The Activity of Single Motor Fibres in Arthropods I. The Dragonfly Nymph

1965 ◽  
Vol 42 (3) ◽  
pp. 447-461
Author(s):  
ANN KNIGHTS
Keyword(s):  
Electrical Stimulation ◽  
Temporal Summation ◽  
Reciprocal Relationship ◽  
Response Patterns ◽  
Insect Muscle ◽  
Frequency Sensitivity ◽  
Single Motor ◽  
Dragonfly Nymph ◽  
Central Inhibition ◽  
Stimulation Of

1. Responses to mechanical and electrical stimulation have been investigated in single motor fibres dissected in the segmental nerves of the dragonfly nymph. 2. A large proportion of fibres possessed a background discharge which was often accelerated of inhibited on stimulation. Examples of central inhibition were common. 3. Efferent responses varied in type, delay and regularity, both with the input under stimulation and with the frequency and intensity of the volley. The majority of fibres responded to stimulation of more than one nerve root. 4. In many motor fibres changes in the parameters of stimulation demonstrated a reciprocal relationship between and frequency. An enhanced responsiveness occurred with frequency increases in the range of 10-100/sec. indicatind a considerable importance of temporal summation/facilitation. 5. The characteristic frequency-sensitivity of motor fibres and the variability of their response patterns are discussed in relation to the control of insect muscle.

scholarly journals Propofol Suppresses Synaptic Responsiveness of Somatosensory Relay Neurons to Excitatory Input by Potentiating GABAA Receptor Chloride Channels

2005 ◽  
Vol 1 ◽  
pp. 1744-8069-1-2 ◽  
Author(s):  
Shui-Wang Ying ◽  
Peter A Goldstein
Keyword(s):  
Electrical Stimulation ◽  
Chloride Channel ◽  
Temporal Summation ◽  
Brain Slices ◽  
Excitatory Input ◽  
Dependent Manner ◽  
Sensory Stimuli ◽  
Shunting Inhibition ◽  
Stimulation Of ◽  
Relay Neurons

Propofol is a widely used intravenous general anesthetic. Propofol-induced unconsciousness in humans is associated with inhibition of thalamic activity evoked by somatosensory stimuli. However, the cellular mechanisms underlying the effects of propofol in thalamic circuits are largely unknown. We investigated the influence of propofol on synaptic responsiveness of thalamocortical relay neurons in the ventrobasal complex (VB) to excitatory input in mouse brain slices, using both current- and voltage-clamp recording techniques. Excitatory responses including EPSP temporal summation and action potential firing were evoked in VB neurons by electrical stimulation of corticothalamic fibers or pharmacological activation of glutamate receptors. Propofol (0.6 – 3 μM) suppressed temporal summation and spike firing in a concentration-dependent manner. The thalamocortical suppression was accompanied by a marked decrease in both EPSP amplitude and input resistance, indicating that a shunting mechanism was involved. The propofol-mediated thalamocortical suppression could be blocked by a GABAA receptor antagonist or chloride channel blocker, suggesting that postsynaptic GABAA receptors in VB neurons were involved in the shunting inhibition. GABAA receptor-mediated inhibitory postsynaptic currents (IPSCs) were evoked in VB neurons by electrical stimulation of the reticular thalamic nucleus. Propofol markedly increased amplitude, decay time, and charge transfer of GABAA IPSCs. The results demonstrated that shunting inhibition of thalamic somatosensory relay neurons by propofol at clinically relevant concentrations is primarily mediated through the potentiation of the GABAA receptor chloride channel-mediated conductance, and such inhibition may contribute to the impaired thalamic responses to sensory stimuli seen during propofol-induced anesthesia.

scholarly journals A Movement Generated in the Peripheral Nervous System: Rhythmic Flexion by Autotomized Legs of the Stick Insect Cuniculina Impigra

1984 ◽  
Vol 111 (1) ◽  
pp. 191-199
Author(s):  
U. BÄSSLER
Keyword(s):  
Nervous System ◽  
Electrical Stimulation ◽  
Peripheral Nervous System ◽  
Related Species ◽  
Action Potentials ◽  
Small Diameter ◽  
Stick Insect ◽  
Muscle Twitch ◽  
Single Motor ◽  
Stimulation Of

Autotomized legs of the stick insect Cuniculina impigra bend rapidly and rhythmically at the femur-tibia joint. These flexions occur at a frequency 1–6 Hz immediately after autotomy and decrease in frequency and amplitude with time. Each flexion is produced by a burst of 1–14 action potentials in a single motor axon of the flexor tibiae muscle (bursting axon). These rhythmic discharges are generated in a very restricted part of the crural nerve, which contains the bursting axon, close to the autotomy point and appear whenever the nerve is cut in the immediate vicinity of this generator region. Rhythmic flexion can also be elicited by electrical stimulation of the crural nerve. The bursting axon is of small diameter. It innervates all or most of flexor tibiae muscle in which it produces relatively large EPSPs. Each EPSP elicits one muscle twitch. These fuse into a brief tetanus, whose amplitude is proportional to the number of spikes in a burst. Each tetanus produces one flexion. This behaviour does not occur in the autotomized legs of several related species.

Epidural Epinephrine and Clonidine 

1997 ◽  
Vol 87 (4) ◽  
pp. 785-794 ◽  
Author(s):  
Michele Curatolo ◽  
Steen Petersen-Felix ◽  
Lars Arendt-Nielsen ◽  
Alex M. Zbinden
Keyword(s):  
Electrical Stimulation ◽  
Sural Nerve ◽  
Temporal Summation ◽  
Pain Tolerance ◽  
Pain Rating ◽  
Double Blind ◽  
Pressure Pain ◽  
Different Types ◽  
Painful Area ◽  
Stimulation Of

Background It is not known whether epidural epinephrine has an analgesic effect per se. The segmental distribution of clonidine epidural analgesia and its effects on temporal summation and different types of noxious stimuli are unknown. The aim of this study was to clarify these issues. Methods Fifteen healthy volunteers received epidurally (L2-L3 or L3-L4) 20 ml of either epinephrine, 100 microg, in saline; clonidine, 8 microg/kg, in saline; or saline, 0.9%, alone, on three different days in a randomized, double-blind, cross-over fashion. Pain rating after electrical stimulation, pinprick, and cold perception were recorded on the dermatomes S1, L4, L1, T9, T6, T1, and forehead. Pressure pain tolerance threshold was recorded at S1, T6, and ear. Pain thresholds to single and repeated (temporal summation) electrical stimulation of the sural nerve were determined. Results Epinephrine significantly reduced sensitivity to pinprick at L1-L4-S1. Clonidine significantly decreased pain rating after electrical stimulation at L1-L4 and sensitivity to pinprick and cold at L1-L4-S1, increased pressure pain tolerance threshold at S1, and increased thresholds after single and repeated stimulation of the sural nerve. Conclusions Epidural epinephrine and clonidine produce segmental hypoalgesia. Clonidine bolus should be administered at a spinal level corresponding to the painful area. Clonidine inhibits temporal summation elicited by repeated electrical stimulation and may therefore attenuate spinal cord hyperexcitability.

scholarly journals Comparison of fMRI BOLD Response Patterns by Electrical Stimulation of the Ventroposterior Complex and Medial Thalamus of the Rat

PLoS ONE ◽  
2013 ◽  
Vol 8 (6) ◽  
pp. e66821 ◽  
Author(s):  
Pai-Feng Yang ◽  
You-Yin Chen ◽  
Der-Yow Chen ◽  
James W. Hu ◽  
Jyh-Horng Chen ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Response Patterns ◽  
Bold Response ◽  
Medial Thalamus ◽  
Stimulation Of

Monosynaptic and oligosynaptic contributions to human ankle jerk and H-reflex

1984 ◽  
Vol 52 (3) ◽  
pp. 435-448 ◽  
Author(s):  
D. Burke ◽  
S. C. Gandevia ◽  
B. McKeon
Keyword(s):  
Electrical Stimulation ◽  
Rise Time ◽  
Tibial Nerve ◽  
Motor Units ◽  
H Reflex ◽  
Single Motor ◽  
Motoneuron Pool ◽  
Single Motor Units ◽  
Tendon Jerk ◽  
Stimulation Of

Studies were undertaken in normal subjects to determine whether it is possible for oligosynaptic reflex pathways to affect motoneuron discharge in the ankle jerk and H-reflex of the soleus. It is argued that if the rising phase of the increase in excitability of the soleus motoneuron pool produced by tendon percussion or by electrical stimulation of the peripheral nerve lasts more than a few milliseconds and if the increase in excitability takes several milliseconds to reach the threshold for motoneuron discharge, these reflexes are unlikely to be exclusively monosynaptic. In relaxed subjects, changes in excitability of the soleus motoneuron pool produced by tendon percussion and by electrical stimulation of the tibial nerve were examined using conditioning stimuli just below threshold and a test H-reflex just above threshold for a reflex response. The increase in excitability due to tendon percussion had an average rise time of 10.8 ms and a total duration of approximately 25 ms. With electrical stimulation the rising phase appeared shorter, but it could not be measured accurately due to afferent refractoriness. In single motor units, the rise times of the composite excitatory postsynaptic potentials (EPSPs) set up by subthreshold tendon percussion and by subthreshold electrical stimulation of the tibial nerve were estimated from changes in the probability of discharge of voluntarily activated single motor units. Rise times were significantly longer with tendon percussion (mean +/- SD, 7.1 +/- 2.3 ms; n = 34) than with electrical stimulation (2.4 +/- 1.4 ms; n = 32). In four experiments in which a number of motor units were studied using identical mechanical and identical electrical stimuli, the poststimulus time histograms (PSTHs) for each stimulus were pooled to provide an estimate of the rise time of the excitability change in the motoneuron pool. The mean rise times of these four samples were 10.5 ms with mechanical stimulation and 4.5 ms with electrical stimulation. The spontaneous variability in latency of reflexly activated single motor units was 0.8-3.1 ms (average SD, 0.34 ms) in the tendon jerk, and 0.6-1.4 ms (average SD, 0.19 ms) in the H-reflex. Comparison of these figures with the measurements of rise time given above suggests that the composite EPSPs are larger than the background synaptic noise. With six motor units, the timing of reflex discharge in the tendon jerk when the subject was relaxed was compared with the timing of the change in probability of discharge due to apparently identical percussion when the units were activated voluntarily.(ABSTRACT TRUNCATED AT 400 WORDS)

Transmission Through the Last Abdominal Ganglion of the Dragonfly Nymph, Anax Imperator

1960 ◽  
Vol 37 (4) ◽  
pp. 832-844
Author(s):  
ANN FIELDEN
Keyword(s):  
Spinal Cord ◽  
Motor Neurons ◽  
Temporal Summation ◽  
Ventral Nerve Cord ◽  
Abdominal Ganglion ◽  
Insect Nervous System ◽  
Dragonfly Nymph ◽  
Thoracic And Abdominal ◽  
The Relationship ◽  
Stimulation Of

1. In the last abdominal ganglion of the dragonfly nymph afferent fibres from tactile endings on the paraprocts synapse with large ascending fibres in the ventral nerve cord. The latter run the length of the cord and synapse with efferent fibres in the segmental nerves of the thoracic and abdominal ganglia. The evasion response is mediated by this pathway and can be elicited by electrical stimulation of the nerves from the paraprocts. 2. The synapses between tactile afferents and ascending fibres show delays of 2.0-4.5 msec. and transmit synchronously to frequencies of 50-60/sec. There is no evidence for facilitation at these synapses, but facilitation and/or temporal summation is of importance at the efferent synapses which appear more labile in their properties. 3. Stimulation of the paraproct nerves shows the existence of a reflex connexion between afferents and efferents of the same nerve comparable to that of the vertebrate spinal cord. This provides a preparation for a study of the relationship between sensory and motor neurons in the insect nervous system. 4. Transmission through the last abdominal ganglion and cord is compared with that in the cockroach and locust.

Properties of Interneurones in the Abdominal Nerve Cord of a Dragonfly Nymph

1963 ◽  
Vol 40 (3) ◽  
pp. 541-552
Author(s):  
ANN FIELDEN
Keyword(s):  
Electrical Stimulation ◽  
Nerve Cord ◽  
Afferent Pathway ◽  
Spinal Interneurones ◽  
Dragonfly Nymph ◽  
Afferent Volley ◽  
Frequency Of Stimulation ◽  
Stimulation Of

1. Responses of single interneurones in the abdominal connectives of the dragonfly nymph following electrical stimulation of the segmental nerves were investigated. 2. Excitation and inhibition were seen in fibres with a resting discharge. Repetitive trains of impulses, varying between units and with the source of the afferent volley, were common. 3. Changes in the intensity and frequency of stimulation affected the pattern of the repetitive responses. An increase in the intensity of the volley shortened the latency and increased the length of the train, while an increase in rate reduced the number of impulses. 4. Most interneurones responded to stimulation of more than one afferent pathway. Multisegmental fibres and multiple connexions of fibres were common. 5. These responses are compared with those of spinal interneurones and discussed in relation to their function in the animal.

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