scholarly journals Control of Stepping Velocity in the Stick Insect Carausius morosus

2009 ◽  
Vol 102 (2) ◽  
pp. 1180-1192 ◽  
Author(s):  
Matthias Gruhn ◽  
Géraldine von Uckermann ◽  
Sandra Westmark ◽  
Anne Wosnitza ◽  
Ansgar Büschges ◽  
...  
Keyword(s):  
Motor Neurons ◽  
Walking Speed ◽  
Stick Insect ◽  
Behavioral Experiments ◽  
General Increase ◽  
Carausius Morosus ◽  
Mechanical Coupling ◽  
Stick Insects ◽  
Motoneuron Activity ◽  
Slippery Surface

We performed electrophysiological and behavioral experiments in single-leg preparations and intact animals of the stick insect Carausius morosus to understand mechanisms underlying the control of walking speed. At the level of the single leg, we found no significant correlation between stepping velocity and spike frequency of motor neurons (MNs) other than the previously shown modification in flexor (stance) MN activity. However, pauses between stance and swing motoneuron activity at the transition from stance to swing phase and stepping velocity are correlated. Pauses become shorter with increasing speed and completely disappear during fast stepping sequences. By means of extra- and intracellular recordings in single-leg stick insect preparations we found no systematic relationship between the velocity of a stepping front leg and the motoneuronal activity in the ipsi- or contralateral mesothoracic protractor and retractor, as well as flexor and extensor MNs. The observations on the lack of coordination of stepping velocity between legs in single-leg preparations were confirmed in behavioral experiments with intact stick insects tethered above a slippery surface, thereby effectively removing mechanical coupling through the ground. In this situation, there were again no systematic correlations between the stepping velocities of different legs, despite the finding that an increase in stepping velocity in a single front leg is correlated with a general increase in nerve activity in all connectives between the subesophageal and all thoracic ganglia. However, when the tethered animal increased walking speed due to a short tactile stimulus, provoking an escape-like response, stepping velocities of ipsilateral legs were found to be correlated for several steps. These results indicate that there is no permanent coordination of stepping velocities between legs, but that such coordination can be activated under certain circumstances.

scholarly journals Descending octopaminergic neurons modulate sensory-evoked activity of thoracic motor neurons in stick insects

2019 ◽  
Vol 122 (6) ◽  
pp. 2388-2413 ◽  
Author(s):  
Thomas Stolz ◽  
Max Diesner ◽  
Susanne Neupert ◽  
Martin E. Hess ◽  
Estefania Delgado-Betancourt ◽  
...  
Keyword(s):  
Motor Neurons ◽  
Stick Insect ◽  
Neuron Activity ◽  
Sense Organs ◽  
Descending Neurons ◽  
Walking Activity ◽  
Stick Insects ◽  
Evoked Activity ◽  
Sensory Evoked ◽  
Stimulation Of

Neuromodulatory neurons located in the brain can influence activity in locomotor networks residing in the spinal cord or ventral nerve cords of invertebrates. How inputs to and outputs of neuromodulatory descending neurons affect walking activity is largely unknown. With the use of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and immunohistochemistry, we show that a population of dorsal unpaired median (DUM) neurons descending from the gnathal ganglion to thoracic ganglia of the stick insect Carausius morosus contains the neuromodulatory amine octopamine. These neurons receive excitatory input coupled to the legs’ stance phases during treadmill walking. Inputs did not result from connections with thoracic central pattern-generating networks, but, instead, most are derived from leg load sensors. In excitatory and inhibitory retractor coxae motor neurons, spike activity in the descending DUM (desDUM) neurons increased depolarizing reflexlike responses to stimulation of leg load sensors. In these motor neurons, descending octopaminergic neurons apparently functioned as components of a positive feedback network mainly driven by load-detecting sense organs. Reflexlike responses in excitatory extensor tibiae motor neurons evoked by stimulations of a femur-tibia movement sensor either are increased or decreased or were not affected by the activity of the descending neurons, indicating different functions of desDUM neurons. The increase in motor neuron activity is often accompanied by a reflex reversal, which is characteristic for actively moving animals. Our findings indicate that some descending octopaminergic neurons can facilitate motor activity during walking and support a sensory-motor state necessary for active leg movements. NEW & NOTEWORTHY We investigated the role of descending octopaminergic neurons in the gnathal ganglion of stick insects. The neurons become active during walking, mainly triggered by input from load sensors in the legs rather than pattern-generating networks. This report provides novel evidence that octopamine released by descending neurons on stimulation of leg sense organs contributes to the modulation of leg sensory-evoked activity in a leg motor control system.

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 The Inherent Walking Direction Differs for the Prothoracic and Metathoracic Legs of Stick Insects

1985 ◽  
Vol 116 (1) ◽  
pp. 301-311 ◽  
Author(s):  
ULRICH BÄSSLER ◽  
EVA FOTH ◽  
GERHARD BREUTEL
Keyword(s):  
Positive Feedback ◽  
Stick Insect ◽  
Chordotonal Organ ◽  
Suboesophageal Ganglion ◽  
Stick Insects ◽  
Motor Neurones ◽  
Direction Of Movement ◽  
Slippery Surface

On a slippery surface the forelegs of a decapitated stick insect walk forwards and the hindlegs, backwards. Animals with only forelegs but that are otherwise intact walk forwards, whereas animals with only hindlegs walk mostly backwards. Usually when intact animals start to walk, their hindlegs exert a rearwards thrust on the substrate, but occasionally the starting forces are directed forwards. A rampwise extension of the femoral chordotonal organ in the fixed foreleg of a walking animal first excites the flexor tibiae muscle (positive feedback). Towards the end of the ramp stimulus the activity of the flexor decreases, and the extensor tibiae motor neurones become strongly active. All experiments indicated that the inherent direction of movement of the metathorax is rearwards. In intact animals there must be a coordinating pathway from the prothorax to the metathorax that, together with the suboesophageal ganglion, induces the hindlegs to walk forwards.

Processing of Sensory Input from the Femoral Chordotonal Organ by Spiking Interneurones of Stick Insects

1989 ◽  
Vol 144 (1) ◽  
pp. 81-111 ◽  
Author(s):  
ANSGAR BÜSCHGES
Keyword(s):  
Time Course ◽  
Sensory Input ◽  
Stick Insect ◽  
Chordotonal Organ ◽  
Carausius Morosus ◽  
Median Part ◽  
Stick Insects ◽  
Position Sensitivity ◽  
The Right ◽  
Stimulation Of

The femoral chordotonal organ (ChO) of the right middle leg of the inactive stick insect Carausius morosus was stimulated by applying movements having a ramp-like time course, while recordings were made from local and interganglionic interneurones in the anterior ventral median part of the ganglion. Position, velocity and acceleration of the movements were varied independently and the interneurones were categorized on the basis of their responses to the changes in these parameters. Position-sensitivity was always accompanied by responses to velocity and/or acceleration. Velocity-sensitive responses were excitatory or inhibitory and were produced by elongation or relaxation, or by both. In some cases, velocity-sensitive neurones were also affected by position and acceleration. Acceleration responses were always excitatory and were often found in neurones that showed no effects of velocity or position. It is inferred that sensory input from different receptors in the ChO is processed by single interneurones. No interneurone in the recording region was found to be directly involved in the resistance reflex of the extensor tibiae motoneurones, elicited by stimulation of the ChO.

Carotenoid Biogenesis in the Stick Insect, Carausius morosus, during a Larval Instar

1982 ◽  
Vol 37 (1-2) ◽  
pp. 13-18 ◽  
Author(s):  
Hartmut Kayser
Keyword(s):  
Larval Instar ◽  
Stick Insect ◽  
Carausius Morosus ◽  
Stick Insects ◽  
Microbial Symbionts ◽  
Β Carotene

[14C]β-Carotene was fed to juvenile stick insects, Carausius morosus, of the fifth instar. Radioactivity was incorporated into 2-hydroxy-, 2-oxo-, and 3,4-didehydro-2-oxo-carotenoids of the β,β-type. These transformations are due to the insect’s own capacity; any contribution by microbial symbionts can be ruled out. A study on the labelling kinetics clearly shows that the biogenesis of hydroxy- and oxo-carotenoids is correlated to a decrease in the carotene precursor, but only up to mid instar. Thereafter, oxidation of the carotene is very low but the transformations of its metabolites continue as before. Predominantly β,β-carotene-2,2'-diol is dehydrogenated to 3,4,3',4'-tetradehydro-β,β-carotene-2,2'-dione via two hydroxyketones. This discontinuous utilization of β-carotene could be due to a stop at mid instar either in the oxidation or in the absorption in the gut of this precursor.

scholarly journals Coupling Mechanisms Between the Contralateral Legs of a Walking Insect (Carausius Morosus)

1989 ◽  
Vol 144 (1) ◽  
pp. 199-213 ◽  
Author(s):  
H. CRUSE ◽  
A. KNAUTH
Keyword(s):  
Thin Film ◽  
Horizontal Plane ◽  
Silicone Oil ◽  
The Other ◽  
Carausius Morosus ◽  
Mechanical Coupling ◽  
Stick Insects ◽  
Coupling Mechanisms

Interactions between contralateral legs of stick insects during walking were examined in the absence of mechanical coupling between the legs by studying animals walking on a horizontal plane covered with a thin film of silicone oil. Investigations of undisturbed walks showed that contralateral coupling is weaker han ipsilateral coupling. Two types of influence were found, (i) For each pair of front, middle and rear legs, when one leg started a retraction movement, the probability for the contralateral leg to start a protraction was increased, (ii) For front- and hind-leg pairs, it was found that the probability of starting a protraction in one leg was also increased, the farther the other leg was moved backwards during retraction. Whether such influences exist between middle legs could not be determined. Both ‘excitatory’ mechanisms very much resemble those influences which have been found to exist between ipsilateral legs. However, in contrast to ipsilateral legs, the interaction between two contralateral legs was found to act in both directions.

scholarly journals Behaviour and Motor Output of Stick Insects Walking on a Slippery Surface: I. Forward Walking

1983 ◽  
Vol 105 (1) ◽  
pp. 215-229 ◽  
Author(s):  
S. EPSTEIN ◽  
D. GRAHAM
Keyword(s):  
Glass Surface ◽  
Silicone Oil ◽  
Swing Phase ◽  
Motor Output ◽  
Mechanical Coupling ◽  
Stick Insects ◽  
Weak Activity ◽  
Slippery Surface ◽  
Coordination Patterns

The walking coordination and motor output of intact adult stick insects was examined when they were supported above an oiled glass surface. The viscosity of the silicone oil was adjusted so that the animal walked with either tripod or slow-walk coordination. In the absence of mechanical coupling through the substrate, the legs typically moved at different speeds in retraction. If these differences were not too large the walks were well-coordinated in the transitions from stance to swing phase. Motor output was variable and sometimes showed periods of very weak activity in depressors and retractors. Under these conditions an individual leg moved much more slowly than its neighbours, producing 2:1 coordination patterns.

scholarly journals Task-dependent modification of leg motor neuron synaptic input underlying changes in walking direction and walking speed

2015 ◽  
Vol 114 (2) ◽  
pp. 1090-1101 ◽  
Author(s):  
Philipp Rosenbaum ◽  
Josef Schmitz ◽  
Joachim Schmidt ◽  
Ansgar Büschges
Keyword(s):  
Motor Neuron ◽  
Motor Neurons ◽  
Synaptic Input ◽  
Walking Speed ◽  
Vertical Plane ◽  
Stick Insect ◽  
Neuron Activity ◽  
Step Cycle ◽  
Synaptic Inputs ◽  
Dependent Modification

Animals modify their behavior constantly to perform adequately in their environment. In terrestrial locomotion many forms of adaptation exist. Two tasks are changes of walking direction and walking speed. We investigated these two changes in motor output in the stick insect Cuniculina impigra to see how they are brought about at the level of leg motor neurons. We used a semi-intact preparation in which we can record intracellularly from leg motor neurons during walking. In this single-leg preparation the middle leg of the animal steps in a vertical plane on a treadwheel. Stimulation of either abdomen or head reliably elicits fictive forward or backward motor activity, respectively, in the fixed and otherwise deafferented thorax-coxa joint. With a change of walking direction only thorax-coxa-joint motor neurons protractor and retractor changed their activity. The protractor switched from swing activity during forward to stance activity during backward walking, and the retractor from stance to swing. This phase switch was due to corresponding change of phasic synaptic inputs from inhibitory to excitatory and vice versa at specific phases of the step cycle. In addition to phasic synaptic input a tonic depolarization of the motor neurons was present. Analysis of changes in stepping velocity during stance showed only a significant correlation to flexor motor neuron activity, but not to that of retractor and depressor motor neurons during forward walking. These results show that different tasks in the stick insect walking system are generated by altering synaptic inputs to specific leg joint motor neurons only.

The effects of ionic lanthanum and hypertonic physiological salines on the nervous systems of larval and adult stick insects

1975 ◽  
Vol 18 (2) ◽  
pp. 271-286
Author(s):  
R.A. Leslie
Keyword(s):  
Nervous System ◽  
Diffusion Barrier ◽  
Physiological Saline ◽  
Stick Insect ◽  
Nervous Systems ◽  
Carausius Morosus ◽  
Nerve Sheath ◽  
Ionic Lanthanum ◽  
Stick Insects ◽  
Peripheral Nervous Systems

The effects of the electron-opaque tracer ionic lanthanum in various concentrations and of hyperosmotic physiological salines on the nervous system of the stick insect, Carausius morosus, have been studied. Examination of the experimentally treated tissues revealed that the diffusion barrier to the exogenous tracer was maintained in all cases in the adult central and peripheral nervous systems, but not in the hatchling. When hatchling nervous tissues were incubated in 50 mM ionic lanthanum in phyerosmotic physiological saline, the tracer readily infiltrated all the extracellular spaces between axons and glia of all components of the nervous system examined. No difference was noted in this regard between fed and unfed hatchlings, Further, in all cases examined of adults and hatchlings, lanthanum readily surrounded those neurosecretory axons which are found in the neutral lamella, or extracellular nerve sheath, of the insect. The possible meanings of these variations in hatchling and adult nervous systems and in the accessibility of different elements of the nervous system to exogenous ionic lanthanum are discussed.

scholarly journals Mechanisms of Coupling Between the Ipsilateral Legs of a Walking Insect (Carausius Morosus)

1988 ◽  
Vol 138 (1) ◽  
pp. 455-469 ◽  
Author(s):  
H. CRUSE ◽  
W. SCHWARZE
Keyword(s):  
Thin Film ◽  
Horizontal Plane ◽  
Silicone Oil ◽  
Stick Insect ◽  
Power Stroke ◽  
Carausius Morosus ◽  
Mechanical Coupling ◽  
Short Time ◽  
Coupling Mechanisms

The mechanisms by which the legs of a stick insect influence one another during walking were investigated by running the animals on a horizontal plane covered with a thin film of silicone oil to prevent mechanical coupling between the legs. Coupling between ipsilateral legs was investigated by interrupting the retraction (power stroke) of a leg for a short time and observing how the legs return to normal coordination following this disturbance. The results show that three ipsilateral coupling mechanisms exist: (a) a forwarddirected influence that inhibits the start of a protraction of the leg as long as the posterior leg is performing a protraction; (b) a forward-directed influence that excites the start of a protraction of the leg when the posterior leg starts a retraction movement; (c) a backward-directed influence that excites the start of a protraction, the influence being stronger the further the anterior leg has moved backwards during its retraction. The latter influence depends on the position but not the phase of the anterior leg.

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