The role of leg touchdown for the control of locomotor activity in the walking stick insect

Much is known on how select sensory feedback contributes to the activation of different motoneuron pools in the locomotor control system of stick insects. However, even though activation of the stance phase muscles depressor trochanteris, retractor unguis, flexor tibiae and retractor coxae is correlated with the touchdown of the leg, the potential sensory basis of this correlation or its connection to burst intensity remains unknown. In our experiments, we are using a trap door setup to investigate how ground contact contributes to stance phase muscle activation and burst intensity in different stick insect species, and which afferent input is involved in the respective changes. While the magnitude of activation is changed in all of the above stance phase muscles, only the timing of the flexor tibiae muscle is changed if the animal unexpectedly steps into a hole. Individual and combined ablation of different force sensors on the leg demonstrated influence from femoral campaniform sensilla on flexor muscle timing, causing a significant increase in the latencies during control and air steps. Our results show that specific load feedback signals determine the timing of flexor tibiae activation at the swing-to-stance transition in stepping stick insects, but that additional feedback may also be involved in flexor muscle activation during stick insect locomotion. With respect to timing, all other investigated stance phase muscles appear to be under sensory control other than that elicited through touchdown.

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

Journal of Experimental Biology ◽

10.1242/jeb.120.1.59 ◽

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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Force dynamics and synergist muscle activation in stick insects: the effects of using joint torques as mechanical stimuli

Journal of Neurophysiology ◽

10.1152/jn.00371.2018 ◽

2018 ◽

Vol 120 (4) ◽

pp. 1807-1823 ◽

Cited By ~ 6

Author(s):

Sasha N. Zill ◽

Chris J. Dallmann ◽

Ansgar Büschges ◽

Sumaiya Chaudhry ◽

Josef Schmitz

Keyword(s):

Muscle Activation ◽

Force Feedback ◽

Inverse Dynamics ◽

Muscle Synergies ◽

Mechanical Stimuli ◽

Flexor Muscle ◽

Joint Torques ◽

Force Dynamics ◽

Stick Insects ◽

Depressor Muscle

Many sensory systems are tuned to specific parameters of behaviors and have effects that are task-specific. We have studied how force feedback contributes to activation of synergist muscles in serially homologous legs of stick insects. Forces were applied using conventional half-sine or ramp and hold functions. We also utilized waveforms of joint torques calculated from experiments in freely walking animals. In all legs, forces applied to either the tarsus (foot) or proximal leg segment (trochanter) activated synergist muscles that generate substrate grip and support, but coupling of the depressor muscle to tarsal forces was weak in the front legs. Activation of trochanteral receptors using ramp and hold functions generated positive feedback to the depressor muscle in all legs when animals were induced to seek substrate grip. However, discharges of the synergist flexor muscle showed adaptation at moderate force levels. In contrast, application of forces using torque waveforms, which do not have a static hold phase, produced sustained discharges in muscle synergies with little adaptation. Firing frequencies reflected the magnitude of ground reaction forces, were graded to changes in force amplitude, and could also be modulated by transient force perturbations added to the waveforms. Comparison of synergist activation by torques and ramp and hold functions revealed a strong influence of force dynamics (dF/d t). These studies support the idea that force receptors can act to tune muscle synergies synchronously to the range of force magnitudes and dynamics that occur in each leg according to their specific use in behavior. NEW & NOTEWORTHY The effects of force receptors (campaniform sensilla) on leg muscles and synergies were characterized in stick insects using both ramp and hold functions and waveforms of joint torques calculated by inverse dynamics. Motor responses were sustained and showed reduced adaptation to the more “natural” and nonlinear torque stimuli. Calculation of the first derivative (dF/d t) of the torque waveforms demonstrated that this difference was correlated with the dynamic sensitivities of the system.

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Sensory Feedback During Active Movements of Stick Insects

Journal of Experimental Biology ◽

10.1242/jeb.133.1.137 ◽

1987 ◽

Vol 133 (1) ◽

pp. 137-156 ◽

Cited By ~ 2

Author(s):

G. WEILAND ◽

U. T. KOCH

Keyword(s):

Control System ◽

Stick Insect ◽

Middle Part ◽

Chordotonal Organ ◽

Voluntary Movements ◽

Joint Movement ◽

Stick Insects ◽

Velocity Changes ◽

Changing Role

In the stick insect Carausius momsus, the role of the chordotonal organ was investigated using a new experimental arrangement which artificially closes the femur-tibia control system. The chordotonal organ was stimulated during voluntary movements by applying trapezoidal ramp stimuli in the closed-loop configuration. The results demonstrate that the feedback loop is used to control the end points of joint movement. In addition, it was found that the control system counteracts experimentally applied velocity changes imposed during the middle part of the movements. Acceleration-sensitive units are shown to contribute to the reaction. The results show that during active voluntary movements reflexes measured in the inactive animal are neither simply incorporated in a servo-system nor suppressed. Instead their characteristics are altered so that the voluntary movements are executed as intended by the animal. Thus reflexes cannot be considered as a fixed behavioural unit; rather their changing role must be analysed in the context of the behaviour studied.

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The forewing tegulae: their significance in steering manoeuvres and free flight in Locusta migratoria

Canadian Journal of Zoology ◽

10.1139/z97-243 ◽

1998 ◽

Vol 76 (4) ◽

pp. 660-667 ◽

Cited By ~ 1

Author(s):

Christine E Gee ◽

Kelly L Shoemaker ◽

R Meldrum Robertson

Keyword(s):

Muscle Activation ◽

Locusta Migratoria ◽

Motor Pattern ◽

Afferent Input ◽

Open Loop ◽

Free Flight ◽

Flight System ◽

Depressor Muscle ◽

Flight Motor

The flight system of Locusta migratoria is widely used to investigate the principles of sensory-motor control. The four tegulae are proprioceptors of the flight system that are active during the downstroke and provide afferent input to flight-system neurons. While the role of the hindwing tegulae in the flight motor pattern has been well characterized, the role of the forewing tegulae is unclear. We tested whether the forewing tegulae may be more important for the generation of intentional steering manoeuvres than for generation of the basic flight motor pattern. Following ablation of the forewing tegulae, tethered flying locusts continued to generate characteristic intentional steering manoeuvres in open-loop conditions. In contrast, we found that locusts were less likely to sustain unrestrained free flight following ablation of the forewing tegulae. We also found that the number of spikes in a forewing depressor muscle increased, as did the hindwing to forewing delay in elevator-muscle activation after ablation of the forewing tegulae. We conclude that the forewing tegulae promote free flight in locusts and we discuss the role they may play in locust flight.

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Neuronal Innervation of the Subgenual Organ Complex and the Tibial Campaniform Sensilla in the Stick Insect Midleg

Insects ◽

10.3390/insects11010040 ◽

2020 ◽

Vol 11 (1) ◽

pp. 40 ◽

Cited By ~ 1

Author(s):

Johannes Strauß

Keyword(s):

Physiological Role ◽

Stick Insect ◽

Campaniform Sensilla ◽

Innervation Pattern ◽

Branching Points ◽

Stick Insects ◽

Sensory Structures ◽

Evolutionary Comparisons ◽

Subgenual Organ

Mechanosensory organs in legs play are crucial receptors in the feedback control of walking and in the detection of substrate-borne vibrations. Stick insects serve as a model for the physiological role of chordotonal organs and campaniform sensilla. This study documents, by axonal tracing, the neural innervation of the complex chordotonal organs and groups of campaniform sensilla in the proximal tibia of the midleg in Sipyloidea sipylus. In total, 6 nerve branches innervate the different sensory structures, and the innervation pattern associates different sensilla types by their position. Sensilla on the anterior and posterior tibia are innervated from distinct nerve branches. In addition, the variation in innervation is studied for five anatomical branching points. The most common variation is the innervation of the subgenual organ sensilla by two nerve branches rather than a single one. The fusion of commonly separated nerve branches also occurred. However, a common innervation pattern can be demonstrated, which is found in >75% of preparations. The variation did not include crossings of nerves between the anterior and posterior side of the leg. The study corrects the innervation of the posterior subgenual organ reported previously. The sensory neuroanatomy and innervation pattern can guide further physiological studies of mechanoreceptor organs and allow evolutionary comparisons to related insect groups.

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Faculty Opinions recommendation of How central is central poststroke pain? The role of afferent input in poststroke neuropathic pain: a prospective, open-label pilot study.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.732892352.793551838 ◽

2018 ◽

Author(s):

Marshall Devor

Keyword(s):

Neuropathic Pain ◽

Pilot Study ◽

Afferent Input ◽

Open Label

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Interruption of searching movements of partly restrained front legs of stick insects, a model situation for the start of a stance phase?

Biological Cybernetics ◽

10.1007/bf00204664 ◽

1991 ◽

Vol 65 (6) ◽

pp. 507-514 ◽

Cited By ~ 28

Author(s):

U. Bässler ◽

J. Rohrbacher ◽

G. Karg ◽

G. Breutel

Keyword(s):

Stance Phase ◽

Model Situation ◽

Stick Insects

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Ankle Muscle Activations during Different Foot-Strike Patterns in Running

Sensors ◽

10.3390/s21103422 ◽

2021 ◽

Vol 21 (10) ◽

pp. 3422

Author(s):

Jian-Zhi Lin ◽

Wen-Yu Chiu ◽

Wei-Hsun Tai ◽

Yu-Xiang Hong ◽

Chung-Yu Chen

Keyword(s):

Muscle Activity ◽

Muscle Activation ◽

Stance Phase ◽

Inertial Sensors ◽

Plantar Flexion ◽

Intraclass Correlation ◽

Biceps Femoris ◽

Ankle Muscle ◽

Foot Strike ◽

Muscle Activations

This study analysed the landing performance and muscle activity of athletes in forefoot strike (FFS) and rearfoot strike (RFS) patterns. Ten male college participants were asked to perform two foot strikes patterns, each at a running speed of 6 km/h. Three inertial sensors and five EMG sensors as well as one 24 G accelerometer were synchronised to acquire joint kinematics parameters as well as muscle activation, respectively. In both the FFS and RFS patterns, according to the intraclass correlation coefficient, excellent reliability was found for landing performance and muscle activation. Paired t tests indicated significantly higher ankle plantar flexion in the FFS pattern. Moreover, biceps femoris (BF) and gastrocnemius medialis (GM) activation increased in the pre-stance phase of the FFS compared with that of RFS. The FFS pattern had significantly decreased tibialis anterior (TA) muscle activity compared with the RFS pattern during the pre-stance phase. The results demonstrated that the ankle strategy focused on controlling the foot strike pattern. The influence of the FFS pattern on muscle activity likely indicates that an athlete can increase both BF and GM muscles activity. Altered landing strategy in cases of FFS pattern may contribute both to the running efficiency and muscle activation of the lower extremity. Therefore, neuromuscular training and education are required to enable activation in dynamic running tasks.

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