given MN pool, although it was not consistent with functional leg movements for all MN pools. In an isolated preparation of a pair of ganglia, where one ganglion was made rhythmically active by application of pilocarpine, we found no evidence for coupling between segmental central pattern generators (CPGs) that could account for the modulation of MN activity observed in the semi-intact walking preparation. However, a third preparation provided evidence that signals from the front leg's femoral chordotonal organ (fCO) influenced activity of ipsilateral MNs in the adjacent mesothoracic ganglion. These intersegmental signals could be partially responsible for the observed MN activity modulation during front leg walking. While afferent signals from a single walking front leg modulate the activity of MNs in the adjacent segment, additional afferent signals, local or from contralateral or posterior legs, might be necessary to produce the functional motor pattern observed in freely walking animals.

scholarly journals The Whisking Rhythm Generator: A Novel Mammalian Network for the Generation of Movement

2007 ◽  
Vol 97 (3) ◽  
pp. 2148-2158 ◽  
Author(s):  
Nathan P. Cramer ◽  
Ying Li ◽  
Asaf Keller
Keyword(s):  
Firing Rate ◽  
Serotonin Receptor ◽  
Central Pattern Generators ◽  
Rhythm Generator ◽  
Low Concentrations ◽  
Rhythmic Firing ◽  
Pattern Generators ◽  
Cortical Inputs

Using the rat vibrissa system, we provide evidence for a novel mechanism for the generation of movement. Like other central pattern generators (CPGs) that underlie many movements, the rhythm generator for whisking can operate without cortical inputs or sensory feedback. However, unlike conventional mammalian CPGs, vibrissa motoneurons (vMNs) actively participate in the rhythmogenesis by converting tonic serotonergic inputs into the patterned motor output responsible for movement of the vibrissae. We find that, in vitro, a serotonin receptor agonist, α-Me-5HT, facilitates a persistent inward current (PIC) and evokes rhythmic firing in vMNs. Within each motoneuron, increasing the concentration of α-Me-5HT significantly increases the both the magnitude of the PIC and the motoneuron's firing rate. Riluzole, which selectively suppresses the Na+ component of PICs at low concentrations, causes a reduction in both of these phenomena. The magnitude of this reduction is directly correlated with the concentration of riluzole. The joint effects of riluzole on PIC magnitude and firing rate in vMNs suggest that the two are causally related. In vivo we find that the tonic activity of putative serotonergic premotoneurons is positively correlated with the frequency of whisking evoked by cortical stimulation. Taken together, these results support the hypothesized novel mammalian mechanism for movement generation in the vibrissa motor system where vMNs actively participate in the rhythmogenesis in response to tonic drive from serotonergic premotoneurons.

scholarly journals Systematic elucidation of neuron-astrocyte interaction in models of amyotrophic lateral sclerosis using multi-modal integrated bioinformatics workflow

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Vartika Mishra ◽  
Diane B. Re ◽  
Virginia Le Verche ◽  
Mariano J. Alvarez ◽  
Alessandro Vasciaveo ◽  
...  
Keyword(s):  
Amyotrophic Lateral Sclerosis ◽  
Motor Neurons ◽  
Death Receptor ◽  
Cell Interaction ◽  
Type Motor ◽  
Cellular Compartments ◽  
Death Receptor 6 ◽  
Lateral Sclerosis

Abstract Cell-to-cell communications are critical determinants of pathophysiological phenotypes, but methodologies for their systematic elucidation are lacking. Herein, we propose an approach for the Systematic Elucidation and Assessment of Regulatory Cell-to-cell Interaction Networks (SEARCHIN) to identify ligand-mediated interactions between distinct cellular compartments. To test this approach, we selected a model of amyotrophic lateral sclerosis (ALS), in which astrocytes expressing mutant superoxide dismutase-1 (mutSOD1) kill wild-type motor neurons (MNs) by an unknown mechanism. Our integrative analysis that combines proteomics and regulatory network analysis infers the interaction between astrocyte-released amyloid precursor protein (APP) and death receptor-6 (DR6) on MNs as the top predicted ligand-receptor pair. The inferred deleterious role of APP and DR6 is confirmed in vitro in models of ALS. Moreover, the DR6 knockdown in MNs of transgenic mutSOD1 mice attenuates the ALS-like phenotype. Our results support the usefulness of integrative, systems biology approach to gain insights into complex neurobiological disease processes as in ALS and posit that the proposed methodology is not restricted to this biological context and could be used in a variety of other non-cell-autonomous communication mechanisms.

Endogenous Motor Neuron Properties Contribute to a Program-Specific Phase of Activity in the Multifunctional Feeding Central Pattern Generator of Aplysia

2007 ◽  
Vol 98 (1) ◽  
pp. 29-42 ◽  
Author(s):  
Geidy E. Serrano ◽  
Clarissa Martínez-Rubio ◽  
Mark W. Miller
Keyword(s):  
Motor Neuron ◽  
Motor Neurons ◽  
Central Pattern Generators ◽  
Ingestive Behavior ◽  
Membrane Properties ◽  
Motor Patterns ◽  
Effector System ◽  
Bilateral Pair ◽  
Pattern Generators ◽  
Specific Phase

Multifunctional central pattern generators (CPGs) are circuits of neurons that can generate manifold actions from a single effector system. This study examined a bilateral pair of pharyngeal motor neurons, designated B67, that participate in the multifunctional feeding network of Aplysia californica. Fictive buccal motor programs (BMPs) were elicited with four distinct stimulus paradigms to assess the activity of B67 during ingestive versus egestive patterns. In both classes of programs, B67 fired during the phase of radula protraction and received a potent inhibitory postsynaptic potential (IPSP) during fictive radula retraction. When programs were ingestive, the retraction phase IPSP exhibited a depolarizing sag and was followed by a postinhibitory rebound (PIR) that could generate a postretraction phase of impulse activity. When programs were egestive, the depolarizing sag potential and PIR were both diminished or were not present. Examination of the membrane properties of B67 disclosed a cesium-sensitive depolarizing sag, a corresponding Ih-like current, and PIR in its responses to hyperpolarizing pulses. Direct IPSPs originating from the influential CPG retraction phase interneuron B64 were also found to activate the sag potential and PIR of B67. Dopamine, a modulator that can promote ingestive behavior in this system, enhanced the sag potential, Ih-like current, and PIR of B67. Finally, a pharyngeal muscle contraction followed the radula retraction phase of ingestive, but not egestive motor patterns. It is proposed that regulation of the intrinsic properties of this motor neuron can contribute to generating a program-specific phase of motor activity.

Neuronal control of walking: studies on insects

e-Neuroforum ◽  
2015 ◽  
Vol 21 (4) ◽  
Author(s):  
Ansgar Büschges ◽  
Joachim Schmidt
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Sensory Input ◽  
Central Pattern Generators ◽  
Movement Direction ◽  
Coordination Pattern ◽  
Differential Processing ◽  
Neuronal Control ◽  
Pattern Generators ◽  
Leg Movements

AbstractThe control of walking in insects is to a substantial amount a function of neuronal networks in the thoracic ganglia. While descending signals from head ganglia provide general commands such as for walking direction and velocity, it is the thoracic central nervous system that controls movements of individual joints and legs. The coordination pattern of legs is velocity dependent. However, a clear stereotypic coordination pattern appears only at high velocities. In accordance with the unit burst oscillator concept, oscillatory networks (central pattern generators (CPGs)) interlocked with movement and load sensors control the timing and amplitude of joint movements. For a leg’s movements different joint CPGs of a leg are mainly coupled by proprioceptors. Differential processing of proprioceptive signals allows a task specific modulation of leg movements, for example, for changing movement direction. A switch between walking and searching movements of a leg is under local control. When stepping into a gap missing sensory input and the activation of a local command neuron evokes stereotypic searching movements of the leg.

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