Premotor Interneurons in the Local Control of Stepping Motor Output for the Stick Insect Single Middle Leg

2009 ◽  
Vol 102 (3) ◽  
pp. 1956-1975 ◽  
Author(s):  
Géraldine von Uckermann ◽  
Ansgar Büschges
Keyword(s):  
Stance Phase ◽  
Stick Insect ◽  
Motor Output ◽  
Chordotonal Organ ◽  
Locomotor System ◽  
State Dependent ◽  
Nonspiking Interneurons ◽  
Leg Kinematics ◽  
Control Regime

In insect walking systems, nonspiking interneurons (NSIs) play an important role in the control of posture and movement. As such NSIs are known to contribute to state-dependent modifications in processing of proprioceptive signals from the legs. For example, NSIs process a flexion of the femur-tibia (FTi) joint signaled by the femoral chordotonal organ (fCO) such that the stance phase motor output is reinforced in the active locomotor system. This phenomenon representing a reflex reversal is the first part of the “active reaction” (AR) and was hypothesized to functionally represent a major control feature by which sensory feedback supports stance generation. As NSIs are known to contribute to the AR, the question arises, whether they serve similar functions during stepping and whether the AR is generally part of the control system for walking. We studied these issues in vivo, in a single leg preparation of Carausius morosus with the leg kinematics being confined to changes in one plane, along the coxa-trochanteral and the FTi-joint. Following kinematic analysis, identified NSIs (E1-E8, I1, I2, and I4) were recorded intracellularly during single leg stepping at different velocities. We detected clear similarities between the activity pattern of NSIs during single leg stepping and their responses to fCO-stimulation during the generation of the AR. This strongly supports the notion that the motor output generated during the AR reflects part of the control regime for stepping. Furthermore, our experiments revealed that alterations in stepping velocity result from modifications in the activity of the premotor NSIs involved in stance phase generation.

scholarly journals Body side-specific changes in sensorimotor processing of movement feedback in a walking insect

2019 ◽  
Vol 122 (5) ◽  
pp. 2173-2186 ◽  
Author(s):  
Joscha Schmitz ◽  
Matthias Gruhn ◽  
Ansgar Büschges
Keyword(s):  
Stick Insect ◽  
The Body ◽  
Motor Output ◽  
Chordotonal Organ ◽  
Stimulus Velocity ◽  
Motor Processing ◽  
Sensorimotor Processing ◽  
Body Side ◽  
The Difference ◽  
Leg Kinematics

Feedback from load and movement sensors can modify timing and magnitude of the motor output in the stepping stick insect. One source of feedback is stretch reception by the femoral chordotonal organ (fCO), which encodes such parameters as the femorotibial (FTi) joint angle, the angular velocity, and its acceleration. Stimulation of the fCO causes a postural resistance reflex, during quiescence, and can elicit the opposite, so-called active reaction (AR), which assists ongoing flexion during active movements. In the present study, we investigated the role of fCO feedback for the difference in likelihood of generating ARs on the inside vs. the outside during curve stepping. We analyzed the effects of fCO stimulation on the motor output to the FTi and the neighboring coxa-trochanter and thorax-coxa joints of the middle leg. In inside and outside turns, the probability for ARs increases with increasing starting angle and decreasing stimulus velocity; furthermore, it is independent of the total angular excursion. However, the transition between stance and swing motor activity always occurs after a specific angular excursion, independent of the turning direction. Feedback from the fCO also has an excitatory influence on levator trochanteris motoneurons (MNs) during inside and outside turns, whereas the same feedback affects protractor coxae MNs only during outside steps. Our results suggest joint- and body side-dependent processing of fCO feedback. A shift in gain may be responsible for different AR probabilities between inside and outside turning, whereas the general control mechanism for ARs is unchanged. NEW & NOTEWORTHY We show that parameters of movement feedback from the tibia in an insect during curve walking are processed in a body side-specific manner, and how. From our results it is highly conceivable that the difference in motor response to the feedback supports the body side-specific leg kinematics during turning. Future studies will need to determine the source for the inputs that determine the local changes in sensory-motor processing.

Load Signals Assist the Generation of Movement-Dependent Reflex Reversal in the Femur–Tibia Joint of Stick Insects

2006 ◽  
Vol 96 (6) ◽  
pp. 3532-3537 ◽  
Author(s):  
Turgay Akay ◽  
Ansgar Büschges
Keyword(s):  
Time Course ◽  
Stick Insect ◽  
Motor Output ◽  
Chordotonal Organ ◽  
Frequency Of Occurrence ◽  
Stick Insects ◽  
Extensor Motoneuron ◽  
Motoneuron Activity ◽  
First Time ◽  
Stimulation Of

Reinforcement of movement is an important mechanism by which sensory feedback contributes to motor control for walking. We investigate how sensory signals from movement and load sensors interact in controlling the motor output of the stick insect femur–tibia (FT) joint. In stick insects, flexion signals from the femoral chordotonal organ (fCO) at the FT joint and load signals from the femoral campaniform sensilla (fCS) are known to individually reinforce stance-phase motor output of the FT joint by promoting flexor and inhibiting extensor motoneuron activity. We quantitatively compared the time course of inactivation in extensor tibiae motoneurons in response to selective stimulation of fCS and fCO. Stimulation of either sensor generates extensor activity in a qualitatively similar manner but with a significantly different time course and frequency of occurrence. Inactivation of extensor motoneurons arising from fCS stimulation was more reliable but more than threefold slower compared with the extensor inactivation in response to flexion signals from the fCO. In contrast, simultaneous stimulation of both sense organs produced inactivation in motoneurons with a time course typical for fCO stimulation alone, but with a frequency of occurrence characteristic for fCS stimulation. This increase in probability of occurrence was also accompanied by a delayed reactivation of the extensor motoneurons. Our results indicate for the first time that load signals from the leg affect the processing of movement-related feedback in controlling motor output.

scholarly journals Motor Output of the Denervated Thoracic Ventral Nerve Cord in the Stick Insect Carausius Morosus

1983 ◽  
Vol 105 (1) ◽  
pp. 127-145 ◽  
Author(s):  
ULRICH BÄSSLER ◽  
U. T. A. WEGNER
Keyword(s):  
Nerve Cord ◽  
Ventral Nerve Cord ◽  
Intact Animal ◽  
Stick Insect ◽  
Motor Output ◽  
The Other ◽  
Chordotonal Organ ◽  
Motor Neurones ◽  
Leg Movements ◽  
Stimulation Of

The denervated thoracic ventral nerve cord produces a motor output which is similar to that observed in the intact animal during irregular leg movements (seeking movements) or rocking, but not walking. When the nerves to some legs are left intact, and the animal walks on a wheel, the motor output in the protractor and retractor motor neurones of the denervated legs is modulated by the stepping frequency of the walking legs. The modulation is similar to that observed in the motor output to a not actually stepping leg of an intact walking animal. When only the crural nerve of one leg is left intact, stimulation of the trochanteral campaniform sensilli induces protractor and retractor motor output to that leg and the leg behind it. In this case the motor output to the ipsilateral leg is in phase. Stimulation of the femoral chordotonal organ influences activity in motor neurones of the extensor tibiae (FETi and SETi) but not those of the protractor and retractor coxae muscles. In a restrained leg of an intact animal stretching of the femoral chordotonal organ excites FETi and SETi as long as the other legs walk (as in a walking leg) and inhibits FETi and SETi (as in a seeking leg) when the other legs are unable to walk.

Glutamate Neurotransmission Is Not Required for, But May Modulate, Hypoxic Sensitivity of Pre-Bötzinger Complex In Vivo

2005 ◽  
Vol 93 (3) ◽  
pp. 1278-1284 ◽  
Author(s):  
Irene C. Solomon
Keyword(s):  
Phrenic Nerve ◽  
Excitatory Amino Acid ◽  
Glutamate Release ◽  
Receptor Activation ◽  
Motor Output ◽  
Induced Response ◽  
Homocysteic Acid ◽  
Bötzinger Complex ◽  
Nerve Discharge

Focal hypoxia in the pre-Bötzinger complex (pre-BötC) in vivo elicits excitation of inspiratory motor output by modifying the patterning and timing of phrenic bursts. Hypoxia, however, has been reported to enhance glutamate release in some regions of the brain, including the medullary ventral respiratory column; thus the pre-BötC–mediated hypoxic respiratory excitation may result from, or be influenced by, hypoxia-induced activation of ionotropic glutamate [i.e., excitatory amino acid (EAA)] receptors. To test this possibility, the effects of focal pre-BötC hypoxia [induced by sodium cyanide (NaCN)] were examined before and after blockade of ionotropic EAA receptors [using kynurenic acid (KYN)] in this region in chloralose-anesthetized, vagotomized, mechanically ventilated cats. Before blockade of ionotropic EAA receptors, unilateral microinjection of NaCN (1 mM; 10–20 nl) into the pre-BötC produced either phasic or tonic excitation of phrenic nerve discharge. Unilateral microinjection of KYN (50–100 mM; 40 nl) decreased the amplitude and frequency of basal phrenic nerve discharge; however, subsequent microinjection of NaCN, but not dl-homocysteic acid (DLH, a glutamate analog), still produced excitation of phrenic motor output. Under these conditions, the NaCN-induced excitation included frequency modulation (FM) of phasic phrenic bursts, and in many cases, augmented and/or fractionated phrenic bursts. These findings show that the hypoxia-sensing function of the in vivo pre-BötC, which produces excitation of phrenic nerve discharge, is not dependent on activation of ionotropic glutamate receptors, but ionotropic glutamate receptor activation may modify the expression of the focal hypoxia-induced response. Thus these findings provide additional support to the concept of intrinsic hypoxic sensitivity of the pre-BötC.

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 Neural and genetic degeneracy underlies Caenorhabditis elegans feeding behavior

2014 ◽  
Vol 112 (4) ◽  
pp. 951-961 ◽  
Author(s):  
Nicholas F. Trojanowski ◽  
Olivia Padovan-Merhar ◽  
David M. Raizen ◽  
Christopher Fang-Yen
Keyword(s):  
Caenorhabditis Elegans ◽  
Neural Circuit ◽  
Dependent Manner ◽  
State Dependent ◽  
Excitatory Pathways ◽  
Genetic Mechanisms ◽  
Genetic Level ◽  
Pharyngeal Pumping ◽  
Robust Network

Degenerate networks, in which structurally distinct elements can perform the same function or yield the same output, are ubiquitous in biology. Degeneracy contributes to the robustness and adaptability of networks in varied environmental and evolutionary contexts. However, how degenerate neural networks regulate behavior in vivo is poorly understood, especially at the genetic level. Here, we identify degenerate neural and genetic mechanisms that underlie excitation of the pharynx (feeding organ) in the nematode Caenorhabditis elegans using cell-specific optogenetic excitation and inhibition. We show that the pharyngeal neurons MC, M2, M4, and I1 form multiple direct and indirect excitatory pathways in a robust network for control of pharyngeal pumping. I1 excites pumping via MC and M2 in a state-dependent manner. We identify nicotinic and muscarinic receptors through which the pharyngeal network regulates feeding rate. These results identify two different mechanisms by which degeneracy is manifest in a neural circuit in vivo.

scholarly journals A three-dimensional musculoskeletal model of the dog

2020 ◽  
Author(s):  
Heiko Stark ◽  
Martin S. Fischer ◽  
Alexander Hunt ◽  
Fletcher Young ◽  
Roger Quinn ◽  
...  
Keyword(s):  
Experimental Data ◽  
Body Size ◽  
Degrees Of Freedom ◽  
Inverse Dynamics ◽  
Musculoskeletal Model ◽  
Muscle Synergy ◽  
Locomotor System ◽  
Wide Range ◽  
Joint Load

AbstractDogs are an interesting object of investigation because of the wide range of body size, body mass, and physique. In the last several years, the number of clinical and biomechanical studies on dog locomotion has increased. However, the relationship between body structure and joint load during locomotion, as well as between joint load and degenerative diseases of the locomotor system (e.g. dysplasia), are not sufficiently understood. In vivo measurements/records of joint forces and loads or deep/small muscles are complex, invasive, and sometimes ethically questionable. The use of detailed musculoskeletal models may help in filling that knowledge gap. We describe here the methods we used to create a detailed musculoskeletal model with 84 degrees of freedom and 134 muscles. Our model has three key-features: Three-dimensionality, scalability, and modularity. We tested the validity of the model by identifying forelimb muscle synergies of a beagle at walk. We used inverse dynamics and static optimization to estimate muscle activations based on experimental data. We identified three muscle synergy groups by using hierarchical clustering. Predicted activation patterns exhibited good agreement with experimental data for most of the forelimb muscles. We expect that our model will speed up the analysis of how body size, physique, agility, and disease influence joint neuronal control and loading in dog locomotion.

scholarly journals Motoneuron output regulated by ionic channels: a modeling study of motoneuron frequency-current relationships during fictive locomotion

2018 ◽  
Vol 120 (4) ◽  
pp. 1840-1858 ◽  
Author(s):  
Yue Dai ◽  
Yi Cheng ◽  
Brent Fedirchuk ◽  
Larry M. Jordan ◽  
Junhao Chu
Keyword(s):  
Input Resistance ◽  
Ionic Channels ◽  
Motor Output ◽  
Membrane Properties ◽  
Fictive Locomotion ◽  
State Dependent ◽  
Simulation Results ◽  
The Individual ◽  
Ionic Basis ◽  
Frequency Current

Cat lumbar motoneurons display changes in membrane properties during fictive locomotion. These changes include reduction of input resistance and afterhyperpolarization, hyperpolarization of voltage threshold, and voltage-dependent excitation of the motoneurons. The state-dependent alteration of membrane properties leads to dramatic changes in frequency-current (F-I) relationship. The mechanism underlying these changes remains unknown. Using a motoneuron model combined with electrophysiological data, we investigated the channel mechanisms underlying the regulation of motoneuronal excitability and motor output. Simulation results showed that upregulation of transient sodium, persistent sodium, or Cav1.3 calcium conductances or downregulation of calcium-activated potassium or KCNQ/Kv7 potassium conductances could increase motoneuronal excitability and motor output through hyperpolarizing (left shifting) the F-I relationships or increasing the F-I slopes, whereas downregulation of input resistance or upregulation of potassium-mediated leak conductance produced the opposite effects. The excitatory phase of locomotor drive potentials (LDPs) also substantially hyperpolarized the F-I relationships and increased the F-I slopes, whereas the inhibitory phase of the LDPs had opposite effects to a similar extent. The simulation results also showed that none of the individual channel modulations could produce all the changes in the F-I relationships. The effects of modulation of Cav1.3 and KCNQ/Kv7 on F-I relationships were supported by slice experiments with the Cav1.3 agonist Bay K8644 and the KCNQ/Kv7 antagonist XE-991. The conclusion is that the varying changes in F-I relationships during fictive locomotion could be regulated by multichannel modulations. This study provides insight into the ionic basis for control of motor output in walking. NEW & NOTEWORTHY Mammalian spinal motoneurons have their excitability adapted to facilitate recruitment and firing during locomotion. Cat lumbar motoneurons display dramatic changes in membrane properties during fictive locomotion. These changes lead to a varying alteration of frequency-current relationship. The mechanisms underlying the changes remain unknown. In particular, little is known about the ionic basis for regulation of motoneuronal excitability and thus control of the motor output for walking by the spinal motor system.

Hormonal Control of the Malpighian Tubules of the Stick Insect, Carausius Morosus

1970 ◽  
Vol 52 (3) ◽  
pp. 653-665 ◽  
Author(s):  
DIANA E. M. PILCHER
Keyword(s):  
Stick Insect ◽  
Hormonal Control ◽  
The State ◽  
Malpighian Tubules ◽  
Suboesophageal Ganglion ◽  
Carausius Morosus ◽  
Corpora Cardiaca ◽  
Diuretic Hormone ◽  
The Brain

1. Urine secretion by isolated Malpighian tubules of Carausius is accelerated by a diuretic hormone which can be extracted from the brain, corpora cardiaca and suboesophageal ganglion. 2. The level of this hormone in the haemolymph varies according to the state of hydration of the insect. 3. The hormone is inactivated by the tubules, and a mechanism is proposed whereby the tubules might be controlled by the hormone in vivo.

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