Control of reflex reversal in stick insect walking: effects of intersegmental signals, changes in direction, and optomotor-induced turning

2012 ◽  
Vol 107 (1) ◽  
pp. 239-249 ◽  
Author(s):  
Katja Hellekes ◽  
Eric Blincow ◽  
Julia Hoffmann ◽  
Ansgar Büschges
Keyword(s):  
Nervous System ◽  
Sensory Feedback ◽  
Stick Insect ◽  
Chordotonal Organ ◽  
Sense Organs ◽  
Carausius Morosus ◽  
Output Change ◽  
Reflex Reversal ◽  
Leg Movement ◽  
First Time

In many animals, the effects of sensory feedback on motor output change during locomotion. These changes can occur as reflex reversals in which sense organs that activate muscles to counter perturbations in posture control instead reinforce movements in walking. The mechanisms underlying these changes are only partially understood. As such, it is unclear whether reflex reversals are modulated when locomotion is adapted, such as during changes in walking direction or in turning movements. We investigated these questions in the stick insect Carausius morosus, where sensory signals from the femoral chordotonal organ are known to produce resistance reflexes at rest but assistive movements during walking. We studied how intersegmental signals from neighboring legs affect the generation of reflex reversals in a semi-intact preparation that allows free leg movement during walking. We found that reflex reversal was enhanced by stepping activity of the ipsilateral neighboring rostral leg, whereas stepping of contralateral legs had no effect. Furthermore, we found that the occurrence of reflex reversals was task-specific: in the front legs of animals with five legs walking, reflex reversal was generated only during forward and not backward walking. Similarly, during optomotor-induced curved walking, reflex reversal occurred only in the middle leg on the inside of the turn and not in the contralateral leg on the outside of the turn. Thus our results show for the first time that the nervous system modulates reflexes in individual legs in the adaptation of walking to specific tasks.

Sensory Control and Organization of Neural Networks Mediating Coordination of Multisegmental Organs for Locomotion

2005 ◽  
Vol 93 (3) ◽  
pp. 1127-1135 ◽  
Author(s):  
Ansgar Büschges
Keyword(s):  
Neural Networks ◽  
Nervous System ◽  
Sensory Neurons ◽  
Sensory Feedback ◽  
Stick Insect ◽  
Sensory Control ◽  
Recent Advances ◽  
New Findings ◽  
Local Feedback ◽  
Locomotor Patterns

It is well established that locomotor patterns result from the interaction between central pattern generating networks in the nervous system, local feedback from sensory neurons about movements and forces generated in the locomotor organs, and coordinating signals from neighboring segments or appendages. This review addresses the issue of how the movements of multi-segmented locomotor organs are coordinated and provides an overview of recent advances in understanding sensory control and the internal organization of central pattern generating networks that operate multi-segmented locomotor organs, such as a walking leg. Findings from the stick insect and the cat are compared and discussed in relation to new findings on the lamprey swimming network. These findings support the notion that common schemes of sensory feedback are used for generating walking and that central neural networks controlling multi-segmented locomotor organs generally encompass multiple central pattern generating networks that correspond with the segmental structure of the locomotor organ.

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.

Multimodal Convergence of Presynaptic Afferent Inhibition in Insect Proprioceptors

1999 ◽  
Vol 82 (1) ◽  
pp. 512-514 ◽  
Author(s):  
Wolfgang Stein ◽  
Josef Schmitz
Keyword(s):  
Presynaptic Inhibition ◽  
Sensory Information ◽  
Reversal Potential ◽  
Stick Insect ◽  
Chordotonal Organ ◽  
Primary Afferent Depolarization ◽  
Campaniform Sensilla ◽  
Sense Organs ◽  
Position Sensitive ◽  
Conductance Increase

In the leg motor system of insects, several proprioceptive sense organs provide the CNS with information about posture and movement. Within one sensory organ, presynaptic inhibition shapes the inflow of sensory information to the CNS. We show here that also different proprioceptive sense organs can exert a presynaptic inhibition on each other. The afferents of one leg proprioceptor in the stick insect, either the position-sensitive femoral chordotonal organ or the load-sensitive campaniform sensilla, receive a primary afferent depolarization (PAD) from two other leg proprioceptors, the campaniform sensilla and/or the coxal hairplate. The reversal potential of this PAD is about −59 mV, and the PAD is associated with a conductance increase. The properties of this presynaptic input support the hypothesis that this PAD acts as presynaptic inhibition. The PAD reduces the amplitude of afferent action potentials and thus likely also afferent transmitter release and synaptic efficacy. These findings imply that PAD mechanisms of arthropod proprioceptors might be as complex as in vertebrates.

The effect of sensory feedback on crayfish posture and locomotion: II. Neuromechanical simulation of closing the loop

2015 ◽  
Vol 113 (6) ◽  
pp. 1772-1783 ◽  
Author(s):  
Julien Bacqué-Cazenave ◽  
Bryce Chung ◽  
David W. Cofer ◽  
Daniel Cattaert ◽  
Donald H. Edwards
Keyword(s):  
Sensory Feedback ◽  
Feedback Loop ◽  
Motor Nerve ◽  
Proprioceptive Feedback ◽  
Chordotonal Organ ◽  
Quiescent State ◽  
Reflex Reversal ◽  
Closing The Loop ◽  
Recorded Activity

Neuromechanical simulation was used to determine whether proposed thoracic circuit mechanisms for the control of leg elevation and depression in crayfish could account for the responses of an experimental hybrid neuromechanical preparation when the proprioceptive feedback loop was open and closed. The hybrid neuromechanical preparation consisted of a computational model of the fifth crayfish leg driven in real time by the experimentally recorded activity of the levator and depressor (Lev/Dep) nerves of an in vitro preparation of the crayfish thoracic nerve cord. Up and down movements of the model leg evoked by motor nerve activity released and stretched the model coxobasal chordotonal organ (CBCO); variations in the CBCO length were used to drive identical variations in the length of the live CBCO in the in vitro preparation. CBCO afferent responses provided proprioceptive feedback to affect the thoracic motor output. Experiments performed with this hybrid neuromechanical preparation were simulated with a neuromechanical model in which a computational circuit model represented the relevant thoracic circuitry. Model simulations were able to reproduce the hybrid neuromechanical experimental results to show that proposed circuit mechanisms with sensory feedback could account for resistance reflexes displayed in the quiescent state and for reflex reversal and spontaneous Lev/Dep bursting seen in the active state.

scholarly journals Which Parameters Control the Leg Movement of a Walking Insect?: I. Velocity Control during the Stance Phase

1985 ◽  
Vol 116 (1) ◽  
pp. 343-355 ◽  
Author(s):  
H. CRUSE
Keyword(s):  
Stance Phase ◽  
Stick Insect ◽  
Experimental Results ◽  
Velocity Control ◽  
Carausius Morosus ◽  
Different Types ◽  
Leg Movement ◽  
Position Servo

In treadwheel walking, the front and middle legs of the stick insect (Carausius morosus) propel the wheel, while the hind legs exert very little force and can even decelerate the wheel. This result is compared with observations on the function of the legs in different walking situations. Several hypotheses assuming different types of position servo-mechanisms have been proposed in the literature on the control of leg movement during walking in insects. The experimental results support none of these hypotheses. Instead, they indicate that velocity rather than position is the variable controlled during the stance phase.

scholarly journals FUNCTIONAL SPECIALIZATION OF THE SCOLOPARIA OF THE FEMORAL CHORDOTONAL ORGAN IN STICK INSECTS

1992 ◽  
Vol 173 (1) ◽  
pp. 91-108 ◽  
Author(s):  
R. Kittmann ◽  
J. Schmitz
Keyword(s):  
Stick Insect ◽  
Sensory Cells ◽  
Chordotonal Organ ◽  
Functional Specialization ◽  
Control Loop ◽  
Sense Organs ◽  
Stick Insects ◽  
Extensor Motoneurones

The femoral chordotonal organ (fCO), one of the largest proprioceptive sense organs in the leg of the stick insect, is important for the control of the femur-tibia joint during standing and walking. It consists of a ventral scoloparium with about 80 sensory cells and a dorsal scoloparium with about 420 sensory cells. The present study examines the function of these scoloparia in the femur-tibia control loop. Both scoloparia were stimulated independently and the responses in the extensor tibiae motoneurones were recorded extra- and intracellularly. The ventral scoloparium, which is the smaller of the two, functions as the transducer of the femur-tibia control loop. Its sensory cells can generate the known resistance reflexes. The dorsal scoloparium serves no function in the femur-tibia control loop and its stimulation elicited no or only minor reactions in the extensor motoneurones. A comparison with other insect leg proprioceptors shows that a morphological subdivision of these organs often indicates a functional specialization.

scholarly journals Which Parameters Control the Leg Movement of a Walking Insect?: II. The Start of the Swing Phase

1985 ◽  
Vol 116 (1) ◽  
pp. 357-362 ◽  
Author(s):  
H. CRUSE
Keyword(s):  
Stance Phase ◽  
Stick Insect ◽  
Swing Phase ◽  
Feedback Mechanism ◽  
Threshold Values ◽  
Forward Movement ◽  
Carausius Morosus ◽  
Position Feedback ◽  
Leg Movement ◽  
Leg Position

When a stick insect (Carausius morosus) walks on a treadwheel with one leg standing on a platform beside the wheel, this leg can be considered to perform a prolonged stance phase. To elicit a swing phase in this situation, both load and position must decline below definite threshold values. The swing phase can be elicited when - given a sufficiently posterior leg position - a central temporal signal initiates a small forward movement, and this is followed by a decrease of load. It is possible for signals from the next posterior leg to change the position threshold at which the swing phase can be started, but these commands do not influence the force values during the stance phase. Thus position is one parameter used for the decision to end the stance phase. But it does not serve as a signal for a position feedback mechanism controlling leg movement during the stance phase.

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.

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