The femur-tibia control system of stick insects — a model system for the study of the neural basis of joint control

Bässler, Ulrich

doi:10.1016/0165-0173(93)90002-h

Cited by 135 publications

(92 citation statements)

References 45 publications

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“…In fact, the femur-tibia joint control system (f-t loop) of the middle leg was chosen as the 'experimental platform' since its elements have been studied in particular detail (locust data in Burrows, 1996; stick insect data in Ebner and Bässler, 1978;Bässler, 1993) and lend themselves to the analysis of limb motor control in general.…”

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confidence: 99%

The insecticide pymetrozine selectively affects chordotonal mechanoreceptors

Ausborn

Wolf

Mader

et al. 2005

Journal of Experimental Biology

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Pymetrozine is a neuroactive insecticide but its site of action in the nervous system is unknown. Based on previous studies of symptoms in the locust, the feedback loop controlling the femur-tibia joint of the middle leg was chosen to examine possible targets of the insecticide. The femoral chordotonal organ, which monitors joint position and movement, turned out to be the primary site of pymetrozine action, while interneurons, motoneurons and central motor control circuitry in general did not noticeably respond to the insecticide. The chordotonal organs associated with the wing hinge stretch receptor and the tegula were influenced by pymetrozine in the same way as the femoral chordotonal organ, indicating that the insecticide affects chordotonal sensillae in general.Pymetrozine at concentrations down to 10 -8 ·mol·l -1 resulted in the loss of stimulus-related responses and either elicited (temporary) tonic discharges or eliminated spike activity altogether. Remarkably, pymetrozine affected the chordotonal organs in an all-or-none fashion, in agreement with previous independent studies. Other examined sense organs did not respond to pymetrozine, namely campaniform sensillae on the tibia and the subcosta vein, hair sensillae of the tegula (type I sensillae), and the wing hinge stretch receptor (type II sensillae).

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confidence: 99%

The insecticide pymetrozine selectively affects chordotonal mechanoreceptors

Ausborn

Wolf

Mader

et al. 2005

Journal of Experimental Biology

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“…The rate of SETi activity declined by approximately 50% after 10 s of stimulation, and FETi activity decreased to almost zero after only 5 s of stimulation. The difference in response of the tibial motoneurons over time is typical for reflex activation of fast and slow motoneurons in the insect-leg control system (Bässler 1993;Burrows 1996), where fast motor neurons are usually activated transiently. When the response of the system to a ramp-andhold stimulus was tested after the random stimulation of the fCO, a very large decrease in the stimulus evoked response was observed.…”

Section: R E S U L T Smentioning

confidence: 99%

“…In insects, detailed knowledge has been gathered about the structure of the underlying neuronal networks and the role of sensory signals from leg proprioceptors to the CNS in locomotor control (Bässler and Büschges 1998;Burrows 1996). Sensory signals participate in regulating the magnitude and time course of motor activity as well as in controlling phase transitions in locomotor programs (Bässler 1993;Büschges and El Manira 1998;Pearson 1995Pearson , 2000. Sensorimotor processing is highly flexible and depends on the state of the locomotor system as well as on the history of stimulation during repetitive movements.…”

Section: Fco Afferent Adaptation and The Ft-control Networkmentioning

confidence: 99%

“…For example, signals from the fCO mediate reflexes regulating position and movements of the FT joint during standing and voluntary movements (Büschges et al 2000). These reflexes are highly flexible and are adapted to suit the actual behavioral state, thereby exhibiting significant changes in gain or even a reversal in sign (for review, see Bässler 1993;Bässler and Büschges 1998). On the basis of this extensive knowledge of the role of specific fCO signals and their subsequent processing, fCO afferents are well suited for investigating the significance of adaptation in a sense organ contributing to motor control.…”

Section: Introductionmentioning

confidence: 99%

“…The sensory neurons of the fCO encode signals relating to movement and position of the tibia at the femur-tibia (FT) joint (Bässler 1967(Bässler , 1993; for a comprehensive review of insect chordotonal organs see Field and Matheson 1998). Sensory signals from the fCO are utilized for controlling posture and movement of the tibia during standing and voluntary movements, such as walking (Bässler 1974(Bässler , 1988Field and Burrows 1982;Zill 1985;summary in Bässler and Büschges 1998).…”

Section: Introductionmentioning

confidence: 99%

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Activity-Dependent Sensitivity of Proprioceptive Sensory Neurons in the Stick Insect Femoral Chordotonal Organ

DiCaprio

Wolf

Büschges

2002

Journal of Neurophysiology

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schges. Activitydependent sensitivity of proprioceptive sensory neurons in the stick insect femoral chordotonal organ. J Neurophysiol 88: 2387-2398, 2002; 10.1152/jn.00339.2002. Mechanosensory neurons exhibit a wide range of dynamic changes in response, including rapid and slow adaptation. In addition to mechanical factors, electrical processes may also contribute to sensory adaptation. We have investigated adaptation of afferent neurons in the stick insect femoral chordotonal organ (fCO). The fCO contains sensory neurons that respond to position, velocity, and acceleration of the tibia. We describe the influence of random mechanical stimulation of the fCO on the response of fCO afferent neurons. The activity of individual sensory neurons was recorded intracellularly from their axons in the main leg nerve. Most fCO afferents (93%) exhibited a marked decrease in response to trapezoidal stimuli following sustained white noise stimulation (bandwidth ϭ 60 Hz, amplitudes from Ϯ5 to Ϯ30°). Concurrent decreases in the synaptic drive to leg motoneurons and interneurons were also observed. Electrical stimulation of spike activity in individual fCO afferents in the absence of mechanical stimulation also led to a dramatic decrease in response in 15 of 19 afferents tested. This indicated that electrical processes are involved in the regulation of the generator potential or encoding of action potentials and partially responsible for the decreased response of the afferents. Replacing Ca 2ϩ with Ba 2ϩ in the saline surrounding the fCO greatly reduced or blocked the decrease in response elicited by electrically induced activity or mechanical stimulation when compared with control responses. Our results indicate that activity of fCO sensory neurons strongly affects their sensitivity, most likely via Ca 2ϩ -dependent processes.

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