scholarly journals THE PHYSIOLOGY OF SENSORY CELLS IN THE VENTRAL SCOLOPARIUM OF THE STICK INSECT FEMORAL CHORDOTONAL ORGAN

1994 ◽  
Vol 189 (1) ◽  
pp. 285-292 ◽  
Author(s):  
A Büschges
Keyword(s):  
Sensory Feedback ◽  
Neural Control ◽  
Sensory Information ◽  
Stick Insect ◽  
Sensory Cells ◽  
Chordotonal Organ ◽  
Joint Movement ◽  
Control Loop ◽  
Sensory Neurones ◽  
Control Loops

The leg joints of invertebrates are governed by neural control loops that control their position and velocity during movements (for reviews, see Bassler, 1983, 1993). These neural control loops rely on sensory feedback about the position and velocity of the controlled leg joint. In invertebrates, this sensory feedback is provided by external (e.g. hair fields, hair rows) and/or internal sense organs (e.g. chordotonal organs). The femoral chordotonal organ (fCO) serves as the main proprioceptor in the control loop governing the femur-tibia (FT) joint of the insect leg. The fCO measures the position and movement of this joint (e.g. Bassler, 1965, 1993; Burns, 1974; Usherwood et al. 1968; Zill, 1985). Previous investigations have described the physiology of sensory cells within femoral chordotonal organs (e.g. stick insect, Hofmann et al. 1985; Hofmann and Koch, 1985; locust, Matheson, 1990; Matheson and Field, 1990). Numerous investigations have been undertaken into the central processing of sensory information provided by the fCO to gain an insight into the control of FT joint movement during different behavioural tasks, for example during resistance reflexes in the standing animal (locust, Burrows, 1987, 1988; Burrows et al. 1988; stick insect, Bassler, 1988; Buschges, 1989, 1990; Driesang and Buschges, 1993) or during active movements (stick insect, Bassler, 1988; Bassler and Buschges, 1990). Most previous studies have not, however, taken into account the morphological separation of the fCO into two distinct scoloparia in the legs of some species (stick insect, Fuller and Ernst, 1973; Hofmann et al. 1985; Hofmann and Koch, 1985; locust middle leg, Burns, 1974). It has been inferred that the whole fCO supplies position and velocity information about the FT joint. In contrast, recent studies of leg reflexes have shown that only its smaller scoloparium (Fig. 1A), containing approximately one-sixth of the total number of sensory neurones, provides the sensory information that is used by the FT control loop (locust, Field and Pfluger, 1989; stick insect, Kittmann and Schmitz, 1992). These studies did not show what types of sensory neurones are located in the ventral part of the fCO and thus contribute to the FT control loop. We have therefore investigated the physiology of sensory neurones that are located in the ventral scoloparium of the fCO.

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.

Nonspiking Pathways in a Joint-control Loop of the Stick Insect Carausius Morosus

1990 ◽  
Vol 151 (1) ◽  
pp. 133-160 ◽  
Author(s):  
ANSGAR BÜSCHGES
Keyword(s):  
Sensory Information ◽  
Stick Insect ◽  
Chordotonal Organ ◽  
Joint Control ◽  
Control Loop ◽  
Carausius Morosus ◽  
Extensor Motoneurones ◽  
Reflex Activation ◽  
Flexion And Extension ◽  
Stimulation Of

In the stick insect Carausius morosus (Phasmida) intracellular recordings were made from local nonspiking interneurones involved in the reflex activation of the extensor motoneurones of the femur-tibia joint during ramp-like stimulation of the transducer of this joint, the femoral chordotonal organ (ChO). The nonspiking interneurones in the femur-tibia control loop were characterized by their inputs from the ChO, their output properties onto the extensor motoneurones and their morphology. Eight different morphological and physiological types of nonspiking interneurones are described that are involved in the femur-tibia control loop. The results show that velocity signals from the ChO are the most important movement parameter processed by the nonspiking interneurones. Altering the membrane potential of these interneurones had marked effects on the reflex activation in the extensor motoneurones as the interneurones were able to increase or decrease the response of the participating motoneurones. The processing of information by the nonspiking pathways showed another remarkable aspect: nonspiking interneurones were found to process sensory information from the ChO onto extensor motoneurones in a way that seems not always to support the generation of the visible resistance reflexes in the extensor tibiae motoneurones in response to imposed flexion and extension movements of the joint. The present investigation demonstrated interneuronal pathways in the joint-control loop that show ‘assisting’ characteristics.

scholarly journals Intra- and intersegmental influences among central pattern generating networks in the walking system of the stick insect

2017 ◽  
Vol 118 (4) ◽  
pp. 2296-2310 ◽  
Author(s):  
Charalampos Mantziaris ◽  
Till Bockemühl ◽  
Philip Holmes ◽  
Anke Borgmann ◽  
Silvia Daun ◽  
...  
Keyword(s):  
Neural Networks ◽  
Sensory Feedback ◽  
Muscarinic Acetylcholine Receptor ◽  
Central Pattern Generators ◽  
Sensory Information ◽  
Direct Interaction ◽  
Stick Insect ◽  
Weakly Coupled ◽  
The Neural Networks ◽  
Pattern Generators

To efficiently move around, animals need to coordinate their limbs. Proper, context-dependent coupling among the neural networks underlying leg movement is necessary for generating intersegmental coordination. In the slow-walking stick insect, local sensory information is very important for shaping coordination. However, central coupling mechanisms among segmental central pattern generators (CPGs) may also contribute to this. Here, we analyzed the interactions between contralateral networks that drive the depressor trochanteris muscle of the legs in both isolated and interconnected deafferented thoracic ganglia of the stick insect on application of pilocarpine, a muscarinic acetylcholine receptor agonist. Our results show that depressor CPG activity is only weakly coupled between all segments. Intrasegmental phase relationships differ between the three isolated ganglia, and they are modified and stabilized when ganglia are interconnected. However, the coordination patterns that emerge do not resemble those observed during walking. Our findings are in line with recent studies and highlight the influence of sensory input on coordination in slowly walking insects. Finally, as a direct interaction between depressor CPG networks and contralateral motoneurons could not be observed, we hypothesize that coupling is based on interactions at the level of CPG interneurons. NEW & NOTEWORTHY Maintaining functional interleg coordination is vitally important as animals locomote through changing environments. The relative importance of central mechanisms vs. sensory feedback in this process is not well understood. We analyzed coordination among the neural networks generating leg movements in stick insect preparations lacking phasic sensory feedback. Under these conditions, the networks governing different legs were only weakly coupled. In stick insect, central connections alone are thus insufficient to produce the leg coordination observed behaviorally.

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.

scholarly journals Body side-specific control of motor activity during turning in a walking animal

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Matthias Gruhn ◽  
Philipp Rosenbaum ◽  
Till Bockemühl ◽  
Ansgar Büschges
Keyword(s):  
Sensory Feedback ◽  
Neural Control ◽  
Motor Behavior ◽  
Large Body ◽  
Motor Task ◽  
Stick Insect ◽  
Body Side ◽  
Neuronal Mechanisms ◽  
Specific Control ◽  
Environmental Demands

Animals and humans need to move deftly and flexibly to adapt to environmental demands. Despite a large body of work on the neural control of walking in invertebrates and vertebrates alike, the mechanisms underlying the motor flexibility that is needed to adjust the motor behavior remain largely unknown. Here, we investigated optomotor-induced turning and the neuronal mechanisms underlying the differences between the leg movements of the two body sides in the stick insect Carausius morosus. We present data to show that the generation of turning kinematics in an insect are the combined result of descending unilateral commands that change the leg motor output via task-specific modifications in the processing of local sensory feedback as well as modification of the activity of local central pattern generating networks in a body-side-specific way. To our knowledge, this is the first study to demonstrate the specificity of such modifications in a defined motor task.

scholarly journals Sensory Feedback During Active Movements of Stick Insects

1987 ◽  
Vol 133 (1) ◽  
pp. 137-156 ◽  
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.

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.

scholarly journals The emulation theory of representation: Motor control, imagery, and perception

2004 ◽  
Vol 27 (3) ◽  
pp. 377-396 ◽  
Author(s):  
Rick Grush
Keyword(s):  
Motor Control ◽  
Sensory Feedback ◽  
Sensory Input ◽  
Neural Circuits ◽  
Sensory Information ◽  
The Body ◽  
Feedback Delay ◽  
Run Off ◽  
Effects Of Feedback ◽  
The Brain

The emulation theory of representation is developed and explored as a framework that can revealingly synthesize a wide variety of representational functions of the brain. The framework is based on constructs from control theory (forward models) and signal processing (Kalman filters). The idea is that in addition to simply engaging with the body and environment, the brain constructs neural circuits that act as models of the body and environment. During overt sensorimotor engagement, these models are driven by efference copies in parallel with the body and environment, in order to provide expectations of the sensory feedback, and to enhance and process sensory information. These models can also be run off-line in order to produce imagery, estimate outcomes of different actions, and evaluate and develop motor plans. The framework is initially developed within the context of motor control, where it has been shown that inner models running in parallel with the body can reduce the effects of feedback delay problems. The same mechanisms can account for motor imagery as the off-line driving of the emulator via efference copies. The framework is extended to account for visual imagery as the off-line driving of an emulator of the motor-visual loop. I also show how such systems can provide for amodal spatial imagery. Perception, including visual perception, results from such models being used to form expectations of, and to interpret, sensory input. I close by briefly outlining other cognitive functions that might also be synthesized within this framework, including reasoning, theory of mind phenomena, and language.

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