Force encoding in stick insect legs delineates a reference frame for motor control

Zill, Sasha N.; Schmitz, Josef; Chaudhry, Sumaiya; Büschges, Ansgar

doi:10.1152/jn.00274.2012

Cited by 60 publications

(75 citation statements)

References 96 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…First, stick insect legs do perform stereotypic searching movements in the context of loss of ground contact when reaching a gap (Dürr, 2001), although we do not know whether the multiple stepping that we observed is related to searching. Second, afferent feedback during ground contact in probing behaviour is likely to be different from feedback during ground contact in stance phase, in which the leg supports the body or provides a propulsive force (Zill et al, 2012). Such feedback does matter for inter-leg coordination (Wendler, 1965) and may be different during irregular gaits versus regular ones.…”

Section: Discussionmentioning

confidence: 99%

Quadrupedal gaits in hexapod animals - inter-leg coordination in free-walking adult stick insects

Grabowska

Godlewska

Schmidt

et al. 2012

Journal of Experimental Biology

120

View full text Add to dashboard Cite

SUMMARYThe analysis of inter-leg coordination in insect walking is generally a study of six-legged locomotion. For decades, the stick insect Carausius morosus has been instrumental for unravelling the rules and mechanisms that control leg coordination in hexapeds. We analysed inter-leg coordination in C. morosus that freely walked on straight paths on plane surfaces with different slopes. Consecutive 1.7s sections were assigned inter-leg coordination patterns (which we call gaits) based on footfall patterns. Regular gaits, i.e. wave, tetrapod or tripod gaits, occurred in different proportions depending on surface slopes. Tetrapod gaits were observed most frequently, wave gaits only occurred on 90deg inclining slopes and tripod gaits occurred most often on 15deg declining slopes, i.e. in 40% of the sections. Depending on the slope, 36-66% of the sections were assigned irregular gaits. Irregular gaits were mostly due to multiple stepping by the front legs, which is perhaps probing behaviour, not phase coupled to the middle legsʼ cycles. In irregular gaits, middle leg and hindleg coordination was regular, related to quadrupedal walk and wave gaits. Apparently, front legs uncouple from and couple to the walking system without compromising middle leg and hindleg coordination. In front leg amputees, the remaining legs were strictly coordinated. In hindleg and middle leg amputees, the front legs continued multiple stepping. The coordination of middle leg amputees was maladapted, with front legs and hindlegs performing multiple steps or ipsilateral legs being in simultaneous swing. Thus, afferent information from middle legs might be necessary for a regular hindleg stepping pattern. Supplementary material available online at

show abstract

Section: Discussionmentioning

confidence: 99%

Quadrupedal gaits in hexapod animals - inter-leg coordination in free-walking adult stick insects

Grabowska

Godlewska

Schmidt

et al. 2012

Journal of Experimental Biology

120

View full text Add to dashboard Cite

show abstract

“…For example, campaniform sensilla on the stick insect trochanter are positioned to encode increases and decreases in mechanical load at the nearby leg joint [63]. Campaniform sensilla neurons are active when leg movements are resisted with a mechanical probe, but do not fire during unresisted leg movements, indicating that they encode mechanical load as resistance to muscle contraction [63, 64]. In this regard, the campaniform sensilla perform a function similar to that of vertebrate Golgi tendon organs [4].…”

Section: Insect Mechanoreceptorsmentioning

confidence: 99%

Mechanosensation and Adaptive Motor Control in Insects

2016

View full text Add to dashboard Cite

Summary The ability of animals to flexibly navigate through complex environments depends on the integration of sensory information with motor commands. The sensory modality most tightly linked to motor control is mechanosensation. Adaptive motor control depends critically on an animal’s ability to respond to mechanical forces generated both within and outside the body. The compact neural circuits of insects provide appealing systems to investigate how mechanical cues guide locomotion in rugged environments. Here, we review our current understanding of mechanosensation in insects and its role in adaptive motor control. We first examine the detection and encoding of mechanical forces by primary mechanoreceptor neurons. We then discuss how central circuits integrate and transform mechanosensory information to guide locomotion. Because most studies in this field have been performed in locusts, cockroaches, crickets, and stick insects, the examples we cite here are drawn mainly from these ‘big insects’. However, we also pay particular attention to the tiny fruit fly, Drosophila, where new tools are creating new opportunities, particularly for understanding central circuits. Our aim is to show how studies of big insects have yielded fundamental insights relevant to mechanosensation in all animals, and also to point out how the Drosophila toolkit can contribute to future progress in understanding mechanosensory processing.

show abstract

“…From a control perspective, on the other hand, strong and reliable changes in CTr torques may facilitate the control of stance by means of local load sensors. Indeed, strain sensors in the form of campaniform sensilla are highly concentrated near the CTr joint and are known to provide reinforcing excitatory input to the motor neurons of the depressor muscle [39]. A strong decrease in torques could cause a sudden drop in this excitatory input and terminate the stance phase in a reliable manner.…”

Section: (C) Implications Of Joint Torques For Models Of Walking Controlmentioning

confidence: 99%

Joint torques in a freely walking insect reveal distinct functions of leg joints in propulsion and posture control

2016

Self Cite

View full text Add to dashboard Cite

Determining the mechanical output of limb joints is critical for understanding the control of complex motor behaviours such as walking. In the case of insect walking, the neural infrastructure for single-joint control is well described. However, a detailed description of the motor output in form of time-varying joint torques is lacking. Here, we determine joint torques in the stick insect to identify leg joint function in the control of body height and propulsion. Torques were determined by measuring whole-body kinematics and ground reaction forces in freely walking animals. We demonstrate that despite strong differences in morphology and posture, stick insects show a functional division of joints similar to other insect model systems. Propulsion was generated by strong depression torques about the coxatrochanter joint, not by retraction or flexion/extension torques. Torques about the respective thorax-coxa and femur-tibia joints were often directed opposite to fore-aft forces and joint movements. This suggests a posturedependent mechanism that counteracts collapse of the leg under body load and directs the resultant force vector such that strong depression torques can control both body height and propulsion. Our findings parallel propulsive mechanisms described in other walking, jumping and flying insects, and challenge current control models of insect walking.

show abstract

Force encoding in stick insect legs delineates a reference frame for motor control

Cited by 60 publications

References 96 publications

Quadrupedal gaits in hexapod animals - inter-leg coordination in free-walking adult stick insects

Quadrupedal gaits in hexapod animals - inter-leg coordination in free-walking adult stick insects

Mechanosensation and Adaptive Motor Control in Insects

Joint torques in a freely walking insect reveal distinct functions of leg joints in propulsion and posture control

Contact Info

Product

Resources

About