scholarly journals Leg Coordination in the Stick Insect Carausius Morosus: Effects of Cutting Thoracic Connectives

1989 ◽  
Vol 145 (1) ◽  
pp. 103-131 ◽  
Author(s):  
JEFFREY DEAN
Keyword(s):  
Stick Insect ◽  
Swing Phase ◽  
Extreme Position ◽  
Position Information ◽  
Behavioral Studies ◽  
Stick Insects ◽  
Leg Coordination ◽  
Segmental Ganglion ◽  
Swing Movement ◽  
Temporal And Spatial

Behavioral studies of stick insects have identified six mechanisms which coordinate leg stepping. All six are active between ipsilateral leg pairs. As a first step towards locating the neurons mediating these interactions, the present study describes the effects of cutting one of the paired thoracic connectives. After the operation the following changes in step coordination occurred. The ipsilateral leg immediately caudal to the severed connective generally showed weak stepping. In free-walking animals it often remained near its posterior extreme position and dragged along the substratum. During supported walking, rhythmic stepping was common, but the swing phase of this leg was longer and both temporal and spatial coordination were disturbed. When the leg made a pause it usually stopped in the air near the end of its swing movement. During steady walking, the operation interrupted information from the adjacent forward leg normally used to guide the end-point of the swing or to signal errors in leg placement and elicit a correctivetreading-on-tarsus reflex. It also interrupted position information affecting the start of the swing. For the leg rostral to the cut, the inhibition during the swing of the posterior leg and the excitation when the latter started its retraction were both interrupted. These results indicate that all six ipsilateral coordination mechanisms are primarily mediated by the ipsilateral connective. In addition, the data show that contralateral coordination within the segmental ganglion is strongest for the front legs, weaker for the rear legs, and not discernible for the middle legs.

scholarly journals Stick Insect Locomotion on a Wheel: Patterns Of Stopping And Starting

1984 ◽  
Vol 110 (1) ◽  
pp. 203-216
Author(s):  
JEFFREY DEAN ◽  
GERNOT WENDLER
Keyword(s):  
Gait Cycle ◽  
Static Stability ◽  
Stick Insect ◽  
Insect Locomotion ◽  
Stick Insects ◽  
Leg Coordination ◽  
Left Right Asymmetry ◽  
Coordination Patterns ◽  
The Relationship ◽  
Leg Position

The relationship between standing and steady walking was investigated for stick insects walking on a wheel. Normal hexapod coordination patterns ensure that each point in the gait cycle has static stability. Nevertheless, stick insects show preferred stopping sequences: the final protraction in ipsilateral metachronal sequences is most often by a front leg and least often by a rear leg (Fig. 1, Table 1). The associated preferred stance is one in which front, middle, and rear legs are spread apart (Fig. 2). This preferred stance does not conform precisely to those of steady walking, necessitating small adjustments to the walk in the final steps. First, the final leg protraction often occurs in the absence of strong retraction by the supporting legs. Second, the insect often takes advantage of the left/right asymmetry, letting rear and middle legs on the leading side retract beyond their normal endpoints while completing the metachronal sequence on the trailing side. Walking typically resumes with an initial retraction by all legs. Stances are close enough to leg configurations of steady walking that metachronal rhythms are often continuous across pauses, a feature which suggests that leg coordination is affected by peripheral parameters, such as leg position.

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 Peripheral Influences on the Movement of the Legs in a Walking Insect Carausius Morosus

1982 ◽  
Vol 101 (1) ◽  
pp. 161-170 ◽  
Author(s):  
H. CRUSE ◽  
S. EPSTEIN
Keyword(s):  
Glass Plate ◽  
The Other ◽  
Extreme Position ◽  
Carausius Morosus ◽  
Stick Insects

Anterior extreme position (AEP) and posterior extreme position (PEP)of the legs of stick insects were measured during walking on a tread wheelor on a slippery glass plate. In several experiments, either protraction or retraction of a middle or hind leg was interrupted. The AEP of ot her legs was independent of a protraction interruption but PEP was displaced backward in the leg anterior to the interrupted leg. When a leg was standing on a fixed platform (interruption of retraction) no changes were found in AEP and PEP for the other legs but if the platform was slowly moved, PEP of leg on the platform was moved forward. These results disagree with several publishedhypotheses. The results suggest the hypothesis of a position-dependentthreshold value for protraction which is modulated by co-ordinating influencesfrom other legs. Note:

Pathological and Microbiological Study of Mortality in a Captive Breeding Colony of the Endangered Lord Howe Island Stick Insect (Dryococelus australis)

2018 ◽  
Vol 55 (5) ◽  
pp. 719-730
Author(s):  
Christine Bayley ◽  
Christina Cheng ◽  
Michael Lynch
Keyword(s):  
Captive Breeding ◽  
Positive Culture ◽  
Opportunistic Pathogen ◽  
Stick Insect ◽  
Innate Immune ◽  
Breeding Colony ◽  
Lord Howe Island ◽  
Stick Insects ◽  
Gross Lesions ◽  
Increased Susceptibility

The authors describe pathological and microbiological features of mortalities in a captive breeding colony of Lord Howe Island stick insects ( Dryococelus australis) over a period of 18 months. There were 2 peaks of mortality in this period. In the first, insects presented dead with minimal premonitory signs of illness. In the second, affected insects were ataxic with contracted limbs and inability to climb or right themselves. Gross lesions were uncommon but included pigmented plaques on the gut and cloacal prolapse. Histological lesions in both outbreaks indicated a cellular innate immune response including nodulation characterized by Gram-negative bacterial bacilli entrapped within nodules of pigmented hemocytes, and melanization characterized by melanin within hemocyte nodules and around bacteria. Hemolymph culture findings varied and often yielded a mixed growth. Pure growth of Serratia marcescens was cultured in 44% of animals in Outbreak 1, while pure growth of Pseudomonas aeruginosa was cultured in 30% of animals in Outbreak 2. Cases with S. marcescens-positive culture often showed inflammation at the foregut-midgut junction. The frequency of mixed bacterial culture results did not allow firm conclusions about causality to be made, and may indicate primary bacterial infection or increased susceptibility to hemolymph colonization with an opportunistic pathogen. These findings highlight the utility of histopathology combined with ancillary testing when investigating mortality in captive insect colonies.

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.

Intersegmental and local interneurons in the metathorax of the stick insect Carausius morosus that monitor middle leg position

1994 ◽  
Vol 72 (3) ◽  
pp. 1208-1219 ◽  
Author(s):  
D. E. Brunn ◽  
J. Dean
Keyword(s):  
Longitudinal Direction ◽  
Stick Insect ◽  
Proprioceptive Information ◽  
Joint Angles ◽  
Local Interneuron ◽  
Starting Position ◽  
Metathoracic Ganglion ◽  
Adequate Stimulus ◽  
Swing Movement ◽  
Made In

1. In the stick insect, proprioceptive information from the middle leg is used to define the target for the swing movement of the adjacent rear leg ("targeting behavior"). To investigate the underlying neural circuits, intracellular recordings were made in the ganglion controlling the rear leg, the metathoracic ganglion, while systematically moving the tarsus of the middle leg. 2. Several intersegmental interneurons and one local interneuron were identified as possible contributors to the targeting behavior. The intersegmental interneurons code the position of the middle leg tarsus in a highly simplified manner: test movements of the middle leg in the dorsal, lateral, and caudal directions from the standard starting position at right angles to the thorax elicit phasic-tonic responses in three different intersegmental neurons. The response in each interneuron actually reflects the movement and position at only one joint of the middle leg: for the neurons responding primarily to movement in the caudal, dorsal, and lateral test directions, the adequate stimulus is movement at the subcoxal joint, the coxa-trochanter joint, and the femur-tibia joint, respectively. 3. The metathoracic local interneuron integrates information from ipsilateral middle and rear legs in such a way as to provide an approximate measure of the distance between the two tarsi in the longitudinal direction. It is depolarized in a phasic-tonic manner both by caudal movements of the ipsilateral middle leg and by rostral movements of the ipsilateral rear leg. The adequate stimulus in each case is the change in the angle at the subcoxal joint of the leg moved. Depolarization of this neuron activates retractor motoneurons, which is consistent with a role in terminating the swing movement. 4. Altogether the results indicate first, that the targeting behavior could be controlled by very few intersegmental channels and, second, that the nervous system encodes the position of the middle leg tarsus in terms of joint angles rather than in abstract, body-centered coordinates.

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.

Signals From Load Sensors Underlie Interjoint Coordination During Stepping Movements of the Stick Insect Leg

2004 ◽  
Vol 92 (1) ◽  
pp. 42-51 ◽  
Author(s):  
Turgay Akay ◽  
Sebastian Haehn ◽  
Josef Schmitz ◽  
Ansgar Büschges
Keyword(s):  
Stick Insect ◽  
Swing Phase ◽  
Campaniform Sensilla ◽  
Locomotor System ◽  
Interjoint Coordination ◽  
Stepping Pattern ◽  
Tightly Coupled ◽  
Motoneuron Activity ◽  
Walking Stick ◽  
Stimulation Of

During stance and swing phase of a walking stick insect, the retractor coxae (RetCx) and protractor coxae (ProCx) motoneurons and muscles supplying the thorax-coxa (TC)-joint generate backward and forward movements of the leg. Their activity is tightly coupled to the movement of the more distal leg segments, i.e., femur, tibia, and tarsus. We used the single middle leg preparation to study how this coupling is generated. With only the distal leg segments of the middle leg being free to move, motoneuronal activity of the de-afferented and -efferented TC-joint is similarly coupled to leg stepping. RetCx motoneurons are active during stance and ProCx motoneurons during swing. We studied whether sensory signals are involved in this coordination of TC-joint motoneuronal activity. Ablation of the load measuring campaniform sensilla (CS) revealed that they substantially contribute to the coupling of TC-joint motoneuronal activity to leg stepping. Individually ablating trochanteral and femoral CS revealed the trochanteral CS to be necessary for establishing the coupling between leg stepping and coxal motoneuron activity. When the locomotor system was active and generated alternating bursts of activity in ProCx and RetCx motoneurons, stimulation of the CS by rearward bending of the femur in otherwise de-afferented mesothoracic ganglion terminated ongoing ProCx motoneuronal activity and initiated RetCx motoneuronal activity. We show that cuticular strain signals from the trochanteral CS play a major role in shaping TC-joint motoneuronal activity during walking and contribute to their coordination with the stepping pattern of the distal leg joints. We present a model for the sensory control of timing of motoneuronal activity in walking movements of the single middle leg.

scholarly journals Distance and Size Discrimination in a Water Stick Insect, ranatra linearis (Heteroptera)

1986 ◽  
Vol 120 (1) ◽  
pp. 59-77
Author(s):  
ANN CLOAREC
Keyword(s):  
Prey Capture ◽  
Stick Insect ◽  
Normal Adult ◽  
Central Position ◽  
Size Discrimination ◽  
Stick Insects ◽  
Distance Position ◽  
Prey Items

The role of vision in distance, position and size discrimination in prey capture has been investigated in normal adult water stick insects (Ranatra linearis L.: Heteroptera) and in ones with one eye covered. Both monocular and intact Ranatra were able to discriminate between two targets subtending the same angle but presented at different distances. They usually chose the target nearer to their foreleg claws. Although monocular subjects undershot more often than controls, they could still estimate distance correctly. When presented with two different-sized targets at the same distance, both monocular and intact subjects usually preferred the larger target within a 1°-10° range, even though monocular animals chose the larger object less consistently. They were able to distinguish between two targets differing in size by only 1°. Asymmetrical presentations of two identical targets stressed the importance of the central position. Intact animals always preferred the target nearer their midline. These data also revealed the unexpected ability of Ranatra to strike accurately at two targets or prey items simultaneously. When two identical targets were presented simultaneously and symmetrically, aims were directed at both targets, and one was grasped by each raptorial foreleg, thus indicating an absence of confusion.

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