scholarly journals Plasticity and proprioception in insects. II. Modes of reflex action of the locust metathoracic femoral chordotonal organ

1985 ◽  
Vol 116 (1) ◽  
pp. 463-480
Author(s):  
S. N. Zill
Keyword(s):  
Joint Angle ◽  
Chordotonal Organ ◽  
Joint Movement ◽  
Reflex Responses ◽  
Support Resistance ◽  
Extensor Motoneurones ◽  
Excitatory Responses ◽  
Simple Summation ◽  
Stimulation Of ◽  
Active Searching

Reflex responses of tibial motoneurones were examined during mechanical stimulation of the femoral chordotonal organ, a joint angle receptor of the locust hindleg. Step displacements of the main ligament of the organ, mimicking 10–15 degree changes in joint angle, produced different patterns of discharge in motoneurones (1) when the leg was resting against a support and (2) when the support was removed to induce active searching movements. Tibial motoneurones showed resistance reflex responses to oppose the apparent joint movement when the leg rested against a support. Resistance reflexes consisted of constant, short latency excitatory responses followed by discharges that varied in intensity (gain) and degree of tonic coupling. These variations were not due to simple summation with other inputs to motoneurones. Responses changed during periods of active searching movements. Tibial flexor motoneurones fired phasically in response to apparent joint movement in any direction. Tibial extensor motoneurones were generally inhibited by chordotonal inputs. These reflex changes are not simple reflex ‘reversals’, but represent more complex changes in reflex mode. Potential functions of each of these reflex modes and the need for plasticity in reflexes of the chordotonal organ are discussed.

scholarly journals Proprioceptive Reflexes Change when an Insect Assumes an Active, Learned Posture

1983 ◽  
Vol 107 (1) ◽  
pp. 385-390
Author(s):  
SASHA N. ZILL ◽  
ROBIN R. FORMAN
Keyword(s):  
Joint Angle ◽  
Chordotonal Organ ◽  
Afferent Activity ◽  
Reflex Responses ◽  
Proprioceptive Reflexes ◽  
Receptor Input

Imposed changes in activity of a joint angle receptor of the locust leg, the metathoracic femoral chordotonal organ, produce variable, phasic reflex responses in a leg extensor motoneurone in untrained animals. After training the locust to maintain a posture in extension beyond a minimum required joint angle, these reflexes are consistently tonic and excitatory. This plasticity of reflex responsiveness permits the locust to couple motoneurone firing to afferent activity when receptor input is behaviourally relevant.

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.

Modulation of ipsi- and contralateral reflex responses in unrestrained walking cats

1980 ◽  
Vol 44 (5) ◽  
pp. 1024-1037 ◽  
Author(s):  
J. Duysens ◽  
G. E. Loeb
Keyword(s):  
Emg Activity ◽  
Strict Sense ◽  
Skin Area ◽  
Step Cycle ◽  
Reflex Responses ◽  
Plantar Surface ◽  
Electrical Shocks ◽  
Excitatory Responses ◽  
Flexor Digitorum ◽  
Stimulation Of

1. The modulation of reflex responses in up to 10 simultaneously recorded hindlimb muscles was studied in unrestrained cats walking on a treadmill. Single electrical shocks of various strengths were applied to different skin areas of teh hindlimb at different times of the step cycle while the resulting EMG responses were sampled and analyzed. 2. Two excitatory response peaks (P1 and P2) at a latency of about 10 and 25 ms, respectively, were seen in all flexors examined (sartorius, semitendinosus, tibialis anterior, extensor digitorum longus). Stimulation of most skin areas was effective but responses were most easily obtained from stimuli applied to the foot or ankle. During the step cycle there was a marked modulation of the amplitudes of the responses, especially the P2 responses, which grew larger toward the end of stance when a maximum was reached, followed by a steady decline throughout swing. This pattern was very similar for various flexors, although these muscles differed considerably in their normal EMG activity pattern during walking. 3. Flexor responses were absent when the same stimuli were applied during the early stance phase. Instead, inhibition of the ongoing EMG activity was seen at a latency of 10 ms or less in all extensors examined (semimembranosus, quadriceps, soleus, gastrocnemius medialis, flexor digitorum longus). The inhibition was followed by a late excitatory peak (P3) at about 35-ms latency in all extensors except soleus. 4. Certain stimulation sites yielded exceptions to the above patterns. Stimulation of the skin area innervated by the sural nerve yielded larger and earlier MG excitatory responses as compared to stimulation of other skin areas. Activation of the plantar surface of the foot often failed to elicit P2 responses in the hip flexor sartorius, which showed inhibition instead. 5. In the hindlimb contralateral to the stimulus, excitatory responses occurred both in flexors and extensors at a latency of 20-25 ms. The pattern of modulation of these responses was similar to the ipsilateral modulation of P2 flexor and P3 extensor responses. Soleus failed to show a crossed response. 6. The data indicate that flexor and extensor responses differ both with respect to their latency and to their correlation with the ongoing EMG reactivity. It is concluded that these stimuli do not demonstrate reflex reversal in the strict sense in the normal walking cat but that there is modulation of transmission in a flexor excitatory and extensor inhibitory pathway, possibly by the flexor part of the spinal locomotor oscillator. In addition, there are some specialized flexor inhibitory and extensor excitatory pathways. The slow soleus muscle does not seem to be excited through these pathways.

Plasticity and proprioception in insects. I. Responses and cellular properties of individual receptors of the locust metathoracic femoral chordotonal organ

1985 ◽  
Vol 116 (1) ◽  
pp. 435-461 ◽  
Author(s):  
S. N. Zill
Keyword(s):  
Joint Angle ◽  
Firing Frequency ◽  
Muscle Contractions ◽  
Current Injection ◽  
Chordotonal Organ ◽  
Muscle Fibres ◽  
Joint Position ◽  
Joint Movement ◽  
Single Action ◽  
Response Characteristics

The metathoracic femoral chordotonal organ is a joint angle receptor of the locust hindleg. It consists of 45–55 bipolar sensory neurones located distally in the femur and mechanically coupled to the tibia. Responses of receptors of the organ were examined by extracellular and intracellular recording. The organ as a whole encodes the angle of the femorotibial joint but shows substantial hysteresis. Tonic activity is greatest at the extremes of joint position. The organ possesses no direct linkage to tibial muscle fibres and shows no response to resisted muscle contractions in most ranges of joint angle. However, responses to extensor muscle contractions are obtained when the tibia is held in full flexion due to specializations of the femoro-tibial joint. These responses could be of importance in signalling preparedness for a jump. Intracellular soma recordings of activity in individual receptors indicate that the organ contains two types of receptors: phasic units that respond to joint movement and tonic units that encode joint position and also show some response to movement. All units are directionally sensitive and respond only in limited ranges of joint angle. Some phasic units increase firing frequency with increasing rate of movement and thus encode joint velocity. Other phasic units fire only single action potentials and can encode only the occurrence and direction of joint movement. All tonic units increase activity in the extremes of joint position and show substantial hysteresis upon return to more median positions. Direct soma depolarization produces different responses in different types of units: phasic receptors show only transient discharges to current injection; tonic receptors exhibit sustained increases in activity that are followed by periods of inhibition of background firing upon cessation of current injection. Receptors of the chordotonal organ are separable into two major groups, based upon their response characteristics, soma location and dendritic orientation: a dorsal group of receptors contains tonic units that respond in ranges of joint flexion (joint angle 0–80 degrees) and phasic units that respond to flexion movements; a ventral group of sensilla contains tonic units active in ranges of joint extension (joint angle 80–170 degrees) and phasic receptors that respond to extension movements. The response properties of these receptors are discussed with reference to the potential functions of the chordotonal organ in the locust's behavioural repertoire.

Reflex responses evoked from cats' coccygeal ventral roots by electrical stimulation of the tail nerves

1987 ◽  
Vol 96 (1) ◽  
pp. 11-18 ◽  
Author(s):  
Margarita Martinez-Gomez ◽  
Pablo Pacheco ◽  
Bernardo Dubrovsky
Keyword(s):  
Electrical Stimulation ◽  
Reflex Responses ◽  
Ventral Roots ◽  
Stimulation Of

Connections between thoraco-coxal proprioceptive afferents and motor neurons in the locust

2000 ◽  
Vol 203 (3) ◽  
pp. 435-445
Author(s):  
M. Wildman
Keyword(s):  
Electrical Stimulation ◽  
Sensory Neurons ◽  
Motor Neurons ◽  
Chordotonal Organ ◽  
Synaptic Connections ◽  
Afferent Neurons ◽  
Postsynaptic Potentials ◽  
The Common ◽  
Proprioceptive Afferents ◽  
Stimulation Of

The position of the coxal segment of the locust hind leg relative to the thorax is monitored by a variety of proprioceptors, including three chordotonal organs and a myochordotonal organ. The sensory neurons of two of these proprioceptors, the posterior joint chordotonal organ (pjCO) and the myochordotonal organ (MCO), have axons in the purely sensory metathoracic nerve 2C (N2C). The connections made by these afferents with metathoracic motor neurons innervating thoraco-coxal and wing muscles were investigated by electrical stimulation of N2C and by matching postsynaptic potentials in motor neurons with afferent spikes in N2C. Stretch applied to the anterior rotator muscle of the coxa (M121), with which the MCO is associated, evoked sensory spikes in N2C. Some of the MCO afferent neurons make direct excitatory chemical synaptic connections with motor neurons innervating the thoraco-coxal muscles M121, M126 and M125. Parallel polysynaptic pathways via unidentified interneurons also exist between MCO afferents and these motor neurons. Connections with the common inhibitor 1 neuron and motor neurons innervating the thoraco-coxal muscles M123/4 and wing muscles M113 and M127 are polysynaptic. Afferents of the pjCO also make polysynaptic connections with motor neurons innervating thoraco-coxal and wing muscles, but no evidence for monosynaptic pathways was found.

Response of primate joint afferent neurons to mechanical stimulation of knee joint

1977 ◽  
Vol 40 (1) ◽  
pp. 1-8 ◽  
Author(s):  
P. Grigg ◽  
B. J. Greenspan
Keyword(s):  
Knee Joint ◽  
Dorsal Root ◽  
Joint Angle ◽  
Afferent Neurons ◽  
Time Constants ◽  
Joint Afferents ◽  
Stretch Receptors ◽  
Angular Displacements ◽  
Gastrocnemius Muscles ◽  
Stimulation Of

1. One hundred thirty-eight knee joint afferents from posterior articular nerve (PAN), in primates, were recorded in dorsal root filaments. Responses of afferents were studied in relation to both passive manipulations of the knee and active contractions of quadriceps, semimembranosus, and gastrocnemius muscles. 2. When the knee was passively rotated, most neurons discharged only when extreme angular displacements were achieved. Response of neurons responding to passive extensions was linearly related to the torque applied to the knee. With maintained extensions, discharge in extension neurons adapted slowly. Some of the time constants of adaptation were similar to those for simultaneously recorded torque relaxation. 3. Contractions of quadriceps, semimembranosus, or gastrocnemius muscles could activate many neurons in the absence of changes in joint angle. For quadriceps-activated neurons, rather high torques (mean = 2,450 g with cm) were required. 4. The results support the hypothesis that joint afferents function as capsullar stretch receptors, responding to those mechanical events which result in loading of the capsule.

Jaw Reflexes Evoked by Mechanical Stimulation of Teeth in Humans

1999 ◽  
Vol 81 (5) ◽  
pp. 2156-2163 ◽  
Author(s):  
J. Yang ◽  
K. S. Türker
Keyword(s):  
Mechanical Stimulation ◽  
Masseter Muscle ◽  
Response Pattern ◽  
Bite Force ◽  
Reflex Response ◽  
Incisor Tooth ◽  
Jaw Muscles ◽  
Reflex Responses ◽  
Closing Force ◽  
Stimulation Of

Jaw reflexes evoked by mechanical stimulation of teeth in humans. The reflex response of jaw muscles to mechanical stimulation of an upper incisor tooth was investigated using the surface electromyogram (SEMG) of the masseter muscle and the bite force. With a slowly rising stimulus, the reflex response obtained on the masseter SEMG showed three different patterns of reflex responses; sole excitation, sole inhibition, and inhibition followed by excitation. Simultaneously recorded bite force, however, exhibited mainly one reflex response pattern, a decrease followed by an increase in the net closing force. A rapidly rising stimulus also induced several different patterns of reflex responses in the masseter SEMG. When the simultaneously recorded bite force was analyzed, however, there was only one reflex response pattern, a decrease in the net closing force. Therefore, the reflex change in the masseter muscle is not a good representative of the net reflex response of all jaw muscles to mechanical tooth stimulation. The net response is best expressed by the averaged bite force. The averaged bite force records showed that when the stimulus force was developing rapidly, the periodontal reflex could reduce the bite force and hence protect the teeth and supporting tissues from damaging forces. It also can increase the bite force; this might help keep food between the teeth if the change in force rate is slow, especially when the initial bite force is low.

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